Across the southern Andes on fin: glacial refugia, drainage reversals and a secondary contact zone revealed by the phylogeographical signal of Galaxias platei in Patagonia

Abstract

We employed DNA sequence variation at two mitochondrial (control region, COI) regions from 212 individuals of Galaxias platei (Pisces, Galaxiidae) collected throughout Patagonia (25 lakes/rivers) to examine how Andean orogeny and the climatic cycles throughout the Quaternary affected the genetic diversity and phylogeography of this species. Phylogenetic analyses revealed four deep genealogical lineages which likely represent the initial division of G. platei into eastern and western lineages by Andean uplift, followed by further subdivision of each lineage into separate glacial refugia by repeated Pleistocene glacial cycles. West of the Andes, refugia were likely restricted to the northern region of Patagonia with small relicts in the south, whereas eastern refugia appear to have been much larger and widespread, consisting of separate northern and southern regions that collectively spanned most of Argentinean Patagonia. The retreat of glacial ice following the last glacial maximum allowed re-colonization of central Chile from nonlocal refugia from the north and east, representing a region of secondary contact between all four glacial lineages. Northwestern glacial relicts likely followed pro-glacial lakes into central Chilean Patagonia, whereas catastrophic changes in drainage direction (Atlantic --> Pacific) for several eastern palaeolakes were the likely avenues for invasions from the east. These mechanisms, combined with evidence for recent, rapid and widespread population growth could explain the extensive contemporary distribution of G. platei throughout Patagonia.

Spatial pattern of genetic and morphological diversity in the direct developer Acanthina monodon (Gastropoda: Mollusca)

“…only present in one location) haplotype (H2), may be the result of past glaciation processes reported for this area. Genetic evidence of postglacial recolonization in this area has recently been documented in the kelps Durvilleae antarctica (Fraser et al 2010) and Macrocystis pyrifera (Macaya & Zuccarello 2010) and also in a variety of Patagonian freshwater taxa (Cussac et al 2004, Zemlak et al 2008). For A. monodon the observations of genetic isolation, absence of genetic diversity in the most southerly location, and the star-like haplotype network observed in Clade II (Fig.…”

Quaternary phylogeography: the roots of hybrid zones

“…Several species in the wet tropics of NE Australia show multiple geographic clades with a range of genetic divergences going back into the Pliocene(Schneider et al 1998;Moritz et al 2009). Following pioneering phylogeographic work on some Amazonian small mammals(Patton and Da Silva 1998) there is now growing effort to understand the great diversity in Amazonia and elsewhere in South America and Mesoamerica (eg Quijada-Mascarenas et al 2007;Zemlak et al 2008;Daza et al 2009;. …”

Population structure and long-term decline in three species of heart urchins Abatus spp. near-shore in the Vestfold Hills region, East Antarctica

“…In addition, 2 genetic clusters were inferred both for A. ingens and A. shackletoni that suggest long-term persistence and secondary contact after the 2 populations survived in different refugia, where the populations would have diverge d. It has been proposed that ice-free areas existed on the shelf in Prydz Bay during the LGM (Domack et al 1998, O'Brien et al 1999, and these could have provided habitat for benthic organisms. Refugial populations and post-recolonization secondary population admixture has been identified in the Ross Sea (East Antarctica) in Adèlie penguins (Ritchie et al 2004) and has been documented as a genetic legacy to glacial cycles in different species from both the Southern (Zemlak et al 2008) and Northern (Hewitt 2000) Hemispheres. Additionally, the low genetic diversity and low effective population size observed for the 3 species could be associated with a relatively recent recolonization of the area.…”