Abstract
Theory predicts that genetic variation is a determinant of persistence, and that the abundance and distribution of variation is strongly dependent on genetic drift and gene flow. Small, isolated populations are expected to be less diverse and more differentiated than large, inter-connected populations. Thus rare species may be more at risk of extinction. We used 389 putative AFLP loci to compare genetic variation and structuring in two pairs of closely-related common (large populations geographically widespread) and rare (small populations spatially restricted) Persoonia species. We genotyped 15–22 adult plants, from four populations, covering the geographic range of each species. Although genetic diversity was low for all four species (for long-lived outcrossing perennials), we found significantly more diversity within populations of the rare species than within those of the common species. AMOVA revealed significant levels of structure both among species (21%) and populations (15%). The proportion of inter-population variation within species did not vary consistently with rarity (Pair 1 rare 21.1% versus common 16.5%; Pair 2 rare 15.8% versus common 20.6%). However populations of the rare species were more differentiated than common species with similar geographic separation, suggesting greater gene flow between populations of the common species. Therefore, even relatively small genetically isolated populations of rare Persoonia species were more diverse than large populations of common Persoonia species. We hypothesise that common Persoonia species have undergone a rapid range expansion from a narrow gene pool, while genetic diversity is maintained in the soil seed-bank of rare remnants.
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Acknowledgements
This project was supported by an Australian Research Council linkage grant to R.J. Whelan and D.J. Ayre (C00001913), with logistical and financial assistance provided by the Department for Environment and Conservation (National Parks & Wildlife Service and Botanic Gardens Trust divisions). We thank Siegy Krauss for technical advice on AFLPs. Special thanks to Tanya Llorens and Annette Usher for assistance in the Molecular Ecology Lab at UOW. This manuscript has been improved by the input of Rob Whelan and Peter Weston, and two anonymous reviewers. We conducted this work under the specifications of a section 91 license to pick/collect threatened species and a scientific licence to work in National Parks (B2199).
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Rymer, P.D., Ayre, D.J. Does genetic variation and gene flow vary with rarity in obligate seeding Persoonia species (Proteaceae)?. Conserv Genet 7, 919–930 (2006). https://doi.org/10.1007/s10592-006-9135-8
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DOI: https://doi.org/10.1007/s10592-006-9135-8