CORE AND PERIPHERAL-POPULATIONS AND GLOBAL CLIMATE-CHANGE

Environmental conditions outside the periphery of a species' distribut ion prevent population persistence, hence peripheral populations live under conditions different from those of core populations. Peripheral areas are characterized by variable and unstable conditions, relative to core areas. Peripheral populations are expected to be genetically m ore variable, since the variable conditions induce fluctuating selecti on, which maintains high genetic diversity. Alternatively, due to marg inal ecological conditions at the periphery, populations there are sma ll and isolated; the within-population diversity is low, but the betwe en-population genetic diversity is high due to genetic drift. It is al so likely that peripheral populations evolve resistance to extreme con ditions. Thus, peripheral populations rather than core ones may be res istant to environmental extremes and changes, such as global climate c hange induced by the anthropogenically emitted ''greenhouse gases''. T hey should be treated as a biogenetic resource used for rehabilitation and restoration of damaged ecosystems. Climatic transition zones are characterized by a high incidence of species represented by peripheral populations, and therefore should be conserved now as repositories of these resources, to be used in the future for mitigating undesirable effects of global climate change. Preliminary research revealed high p henotypic variability and high genetic diversity in peripheral populat ions relative to core populations of wild barley and the chukar partri dge, respectively.