Genie differentiation of Daphnia magna populations

KORPELAINEN, H. 1984. Genie differentiation of Daphnia magna populations.—Hereditas 101: 209–216. Lund, Sweden. ISSN0018–0661. Enzyme gene variation was studied in 22 natural populations of the cyclical parthenogen Daphnia magna Straus (Crustacea: Cladocera) on the coast of southern Finland. Allozyme variation was detected at 7 of 13 loci examined. The number of polymorphic loci varied from one to five, and the average degree of genie polymorphism was 0.252. The average heterozygosity across all populations was revealed to be low, only 0.072, and showed no dependence on the permanence of the population. On the basis of genetic distances. populations near each other tended to be more similar than populations far apart. However, several exceptions were found, which are suggested to result from founder effect. In most populations, the genotype frequencies deviated significantly from the Hardy-Weinberg equilibrium. These deviations were mainly due to a deficiency of heterozygous individuals, which is believed to be caused by different selection coefficients acting against particular genotypes.