Pleistocene glaciation leaves deep signature on the freshwater crab Aegla alacalufi in Chilean Patagonia

Abstract

Quaternary glacial cycles have played an important role in shaping the biodiversity in temperate regions. This is well documented in Northern Hemisphere, but much less understood for Southern Hemisphere. We used mitochondrial DNA and nuclear elongation factor 1α intron sequences to examine the Pleistocene glacial impacts on the phylogeographical pattern of the freshwater crab Aegla alacalufi in Chilean Patagonia. Phylogenetic analyses, which separated the glaciated populations on eastern continent into a north group (seven populations) and a south group (one population), revealed a shallow phylogenetic structure in the north group but a deep one in the non-glaciated populations on western islands, indicating the significant influence of glaciation on these populations. Phylogenies also identified the Yaldad population on Chiloé Island as a potentially unrecognized new species. The non-glaciated populations showed higher among population genetic divergence than the glaciated ones, but lower population genetic diversity was not detected in the latter. The two glaciated groups, which diverged from the non-glaciated populations at ~96,800-29,500 years ago and ~104,200-73,800 years ago, respectively, seem to have different glacial refugia. Unexpectedly, the non-glaciated islands did not serve as refugia for them. Demographic expansion was detected in the glaciated north group, with a constant population increase after the last glacial maximum. Nested clade analyses suggest a possible colonization from western islands to eastern continent. After arriving on the continent and surviving the last glacial period there, populations likely have expanded from high to low altitude, following the flood of melting ice. Aegla alacalufi genetic diversity has been primarily affected by Pleistocene glaciation and minimally by drainage isolation.

A comprehensive and integrative reconstruction of evolutionary history for Anomura (Crustacea: Decapoda)

“…Their morphological and ecological diversity are of doubtless scientific interest, but anomurans also represent an important economic commodity as evident in major commercial fisheries for some king crab and squat lobster genera [3-5] and the common use of hermit crabs as pets in the aquarium trade. Moreover, some species are threatened or endangered due to rarity in nature, e.g., Pylochelidae [6], overfishing, e.g., Lithodidae [7], or habitat loss, e.g., Aeglidae [8-10]. Thus, improved understanding of these groups bears not only on appreciation of their diversity and ecology, but also strategies for their conservation.…”

Genetic structure of the giant kelp Macrocystis pyrifera along the southeastern Pacific

“…2). The impact of glaciations on the distribution and genetic variation of species in southern Chile has been documented, but mostly for terrestrial (Muellner et al 2004, Marchelli & Gallo 2006, Himes et al 2008, Rodriguez-Serrano et al 2008, Victoriano et al 2008 or freshwater biota , Xu et al 2009). A recent colonization, after the LGM and the retreat of sea ice, of Durvillaea antarctica in the subantarctic region by a series of long-distance rafting events has been suggested (Fraser et al 2009).…”

Geothermal activity helps life survive glacial cycles

“…These studies include the inferred persistence of a subterranean amphipod species in geothermally created refugia under the Icelandic ice cap (9), of a Patagonian crab in hot springs (10), of bryophytes on the isolated South Sandwich Islands of the maritime Antarctic (11), and of marine life during Snowball Earth glaciations in the Neoproterozoic (12). No comprehensive assessment of this "geothermal glacial refugia" hypothesis (11) has, however, yet been undertaken.…”