Lineage-specific trait variations and plasticity of obligate parthenogenetic animals following the expansion of distribution range to a continental archipelago.

Two asexual lineages, JPN1 and JPN2, of panarctic Daphnia pulex expanded the distribution range to Japan from North America, independent of each other. According to the mutation rates within these lineages, JPN1 lineage colonized Japan earlier than JPN2 lineage. Moreover, the ratio of nonsynonymous to synonymous mutation rates (dN/dS) was lower in JPN1 than in JPN2 lineage.
Accordingly, it is hypothesized that variations of phenotypic traits differ between these two lineages. In addition, since they are obligate parthenogenetic animals, the lineage occupying a larger distribution range should have a larger phenotypic plasticity. To test these hypotheses, we experimentally examined the phenotypic variations of fitness-related traits, including digestive, life history and morphological traits, among several genotypes of these lineages.
We found that within-lineage variations of most traits were smaller in JPN1 than in JPN2. In addition, the overall phenotypic variations were also smaller ...