Estimating phenotypic heritability of sexual and unisexually reproducing rock lizards (genus Darevskia)

Abstract The difference between phenotypic and genotypic differentiation of conspecific populations is commonly used for detecting natural selection. However, phenotypic variation integrates both genetic and non-genetic components, and this may lead researchers to false conclusions. To avoid bias, the analysis of the heritability of individual phenotypic characters is important, but the means are labor–intensive and require controlled crosses. In this paper, we tried to get around these difficulties by working with a natural system comprised of the coexisting sexually reproducing lizard Darevskia portschinskii, and its daughter parthenogenetic form, Darevskia dahli. The excess of individual and between-population variation in the sexual form relative to the parthenogen was used as a measure of heritability of each of 21 scalation traits and principal components extracted from their analysis. We compared these data with microsatellite genotypes based on the analysis of five variable loci. We showed that D. portschinskii had higher individual and between-population phenotypic diversity than D. dahli. Phenotypic differences between populations of D. portschinskii (but not D. dahli) correlate with both the geographic distances and pairwise fixation indices based on the analysis of the genetic markers. This correlation substantially increased when, instead of the original phenotypic distances, the corrected Qst values are used to assess the heritability of the characters. A similar analysis pattern is recommended for various natural systems with coexisting sexually and asexually reproducing organisms.