1 Introduction

In recent decades, entrepreneurship emerged as a core topic on the agendas of researchers and political leaders (Audretsch 2009; Carlsson et al. 2013; Cornelius et al. 2006; Ferreira et al. 2019). While political leaders perceived entrepreneurial activity as a source of innovation, competitiveness and economic development, researchers set about deepening what we understand about this topic and undertaking analysis across multiple levels (Acs et al. 2016a, b, 2018; Frank and Landström 2016). Hence, as a result of the multiple investigations carried out in this field, the entrepreneurship domain experiences constant evolution (Audretsch et al. 2015; Ferreira et al. 2019; Frank and Landström 2016). As identified by Ferreira et al. (2019), authors who unveiled the foundations of entrepreneurship research, the sheer diversity of research studies conducted within this scope have contributed to widening this field of research. Therefore, according to the same authors, entrepreneurship research now represents a hybrid field comprised of different perspectives and theories. Furthermore, the concept of “entrepreneurial ecosystems” (EEs), or “ecosystems of entrepreneurship”, has recently become one of the themes attracting the greatest interest in the academic community and emerging as one of the most promising research approaches within entrepreneurship research (Acs et al. 2017; Alvedalen and Boschma 2017; Colombo et al. 2019; Kang et al. 2019; Malecki 2018; Maroufkhani et al. 2018; Schäfer and Mayer 2019; Spigel 2017; Spigel and Harrison 2018; Stam 2015).

According to Spigel (2017), the EE approach incorporates characteristics drawn from diverse themes in the literature—this author highlights clusters, innovation systems, economic geography, social capital, and networks– to demonstrate why some regions can continuously foster the success of their new companies alongside high levels of high growth entrepreneurial activities. Thus, EEs, that is the “ecosystems that support entrepreneurs” (Isenberg 2010), emerge with diverse dimensions and attributes that strongly correlate. Isenberg (2011) across six dimensions—policy; finance; culture; supports; human capital; markets—with each dimension containing multiple elements. The different characteristics of these attributes and the relationships developed and ongoing among the diverse actors within each EE, result in them displaying different configurations and characteristics, rendering each particular EE unique and impossible to replicate in another region (Autio et al. 2014; Colombelli et al. 2019; Isenberg 2010, 2011; Spigel 2017). Due to the multiple attributes comprising each EE, which all display distinctive characteristics, and the diverse relationships ongoing among them, the social networks therein established are of paramount importance. According to Aarikka-Stenroos and Ritala (2017) “It is noteworthy that all ecosystems in all cases are comprised of networks; therefore, the ecosystem approach resonates well with established business network streams.” (p. 32). Several authors attest to the importance of the social networks established among the multiple actors within each EE—based on trust and cooperation developed through strongly interconnected ties—demonstrating how those impact on the function and ultimately the resilience of the EE (Motoyama and Knowlton 2017; Muldoon et al. 2018; Spigel 2017; Spigel and Harrison 2018; Stam 2015). As a consequence, social network analysis constitutes a popular and useful practice applied in EE studies (e.g. Apa et al. (2017), Motoyama and Knowlton (2017), Cowell et al. (2018) and Colombelli et al. (2019)).

Due to the sheer multiplicity of the studies carried out on the EE theme, this area, as Maroufkhani et al. (2018) state, remains thematically fragmented and lacking in contributions that articulate the multiple studies developed (Acs et al. 2017; Alvedalen and Boschma 2017; Spigel 2017; Spigel and Harrison 2018; Stam 2015). Indeed, the term “ecosystem” is often described as a “metaphor”, a “buzzword” or a “conceptual umbrella”, extensively applied but lacking in real meaning (Aarikka-Stenroos and Ritala 2017; Audretsch et al. 2019; Brown and Mawson 2019; Colombo et al. 2019; Isenberg and Onyemah 2016; Spigel 2017; Spigel and Harrison 2018). Despite the existence of some systematic reviews carried on the EE topic—as some examples, we may refer to the studies carried out by Malecki (2018), Maroufkhani et al. (2018) or Aarikka-Stenroos and Ritala (2017)—to the best of our knowledge there is no systematic literature review specifically designed to investigate the theme of entrepreneurial ecosystems and networks (EEs&Ns). According to Aarikka-Stenroos and Ritala (2017)–who systematically reviewed the literature published in business-to-business marketing research journals on the subject of ecosystems and their implications for network management—there is a need for more studies on ecosystems and networks adopting a cross disciplinary and broader perspective. In this sense and in keeping with the importance of networks within EEs and according to one of the research lines put forward by Alvedalen and Boschma (2017) and Acs et al. (2017), who state that EE studies would benefit from a greater level of articulation with network studies, our study seeks to contribute to filling this gap in the literature by undertaking a systematic literature review (SLR) on the theme of EEs&N with recourse to bibliometric techniques. As stated by Torraco (2016) a literature review creates new knowledge on the topic under study by articulating and systematizing conflicting perspectives and providing new insights. Thus, this SLR intends to systematize the literature on the topic EEs&N, highlighting and articulating the different streams of the literature on this topic and thereby contributing to the systematization and advancement of this research field. A SLR is guided by specific research questions that it seeks to specifically address (Kraus et al. 2020; Snyder 2019; Torraco 2016). This SLR, therefore, seeks to respond to two core research questions:

Q1:

Which are the most important trends in the literature when EEs&Ns provide the focus of analysis?

Q2:

What is the role of networks in EEs?

Hence, we carried out a systematic approach based on a rigorous and pre-defined protocol for research and analysis of the literature based on scientific articles (Snyder 2019; Torraco 2005, 2016; Tranfield et al. 2003) published in the Web of Science database. The sample articles were then subjected to bibliometric analyses (Cobo et al. 2011; Lawani 1981; van Eck and Waltman 2010), namely the bibliographic coupling of documents (Kessler 1963b)—that allow us to sort the main thematic areas found in the literature on EEs&Ns topic: (1) Context and Cooperation; (2) Established Networks; (3) Challenges to the Affirmation of Minorities; (4) Formal Structures– and co-word occurrence analysis (Callon et al. 1991; Callon et al. 1983)—that consubstantiated the thematic areas found and further allow us to identify the main literature trends on EEs&Ns topic—(1) innovation and dynamics: actors and norms; (2) performance, knowledge, and entrepreneurship; (3) technology and firms. These analyses and systematization of the articles allowed us to establish the institutional/contextual approach, the relational approach, and the organizational/structural approach as the main dimensions observable on the EEs&Ns topic.

In systematically analyzing and developing a thematic codification of the content of prior studies on the entire scope of the EE field, our study seeks to provide a triple contribution to EE theory. Firstly, this returns an updated, reproducible and consolidated general vision on EE research that identifies recent changes and emerging trends, thereby establishing a contribution to EE research in general. Secondly, based on the detailed inductive analysis of the sample article contents, we develop a unique framework that provides an alternative means of grasping this field and may serve whether for theoretical, empirical or practical purposes. In examining the extant research on EEs&Ns we provide a problematic framework for the literature, making explicit suppositions and identifying patterns that span sometimes conflictual paradigms and understandings. Thirdly, we apply a unique framework to establish bridges between different and distinct paradigms in research, and enabling productive cross-referencing and dialogue around the main approaches followed by researchers on EEs&Ns, the four main thematic areas identified in the literature on this topic, and the most important concepts on EEs&Ns. In addition to this, we also set out an agenda for future research.

The structure of this article is as follows: after this introduction (Sects. 1 and 2) presents the theoretical framework for the topics under analysis; Sect. 3 describes the methodology adopted in this research study; Sect. 4 sets out the results that include: the descriptive statistics of the articles selected in accordance with the research protocol defined, the articles grouped by cluster according to the bibliographic coupling of documents and the systematization and analysis of the results obtained for each cluster, and analysis of keywords co-occurrence; Sect. 5 presents the discussion of the systematized paths of research and advances the conceptual framework; finally, Sect. 6 details the main conclusions, contributions, limitations of the research carried out and suggestions for future lines of research.

