Jonas Sponchiado

Chewing on the trees: Constraints and adaptation in the evolution of the primate mandible.

Chewing on different food types is a demanding biological function. The classic assumption in studying the shape of feeding apparatuses is that animals are what they eat, meaning that adaptation to different food items accounts for most of their interspecific variation. Yet, a growing body of evidence points against this concept. We use the primate mandible as a model structure to investigate the complex interplay among shape, size, diet, and phylogeny. We find a weak but significant impact of diet on mandible shape variation in primates as a whole but not in anthropoids and catarrhines as tested in isolation. These clades mainly exhibit allometric shape changes, which are unrelated to diet. Diet is an important factor in the diversification of strepsirrhines and platyrrhines and a phylogenetic signal is detected in all primate clades. Peaks in morphological disparity occur during the Oligocene (between 37 and 25 Ma) supporting the notion that an adaptive radiation characterized the evolution of South American monkeys. In all primate clades, the evolution of mandible size is faster than its shape pointing to a strong effect of allometry on ecomorphological diversification in this group.

Diversidade de Lepidoptera (Papilionoidea e Hesperioidea) em dois fragmentos de floresta no município de Frederico Westphalen, Rio Grande do Sul, Brasil

A systematic survey was carried out in two localities of the Municipal District of Frederico Westphalen, fragment of Villa Faguense and Schoenstatts Sanctuary, situated 1,500 m apart, from March 2005 to April 2006. In 140 hours of sampling, 3123 individuals, distributed in 169 species, were registered. Nymphalidae was the most sampled with approximately 53% of the recorded species. Nine species sampled were still no registered for the State. The Shannon-Wiener diversity index was higher in fragment of Villa Faguense, place less disturbed. The Simpson and Berger-Parker dominance indexes had been more representative in fragment of Schoenstatt Sanctuary, with higher number of abundant species. Among the species captured 126 (74,55%) are accidental, 25 (14,80%) are accessory and 18 (10,65%) are constant.

In and Out the Amazonia: Evolutionary Ecomorphology in Howler and Capuchin Monkeys

The impact of environmental variation on phenotypic diversification is one major issue in evolutionary studies. Environmental variation is thought to be a primary factor in evolution, especially at high latitudes. In contrast, tropical areas are traditionally viewed as the cradle where the long-term effects of biological interactions on phenotypic change reside. We analyse patterns of skull shape variation in two New World monkey groups: capuchins and howlers. These two monophyletic clades are exceptionally similar in terms of the geographic distribution of their species. Yet, their body size and diet are different: howler monkeys are large and almost exclusively folivorous, whereas capuchins are small omnivorous. We found that the size, and direction of vectors of phenotypic changes across South American biomes in those clades are not statistically different. This similarity persists after removing the strong impact of allometry in our data. Additionally, partial least squares and comparative analyses confirm that “allometry free” skull shape is influenced to the same set of environmental variables in both clades. This study remarks the paramount importance of both body size and environmental variation on phenotypic evolution.

Habitat selection by small mammals in Brazilian Pampas biome

The use of microhabitats by small mammals was investigated in an area of Pampas in southern Brazil. We used 10 transect lines with 12 live-traps during six fieldwork sessions between June 2009 and April 2010. Sixteen environmental variables measured were summarized by a principal component analysis (PCA). Richness, total abundance and abundance of each species captured were correlated with the first two PCA axes. The environmental variables were also correlated with the small-mammal abundance through a canonical correspondence analysis (CCA). The first axis was related to variables that characterize forest environments, such as canopy cover and number of trees, and the second axis (with which the species richness and abundance were associated) was related to water, arthropods and herbaceous vegetation. The CCA and PCA showed a significant effect of microhabitat variables on species occurrence. In view of the great variability of environments in the study area and the correlation of the species with the environment variables measured, the degree of heterogeneity seemed to be an important factor associated with the small-mammal variation among microhabitats.

