Genecological Differentiation

Abstract

The above statement was made over half a century ago in the introduction to a book entitled The Phylogenetic Method in Taxonomy: The North American Species of Artemisia, Chrysothamnus, and Atriplex. This work by Hall and Clements marked a new epoch in North American taxonomy, as did the pioneering work by Göte Turesson (1922a, b) and Jens Clausen (1922) in Europe. A new line of taxonomic inquiry, that of genecology, had begun in which genetic relationships and the importance of distinctions between environmentally induced modifications and heredity variations in ecologically important characteristics were emphasized. Since then much progress has certainly been made in the field of biosystematics (or experimental taxonomy) and the necessity for a genecological approach is generally, in theory at least, accepted by modern taxonomists. However, it is still too often ignored in practice. This is not to say that we do not consider classification for its own sake an important and sufficiently respectable activity; in fact we agree with Heslop-Harrison’s (1964) view that redefinition of biosystematics which effectively makes biosystematics synonymous with genecology, is undesirable. One can certainly understand the reluctance of the taxonomist to adopt the genecological approach, realizing the tremendous task of experimentally determining genetic and ecological relationships in genera with worldwide distribution, composed of hundreds of recognized species and thousands of taxa at the subspecific level. Yet, there is no substitute for this approach if the objective is to gain an insight into evolutionary and functional relationships.

“The prevailing practice in the segregation of genera and species is chiefly detached analysis, with little consideration of relationship and practically none of evolution … To be both comprehensive and thorough, taxonomy must draw its materials from all other fields, just as it must serve them in turn. While it leans most heavily upon morphology, it can not afford to neglect histology and physiology, and it must learn to go hand in hand with ecology and genetics in the future. Indeed, if it is to reflect evolution as accurately as it should, it must regard physiological adjustment as the basic process, and morphological and histological adaptations as the measurable results. This means that the taxonomist of the future will think in terms of evolutionary processes, and will learn to treat his morphological criteria as dynamic rather than static.” (Hall and Clements, 1923)