Community structure and population dynamics of small mammals in an urban-sylvatic interface area in Rio de Janeiro, Brazil

The Atlantic Forest is one of the most disturbed Brazilian biomes, with 183 out of 298 species of mammals occurring in the state of Rio de Janeiro. In this study, we aimed to characterize the diversity, community structure, and habitat use of small mammals in the FIOCRUZ Atlantic Forest Campus (CFMA), including areas of Pedra Branca State Park (PBSP, subunit Pau da Fome), state of Rio de Janeiro. We also compared species diversity and composition between two moments 15 years apart (2001 and 2012-2015) and analyzed the population dynamics of the marsupial Didelphis aurita (Wied-Neuwied, 1826). Small mammal captures were made in different habitats: sylvatic-urban interface areas near human dwellings, disturbed forest, and preserved forest areas. Five marsupial species and four rodent species were captured in both periods. There was a reduction in species richness and β diversity between the two periods, indicating that disturbances in the environment over the years may have affected the small mammal community structure. The most altered environment showed the greatest species richness and abundance, while the forest areas showed the smallest values, which may be explained by the loss of mammal species, mainly specialist species in forested areas. We identified three groups of species according to habitat preferences: one related to environments with a higher density of vegetation in upper strata - Marmosa paraguayana (Tate, 1931) and Monodelphis americana (Müller, 1776), another related to a higher density in lower forest strata - Akodon cursor (Winge, 1887), and another with no association with the investigated habitat variables - D. aurita and Oligoryzomys nigripes (Olfers, 1818). The small mammal community structure showed a low level of nestedness in both sampling periods.[...](AU)

Community structure and population dynamics of small mammals in an urban-sylvatic interface area in Rio de Janeiro, Brazil

The Atlantic Forest is one of the most disturbed Brazilian biomes, with 183 out of 298 species of mammals occurring in the state of Rio de Janeiro. In this study, we aimed to characterize the diversity, community structure, and habitat use of small mammals in the FIOCRUZ Atlantic Forest Campus (CFMA), including areas of Pedra Branca State Park (PBSP, subunit Pau da Fome), state of Rio de Janeiro. We also compared species diversity and composition between two moments 15 years apart (2001 and 2012-2015) and analyzed the population dynamics of the marsupial Didelphis aurita (Wied-Neuwied, 1826). Small mammal captures were made in different habitats: sylvatic-urban interface areas near human dwellings, disturbed forest, and preserved forest areas. Five marsupial species and four rodent species were captured in both periods. There was a reduction in species richness and β diversity between the two periods, indicating that disturbances in the environment over the years may have affected the small mammal community structure. The most altered environment showed the greatest species richness and abundance, while the forest areas showed the smallest values, which may be explained by the loss of mammal species, mainly specialist species in forested areas. We identified three groups of species according to habitat preferences: one related to environments with a higher density of vegetation in upper strata - Marmosa paraguayana (Tate, 1931) and Monodelphis americana (Müller, 1776), another related to a higher density in lower forest strata - Akodon cursor (Winge, 1887), and another with no association with the investigated habitat variables - D. aurita and Oligoryzomys nigripes (Olfers, 1818). The small mammal community structure showed a low level of nestedness in both sampling periods.[...]

Scapteromys aquaticus (Rodentia: Sigmodontinae) in Brazil with comments on karyotype and phylogenetics relationships

The swamp rats are distributed in Argentina, southern Paraguay, Uruguay and southern Brazil, with two species currently accepted: Scapteromys aquaticus Thomas, 1920 and Scapteromys tumidus Waterhouse, 1837. While S. aquaticus occurs in Argentina, Paraguay and western Uruguay, S. tumidus occurs in Brazil and Uruguay. Here we report for the first time the occurrence of S. aquaticus in gallery forest remnants in Southern Brazil. Karyologic analysis showed 2n = 32 and FNa = 40. Phylogenetic analyses, based on DNA sequences from the mitochondrial cytochrome-b gene indicate that the Brazilian and the Argentinian specimens of S. aquaticus shared one haplotype, while median joining analysis showed lack of population structure. This register, plus the karyotype data available for Brazilian population, recovered four karyomorphotypes in Brazil, corresponding to the two known species of Scapteromys and two unnamed species. This scenario indicates that more multidisciplinary studies are necessary to understand the actual diversity of Scapteromys.

