Morphological and Genetic Traits of Pikeperch Sander lucioperca of the Volga–Akhtuba Aquatic System: on the Spatial Structure of a Species in the Lower Volga Basin

Resumo

Characters of external morphology and ten loci of microsatellite DNA are investigated in pikeperch Sander lucioperca from the Volga–Akhtuba water system on sites of the Akhtuba and the Volga situated 150 km from the beginning of the Volga Delta and 300 km from the dam of the Volgograd Power Plant. Significant differences in plastic characters are found between samples from the Akhtuba and the Volga. Differences are also found in the genetic diversity of pikeperch: the found alleles are more numerous in most loci and the mean value of allele diversity is higher in the sample from the Akhtuba. At the same time, the calculated distance between samples of pikeperch is not certain. However, this may follow from limitations accompanying the calculation of differentiation parameters. The allele diversity and heterosis of pikeperch from the Akhtuba and the Volga are higher than those in populations from the Baltic basin and Western Europe. The known differences in external morphology and in genetic characters indicate to the present day partial separation of the Volga pikeperch from the Akhtuba pikeperch and that the found polymorphism of morphological and genetic characters reflects the ecological plasticity of the species, which is an adaptive response to changing environmental conditions.