Many studies propose that Quaternary climatic cycles contracted and/or expanded the ranges of species and biomes. Strong expansion-contraction dynamics of biomes presume concerted demographic changes of associated fauna. The analysis of temporal concordance of demographic changes can be used to test the influence of Quaternary climate on diversification processes. Hierarchical approximate Bayesian computation (hABC) is a powerful and flexible approach that models genetic data from multiple species, and can be used to estimate the temporal concordance of demographic processes. Using available single-locus data, we can now perform large-scale analyses, both in terms of number of species and geographic scope. Here, we first compared the power of four alternative hABC models for a collection of single-locus data. We found that the model incorporating an a priori hypothesis about the timing of simultaneous demographic change had the best performance. Second, we applied the hABC models to a data set of seven squamate and four amphibian species occurring in the Seasonally Dry Tropical Forests (Caatinga) in northeastern Brazil, which, according to paleoclimatic evidence, experienced an increase in aridity during the Pleistocene. If this increase was important for the diversification of associated xeric-adapted species, simultaneous population expansions should be evident at the community level. We found a strong signal of synchronous population expansion in the Late Pleistocene, supporting the increase of the Caatinga during this time. This expansion likely enhanced the formation of communities adapted to high aridity and seasonality and caused regional extirpation of taxa adapted to wet forest.

Abstract:We studied the richness and distribution of anuran species on different breeding sites at the Reserva Ecológica da Michelin (13° 50' S and 39° 10' W, approximately 90-400 m above sea level), Municipality of Igrapiúna, Bahia State, Brazil. The reserve includes fragments of Atlantic Rain Forest varying from 140 to 650 ha. Five types of environments were sampled: leaf litter inside forest fragments, streams inside forest fragments, dam on the edge of forest fragment, temporary pond inside forest, and temporary ponds inside banana and rubber groves along the eastern boundary of the reserve. We used active and passive sampling methods for surveys of amphibians, between March 2007 and December 2008. We captured 48 species distributed in 10 families (number of species in parentheses): Aromobatidae (1), Brachycephalidae (4), Bufonidae (2), Craugastoridae (1), Centrolenidae (1), Cycloramphidae (3), Hylidae (29), Leiuperidae (1), Leptodactylidae (3), and Microhylidae (3). Temporary ponds presented the highest number of species in reproductive activity (19 species in native forested areas, and 21 in plantation areas), while leaf litter presented the lowest (6 species). Two species were found in bromeliads (Phyllodytes melanomystax and P. luteolus). Twenty-two species were exclusive to fragments of forest, 11 were found only in anthropized areas (dam, and rubber and banana plantations) and 15 in both environments. Aplastodiscus cavicola and Dendropsophus giesleri had their geographic distribution extended to the State of Bahia. Phasmahyla timbo and Chiasmocleis cordeiroi known only from their type localities were found in the reserve.

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Aim Phylogeographic studies show how historical and current changes in landscapes shape the geographic distribution of genetic diversity in species of animals and plants. In particular, for the species of the Diagonal of Open Formations (DOF), the compartmentalization of the Central Brazilian Plateau (CBP) during the Tertiary and climatic oscillations during the Quaternary have often been invoked to explain the origin and current patterns of biodiversity. We investigated how landscape changes and climatic oscillations shaped the distribution and diversification history of a widespread South American treefrog. Location South American Diagonal of Open Formations (DOF) including Caatinga, Cerrado, and Chaco biomes. Taxon Treefrog Boana raniceps. Methods We used a multi‐locus dataset from 288 individual frogs collected at 115 localities throughout most of the species’ distribution. We used population assignment analysis, species distribution models, historical demography models, approximate Bayesian computation and landscape genetic analyses to test alternative hypotheses of diversification. Results We found two genetic lineages that diverged during the mid‐Pleistocene with continued gene flow. Approximate Bayesian computation supported a scenario of isolation with migration until the Last Glacial Maximum, followed by more recent population expansion in north‐eastern Brazil and stability at the southwest in South America. Isolation by environment was the best predictor of genetic distance between populations, which is in accordance with their different environmental niches. As Boana raniceps is a lowland species, steep slopes in the CBP likely restrained gene flow enough to sustain population divergence. We found evidence for major range contraction during the Last Glacial Maximum, raising the possibility of synergic action of climate change and the CBP compartmentalization in regulating migration. Main conclusions Our findings highlight how landscape and climatic changes can shape the diversification of DOF biota. Past climatic fluctuations and environmental resistance due to topography acted in concert, forming a semipermeable barrier to gene flow, promoting intraspecific differentiation in a continentally distributed species.