ABSTRACT
The South American Dry Diagonal, also called the Diagonal of Open Formations, is a large region of seasonally dry vegetation extending from northeastern Brazil to northern Argentina, comprising the Caatinga, Cerrado, and Chaco subregions. A growing body of phylogeography literature has determined that a complex history of climatic changes coupled with more ancient geological events has produced a diverse and endemic-rich Dry Diagonal biota. However, the exact drivers are still under investigation, and their relative strengths and effects are controversial. Pleistocene climatic fluctuations structured lineages via vegetation shifts, refugium formation, and corridors between the Amazon and Atlantic forests. In some taxa, older geological events, such as the reconfiguration of the São Francisco River, uplift of the Central Brazilian Plateau, or the Miocene inundation of the Chaco by marine incursions, were more important. Here, we review the Dry Diagonal phylogeography literature, discussing each hypothesized driver of diversification and assessing degree of support. Few studies statistically test these hypotheses, with most support drawn from associating encountered phylogeographic patterns such as population structure with the timing of ancient geoclimatic events. Across statistical studies, most hypotheses are well supported, with the exception of the Pleistocene Arc Hypothesis. However, taxonomic and regional biases persist, such as a proportional overabundance of herpetofauna studies, and the under-representation of Chaco studies. Overall, both Pleistocene climate change and Neogene geological events shaped the evolution of the Dry Diagonal biota, though the precise effects are regionally and taxonomically varied. We encourage further use of model-based analyses to test evolutionary scenarios, as well as interdisciplinary collaborations to progress the field beyond its current focus on the traditional set of geoclimatic hypotheses.
Subject(s)
Phylogeography , Climate Change , South America , Biodiversity , Tropical ClimateABSTRACT
RESUMEN La composición de la dieta constituye información básica sobre la historia natural de la especie. A pesar de la cantidad de datos adquiridos en los últimos años, aún queda mucho por conocer, especialmente para especies geográficamente extendidas. Aquí compilamos los elementos dietéticos disponibles de Leptodactylus vastus y reportamos el primer evento de depredación de Rupirana cardosoi por un juvenil de L. vastus. El hecho de que estas especies sean sintópicas en la región probablemente resultó en este nuevo evento de depredación. A diferencia de las observaciones previas de depredación de L. vastus, los especímenes que observamos no presentan una diferencia notable en el tamaño corporal, pero L. vastus fue capaz de casi tragar R. cardosoi, en coherencia con los hallazgos de que el tamaño de la boca está relacionado con la selección de presas en los anuros. Además, nuestra revisión de la literatura mostró que L. vastus es un depredador generalista y oportunista, que se alimenta de pequeños vertebrados (Amphibia, Squamata y Mammalia).
ABSTRACT Diet composition constitutes basic information on the natural history of the species. Despite the amount of data acquired in the last years, much remains to be known specially for geographically widespread species. Here we compiled the available dietary items of Leptodactylus vastus and report the first predation event upon Rupirana cardosoi by a juvenile L. vastus. The fact these species are syntopic in the region probably resulted in this novel predation event. Different from previous L. vastus predation observations, the specimens we observed do not present a striking difference in body size, but L. vastus was able to almost swallow L. cardosoi, coherent with findings that mouth size is related to prey selection in anurans. Also, our literature review showed that L. vastus is a generalist and opportunistic predator, that prey upon small vertebrates (Amphibia, Squamata, and Mammalia).