2 Theoretical framework: entrepreneurship, entrepreneurial ecosystems and networks

Cantillon and Schumpeter constitute two of the founding fathers for the concept of entrepreneurship. Cantillon, in 1755, was the first author to propose the entrepreneurship concept in its economic sense (Hébert and Link 1989; Nijkamp 2003; Van Praag 1999). The work of Schumpeter (20th cen.) receives global recognition as essential to the development of this concept, with this author portraying the entrepreneur as an innovator who plays a central role in the economy, while introducing the concept of creative destruction that has today gained widespread discussion and analysis in the literature (Andersson et al. 2012; Autio et al. 2014; Hébert and Link 1989; Nijkamp 2003; Van Praag 1999). The many years that separate us from Cantillon and Schumpeter have nevertheless seen these concepts of entrepreneur and entrepreneurship always remain the focus of interest not only from the academic community but also from the political sphere (Carlsson et al. 2013; Ferreira et al. 2019; Hébert and Link 1989; Van Praag and Versloot 2007; Wennekers and Thurik 1999). Hence, stemming from this interest, the entrepreneurship domain has undergone a long evolution process (Ferreira et al. 2019).

Even while not always the case, entrepreneurship today holds a central position on the agendas of political leaders who correspondingly strive to foster entrepreneurial activities and thereby boost innovation, economic development and the competitiveness of countries and regions (Acs et al. 2016a, b, 2018; Audretsch 2009; Ferreira et al. 2019; Landström et al. 2012; Sternberg et al. 2019). As demonstrated by the systematic literature analysis undertaken by Urbano et al. (2019), the relationship between the institutional context, entrepreneurship and economic growth has been subject to broad debate and analysis in the literature for many years, with coverage across the macroeconomic, regional and even sectorial levels. Why some regions (within the same country) consistently remain focal points for high levels of entrepreneurship, still today drives the emergence of different theories to explain such phenomena. The work of Porter (1990) on clusters continues to represent one of the most widely praised and referenced in the literature (Martin and Sunley 2003). The diamond structure proposed by Porter (1990) enables explanations as to why some regions emerge as more competitive than others through a simple visual representation. The studies by Porter (1990, 2000) regarding the diamond and cluster concepts have been extremely influential, serving as the foundations for the many policies designed to boost competitiveness and economic development (Acs et al. 2016). Indeed, as was formerly the case with clusters, entrepreneurial ecosystems (EEs) are now the object of multiple policies aimed at fostering the performance of entrepreneurial activities (Sternberg et al. 2019).

The concept of EEs or entrepreneurship ecosystems emerged as one of the most popular topics in the literature and is currently one of the themes receiving greatest discussion across the academic community (Acs et al. 2017; Alvedalen and Boschma 2017; Colombo et al. 2019; Isenberg and Onyemah 2016; Kang et al. 2019; Malecki 2018; Maroufkhani et al. 2018; Schäfer and Mayer 2019; Spigel 2017; Stam 2015). Autio et al. (2018) characterize EEs as a unique type of cluster “the only documented cluster type that is not specific to a given (set) of industry sector(s) or technology domain(s)” (p. 74). Contrary to other research paths, in particular the clusters approach (Pitelis, 2012), EEs provide an entrepreneur focused explanation as to why some geographic regions systematically enable high levels of innovative entrepreneurial activities with similarly high growth potential (Acs et al. 2017; Spigel 2017; Spigel and Harrison 2018; Stam 2015). Thus, as stated by Spigel (2017) “ecosystems are the union of localized cultural outlooks, social networks, investment capital, universities, and active economic policies that create environments supportive of innovation-based ventures” (p. 49).

Formed by multiple dimensions, that each incorporates hundreds of constituent factors, EEs inherently reflect the characteristics of their host regions, and this renders each particular EE a unique and impossible to replicate case (Isenberg 2010, 2011; Isenberg and Onyemah 2016; Spigel 2017; Spigel and Harrison 2018). The contextual characteristics of their respective locations determine the configurations, the relationships (networks) and the core actors in each EE, giving rise to EEs with different characteristics and features (Spigel 2017; Spigel and Harrison 2018).

As Isenberg and Onyemah (2016) describe, despite the EE concept very commonly applying to reference formal structures (business incubators, mentor programs, angel investor networks) that deliberately seek to foster and enhance entrepreneurial activities, such intentions or formal structures are not inherent requirements of EEs. Even while evidence demonstrates how business incubators and mentors programs may contribute to strengthening EEs, nurturing environments more favorable to the development of start-ups (Motoyama and Knowlton 2017; Spigel and Harrison 2018; van Rijnsoever 2020; van Weele et al. 2018). Angel investors may also contribute to the success of entrepreneurs, bringing about the minimization of obstacles and offsetting institutional and market failings (Crick and Crick 2018; Harrison et al. 2018).

Contrary to other currents in the literature, EEs return evidence that innovative and high growth entrepreneurial activities result from the multiple interdependences and relationships developed within the scope of the respective EE, hence, social networks are intrinsic to EEs (Acs et al. 2017; Spigel 2017; Spigel and Harrison 2018; Stam 2015). The very nature of EEs promotes ambiences of coopetition (Bouncken et al. 2015; Bouncken et al. 2018; Roig-Tierno et al. 2018) where, on the one hand, multiple actors need to cooperate to fulfil their interests and ambitions but, on the other hand, due to the same interests, also need to compete to gain access to limited (tangible and intangible) resources. Arising from the multiple and ongoing relationships established among the multiple actors, as well as the coopetition observable in the EEs—which are dynamic environments that undergo permanent evolution—governing any EE constitutes a complex task (Colombelli et al. 2019; Colombo et al. 2019; Cunningham et al. 2019). Furthermore, as detailed by Adner (2016)—who proposed a framework for the characterization of the ecosystem as a structure—the ecosystem approach needs to carefully consider the strategic choices of the multiple actors, given that those will determine the relationships established and ultimately impact on the configuration of the ecosystem itself.

Thus, due to the importance of the relationships established among the multiple stakeholders within the scope of EEs, network analysis constitutes a common practice in EE studies, as exemplified by the studies published by Apa et al. (2017), Motoyama and Knowlton (2017), Cowell et al. (2018) or Colombelli et al. (2019). As the works of Aldrich and Zimmer (1986) and Johannisson (1986, 1988) demonstrate, the application of social networks analysis to the theme of entrepreneurship already holds a long tradition. As explained by Stuart and Sorenson (2005), in keeping with the nature of entrepreneurial activities, analyzing the social networks of entrepreneurs emerges as of core importance. Furthermore, the networks established by the entrepreneurs are not the only determinant to their success but also able to minimize any potential weaknesses that they might display (such as the lack of experience or resources) (Kuschel et al. 2017; McAdam et al. 2019; Motoyama and Knowlton 2017; Theodoraki et al. 2018).

Hence, networks theory provides a theoretical foundation that enables the analysis of these intangible interactions through a systematic and rigorous approach, enabling a thorough understanding of the multiple interactions ongoing among the multiple actors that make up such networks (Carter et al. 2015). The visual representation of these interactions enables the visualization of the key actors in networks, the total of interactions made, their nature, strength and frequency, which collectively enables a wide reaching and systematic understanding of these intangible phenomena (Aldrich and Zimmer 1986; Johannisson 1986, 1988).

3 Methodology

This study applies a systematic literature review (SLR) on entrepreneurial ecosystems and networks (EEs&Ns) as its methodology. Widely adopted across disciplines and fields of study, the SLR research methodology has experienced tremendous growth and evolution over recent years (Kraus et al. 2020; Snyder 2019; Torraco 2016).

According to Snyder (2019), the core characteristics of SLRs are their rigour and predefined methods that, on the one hand, enable the identification of all the empirical evidence that matches the criteria predefined for answering the research question(s) and, on the other hand, minimizes the scope for bias and ensures the replicability of the study. SLRs reveal different characteristics (specifically, the total of articles under consideration, their purposes and contributions to the literature) according to nature (mature or emerging) of the topic under study (Kraus et al. 2020; Snyder 2019; Torraco 2005, 2016). Kraus et al. (2020) propose a series of best practices to improve the quality of SLRs undertaken on the domain of entrepreneurship research. Hence, and in accordance with the objectives and research questions defined for this investigation, we carried out an SLR with bibliometric techniques (bibliographic coupling and co-word occurrence analysis) on the theme of EEs&Ns, an emerging topic of research. Bibliometric analysis, widely adopted on the entrepreneurship domain (e.g. Ferreira et al. (2019) and Kraus et al. (2019)) incorporates scientific methods for analysis of the literature (Lawani 1981).

