Contrasting phylogeographical patterns for springtails reflect different evolutionary histories between the Antarctic Peninsula and continental Antarctica

Abstract

We examined the genetic structure among populations and regions for thespringtails Cryptopygus antarcticus antarcticus and Gomphiocephalus hodgsoni(Collembola) to identify potential historical refugia and subsequent colonizationroutes, and to examine population growth/expansion and relative ages ofpopulation divergence.Location Antarctic Peninsula for C. a. antarcticus; Antarctic continent (southernVictoria Land) for G. hodgsoni.Methods Samples were collected from 24 and 28 locations across the AntarcticPeninsula and southern Victoria Land regions for C. a. antarcticus andG. hodgsoni, respectively. We used population genetic, demographic and nestedclade analyses based on mitochondrial DNA (cytochrome c oxidase subunit I andsubunit II).Results Both species were found to have population structures compatiblewith the presence of historical glacial refugia on Pleistocene (2 Ma–present) timescales,followed by post-glacial expansion generating contemporary geographicallyisolated populations. However, G. hodgsoni populations were characterized by afragmented pattern with several ‘phylogroups’ (likely ancestral haplotypes presentin high frequency) retaining strong ancestral linkages among present-daypopulations. Conversely, C. a. antarcticus had an excess of rare haplotypes witha much reduced volume of ancestral lineages, possibly indicating historicalfounder/bottleneck events and widespread expansion.Main conclusions We infer that these differences reflect distinct evolutionaryhistories in each locality despite the resident species having similar life-historycharacteristics. We suggest that this has predominantly been influenced byvariation in the success of colonization events as a result of intrinsic historicalglaciological differences between the Antarctic Peninsula and continentalAntarctic environment

The spatial structure of Antarctic biodiversity

“…At glacial maxima, most of the continental shelf was covered by ice, restricting fauna to isolated refugia or forcing them into deeper water (Thatje et al 2005). Cycles of contraction to refugia followed by re-expansion are likely to have been a major influence on evolution in the Antarctic marine fauna (Clarke and Crame 1989, 1997, Fraser et al 2012, and increasingly it appears also on the Antarctic and sub-Antarctic terrestrial biota, which also shows substantial endemism (Greve et al 2005, McGaughran et al 2010, Grobler et al 2011, Mortimer et al 2011a.…”

“…Within the continent itself, patterns are most distinct, with little overlap between Peninsula/Scotia arc invertebrate faunas and those of Patagonia/South America. There is increasing molecular and classical biogeographic evidence for ancient radiations and vicariance (e.g., Allegrucci et al 2006, Maslen and Convey 2006, Chown and Convey 2007, and/or expansion from refugial centers within the region itself, and survival through (at least) multiple Pleistocene glacial cycles , McGaughran et al 2010, Mortimer et al 2011a). Even apparently highly dispersible groups such as some Antarctic soil microbiota carry a strong signal of long-term geographical isolation, suggesting that local radiation on evolutionary timescales has outweighed the influence of incoming dispersers (De Wever et al 2009, Chong et al 2012, Peeters et al 2012).…”

Colonization of the Aeolian Islands byPimelia rugulosa rugulosaGermar, 1824 (Coleoptera: Tenebrionidae) inferred from the genetic structure of populations: geological and environmental relations

“…Furthermore, owing to its reduced coalescence time, the possibility of observing groups of haplotypes that are associated with structured populations and that reflect their historical patterns of diversification is maximized, making it an excellent tool for phylogeographic investigations (Juan et al, 1995;Emerson & Oromi, 2000;Lohman et al, 2008). The mitochondrial gene cytochrome c oxidase subunit 2 (cox2) has been repeatedly used to address phylogenetic and phylogeographic questions in insects and beetles (Gòmez-Zurrita et al, 2000;Rees et al, 2001;Contreras-Diaz et al, 2003;Suzuki et al, 2004;Emerson & Oromi, 2005;Machado et al, 2008;Moraes et al, 2009;McGaughran et al, 2010) and has proved to be informative with regards to the colonization patterns of the genus Pimelia in Sicily (Stroscio et al, 2011).…”

Biological invasions in terrestrial Antarctica: what is the current status and can we respond?

“…The majority of areas of exposed terrestrial ground are isolated, small and island-like (Bergstrom and Chown 1999;Arnold et al 2003;Hughes et al 2006), factors that are important in driving the evolutionary isolation, divergence and high levels of regional endemism that appear to characterise Antarctic biota (Chown and Convey 2007;Pugh and Convey 2008). Even within the McMurdo Dry Valleys of southern Victoria Land, by far the most extensive area of ice-free ground within the continent, studies of microbial and arthropod communities report signals of isolation and divergence within valleys and catchments (McGaughran et al 2008(McGaughran et al , 2010Chan et al 2013). Isolation, high levels of endemism and a general lack of inter-species competition within many native terrestrial Antarctic communities may make them particularly vulnerable to the impacts of invasive species (Chown and Convey 2007;.…”