Microsatellite variation in marine, freshwater and anadromous fishes compared with other animals

From a total of 524 microsatellite loci considered in nearly 40 000 individ uals of 78 species, freshwater fish displayed levels of population genetic variation (mean heterozygosity, h=0.46, and mean numbers of alleles per loc us, a=7.5) roughly similar to those of non-piscine animals (h=0.58 and a=7. 1). In contrast, local population samples of marine fish displayed on avera ge significantly higher heterozygosities (h=0.79) and nearly three times th e number of alleles per locus (a=20.6). Anadromous fish were intermediate t o marine and freshwater fish (h=0.68 and a=11.3). Results parallel earlier comparative summaries of allozyme variation in marine, anadromous, and fres hwater fishes and probably are attributable in part to differences in evolu tionarily effective population sizes typifying species inhabiting these rea lms. (C) 2000 The Fisheries Society of the British Isles.