The Neotropics harbors a high diversity of species and several hypotheses have been proposed to account for this pattern. However, while species of forested domains are frequently studied, less is known of species from open vegetation formations occupying, altogether, a larger area than the Amazon Forest. Here we evaluate the role of historical barriers and the riverine hypothesis in the speciation patterns of small mammals by analyzing an ancient rodent lineage (Thrichomys, Hystricomorpha). Phylogenetic and biogeographic analyses were carried out with mitochondrial and nuclear DNA markers to analyze the evolutionary relationships between Thrichomys lineages occurring in dry domains along both banks of the Rio São Francisco. This river is one of the longest of South America whose course and water flow have been modified by inland tectonic activities and climate changes. Molecular data showed a higher number of lineages than previously described. The T. inermis species complex with 2n = 26, FN = 48 was observed in both banks of the river showing a paraphyletic arrangement, suggesting that river crossing had occurred, from east to west. A similar pattern was also observed for the T. apereoides complex. Thrichomys speciation occurred in Late Miocene when the river followed a different course. The current geographic distribution of Thrichomys species and their phylogenetic relationships suggested the existence of frequent past connections between both banks in the middle section of the Rio São Francisco. The extensive palaeodune region found in this area has been identified as a centre of endemism of several vertebrate species and is likely to be a center of Thrichomys diversification.

No abstract

Abstract:The Volta Grande Environmental Unity represents one of the few remnants of Cerrado protected by a reserve in the Triângulo Mineiro region, municipalities of Conceição das Alagoas (19°55' S, 48°23' W) and Miguelópolis (20°12' S, 48°03' W), in the states of Minas Gerais and São Paulo, respectively. The mammalian fauna of this reserve was inventoried between 2003 and 2004 to generate estimates about taxonomic composition, richness, and abundance of species. A sampling effort of 832 trapping-nights resulted in 24 species recorded. Cumulative curves suggest that the overall inventory is not complete and that more species are likely to be registered. The majority of species recorded is widespread along the Cerrado, but include some noteworthy records of endangered species, such as the Giant anteater (Myrmecophaga tridactyla) and the Manned wolf (Chrysocyon brachyurus). The record of the arboreal cricetid rodent Oecomys bicolor represents a slight extension of the southeastern limit of its distribution.

Thrichomys fosteri (Rodentia, Echimyidae) is a terrestrial spiny rat displaying frugivorous/ herbivorous diet. Then, why eventually this terrestrial species uses the understory? Here, we report two events of use of understory for fruit feeding by the spiny rat. Monthly from October 2015 through July 2016, we sampled three sites in one woodland savannah fragment in the Pantanal ecoregion. Each site was 1 km apart from each other, and present five camera traps on understory (1.5 m height) in front of different fruit plant species. With an effort of 350 camera trap-days, we recorded twice the punaré on branch of Randia armata (Rubiaceae) feeding on its fruits. Our results highlight a feeding behaviour on understory by the terrestrial spiny rat, which contribute to the understanding of the species' natural history as well as point out questions for further investigations.