Scapteromys aquaticus (Rodentia: Sigmodontinae) in Brazil with comments on karyotype and phylogenetics relationships

The swamp rats are distributed in Argentina, southern Paraguay, Uruguay and southern Brazil, with two species currently accepted: Scapteromys aquaticus Thomas, 1920 and Scapteromys tumidus Waterhouse, 1837. While S. aquaticus occurs in Argentina, Paraguay and western Uruguay, S. tumidus occurs in Brazil and Uruguay. Here we report for the first time the occurrence of S. aquaticus in gallery forest remnants in Southern Brazil. Karyologic analysis showed 2n = 32 and FNa = 40. Phylogenetic analyses, based on DNA sequences from the mitochondrial cytochrome-b gene indicate that the Brazilian and the Argentinian specimens of S. aquaticus shared one haplotype, while median joining analysis showed lack of population structure. This register, plus the karyotype data available for Brazilian population, recovered four karyomorphotypes in Brazil, corresponding to the two known species of Scapteromys and two unnamed species. This scenario indicates that more multidisciplinary studies are necessary to understand the actual diversity of Scapteromys.(AU)

Evidence of hantavirus infection in wild rodents captured in a rural area of the state of São Paulo, Brazil / Evidência de infecção por hantavírus em roedores silvestres capturados em uma área rural do estado de São Paulo, Brasil

Hantavírus é o agente etiológico da síndrome cardio-pulmonar por hantavirus (SCPH), uma importante doença transmitida por roedores no Brasil. Com o objetivo de se conhecer a ocorrência de infecção por hantavírus em pequenos roedores silvestres, uma análise sorológica foi conduzida em três diferentes áreas do subúrbio da cidade de Pedreira, São Paulo. Dos 145 animais silvestres capturados, pertecentes a 12 diferentes espécies identificadas por morfologia e por análise cariológica, 107 eram roedores das seguintes espécies: Akodon montensis, Bolomys lasiurus, Calomys tener, Oligoryzomys nigripes, Oligoryzomys flavescens, e Myocastor coypus. Amostras de sangue desses roedores foram testadas para a presença de anticorpos IgG contra o antígeno do nucleocapsídeo do vírus Andes através do teste ELISA. Reatividade sorológica ao vírus Andes foi observada em duas espécies diferentes, O. nigripes and O. flavescens. Estes resultados indicam o potencial risco de transmissão de hantaví-rus nesta região, onde roedores reservatórios freqüentemente são vistos em peridomicílio.(AU)

Hantaviruses are the etiological agents of the Hantavirus Cardio-Pulmonary Syndrome, a serious rodent-borne disease in Brazil. In order to investigate the occurrence of hantavirus infection in wild rodents, a survey was conducted in three different suburban areas of the municipality of Pedreira, State of São Paulo, Brazil. Of the 145 wild animals captured belonging to 12 different species identified by morphology and karyological analysis, 107 were rodents of the following species: Akodon montensis, Bolomys lasiurus, Calomys tener, Oligoryzomys nigripes, Oligoryzomys flavescens, and Myocastor coypus. Blood samples from these rodents were assayed for the presence of antibodies against hantavirus by IgG ELISA using Andes recombinant nucleocapsid antigen. Antibody reactive to Andes virus was found in two different species, O. nigripes and O. flavescens. These results indicate a potential risk for hantavirus transmission to humans in this area, where reservoir rodents are present in peridomestic settings.(AU)