Climate control on ancestral population dynamics: insight from Patagonian fish phylogeography

Abstract

Changes in lake and stream habitats during the growth and retreat of Pleistocene glaciers repeatedly altered the spatial distributions and population sizes of the aquatic fauna of the southern Andes. Here, we use variation in mtDNA control region sequences to infer the temporal dynamics of two species of southern Andean fish during the past few million years. At least five important climate events were associated with major demographic changes: (i) the widespread glaciations of the mid-Pliocene (c. 3.5 Ma); (ii) the largest Patagonian glaciation (1.1 Ma); (iii) the coldest Pleistocene glaciation as indicated by stacked marine delta(18)O (c. 0.7 Ma); (iv) the last southern Patagonian glaciation to reach the Atlantic coast (180 ka); and (v) the last glacial maximum (LGM, 23-25,000 years ago). The colder-water inhabitant, Galaxias platei, underwent a strong bottleneck during the LGM and its haplotype diversity coalesces c. 0.7 Ma. In contrast, the more warm-adapted and widely distributed Percichthys trucha showed continuous growth through the last two glacial cycles but went through an important bottleneck c. 180,000 years ago, at which time populations east of the Andes may have been eliminated. Haplotype diversity of the most divergent P. trucha populations, found west of the Andes, coalesces c. 3.2 Ma. The demographic timelines obtained for the two species thus illustrate the continent-wide response of aquatic life in Patagonia to climate change during the Pleistocene, but also show how differing ecological traits and distributions led to distinctive responses.

Fishes of southern South America: a story driven by temperature

“…The colder water inhabitant, G. platei, underwent a strong bottleneck during the LGM. In contrast, the more warm-adapted and widely distributed P. trucha showed continuous population growth through the last two glacial cycles but went through an important bottleneck approximately 180 ka, which may have eliminated the eastern populations (Ruzzante et al 2008). …”

Inferring population size changes with sequence and SNP data: lessons from human bottlenecks

“…Recovering the temporal fluctuations of the population size and understanding their causes convey information about how species reacted to past events such as glacial cycles, climate change or human-driven perturbations (for example, Ruzzante et al, 2008;Mondol et al, 2009). When deciphering the potential causes of speciation, bottlenecks are also of primary interest since speciation can result from enhanced genetic drift that has been caused by bottlenecks and founder effects (Barton and Charlesworth, 1984).…”

Early Pleistocene lineages of Bagre bagre (Linnaeus, 1766) (Siluriformes: Ariidae), from the Atlantic coast of South America, with insights into the demography and biogeography of the species

“…The reduced haplotype diversity found in the southern lineage provides evidence of recent bottlenecks, possibly related to reductions in population size during the Holocene regression events (Rabassa et al, 2005;Ruzzante et al, 2008). This conclusion is supported by the significantly higher indices of nucleotide diversity found in the northern lineage (populations from the northern and semi-arid northeastern coasts of Brazil) in comparison with the southeastern lineage, i.e., the humid northeastern, eastern, and southeastern coasts of Brazil (Fig.…”