The bibliographic coupling of documents method (Kessler 1963b) groups documents based on the references they share. As demonstrated by Kessler (1963a), two documents are coupled when they have one or more references in common. Thus, the bibliographic coupling of documents allows for the identification of the intellectual structure of the research field under analysis (Cobo et al. 2011) through clustering documents with similar research focuses (Jarneving 2007). As demonstrated by Boyack and Klavans (2010), the bibliographic coupling of documents presents advantages over other methods (such as co-citation), both in terms of accuracy and in grouping very recent papers.

Co-word occurrence analysis (Callon et al. 1991, 1983) by identifying the most common words in a field of research, allows for the identification of the conceptual structure of the research field under analysis (Cobo et al. 2011; De Brito and Leitão 2020; van Eck and Waltman 2009).

In accordance with the previously defined research protocol, the search for articles of relevance to the topic under analysis took place on the Web of Science (WoS) database, without any temporal restrictions. We opted for the WoS database due to its prestige and extent of coverage (Gasparyan et al. 2013) that ensures both the quality and the diversity of the articles therein collected. Given we sought to articulate both dimensions of the topic—thus, articles that analyzed both topics (EEs and networks) in conjunction—we undertook a search by topic of the WoS Core Collection (indexes: SCI-EXPANDED, SSCI, A&HCI, CPCI-S, CPCI-SSH, ESCI, CCR-EXPANDED, IC), applying the keywords “entrepreneur* ecosystem*” and “network*” that returned 105 results. The application of quotation marks to the search restricts its scope to include only those articles featuring the words defined while the usage of the * allows for the inclusion of derivations of these words, thereby allowing for the inclusion of entrepreneurial or entrepreneurship, ecosystem or ecosystem, as well as, network, networks or networking. We further limited the search to articles, published within the research area of Business Economics and written in English, with these restrictions leading to a reduction in the total number of articles, dropping from the 105 initial results to the 65 articles that met the stipulated conditions. Figure 1 illustrates the research protocol implemented and details the stages followed, and their respective numbers of articles.

Fig. 1
figure 1

Research protocol applied

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We then analyzed these 65 articles by reading their abstracts before subsequently subjecting them to bibliometric analyses by the VOSviewer software (version 1.6.13), a software specifically designed for bibliometric mapping (van Eck and Waltman 2010).

The first analysis deployed on the VOSviewer software was the bibliographic coupling of documents. We began by creating a map based on the bibliographic data previously collected by the WoS. Then, we selected bibliographic coupling as the type of analysis with documents being the unit of analysis and full counting as the counting method, which has proven the method that returns the greatest advantages from bibliographic coupling (Perianes-Rodriguez et al. 2016). After that, we selected two as a minimum number of citations for any document in the WoS, with this criterion then reducing the number of articles eligible for clustering to 34. To improve the quality of SLRs, the implementation of procedures to ensure the quality of the articles under analysis is a common and encouraged practice (Kraus et al. 2020). In that sense, due to the growing interest in the EE domain, as attested to by the multiple investigations undergoing publication at a rapid pace, we implemented the criterion of only clustering documents with a minimum of two citations—which is not a new practice in the bibliographic coupling of documents method (e.g. Patrício and Ferreira 2020)—within the scope of identifying those articles already proven and recognized by academic peers and that, in keeping with the established goal of meaningfully systematizing this topic, are of particular interest.

Then, aiming to corroborate the insights revealed by the bibliographic coupling of documents analysis, namely in terms of identifying the most important trends on EEs&Ns topic, was performed an analysis of keywords co-occurrence. We again started by creating a map based on the bibliographic data previously collected by the WoS. Then, we selected co-occurrence as the type of analysis, with all keywords being the unit of analysis and full counting as the counting method. After that, we defined five as the minimum number of occurrences of a keyword, with this criterion aggregating 24 keywords from a total of 425 keywords.

4 Results

4.1 Descriptive statistics

Figure 2 portrays the trends in both the number of articles and in the citations of the 65 articles included in the sample.

Fig. 2
figure 2

Total number of publications and citations per year

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As Fig. 2 demonstrates, this is a recent field of study (the first article encountered here dates to 2014) and now experiencing sharp growth, as reflected in the exponential rise in both publications and citations. This duly notes how between 2018 and 2019 (which on the date of the search had not yet ended), the number of publications almost doubled (from 16 in 2018 to 30 in 2019) and with the number of citations surging considerably (198 in 2018 and 306 in 2019).

Table 1 contains the five most cited articles among the 65 articles identified in accordance with the defined research protocol.

Table 1 Top 5 most cited articles
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All the articles presented in Table 1 stand out for their theoretically contributions that contribute to the building of EE research theory. As set out in Table 1, the two most cited articles stand far in front of their peers in terms of their citation totals. The most cited article “Entrepreneurial innovation: The importance of context”, by Autio et al. (2014 )is simultaneously also the oldest article among all of those selected for analysis. In this theoretical article, Autio et al. (2014) emphasize how different contexts impact on the innovations resulting from entrepreneurial activities. With a related argument, Spigel (2017) attests to how the different attributes observable in different EEs impact on both the configuration and the entrepreneurial activities resulting from each EE. Indeed, the unique characteristics of EEs motivate Autio et al. (2018) to differentiate EEs from other types of clusters.

To a certain extent, Spigel and Harrison (2018) complement the work of Spigel (2017) by emphasizing the importance of the combination of social networks and resources to the functioning of EEs with these authors providing a theoretical framework for the classification of EEs. In a conceptual article, Carayannis et al. (2018) put forward a new approach—quadruple/quintuple helix—to studying and understanding EEs. All of the articles included in Table 1 are subject to analysis in the systematization of articles by cluster and constitute central articles to their respective clusters.

4.2 Bibliographic coupling: clusters identification

The defined clustering criteria (as detailed in the methodology section) led to the formation of four clusters encompassing a total of 34 articles as illustrated in Fig. 3.

Fig. 3
figure 3

Cluster links

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In turn, Table 2 presents the authors included in each cluster.

Table 2 Authors by cluster
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4.3 Entrepreneurial ecosystems and networks: main themes

According to Kraus et al. (2020), to consolidate emerging topics of research mostly comprising of qualitative research—as is the case of entrepreneurial ecosystems and networks (EEs&Ns)—requires analysis of all sources. Hence, all the articles included in the four clusters formed were subject to careful examination. This article content analysis enabled the identification of the core research topics under study in each of the four clusters and led to the attribution of the following designations: (1) Context and Cooperation; (2) Established Networks; (3) Challenges to the Affirmation of Minorities; and (4) Formal Structures. Below, from points 4.3.1 to 4.3.5, we present a summary and systematization of the four thematic areas found in the literature on the EEs&Ns topic.

4.3.1 Context and cooperation (cluster 1)

Cluster 1, the most extensive of the four clusters formed, comprises twelve articles that approach, even if from different perspectives, the importance of the context and relationships (networks) of cooperation established within the scope of entrepreneurial ecosystems (EEs) (Table 3).

Table 3 Characterization of Cluster 1: Context and Cooperation
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The article “Entrepreneurial innovation: The importance of context”, published by Autio et al. (2014), which simultaneously represents the most cited and the oldest article among those under analysis, is the core article in cluster 1. This article makes a valuable theoretical contribution in its analysis of the implications of the various dimensions of the context to innovations deriving from entrepreneurial activities. Autio et al. (2014) identify six mutually interrelated dimensions as making up the contexts—1. Industry and Technological Contexts; 2. Organizational Contexts; 3. Institutional and Policy Context; 4. Social Contexts; 5. Temporal Contexts; 6. Spatial Contexts—that affect and shape the entrepreneurial activities and their resulting innovations. As stated by these authors, different interactions between context and entrepreneurs—i.e. entrepreneurial innovation ecosystems of different natures—result in different entrepreneurial innovations. In this article, Autio et al. (2014) propose various lines of future research that, as a consequence of the surge in interest in this field of study since 2014, have received due exploration, in particular by the other authors included in this cluster.

