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Landscape evolution and phylogeography of Micrablepharus atticolus (Squamata, Gymnophthalmidae), an endemic lizard of the Brazilian Cerrado

Authors


Abstract

Aim

Our aims were to investigate the spatial genetic structure of Micrablepharus atticolus and to assess the relative importance of differentiation in plateaus versus depressions, in areas of historical stability versus instability, and in central versus peripheral regions.

Location

The Brazilian Cerrado.

Methods

We compared the elevational range of M. atticolus with that of its sister species, Micrablepharus maximiliani, to investigate their putative elevational segregation. We identified past (6, 21 and 130 ka) and current variables associated with the distribution of M. atticolus. Based on cytochrome b sequences, we compared genetic diversity indexes and neutrality statistics between plateau/depression, stable/unstable and core/periphery populations. We identified geographically homogeneous and maximally differentiated groups of populations and tested the association between genetic and geographical distances. Finally, we traced elevational range on the phylogeny and tested for a significant phylogenetic signal associated with elevation.

Results

We found no elevational segregation between M. atticolus and M. maximiliani. There is high genetic diversity and structuring among populations, with the primary differentiation occurring between north-eastern and south-western Cerrado localities. We recognized three main groups of populations that roughly correspond to the southern, central-northern and north-western portions of the Cerrado, which diverged between 3.5 and 1.5 Ma. Genetic diversity indices indicated no differences between plateaus and depressions or stable and unstable areas, but samples from peripheral isolates in south-western Amazonia exhibited low haplotype and nucleotide diversity and signs of population expansion.

Main conclusions

The diversification of M. atticolus in the Cerrado was primarily affected by events in the late Neogene. We found no support for the plateau/depression and stability/instability hypotheses, but we did find support for the core/periphery hypothesis. The spatial patterns seemingly resulted from a combination of shifting environmental conditions during climatic cycles, with repeated colonizations of plateaus and depressions, isolation by distance, and divergence in and recolonization of peripheral isolates within Amazonia.

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