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In this study, we used a recently developed supertrees method to test for shared phylogeographical signal in partially overlapping geographical ranges of lizards of the genus Liolaemus from the Andean Range in south-central Chile. We reconstruct mtDNA gene trees for three partially codistributed species (Liolaemus tenuis, L. lemniscatus and L. pictus), and our sampling effort is sufficient to allow statistical tests of shared signal between the combinations L. tenuis-L. pictus, and L. tenuis-L. lemniscatus. For both combinations, standardized maximum agreement subtrees scores showed statistically significant signal for shared pattern in regions of overlap, as evaluated by randomization tests (P < 0.001 and < 0.05, respectively). The matrix representation with parsimony tree obtained from the combination of the three different gene trees revealed concordant phylogeographical associations of all species, and was consistent with the geographical association of intraspecific haploclades with three Chilean bioclimatic zones. A multidimensional scaling analysis of several climate variables showed highly significant differences among these zones, which further suggests that they may have contributed to similar patterns of intraspecific divergence across all three species. In the mesomorphic zone in Central Chile, the species L. tenuis and L. lemniscatus may have codiverged in response to shared orogenic vicariant events, which likely predominated over climatic events associated with cycles of glacial advance and retreat. In the hygromorphic zone in southern Chile, however, glacial cycles likely predominated in structuring the phylogeographical histories of L. tenuis and L. pictus, although important ecological differences between these two caution against broad generalizations at this point.

We examined the role of several earth history events on the phylogeographic distribution of the catfish Trichomycterus areolatus in Chile using the cytochrome b gene. We explored three biogeographic hypotheses: that sea level changes have resulted in the isolation of populations by drainages; that glaciation has impacted genetic diversity; and that ichthyological subprovince boundaries correspond to phylogeographic breaks in our focal species. We found seven well-supported clades within T. areolatus with high levels of genetic divergence. The strongest signal in our data was for an important role of sea level changes structuring populations. Five of the seven clades mapped cleanly to the geographic landscape and breaks corresponded closely to areas of narrowest continental shelf. In addition, few haplotypes were shared between rivers within clades, suggesting that only limited local movement of individuals has occurred. There was no relationship between the levels of genetic diversity and the proportion of individual drainages covered by glaciers during the last glacial maximum. Two phylogeographic breaks within T. areolatus did match the two previously identified faunal boundaries, but we found three additional breaks, which suggests that faunal breaks have only limited utility in explaining phylogeographic patterns. These results imply that the narrow continental shelf coupled with sea level changes had a strong influence on the obligate freshwater fishes in Chile.

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