One of the future lines of research suggested by Autio et al. (2014) consists of analyzing “how does the nature and characteristics of entrepreneurial firms vary by source of the entrepreneurs and innovation?” (p. 1104), with the authors providing the example of innovations and entrepreneurs deriving from university contexts. The articles published by Brem and Radziwon (2017) and Schaeffer and Matt (2016) represent advances in this direction, through researching the role of universities in EEs from different perspectives.

Within the triple helix framework, Brem and Radziwon (2017) explore the dynamics of collaboration observable in an EE innovation project. As demonstrated by these authors, this “network” of collaboration (triple helix—entrepreneurial ecosystems) generates synergies that benefit all the actors involved, and foster university derived innovation processes.

Adopting another perspective, Schaeffer and Matt (2016) focus on the role of universities (and their technology transfer offices) within the scope of EEs. These authors demonstrate how the role of a university (University of Strasbourg) and its technology transfer office has evolved both within the EE and in conjunction with it, ever since the initial phase in the life of the EE through to becoming a central component of a sustainable EE.

Doblinger et al. (2019) also approaches the importance of universities, but alongside other government institutions, within the innovation processes of start-ups. The author’s study, on the clean-technology sector, conveys the importance of start-ups implementing strategic alliances during the innovation process (whether with government institutions, universities or private companies). Their results stress the enormous potential of government institutions as strategic partners, while also nevertheless highlighting how universities also bring unique attributes into such processes that make them valuable partners.

The importance of collaboration is also a central theme of the article by Sekliuckiene et al. (2016). Approaching the topic of Open Innovation, these authors argue that such processes involve continual collaboration between companies and their partners (national and international), which improves the performance and capacity for company based innovations, as well as fostering the involvement of companies in networks that generate added values.

Dealing with the clean-technology sector, the article published by Sunny and Shu (2019) to a certain extent, also falls within a research line proposed by Autio et al. (2014). This article, based on a quantitative methodology, analyzes how diverse institutional factors contribute to the formation of new start-ups in this sector in the United States.

Also focusing on analysis of the context and the multiple observable dynamics ongoing within EEs, and thus advancing another of the research topics suggested by Autio et al. (2014), the Carayannis et al. (2018) article extends the triple helix concept in proposing a quadruple/quintuple helix framework for analyzing EEs. These authors defend how this approach to EEs, through their quadruple/quintuple helix framework, enables the development and implementation of more efficient dynamics and the better coordination of tangible and intangible resources. The approach put forward by Carayannis et al. (2018) stems from the multiple observable interrelationships ongoing in each EE, that incorporate a multitude of actors across different levels, which, in turn, generates diverse challenges and enables multiple research approaches, especially as regards issues surrounding EEs governance.

As Colombo et al. (2019) refer, despite its growing popularity, the EE literature still retains certain failings, especially as regards the structure of EEs governance. Hence, these authors produce an important theoretical contribution able to assist in meeting this gap in the literature. As defended by these authors, this topic is complex in keeping with the different theories existing about how EEs form, develop and evolve, which are the key actors and the established networks they maintain. Colombo et al. (2019) demonstrate that, in accordance with the approach that is applied to analyze the EEs, the most effective means of governing them becomes variable. Emphasizing the importance of (entrepreneurial) networks, Colombo et al. (2019) affirm that governing EEs is governing relationships (of the various actors, who assume different roles and relevance within the EE) to ensure competitive advantages. Furthermore, these authors highlight that the effective governance of any EE needs to consider multiple factors, specifically including the most relevant actors (who hold different interests) and the distribution of resources and incentives across the EE.

The dimension of education, approached from different perspectives, provides the key dimensions to the articles published by Belitski and Heron (2017) and Kenny (2015). In contrast to Brem and Radziwon (2017), who apply the triple helix perspective to analyze “university-industry-government” cooperation, Belitski and Heron (2017) defend that the most effective means of analyzing this cooperation is through the perspective of “entrepreneurship education ecosystems”. These authors highlight how these “entrepreneurship education ecosystems” may configure a channel for disseminating and commercializing knowledge resulting from the ongoing “university-industry—government” collaboration.

Education for entrepreneurship is the central component in the article published by Kenny (2015). Focused on researching the entrepreneurial learning needs of professional rugby players who are preparing to transition their careers, Kenny (2015) defends the importance of these practices beginning during the active life of the players and adapted in accordance with the respective context.

Indeed, the context represents a fundamental founding component of EEs studies. As McKague et al. (2017) refer, the majority of EEs studies take place in developed countries and so, with a view to overcoming this gap in the literature, these authors undertook a case study in a rural region of Bangladesh. Hence, McKague et al. (2017) obtain evidence that social franchising may contribute towards the development of rural EEs, and thus contributing to overcoming the failures in markets and governance observable in developing countries.

Also focusing on emerging economies, the article published by Harrison et al. (2018) highlights the contribution made by angel investors towards the development of these economies and demonstrates how these investors develop networks as a means of overcoming the various failures and climates of uncertainty inherent to their surrounding contexts.

4.3.2 Established networks (cluster 2)

Cluster 2, formed of eight articles, emphasizes the importance of the networks established in entrepreneurial ecosystems (EEs) (Table 4).

The article “The Relational Organization of Entrepreneurial Ecosystems” published by Spigel (2017) constitutes the point of convergence for the articles making up this cluster. This fantastic contribution by Spigel (2017) aggregates a valuable theoretical input –that models the study of the diverse configurations and attributes of EEs—with two case studies that reflect the practical application of the theoretical guide put forward by the author. Thus, Spigel (2017) affirms that the composition of EEs spans ten attributes subdivided into three dimensions: -Cultural Attributes: Cultural Attitudes, Stories (of success) about Entrepreneurship; -Social Attributes: Social Networks; Investment Capital (financing); Mentors and Dealmakers; Worker Talent; -Material Attributes: Universities; Support Services and Facilities; Policy and Governance; Open Markets. Spigel (2017) maintains that these attributes contribute towards fostering entrepreneurial activities and the competitiveness of new companies while, nevertheless, highlighting how it is not realistic to expect that all such attributes are observable in all EEs all of the time, even while such shortcomings do not impede their overall success. The author does emphasize the interconnected nature of all these attributes, and how their interactions may vary in terms of their density, and that this dimension conditions the EE configuration. The case studies undertaken by Spigel (2017) on the Calgary and Waterloo EE, illustrate the practical applications of the theoretical contribution made by the author, demonstrating how the characteristics of the respective attributes shape the configuration and the nature of the respective EE.

Table 4 - Characterization of Cluster 2: Established Networks
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The article published by Spigel and Harrison (2018) to a large extent serves to deepen the scope of Spigel’s article (2017), providing wider reaching insights into how the observable resources and networks in EEs influence their strength and functionality. In this theoretical contribution, the authors differentiate between the literature on EEs and the literature on industrial clusters and regional innovation systems, before affirming that EE studies enable a broader and better integrated vision (in relation to the other two perspectives) on the phenomena surrounding entrepreneurial activities and why some regions are able to leverage the high growth and innovation potential of companies. Hence, these authors defend how EEs require approaching as the “ongoing processes through which resources develop within an ecosystem, flow between entrepreneurs and other actors, and create or attract more resources over time, changing the overall structure of the ecosystem” (p. 164).

