Genetic population structure of the pelagic mollusk in the Kara Sea.

BACKGROUND

Pelagic pteropods are widespread and can play an important role in the food webs and in biosedimentation in Arctic and Subarctic ecosystems. Previous publications have shown differences in the genetic structure of populations of from populations found in the Pacific Ocean and Svalbard area. Currently, there are no data on the genetic structure of populations in the seas of the Siberian Arctic. We assessed the genetic structure of from the Kara Sea populations and compared them with samples from around Svalbard and the North Pacific.

METHODS

We examined genetic differences in from three different locations in the Kara Sea via analysis of a fragment of the mitochondrial gene COI. We also compared a subset of samples with from previous studies to find connections between populations from the Atlantic and Pacific Oceans.

RESULTS

65 individual from the Kara Sea were sequenced to produce 19 different haplotypes. This is comparable with numbers of haplotypes found in Svalbard and Pacific samples (24 and 25, respectively). Haplotypes from different locations sampled around the Arctic and Subarctic were combined into two different groups: H1 and H2. The H2 includes sequences from the Kara Sea and Svalbard, was present only in the Atlantic sector of the Arctic. The other genetic group, H1, is widespread and found throughout all populations. ϕ ST analyses also indicated significant genetic difference between the Atlantic and Pacific regions, but no differences between Svalbard and the Kara Sea.

DISCUSSION

The obtained results support our hypothesis about genetic similarity of populations from the Kara Sea and Svalbard: the majority of haplotypes belongs to the haplotype group H2, with the H1 group representing a minority of the haplotypes present. In contrast, in the Canadian Arctic and the Pacific Ocean only haplogroup H1 is found. The negative values of Fu's Fs indicate directed selection or expansion of the population. The reason for this pattern could be an isolation of the population during the Pleistocene glaciation and a subsequent rapid expansion of this species after the last glacial maximum.