Vinícius Xavier da Silva

Phylogenetic relationships within Bothrops neuwiedi group (Serpentes, Squamata): Geographically highly-structured lineages, evidence of introgressive hybridization and Neogene/Quaternary diversification

Eight current species of snakes of the Bothrops neuwiedi group are widespread in South American open biomes from northeastern Brazil to southeastern Argentina. In this paper, 140 samples from 93 different localities were used to investigate species boundaries and to provide a hypothesis of phylogenetic relationships among the members of this group based on 1122bp of cyt b and ND4 from mitochondrial DNA and also investigate the patterns and processes occurring in the evolutionary history of the group. Combined data recovered the B. neuwiedi group as a highly supported monophyletic group in maximum parsimony, maximum likelihood and Bayesian analyses, as well as four major clades (Northeast I, Northeast II, East-West, West-South) highly-structured geographically. Monophyly was recovered only for B. pubescens. By contrast, B. diporus, B. lutzi, B. erythromelas, B. mattogrossensis, B. neuwiedi, B. marmoratus, and B. pauloensis, as currently defined on the basis of morphology, were polyphyletic. Sympatry, phenotypic intergrades and shared mtDNA haplotypes, mainly between B. marmoratus and B. pauloensis suggest recent introgressive hybridization and the possible occurrence of a narrow hybrid zone in Central Brazil. Our data suggest at least three candidate species: B. neuwiedi from Espinhaço Range, B. mattogrossensis (TM173) from Serra da Borda (MT) and B. diporus (PT3404) from Castro Barros, Argentina. Divergence estimates highlight the importance of Neogene events in the origin of B. neuwiedi group, and the origin of species and diversification of populations of the Neotropical fauna from open biomes during the Quaternary climate fluctuations. Data reported here represent a remarkable increase of the B. neuwiedi group sampling size, since representatives of all the current recognized species from a wide geographic range are included in this study, providing basic information for understanding the evolution and conservation of Neotropical biodiversity.

Natural history of the lizard Enyalius perditus (Squamata: Leiosauridae) from an Atlantic forest remnant in southeastern Brazil

The natural history of the lizard Enyalius perditus was studied from August 2005 to July 2006, at Parque Estadual Nova Baden, in the municipality of Lambari, State of Minas Gerais, south-eastern Brazil. We found that E. perditus may be considered a semi-arboreal species, like other species in the genus, sleeping on vegetation (slim branches or large leaves) at night, possibly to minimize predation. Females with enlarged follicles or oviducal eggs were found from November to January and juveniles recruited at the end of the dry season and beginning of the rainy season, in October. The diet of this lizard is composed mainly of Lepidoptera larvae, Araneae and Formicidae. Females were larger than males, and juvenile coloration is similar to that of adult females.

Demographic parameters of Akodon montensis (Mammalia: Rodentia) in an Atlantic Forest remnant of Southeastern Brazil.

Abstract Small mammals seem to be affected by edge effects, hence understanding the local dynamics of these populations is important to assess the risks to which they are exposed. The objective of this study was to compare population size, sex ratio and home range size of the rodent Akodon montensis (Cricetidae) between the edge and interior of an Atlantic Forest fragment in the dry (June-August) and rainy (December-February) seasons. The population was sampled using capture-mark-recapture methods and a spool-and-line device was used to map the movements. The population size was significantly higher in the rainy season relative to the dry season, and this pattern can be related to the higher food availability in this period, as observed in other studies. However, there was no difference in the number of individuals captured in the edge and interior. The home range size showed no significant differences between edge and interior and between males and females, although, in a general way, the females showed a greater home range size related to the males. The absence of differences between edge and interior could result from the small size of the remnants and extrapolation of edge conditions to the interior.

Food Storage by the Savanna Termite Cornitermes cumulans (Syntermitinae): a Strategy to Improve Hemicellulose Digestibility?

It has been suggested that food storage inside the nest may offer termites with a nutritional provision during low resource availability. Additionally, feces employed as construction material provide an excellent environment for colonization by microorganisms and, together with the storage of plant material inside the nest, could thus provide some advantage to the termites in terms of lignocellulose decomposition. Here, we conducted for the first time a comprehensive study of the microbial communities associated to a termite exhibiting food storage behavior using Illumina sequencing of the 16S and (ITS2) regions of rRNA genes, together with enzymatic assays and data collected in the field. Cornitermes cumulans (Syntermitinae) stored grass litter in nodules made from feces and saliva located in the nest core. The amount of nodules increased with nest size and isolation, and interestingly, the soluble fraction of extracts from nodules showed a higher activity against hemicellulosic substrates compared to termite guts. Actinobacteria and Sordariales dominated microbial communities of food nodules and nest walls, whereas Spirochetes and Pleosporales dominated gut samples of C. cumulans. Within Syntermitinae, however, gut bacterial assemblages were dissimilar. On the other hand, there is a remarkable convergence of the bacterial community structure of Termitidae nests. Our results suggest that the role of nodules could be related to food storage; however, the higher xylanolytic activity in the nodules and their associated microbiota could also provide C. cumulans with an external source of predigested polysaccharides, which might be advantageous in comparison with litter-feeding termites that do not display food storage behavior.

Fragment edge and isolation affect the food web: effects on the strength of interactions among trophic guilds

Habitat loss and fragmentation are processes that may affect communities by changing species interactions. These changes occur because the strength of linkages between species is not exclusively dependent on predator and prey traits. Species interaction changes also depend on the spatial context in which they take place. We used structural equation modelling to evaluate effects of these processes at patch-scale on top-down and bottom-up controls in food webs in Atlantic Forest. The model was composed of multiple species, and trophic guilds responded differently to fragment edge and isolation. Changes in bottom-up and top-down controls were mainly related to intermediate predator interactions. Efforts to restore connectivity among fragments should help recover the equilibrium of the trophic interactions by benefiting intermediate predators.

New records of snakes (Reptilia: Squamata) in Minas Gerais, Brazil

We report new records of three poorly-known species of snakes in Minas Gerais: Bothrops lutzi (Miranda- Ribeiro, 1915), Psomophis joberti (Sauvage, 1884), and Trilepida brasiliensis (Laurent, 1949). The new records represent important filling gaps for all three species or even southern extensions in the geographic distribution of B. lutzi and P. joberti . The new records are located in areas indicated as priority regions for biodiversity conservation in Cerrado. Maps of known records of these snakes are also provided considering literature data and new records from collections.