Spigel and Harrison (2018) highlight the importance of EEs holding resources (tangible and intangible) and networks (that enable the flow of these resources among the diverse actors), defending how this conjugation determines the sustainability of EEs. In accordance with these characteristics, the authors then differentiate between two types of EEs: Munificent- rich in entrepreneurial resources (namely: “financing, entrepreneurial knowledge, skilled workers and experienced mentors” (p. 161)); Sparser- that do not have such entrepreneurial resources available in the same quantities. As stated by the authors, both types of EE (munificent or sparser) may be of good or poor functioning in accordance with this factor of networks (dense, based on relations of trust and of cooperation between entrepreneurs and stakeholders- investors, mentors, among others) developed within the scope of the respective EE, which ultimately determines the resiliency of the EE. The Calgary EE, one of the EEs analyzed in-depth by Spigel (2017), according to the characterization set out by Spigel and Harrison (2018), emerges as a munificent but poorly functioning EE, thus, an “irrigated” EE (Spigel and Harrison 2018).

Within the same general approach as that developed by Spigel (2017), thus setting out a theoretical framework that enables analysis of the diverse attributes making up EEs, the article written by Roundy (2017) introduces the concept of “small-town entrepreneurial ecosystems (STEEs)”. Roundy (2017) states that EE literature fails to consider the EEs in effect in small urban cities. To overcome this gap, the author introduces the STEEs concept defined as “a community of individuals, social structures, institutions, and cultural values, located in a city of limited reach, scope or size, whose interactions produce entrepreneurial activity” (p. 240). Roundy (2017) defends how the STEEs present limitations relative to EEs located in large urban areas, especially in terms of scale, the resources available and the location. Furthermore, the author highlights how there are ways of overcoming these limitations and to the extent of arguing that, in certain aspects, the STEEs display advantages over the EEs located in major conurbations. Hence, Roundy (2017) highlights the social networks intrinsic to the STEEs as their most unique asset in terms of the EEs located in major cities given that, in keeping with the reduced scale of the city, relationships are denser and able to nurture deeper levels of engagement.

In keeping with Roundy (2017), Cowell et al. (2018) also emphasize the need to analyze EEs that do not fall within the major urban centers. These authors undertake a case study in an EE that incorporates both urban and rural characteristics. Similar again to Roundy (2017), Cowell et al. (2018) point out multiple deficiencies in these EEs (covering both urban and rural characteristics). Thus, the lack of entrepreneurial resources (tangible and intangible) observable in these EEs, reflects in obstacles to companies and entrepreneurs that lead the authors to make an interesting affirmation in maintaining that “there is not one ecosystem in a region, but a collection of linked systems”.

Following that set out by Roundy (2017) and Cowell et al. (2018), and highlighting the obvious differences (in accordance with these EEs locations), we may observe how the EEs explained by these authors fit in the characterization proposed by Spigel and Harrison (2018), displaying some of the characteristics of the sparser EEs, however, with the potential to achieve good functioning (if the entrepreneurs and stakeholders can leverage the available networks). The statement by Cowell et al. (2018), contrasting a genuine EE against an interconnected set of systems, reiterates the need for EEs (irrespective of their rural or urban natures) to foster the development of the strong and dense social networks able to nurture the relationships ongoing among the various EE stakeholders.

Furthermore, the article published by Colombelli et al. (2019) analyzes the relationships established among the various EE actors, and their evolution in parallel with that of the EE, to demonstrate how different actors perform different but still fundamental roles throughout the EE development, shaping their configuration and the relationships developed within the EE.

Even while adopting another scope, the conceptual article published by Cunningham et al. (2019) also focuses on the theme of the social networks established within EEs while setting out a theoretical framework focused on the figure of the “principal investigator (PI)”, to assist EE governance processes. The authors characterize the PI as “an influential entrepreneurial ecosystem actor, whose actions and behaviors shape and influence the management of governance within the EE that supports the creation of new ventures with disruptive knowledge and provides resources and capabilities for existing firms to compete more effectively” (p. 546). Hence, Cunningham et al. (2019) propose a PI focused theoretical framework, i.e. the individual that defines the allocation of public financing to research projects among the multiple actors within the respective EE. As Cunningham et al. (2019) affirm, the PI has to coordinate the diverse interested parties, with their distinct interests, leading them to cooperate in the development of research projects, bringing about the appropriate allocation of resources and guaranteeing innovation processes within the EE. The authors furthermore characterize this role as fundamental and complex due to the competing interests prevailing among all the parties making up the EE.

The impact of financing also plays a central role in the article written by Motoyama and Knowlton (2016). These authors analyze how the Arch Grants awards influence the St. Louis EE. Through their case study, Motoyama and Knowlton (2016) demonstrate that this award, a form of public–private sponsorship, has brought about an overall strengthening of the EE by fostering networks of collaboration.

The importance of the Arch Grants award, as a focal point for cooperation within the St. Louis EE, again gets highlighted in the second article published by Motoyama and Knowlton (2017). On this occasion, the authors approach the networks established within this EE, with Motoyama and Knowlton (2017) arguing that these networks (established among entrepreneurs; and between entrepreneurs and support organizations) are strongly influenced by the networks established among support organizations and by the support that they render. Hence, these authors highlight the importance of relationships involving sharing and collaboration among entrepreneurs, while furthermore emphasizing the importance of mentors.

Following this theoretical and relational analysis of all the articles comprising cluster 2, we may affirm that all of the content making up this cluster falls, to a greater or lesser extent, within the theoretical framework proposed by Spigel (2017). The attributes set out by this author feature clearly in the articles identified here, with the importance both of collaboration networks (social attributes) and mentors (cultural attributes and social attributes), of the formal means of support for entrepreneurs and entrepreneurial activities (social attributes and material attributes), receiving widespread emphasis.

4.3.3 Challenges to the affirmation of minorities (cluster 3)

Cluster 3, containing seven articles, focuses on the challenges faced by minorities making their ways in entrepreneurial ecosystems (EEs) (Table 5).

Table 5 Characterization of cluster 3: affirmation of minorities
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As detailed by Muldoon et al. (2018), the relationships established among the multiple actors making up any EE are essential to their respective sustainability. Nevertheless, Kuschel et al. (2017), McAdam et al. (2019), Neumeyer et al. (2019a, b) and Neumeyer et al. (2019a; b) demonstrate that not all actors included within the scope of EEs gain the same terms and conditions for interrelating and achieving success. Hence, the articles included in this cluster consider the inequalities observable in EEs, with approaches made according to gender (Kuschel et al. 2017; McAdam et al. 2019; Neumeyer et al. 2019a; b), ethnicity (Neumeyer et al. 2019a; b), affiliations and business experience (Neumeyer et al. 2019a; b), and even company types (Kuratko et al. 2017; Neumeyer et al. 2019a, b).

Three of the articles (Kuschel et al. 2017; McAdam et al. 2019; Neumeyer et al. 2019a, b) included in this cluster focus on the gender differences encountered in EEs. These articles highlight the multiple difficulties faced by female entrepreneurs within EEs, with gender based discrimination preventing them from developing the depth or extent of relationships within the EE as their male peers (McAdam et al. 2019)—with the ethno-racial factor further aggravating this differentiated treatment (Neumeyer et al. 2019a, b)—and while also hindering their access to financing (Kuschel et al. 2017).

McAdam et al. (2019) identify how markedly masculine cultures prevail in EEs and, on occasion, biased against female entrepreneurs. These authors maintain that the female entrepreneurs who obtain greatest success are those able to adapt to this culture and its enrooted habits and correspondingly able to participate in and to form the relationships within the scope of the EEs that bring about their business success. Hence, McAdam et al. (2019) defend the importance of mentors and introducing the concept of gender capital, resulting from participation in exclusively female entrepreneurial networks, however as these authors detail, the effect of these networks is the inverse and driving more marginalization rather than contributing towards their integration into the respective EE.

Kuschel et al. (2017) share this perspective, maintaining that these networks (composed exclusively of women) may contribute to the role of victimization of female entrepreneurs within EEs. These authors demonstrate that female entrepreneurs face obstacles in raising capital for their start-ups in accordance with their gender.

Furthermore, the study undertaken by Neumeyer et al. (2019a, b) comes out with differences in the distribution of social capital and the type of networks developed by male and female entrepreneurs in EEs. These authors also include other factors in their study, for example, ethnicity, which poses an additional obstacle and still further contributing towards the difficulties experienced by these entrepreneurs.

