Climate and life history influence ancestral population dynamics of two widespread Patagonian fishes

RUZZANTE D.; ZEMLAK T.; WALDE S.; CUSSAC V.; HABIT E.

Bariloche

Simposio; Simposio: Phylogeography and speciation in Patagonia: a common perspective across taxa? VI Southern Connection Congress; 2010

This presentation will summarize progress in our understanding of how paleoclimate & paleogeography interacted with ecology & life history to effect ancestral population dynamics & phylogeographic patterns within two widespread Patagonian fish groups: Percichthyidae 7 Galaxiidae. We examined variation in mtDNA/nuclear sequences in four species collected throughout their ranges: Percichthys trucha, Percilia sp, Galaxias platei and G. maculatus. We identify glacial refugia, secondary contact zones and infer patterns of demographic expansion. Several important climate events were associated with major demographic changes in P. trucha and G. platei. This last species underwent a strong bottleneck during the LGM and exhibited four deep lineages likely representing its initial division by Andean uplift, followed by further sub-division into separate glacial refugia. The more warm-adapted P. trucha showed continuous growth through the last two glacial cycles, but went through an important bottleneck ca. 180 ka. The demographic timelines obtained for the two species illustrate the continent-wide response of aquatic life in Patagonia to climate change during the Quaternary, but also show how differing ecological traits and distributions led to distinctive responses. Molecular evidence also reveals instances of drainage reversals (Atlantic-> Pacific) in G. platei and G. maculatus. G. maculatus, a diadromous species, extended its range into Argentina via the southern coastal regions.