Population size and genetic diversity in sand lizards (Lacerta agilis) andadders (Vipera berus)

Because low genetic diversity may threaten the viability of isolated popula tions, conservation biologists have devoted much effort to quantify genetic variation. Two techniques routinely used involve levels of mini- and micro satellite polymorphism, with the assumption that levels of variation at the se parts of the genome will be reflected in levels of variation at other lo ci. Our data challenge this assumption. We studied six populations of sand lizards (Lacerta agilis) and five populations of adders (Vipera berus), dif fering considerably in size and degree of isolation. They, therefore, offer an opportunity to examine how population parameters affect genetic variati on at different parts of the genome. Relative population size (based on deg ree of isolation and number of animals) was not correlated with either mini satellite variability or microsatellite heterozygosity. However, our measur es of genetic diversity at the Mhc class I loci of both sand lizards and ad ders revealed a significant correlation between relative population size an d Mhc polymorphism: non-isolated/larger populations exhibited higher geneti c diversity than did isolated/small populations. Consequently, only the Mhc -based estimates of genetic diversity yielded results in agreement with pop ulation genetic theory. (C) 2000 Elsevier Science Ltd. All rights reserved.