The article published by Neumeyer et al. (2019a; b) also dwells on the gender differences observable in EEs and that shape both the type of company getting launched and the networks established, while extending this perspective to defend how EEs display multiple clusters that form in keeping with the social characteristics prevailing (namely: “venture type, gender, ethnicity, organizational affiliation and venture experience”), which influence the networks they develop and undermining the climate of inclusion within EEs.

Nevertheless, the difficulties experienced in EEs extend beyond entrepreneurs belonging to minority groups. The article by Kuratko et al. (2017) puts forward evidence detailing how the characteristics of some companies lead them to encounter difficulties in building up legitimacy within EEs. Kuratko et al. (2017) identify a curious paradox in demonstrating how the new companies that introduce newness are those that face the greatest challenges in gaining legitimacy by the remaining actors in EEs, even when overcoming this barrier by moving beyond their host EE to obtain greater benefits (legitimacy/diffusion) than less innovative companies. Hence, Kuratko et al. (2017) defend the importance of networks formed by strong ties among their members as facilitating this legitimacy process, given the trust and confidence already established among their members.

Muldoon et al. (2018) also stress the relevance of trust and cooperation-based relationships among EE members. These authors maintain that the type of entrepreneurship (positive, non-productive or destructive) resulting from EEs emerges as a consequence of the relationships therein developed. Hence, Muldoon et al. (2018) maintain that relationships of trust or distrust established among EE actors condition their respective success and contribute towards the ongoing development of entrepreneurial activities.

The article published by Bakas et al. (2019) characterizes a particular type of entrepreneur, which operates in rural EEs and establishes a connection between artisans and tourism. Thus, these authors introduce the concept of “artisan entrepreneurs-mediators”, individuals that interconnect artisans and tourists in the tourism experience sector.

4.3.4 Formal structures (cluster 4)

Cluster 4, formed of seven articles, emphasizes the relationships (networks) observable in formal structures set up to promote entrepreneurial activities (Table 6).

Table 6 Characterization of cluster 4: formal structures
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Autio et al. (2018) characterize entrepreneurial ecosystems (EEs) as a unique form of clusters with these authors stating that “entrepreneurial ecosystems constitute the only documented cluster type that is not specific to a given (set) of industry sector(s) or technology domain(s)” (p. 74). Hence, in this theoretical article, the authors put forward a conceptual model for characterizing EE as a particular type of cluster: specialized in exploiting technological affordances, which combines digital affordances and spatial affordances, and fosters the creation and growth of new companies that leverage entrepreneurial opportunities through radical business model innovation.

Three articles in this cluster focus their analysis on the role of business incubators. These articles state that business incubators, due to their specific characteristics and rendering of support services and infrastructural provision for start-ups, contribute towards the success and development of the latter (Apa et al. 2017; Carvalho and Galina 2015; Di Fatta et al. 2018) which, as Apa et al. (2017) detail, ensures business incubators represent a particular type of entrepreneurial environment.

As Carvalho and Galina (2015) and Apa et al. (2017) defend, the incubator management structures must act as a central component in supporting the start-ups they host and provide a determinant input into their sustainability. This role, as Apa et al. (2017) demonstrate, extends beyond the formal component of providing infrastructures, with the incubators (and their management entities) being a central facet of the networks (of cooperation) that their host companies interact with, both at the internal level (among incubator hosted companies) and in networks with external actors (Apa et al. 2017). As conveyed by Di Fatta et al. (2018), these interactions among start-ups within incubators generate a fundamental input. These same authors demonstrate that the start-ups establish different relationships within the incubators, observing how the greater the interconnections among the networks involving the start-ups, thus the greater the number of partnership projects within the incubator, the greater the level of start-up innovations (Di Fatta et al. 2018). Therefore, due to the need for the incubator management entity having to play this active and interventive role, fostering these cooperative relationships, across both the internal and the external levels, these management structures fundamentally require qualified human resources, given that the future sustainability of the incubator depends on their success (Apa et al. 2017; Carvalho and Galina 2015).

Nevertheless, business incubators are not the only particular case of EE analyzed in this cluster. Theodoraki et al. (2018) approach a still more specific case of EE through studying university-based EEs via analysis of university business incubators. Based on the social capital perspective, these authors highlight three core dimensions to the sustainability of this type of EE: access to resources; relationships established among the EE actors; complementarity and trust in the relationships thereby established.

Beyond the scope of business incubators but nevertheless still focused on the collaborative networks built up among companies, Cannavacciuolo et al. (2017) analyze the impact of the entrepreneurial learning of companies on the performance of entrepreneurial clusters. The theoretical simulation developed in this article conveys how the diffusion/exchange of knowledge among companies, within clusters, might impact the performance both at the system and firm level, while also revealing that the logic leading to the choice of business partners may also shape the structures of learning networks.

The article published by Crick and Crick (2018) focuses on a particular type of business partnership, analyzing the processes leading to angel investors deciding to invest in business models still under development. As demonstrated by these authors, the factors determining angel investor decision-making processes do include not only the characteristics of the target business for investment but also the perceptions of risk and reward perceived by the investors, as well as the networks in which these investors participate.

4.4 Analysis of keywords co-occurrence

Seeking to deepen the insights revealed by the bibliographic coupling of documents, as well as to further explore the most important trends in the literature on EEs&Ns, an analysis of keywords co-occurrence was performed (Fig. 4).

Fig. 4
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Keywords co-occurrence links

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As depicted in Fig. 4, the concepts “entrepreneurial ecosystems/entrepreneurial ecosystems” (that together collect 29 occurrences) and “networks” (31 occurrences)/“social networks” (5 occurrences) are the most applied keywords on EEs&Ns topic, which is expected considering that those literally constitute the topic under analysis. Apart from those concepts, “innovation” (27 occurrences), “performance” (19 occurrences), “knowledge” (18 occurrences), “entrepreneurship” (17 occurrences), and “policy” (13 occurrences) are the five most common keywords on the EEs&Ns topic.

In that sense, the red cluster (first literature trend) highlights the paramount importance of innovation on EEs and clusters. It unveils the importance of the dynamics among the multiple EE actors (namely: start-ups, universities, and business (incubators)), as well as regulations (namely: policy and institutions) that facilitate the growth of EEs. The green cluster (second literature trend) emphasizes the importance of knowledge and entrepreneurship on the performance of EEs, while also emphasizing the importance of the creation (e.g. of knowledge and new ventures) promoted through social networks on EEs. Finally, the blue cluster (third literature trend) underlines the importance of technology, firms, and management on EEs.

5 Discussion and conceptual framework

The bibliometric analyses developed (bibliographic coupling of documents and keywords co-occurrence) allowed us to identify the main research approaches on entrepreneurial ecosystems and networks (EEs&Ns) topic. Thus, the institutional/contextual dimension –a perspective that focuses on the impact of the context intrinsic to each EE, as well as the institutions/norms therein observable, which is mainly observed on “Cluster 1: Context and Cooperation”, as well as on the first literature trend–, the relational dimension –a perspective that emphasizes the relationships (networks) and dynamics established among the diverse EE actors, which is mainly observable on “Cluster 2: Established Networks” and “Cluster 3: Challenges to the Affirmation of Minorities”, as well as on the second literature trend– and the organizational/structural dimension –a perspective that focuses on the organizational structures discernible on EEs and other entrepreneurial environments, which is mainly observable on “Cluster 4: Formal Structures, as well as on the third literature trend– are the main approaches followed by researchers on EEs&Ns topic.

The systematization of the extant research in the field of EEs&Ns has enabled the development of an integrative framework (Fig. 5). The conceptual framework advanced seeks to illustrate the main relationships established among the main approaches followed by researchers in this field of research, the four clusters formed in accordance with the bibliographic coupling of documents, and the most important concepts on this topic (as depicted in the analysis of co-word occurrence).

