Impact of glaciations on genetic diversity of pelagic mollusks: Antarctic Limacina antarctica and Arctic Limacina helicina

Abstract

Contemporary genetic constitution of marine species carries signatures of Pliocene-Pleistocene glacial cycles. Molecular studies of polar organisms show that isolation in refugia during glaciation often results in loss of genetic diversity. However, recent studies of marine organisms from the Southern Ocean have highlighted their remarkably high level of infraspecific genetic differentiation and the presence of cryptic species. Thus, demographic responses to climate change vary substantially with geography and life history. To elucidate the relative role of glacial period in driving the evolution of Antarctic and Arctic fauna we examined the genetic diversity and historical demography of the pelagic marine gastropods Limacina antarctica from Drake Passage in the Antarctic and Limacina helicina from Spitsbergen fjords in the Arctic. Diversity was assessed by comparing nucleotide sequences from part of the mitochondrial gene encoding the cytochrome c oxidase subunit I (COI). Sequences from 60 individuals of L. antarctica collected at 7 stations along Drake Passage were compared with those of 67 individuals of L. helicina from the fjords Hornsund and Isfjorden. We identified 47 different haplotypes for L. antarctica and 25 for L. helicina. No spatial genetic structure was found in either species, indicating that studied populations in each species belong to a single evolutionary unit. Demographic analyses of haplotype networks and significant negative Tajima's D and Fu's F S indices suggest recent rapid population expansion in both species. However, L. antarctica populations displayed a higher level of haplotype and nucleotide diversity than L. helicina populations, which suggests that the impact of glaciations was less prominent in L. antarctica.KEY WORDS: Polar regions · Glaciations · Limacina antarctica · Limacina helicina · Cytochrome c oxidase subunit I (COI) · Genetic diversity · Median-joining network · Bottleneck effect Resale or republication not permitted without written consent of the publisher

Biogeography and genetic diversity of the atlantid heteropods

“…Similar cryptic diversity has been identified across a range of planktonic organisms, where previously assumed wide distributions of a morphospecies have been found to consist of a number of evolutionary distinct populations, many of which have more restricted distributions ( Aurahs et al, 2009 , Bode et al, 2017 , Burridge et al, 2015 , Cornils et al, 2017 , Goetze et al, in press , Halbert et al, 2013 , Hirai et al, 2015 , Jennings et al, 2010 , Morard et al, 2009 ). This evolutionary divergence is often caused by physical separation across land masses or by ocean currents, sometimes following large scale environmental changes, such as those caused by glacial cycles or geological events ( Bowen et al, 2016 , Goetze et al, in press , Sromek et al, 2015 ). Similar patterns are revealed by the cryptic clades found in this study, which often have distributions that do not overlap with their closely related clades ( A. meteori, O. inflatus and some A. peronii and A. rosea ).…”

Novel genomic resources for shelled pteropods: a draft genome and target capture probes for Limacina bulimoides, tested for cross-species relevance

“…Analyses using the mitochondrial cytochrome oxidase subunit I (COI) and the nuclear 28S genes have revealed dispersal barriers at basin-wide scales in pteropod species belonging to the genera Cuvierina and Diacavolinia [14,15]. For Limacina helicina, the Arctic and Antarctic populations were discovered to be separate species through differences in the COI gene [16,17]. However, the use of a few molecular markers has often been insufficient to detect subtle patterns of population structure expected in high gene flow species such as marine fish and zooplankton [18][19][20].…”

Divergent ecological histories of two sister Antarctic krill species led to contrasted patterns of genetic diversity in their heat‐shock protein (hsp70) arsenal

“…But, genetic diversity reduction may be also reinforced by the past demographic history of the polar species. Climatic oscillations of the Quaternary seem to have indeed played a nonnegligible role in shaping most of the observed patterns of genetic variation in terrestrial and marine species with accentuated effects in species presently living at the highest latitudes (Hewitt 2004;Sromek et al 2015). During glacial periods, benthic organisms of Antarctica have been heavily impacted with a strong reduction in their effective population size, resulting in bottlenecks (Rogers et al 2012).…”