Genetic diversity among populations of Antarctic springtails (Collembola) within the Mackay Glacier ecotone

Abstract

Climate changes are likely to have major influences on the distribution and abundance of Antarctic terrestrial biota. To assess arthropod distribution and diversity within the Ross Sea region, we examined mitochondrial DNA (COI) sequences for three currently recognized species of springtail (Collembola) collected from sites in the vicinity, and to the north of, the Mackay Glacier (77°S). This area acts as a transition between two biogeographic regions (northern and southern Victoria Land). We found populations of highly divergent individuals (5%-11.3% intraspecific sequence divergence) for each of the three putative springtail species, suggesting the possibility of cryptic diversity. Based on molecular clock estimates, these divergent lineages are likely to have been isolated for 3-5 million years. It was during this time that the Western Antarctic Ice Sheet (WAIS) was likely to have completely collapsed, potentially facilitating springtail dispersal via rafting on running waters and open seaways. The reformation of the WAIS would have isolated newly established populations, with subsequent dispersal restricted by glaciers and ice-covered areas. Given the currently limited distributions for these genetically divergent populations, any future changes in species' distributions can be easily tracked through the DNA barcoding of springtails from within the Mackay Glacier ecotone. Key words: Antarcticinella monoculata, biomonitoring, climate change, Cryptopygus nivicolus, Gomphiocephalus hodgsoni.Résumé : Les changements climatiques antérieurs ont vraisemblablement eu des impacts importants sur la distribution et l'abondance du biota terrestre antarctique. Afin de mesurer la distribution et la diversité des arthropodes dans la région de la Mer de Ross, nous avons examiné les séquences mitochondriales (COI) chez trois espèces connues de collemboles récoltés à proximité ou encore au nord du glacier Mackay (77°S). Cette région marque aussi la transition entre deux régions biogéographiques (régions septentrionale et méridionale de la terre de Victoria). Nous avons trouvé des populations constituées d'individus fortement divergents (5 % -11,3 % de divergence nucléotidique intraspécifique) au sein des trois espèces de collemboles, ce qui suggère la possibilité d'une diversité cryptique. Sur la base d'horloges moléculaires, ces groupes divergents seraient isolés depuis 3 à 5 millions d'années. C'est durant cette période que l'inlandis ouest-antarctique (WAIS, « Western Antarctic Ice Sheet ») se serait complètement effondré, ce qui aurait pu faciliter la dispersion des collemboles sur des radeaux de glace flottant sur des cours d'eau ou la mer. La reconstitution de la WAIS pourrait avoir ensuite isolé des populations nouvellement établies, la dispersion subséquente ayant été limitée par les glaciers et les zones couvertes de glace. Étant données les distributions présentement limitées des distributions de ces populations divergentes sur le plan génétique, tout futur changement dans la distribution de ces espèces de...

Nutrient parsimony shapes diversity and functionality in hyper-oligotrophic Antarctic soils

“…The ∼100km region north of the Mackay Glacier, Eastern Antarctica (Fig. 1) is suggested to be a transitional zone, based on differences in physicochemical features [18] and invertebrate biodiversity compared with surrounding regions [18, 19]. The patchy distribution of micro-invertebrates in the Mackay Glacier region differs substantially from that in the Dry Valleys [20], which is consistent with observations of species patchiness across other transitional zones [21].…”

Spatial and Temporal Scales Matter When Assessing the Species and Genetic Diversity of Springtails (Collembola) in Antarctica

“…However, patterns of population structure vary among the three species. For example, individuals of G. hodgsoni at Mount Gran (n = 3) showed sequence divergences of 7.6% (Bennett et al, 2016), while individuals of C. nivicolus from Mount Gran (n = 7) were similar to those from other nearby sites such as Mount Seuss and Mount England (Beet et al, 2016). No sites were found with all three species present.…”

“…These data have enhanced understanding of their evolutionary histories and allowed testing of hypotheses, such as endemism of the fauna, proposed by earlier researchers (e.g., Wise, 1967). Further, they have provided insights into the long-term persistence of endemic taxa, their survival in refugia and subsequent expansion during interglacial periods (e.g., Convey et al, 2008;McGaughran et al, 2011b;Beet et al, 2016;Carapelli et al, 2017). In turn, this has facilitated predictions as to how populations may respond to future changes in habitat availability and environmental conditions (e.g., Chown and Convey, 2007;Lee et al, 2017).…”

From Barcodes to Biomes: Special Issues from the 6th International Barcode of Life Conference

“…Beet et al (2016) use DNA barcoding to characterize the diversity and distributions of springtail species (Collembola) in a region of Antarctica. Their work reveals historical genetic structuring and establishes a baseline for future biomonitoring in this remote region, which may be influenced by climate change and other impacts.…”