Fig. 5
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Conceptual Framework: EEs&Ns

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The institutional/contextual dimension is most discernible on “Cluster 1: Context and Cooperation”. Part of the contributions made in “Cluster 1: Context and Cooperation” analyze how the context, which contains multiple dimensions, shapes and influences the nature, configuration, governance and innovation of EEs. The importance of cooperation, among the diverse actors participating in any EE, provides another core component to the research featuring in this cluster. With the analysis taking diverse and different perspectives, ranging from the most traditional, such as the triple helix, alliances or strategic partnerships, through to the least common such as the quadruple/quintuple helix framework, the analysis undertaken here has also unveiled an approach that analyzes the EE context and cooperation from an education-focused perspective. Which also steps in the relational dimension and attests to the complementarity and interdependency observable on this topic.

In “Cluster 2: Established Networks”, the networks developed within EEs are a core component to the research undertaken, making this cluster fall into the relational dimension. Several contributions therein included detail how the networks developed among the diverse stakeholders, based on relationships of cooperation and trust, determines the functioning of any EE. Hence, the importance of mentors and cooperation among companies receives attention from some authors, as factors promoting the development of such networks. As this cluster clearly describes, these networks develop and evolve over the time, which ultimately shapes the configuration of the respective EE and challenges the governance of the interests of the different stakeholders inherent to each EE. In this cluster, some authors also approach EEs with particular characteristics, such as those located outside of the major urban centers which, on the one hand, report diverse shortcomings (namely entrepreneurial resources) in comparison with EEs operating in the major urban centers but, on the other hand, display characteristics susceptible to leveraging, especially in terms of their networks of cooperation. These approaches also step in the institutional/contextual dimension, further attesting to the complementarity and interdependency observable on this topic.

Also, in the relational dimension category, we portray “Cluster 3: Challenges to the Affirmation of Minorities”. Cluster in which the authors target the challenges presented by minorities (at the level of individuals and companies) within EEs, emphasizing how EEs, from the outset, are not as inclusive as might be expected or desirable.

The authors in “Cluster 4: Formal Structures” analyze structures that explicitly focus on promoting entrepreneurial activities. Therefore, this cluster conveys the importance of business incubators and angel investors. In that sense, cluster 4 falls into the organizational/structural dimension while also unveiling the importance of the networks therein established and so stepping in the relational approach and so again confirming to the interdependency on this topic.

Moreover, the framework illustrates that the thematic areas found on the EEs&NS topic are correlated. The EEs&Ns established result from their respective contexts (hosting the respective EE) and the relationships therein established (by the diverse EE actors), observing that the context influences the relationships developed, as taken into consideration by “Cluster 1: Context and Cooperation” and “Cluster 2: Established Networks”. The EEs are formed by multiple correlated dimensions that determine the structure, the nature and the output of the EE (Autio et al. 2014; Cowell et al. 2018; Roundy 2017; Spigel 2017; Spigel and Harrison 2018). Differences in context drive the establishment (among the diverse EE actors) of relationships of different natures, which impacts on the configuration and functioning of the respective EE (Spigel 2017; Spigel and Harrison 2018). The context and the networks prevailing undergo permanent evolution which ultimately impacts on the nature and evolution of EEs (Colombelli et al. 2019; Colombo et al. 2019). The dynamism of EEs promotes the constant flow (arrival and exit) of actors and consequently changes their roles within the scope of the respective EE, altering the relationships established and modifying the EE configurations and ultimately challenging the leadership and rendering the task of EE governance difficult (Colombelli et al. 2019; Colombo et al. 2019; Cunningham et al. 2019; Schaeffer and Matt 2016). Even while analysis of EEs takes place according to different perspectives (Belitski and Heron 2017; Brem and Radziwon 2017; Carayannis et al. 2018), the importance of cooperation among the diverse stakeholders in the EE receives widespread emphasis (Motoyama and Knowlton 2016, 2017). The importance of cooperation extends beyond the field of EE and is also a means of fostering innovation in start-ups and minimizing the potential failures/deficiencies of governance, markets or institutions (Doblinger et al. 2019; Harrison et al. 2018; McKague et al. 2017; Sekliuckiene et al. 2016; Sunny and Shu 2019).

Cooperative ambiences promoted through the networks developed may furthermore contribute towards facilitating the affirmation of minorities in EEs (Kuratko et al. 2017; Muldoon et al. 2018; Neumeyer et al. 2019a, b) which, as detailed in “Cluster 3: Challenges to the Affirmation of Minorities”, are not as inclusive as would be desirable.

In turn, “Cluster 4: Formal Structures” observes how the context and cooperation reflect in formal support structures for entrepreneurial activities and EEs, such as business incubators. According to Apa et al. (2017), business incubators constitute a specific type of entrepreneurial environment which, through nurturing and strengthening the cooperation networks (internal and external to the incubators), promote the success and innovation of the companies they host (Apa et al. 2017; Carvalho and Galina 2015; Di Fatta et al. 2018; Theodoraki et al. 2018).

Furthermore, as shown in the analysis of keywords co-occurrence, the EEs&Ns topic is composed of different literature streams that emphasize different yet fundamental and complementary concepts of this topic. Thus, the analysis of keywords co-occurrence highlighted three fundamental literature trends: (1) the importance of the dynamics observable among the multiple EE actors and norms inherent to each EE, that facilitate the growth of the EE and promote the innovation derived therein; (2) the importance of knowledge and entrepreneurship, as well as the creation of knowledge and ventures facilitated by social networks on the performance of EEs; and (3) a more firm centered perspective that highlights the importance of technology (firms and resources) and management (of business incubators and of the EEs themselves) on EEs.

Hence, as demonstrated by the different approaches followed by the researchers on this topic, by the systematization of the clusters formed in accordance with the bibliographic coupling of documents, and by the analysis of co-word occurrence, the EEs&Ns topic is composed of different systematic research paths that focus on different aspects of the EEs&Ns that deeply correlate, as this framework duly conveys.

6 Conclusions, contributions, limitations and research agenda

Entrepreneurial ecosystems (EEs) have definitively staked their place as a topic of interest on the agendas of both researchers and political leaders (Acs et al. 2017; Alvedalen and Boschma 2017; Isenberg and Onyemah 2016; Schäfer and Mayer 2019; Spigel 2017; Stam 2015). The rise in the number of studies focusing on this field attests.

to this still remains an immature topic in the theoretical development phase. While on the one hand, this growing body of research contributes to deepening the development of the knowledge that we have on this topic; on the other hand, the speed and incidence of publication of these new studies have led to a lack of coordination, with EE research lacking in systematization and an appropriate theoretical framework (Acs et al. 2017; Alvedalen and Boschma 2017; Spigel 2017; Spigel and Harrison 2018; Stam 2015).

Aiming to meeting this gap in the literature, this study conducted a systematic literature review (SLR) of the entrepreneurial ecosystems and networks (EEs&Ns) topic. The 65 articles obtained in compliance with the research protocol adopted were subject to descriptive and bibliometric techniques that provided a comprehensive overview of the state of knowledge on this topic. The descriptive and bibliometric techniques herein applied to respond to the first research question; “Q1: Which are the most important trends in the literature when EEs&Ns provide the focus of analysis?”. Thus, the four clusters formed through the bibliographic coupling of documents technique—(1) Context and Cooperation; (2) Established Networks; (3) Challenges to the Affirmation of Minorities; and (4) Formal Structures—attest to the existence of four distinguishable thematic areas. Furthermore, the analysis of keywords co-occurrence developed corroborated the existence of the different thematic areas previously found, while also unveiling the most important trends in the literature on EEs&Ns topic and so highlighting (1) the importance of the dynamics observable among the EEs actors and norms that impact on the growth of the EEs and on the innovation therein resulting; (2) the importance of knowledge and entrepreneurship on the performance of EEs; and (3) the business perspective, that emphasize the importance of technology and firms. Thus, following these bibliometric analyses, we were able to establish the institutional/contextual dimension, the relational dimension, and the organizational/structural dimension as the main approaches followed by researchers on the EEs&Ns topic.

Thus, on the thematic area “(1) Context and Cooperation”, the authors put in evidence the institutional/contextual dimension of the EEs, emphasizing how the regional context inherent to the EEs affects and shapes their nature, namely in terms of networks of cooperation established (partners selection) and entrepreneurial activity resulting therein, which steps in the relational dimension and attests to the interdependences observable on this topic.

