Search

Aim: To test three different scenarios to account for the geographic distribution of genetic variation in Dermatonotus muelleri, a fossorial frog endemic of the South American diagonal of open formations (DOF) formed by Chaco, Cerrado, and Caatinga biomes: (a) The pan‐DOF hypothesis, where these biomes behave as a single biogeographical unit and DOF species lack population structure; (b) the southwest‐northeast (SW‐NE) hypothesis, where structured populations along the DOF have either asymmetric or unidirectional gene flow in the northeast direction; (c) the vicariance hypothesis, where a pattern of population structure with no or reduced gene flow is observed. Location: Caatinga, Cerrado, and Chaco in South America. Methods: We sampled 179 individuals across the species distribution and sequenced one mitochondrial and two nuclear markers. We evaluated population structure, the presence, direction, and asymmetry of gene flow, and demographic changes to test three different phylogeographic hypotheses for D. muelleri using a model‐based simulation approach. Results: We found two geographically structured lineages with no gene flow, refuting pan‐DOF hypothesis. The Southwest lineage occurs in Chaco and western Cerrado and the Northeast lineage in eastern Cerrado and Caatinga. Our results support the model with demographic change for the Northeast lineage and constant size for Southwest lineage. The vicariance model with divergence time estimated around 4 Ma was preferred. Main conclusions: Vicariance was the best explanation for the geographic distribution of genetic variation in Dermatonotus. Divergence time supports the role of Neogene orogeny in central Brazil for the splitting of Dermatonotus lineages. The influence of Pleistocene climatic fluctuations seems restricted to changes in one lineage's population size. Therefore, both ancient and recent events shaped the phylogeography of Dermatonotus. Genetic divergence, lack of gene flow, and the presence of a geographic barrier between lineages indicate the existence of a cryptic, undescribed species in northeastern Brazil. [ABSTRACT FROM AUTHOR]

Anole lizards represent one of the best studied radiations of terrestrial vertebrates. Herein we examine the autecology of Anolis brasiliensis from the Cerrado of central Brazil, based on a large amount of data collected across much of its geographic range. Species Distribution Modelling (SDM) techniques revealed that A. brasiliensis likely has a wider distribution than currently verified. For ecological comparisons, we tested whether i) body temperature is influenced by microhabitat, ii) sexes differ in diet, iii) sexes differ in morphology, and iv) climatic variables influence reproduction. Lizards were collected primarily in seasonally dry forests and gallery forests. Body temperature is strongly associated with air temperature at 5 cm above the substrate. The most important diet items were Araneae, Orthoptera and Formicidae, and high diet niche overlap exists between sexes. Females are significantly larger in body size than males. Males, however, have larger heads than females. Due to allochronic ovulation, A. brasiliensis largely have clutches with single eggs. Females often contain an oviductal egg and an enlarged vitellogenic follicle, suggesting the production of multiple clutches largely in the rainy season from October to January. Recruitment occurred mostly from January to April. Anolis brasiliensis is ecologically more similar to other anoles than to sympatric lizards in other major clades. These results reiterate the impact of evolutionary history on ecological and life history traits of squamate reptiles. [ABSTRACT FROM AUTHOR]

The niche expansion and niche variation hypotheses predict that release from interspecific competition will promote niche expansion in depauperate assemblages. Niche expansion can occur by different mechanisms, including an increase in within-individual, among-individual, or bimodal variation (sexual dimorphism). Here we explore whether populations with larger niche breadth have a higher degree of diet variation. We also test whether populations from depauperate lizard assemblages differ in dietary resource use with respect to variation within and/or among individuals and sexual dimorphism. We found support for the niche expansion and niche variation hypotheses. Populations in assemblages with low phylogenetic diversity had a higher degree of individual variation, suggesting a tendency for niche expansion. We also found evidence suggesting that the mechanism causing niche expansion is an increase in variation among individuals rather than an increase in within-individual variation or an increase in bimodal variation due to sexual dimorphism. [ABSTRACT FROM AUTHOR]

We evaluate the hypothesis, originally proposed for arid Australia, that abundant and diverse termite assemblages can promote lizard radiation, based on a reappraisal of published data and on new data from the Cerrado biome in central Brazil. We found a positive correlation between termite and lizard richness in Cerrado. However, termite abundance and richness cannot actively drive lizard speciation, but can be important in maintaining lizard richness. Cerrado shares with arid Australia a rich and abundant termite fauna, but local Cerrado lizard assemblages are relatively impoverished. We suggest that differences in lizard richness between Cerrado and arid Australia may be explained by a combination of variations in area and latitude controlling speciation rates and present-day ecological factors moderating extinction rates. [ABSTRACT FROM AUTHOR]