干旱区生态环境知识资源中心

Question: How does genetic diversity change as one moves along a species’ range, towards the periphery? Previous work shows contradictory evidence for an increase, decrease or no clear trend along the range.

Hypothesis: A hump-shaped unimodal pattern of within-population genetic diversity will occur along the range with peak diversity in sub-peripheral populations. This hypothesis incorporates and explains some of the apparent contradictions found in the literature.

Organism: Thirteen native chukar partridge (Alectoris chukar) populations.

Location: A steep environmental gradient towards the periphery of the species’ range in Israel.

Methods: Genetic diversity was estimated in 26 allozyme loci.

Conclusions: A unimodal pattern of within-species genetic diversity, as expressed by measures of heterozygosity, is found along the range. Diversity peaks at the sub-periphery of the chukar range. These populations are located at the ecotone between the Mediterranean and desert climatic regions.

Appendix: A mathematical model that explores possible mechanisms generating the unimodal pattern. The model suggests that a unimodal pattern can appear under a range of parameters.