Testing the central-margin hypothesis into a phylogeographical framework in the Patagonian plant Calceolaria polyrhiza Cav.

COSACOV A.; SÉRSIC A. N.; SOSA V.; JOHNSON L.A; COCUCCI A. A.

Bariloche

Congreso; VI Southern Connection Congress; 2010

Southern Connection Comitee

Understanding the patterns and processes associated with geographical variation in population genetic and phenotypic structure across a species range is motivated by conservation concerns and constitutes an important issue in evolutionary ecology.   Recent reviews provide weak support to the accepted central-margin model. This could be the result of a preponderant effect of historical events in determining range-wide genetic structure. However, almost no study has incorporated a phylogeographical framework; therefore we report our phylogeographical study of Calceolaria polyrhiza, a perennial herb endemic to Patagonia, for the evaluation of this hypothesis. We used clDNA sequences from 590 individuals sampled from 68 localities, in the Andean forests and Patagonian steppes, covering all the species range. We tested the central-margin hypothesis at the whole species level and at different levels of the genealogy, using the geographically bounded, monophyletic lineages within the species, as independent replicates. We analyzed the geographic structure of genetic and phenotypic (i.e. variation coefficient of 14 functional phenotypic traits) variability. In general, at lower levels of the genealogy results support the central-margin hypothesis while at higher levels the effect of allopatric fragmentation, secondary contact and Pleistocene refugia dilute these patterns. The associated geographical trends in neutral and quantitative phenotypic trait variation are also discussed.