On the thematic area “(2) Established Networks”, the authors emphasize the relational dimension of the EEs, highlighting how the networks, meaning, the social and business relationships of different natures established among the multiple EE actors, are formed, evolve and ultimately determine the nature of the EE itself, also emphasizing how those are also context-related and thus stepping in the institutional/contextual dimension and again attesting to the interdependences observable on the EEs&Ns.

On the thematic area “(3) Challenges to the Affirmation of Minorities” the authors further explore the relational dimension of the EEs&Ns topic. This cluster highlights how the networks play a dual role on the EEs where, on the one hand, can promote ambiences of inclusion, cooperation, and conductive to innovation but, on the other hand, biased networks can further aggravate the sometimes exclusion climate observable on the EEs.

On thematic area “(4) Formal Structures” the authors emphasize the importance of entrepreneurial environments (organizational/structural approach) that foster and facilitate innovative entrepreneurial endeavours, the importance of networks (relational dimension) is again highlighted in this cluster and so once again attesting to the interdependencies observable on this topic.

In that sense and specifically answering the first research question established “Which are the most important trends in the literature when EEs&Ns provide the focus of analysis?”, the SLR undertaken to emphasize the importance of the contextual/institutional dimension –mostly observable on “Cluster 1: Context and Cooperation” and emphasized by the literature trend related to the dynamics observable between EEs actors and norms that facilitate the growth of the EEs and foster ambiences conductive to innovation–, the relational dimension –mostly observable on “Cluster 2: Established Networks” and “Cluster 3: Challenges to the Affirmation of Minorities”, as well as supported by the literature trend that attests to the importance of knowledge and entrepreneurship on the performance of EEs–, and the structural dimension –mostly observed on “Cluster 4: Formal Structures” and emphasized by the literature trend related to the importance of technology and firms on EEs– on the EEs&Ns topic.

Content analysis and the systematization of each article grouped into the four thematic areas, as well as analysis of keywords co-occurrence, enable us to answer the second research question formulated “Q2: What is the role of networks in EEs?” by demonstrating that the networks established within the scope of EEs are of paramount importance. These networks, deeply impacted by the context and norms inherent to each EE and the relationships and dynamics ongoing among the multiple actors therein established, not only impact on the functioning, configuration, evolution, growth, performance and resilience of EEs but could also contribute to bringing about more inclusive environments that foster the participation of women and the emergence of highly innovative ventures. We further observe that from the EE/networks symbiosis there results the emergence of formal structures –with business incubators, mentor programs and angel investors as the most discernible institutions– that ultimately hold the role of fostering and nurturing entrepreneurial activities and knowledge sharing and creation and within the scope of which networks take on paramount importance. Thus, specifically answering the second research question formulated, networks, meaning, social and business relationships established among the multiple actors embedded on the EEs, are the intangible assets that promote the emergence of productive entrepreneurial activities, the growth of ventures and so of the EEs themselves and the emergence of environments conducive to innovation, that all impact on the performance of the EEs themselves. On the one hand, the SLR undertaken emphasizes how strong, interconnect networks, based on trust and cooperation, established among the EEs actors, promote, and facilitate the high growth innovative entrepreneurial activities. On the other hand, it also unveils how weak or biased networks can possess a problem that not only impacts the inclusiveness and the outcomes of the EEs, namely in terms of innovative entrepreneurial activity but also hinders their performance and growth.

Through the SLR carried out –based on a strict research protocol and on descriptive and bibliometric analyses– we systematized the main research areas within the field of EEs&Ns and thereby responding to the two core research questions. Systematization of the extant research grouped into four clusters enabled the identification and systematization of the main research approaches adopted by researchers in this field and thereby stressing the importance of networks patent in each of these clusters. Results that were further corroborated by analysis of keywords co-occurrence. The systematization of the research areas enabled us to distinguish three fundamental interrelated dimensions on the EEs&Ns topic: the institutional/contextual approach, the relational approach, and the organizational/structural approach.

This research study returned a comprehensive overview of the EEs&Ns topic, articulating the distinct but complementary research paths that may still further advance the academic understanding of EEs&Ns. Furthermore, this investigation generates important practical contributions by highlighting the multiple facets that comprise EEs&Ns and hence the findings –which emphasizes the importance of local and regional elements– can assist political leaders in making better informed decisions.

Despite considering that this study contributes to the systematization and development of the EE literature, especially in terms of systematizing the research areas, the study is not without limitations. It might be argued that the keywords defined –that seek to center analysis on EEs&Ns–, restricting the search to a single database (Web of Science)—that aimed to ensure the quality of the articles that comprised the sample—, limiting the articles to those published in the Business Economics category—intended to focus the analytical scope– and the criteria for grouping the articles into clusters (bibliographic coupling)—chosen due to its nature well suited for grasping the foundations of recent literature trends–, as well as the restrictions applied on that procedure, may have limited the scope of this study.

By accessing and articulating the extant research on the EEs&Ns topic, this study can propose possible future lines of research able to contribute to advancing the academic discussion on the EE approach. As explicitly detailed in the systematization of the research lines by cluster, in the analysis of keywords co-occurrence, and in the framework advanced, despite being correlated, each of these research paths raises its own challenges. Hence, as a result of the findings provided by the SLR undertaken, we conclude by proposing promising paths for future research.

As demonstrated in the systematization of the four thematic areas found in the literature, most of the research studies carried out on EEs&Ns adopt the qualitative methodological approach (in particular, case studies), which is understandable as an emerging research topic. Moreover, given that networks are a central component to the research undertaken, it would also be unreasonable to expect that, due to the nature of EEs, the quantitative methodology may emerge as the dominant research approach in this area. However, considering the systematic research carried out here, we believe that this topic would benefit from methodological triangulation (as already undertaken by some of the authors here included), thus the implementation of mixed methodologies. However, to become reality, this would imply a greater theoretical framework that would enable the development of structural models that interrelate the multiple dimensions, the components, and stakeholders of EEs. As clearly demonstrated, due to the nature of the EEs, this is far from easy to implement. Furthermore, the adoption of mixed methodologies would greatly facilitate comparability –among: EEs/specific components of EEs/established networks in EEs/core actors in EEs/configuration of EEs located in different regions, countries or contexts– that, in accordance with the SLR undertaken here, might make a fundamental contribution towards systematically developing this topic.

Following the SLR undertaken, we also emphasize the importance of developing more research focused on articulating different research approaches. It would be of interest to develop more studies that analyze how the institutions in place reflect in the emergence and structural organization of entrepreneurial/business environments and how that impact on the growth and competitiveness of the ventures therein established (institutional/contextual approach and organizational/structural approach). It would also be of interest to develop more studies that articulate the relational approach and the organizational/structural approach, namely studying the differences observable in the networks established by start-ups hosted in formal structures (such as business incubators) compared to those established by start-ups not incubated, namely in terms of knowledge sharing and coopetitive behaviours, as well as advancing with more investigation that seeks to compare the role of women and minority groups in EEs and other business environments (such as clusters or technology parks). Moreover, it would also be of interest the development of more studies that analyze the role of universities (namely entrepreneurial universities) in the growth, evolution and outcomes of EEs and on the business ventures themselves (relational approach and organizational/structural approach).

Furthermore, the networks and dynamics established among the EEs actors are in permanent evolution, so the relational approach would benefit from more longitudinal studies, that analyze how those interactions evolve over time and how those impact on the evolution and nature of the EEs. It would also be of interest the development of more studies that compare the innovations resulting from EEs and the innovations resulting from other types of business environments (namely clusters or technology parks) to access how the dynamics and networks established affect the rate and nature of innovations. In this same line of research, it would also be of interest to further explore how different EE actors, networks and dynamics affect and shape the technological innovations arising. Some of the researchers on this topic also propose different frameworks to the analysis and understanding of EEs (relational approach), which is also an interesting and promising research path that deserves due exploration. Simultaneously, the hitherto research findings emphasize the highly contextual nature of EEs (institutional/contextual approach), in this sense, it would be of great interest to analyze EEs or at least the entrepreneurial oriented structures, located in emerging economies. Indeed, the EE approach is a promising and vast research path that will continue to motivate the development of multiple studies.