Morcegos de Frederico Westphalen, Rio Grande do Sul, Brasil (Mammalia: Chiroptera): riqueza e utilização de abrigos

O Estado do Rio Grande do Sul possui, ate o momento, registros para 38 das 168 especies de morcegos ocorrentes no Brasil e possui extensas areas carentes de amostragem. Neste trabalho apresenta-se uma lista de especies de quiropteros do municipio de Frederico Westphalen no extremo norte do Rio Grande do Sul e sao fornecidas informacoes sobre a utilizacao de edificacoes humanas e minas abandonadas para sete das 25 especies registradas no municipio. De outubro de 2004 a junho de 2008 esforcos amostrais foram realizados em onze areas no municipio visando inventariar a quiropterofauna local. A presenca das especies foi constatada a partir de capturas com auxilio de redes de neblina, busca ativa em refugios, bem como, de exemplares obtidos junto a comunidade. As especies pertencem a 13 generos, das quais a familia Vespertilionidae e representada por 11 especies, Molossidae por sete especies e Phyllostomidae por sete especies. Os resultados obtidos no presente trabalho colocam o Alto Uruguai entre as regioes com maior riqueza de quiropteros do Rio Grande do Sul.

Interaction of ectoparasites (Mesostigmata, Phthiraptera and Siphonaptera) with small mammals in Cerrado fragments, western Brazil

We describe ectoparasite fauna associated with small mammals in fragments of Cerrado biome, central-western Brazil. We analyzed the level of associations and the aggregation patterns according to seasonal and host variations. Small mammals were systematically captured in 54 woodland fragments from February 2012 to July 2013. A total of 1040 animals belonging to eight marsupial and 12 rodent species were sampled; 354 individuals were parasitized by 33 ectoparasite species (twenty five Mesostigmata, seven Phthiraptera and one Siphonaptera). A total of 49 ecological relationships between ectoparasites and small mammals were observed, 24 being new association records. The overall specialization index of all ectoparasites and host species was 0.91 with significant deviation from a random host-parasite association, suggesting a high host-parasite specialization in this system. Specialization indices for ectoparasites ranged from moderate to high, while among host was high, for most species. Contrary to the overall pattern, some ectoparasites had higher prevalence and mean intensity of infestation in the dry season. Overall, ectoparasite prevalence and mean intensity of infestation were not significantly associated with host gender. This study provides significant information about the ectoparasites ecology in relation to specificity, seasonality and hosts gender, contributing to the understanding of host-parasite relationships in Brazilian savannah.

Use of camera-traps in natural trails and shelters for the mammalian survey in the Atlantic Forest

In order to evaluate the efficiency of different mammalian survey methods, we compared traditional sampling techniques (use of camera-traps on roads and artificial trails, track censuses, and direct field visualization) with an alternative sampling design (camera-traps positioned in natural areas such as natural trails and shelters). We conducted the study in a deciduous Atlantic-Forest park in southern Brazil, and additionally compared our results with a previous intensive study carried out in the same area. Our considerably smaller sampling effort (example: 336 trap.day for our camera-traps versus 2,154 trap.day for the earlier study) registered the presence of 85% of the local known species, with camera-traps being 68% efficient. Moreover, shelter camera-traps revealed a different species composition regarding most of other sampling methods. This sampling strategy involving natural forest sites was therefore able to effectively optimize the chances of evaluating species composition in a shorter period, especially with respect to lower-density and cryptic species, as well as to detect species that avoid open, disturbed sites such as roads and man-made forest trails.

Which Factors Determine Spatial Segregation in the South American Opossums (Didelphis aurita and D. albiventris)? An Ecological Niche Modelling and Geometric Morphometrics Approach

Didelphis albiventris and D. aurita are Neotropical marsupials that share a unique evolutionary history and both are largely distributed throughout South America, being primarily allopatric throughout their ranges. In the Araucaria moist forest of Southern Brazil these species are sympatric and they might potentially compete having similar ecology. For this reason, they are ideal biological models to address questions about ecological character displacement and how closely related species might share their geographic space. Little is known about how two morphologically similar species of marsupials may affect each other through competition, if by competitive exclusion and competitive release. We combined ecological niche modeling and geometric morphometrics to explore the possible effects of competition on their distributional ranges and skull morphology. Ecological niche modeling was used to predict their potential distribution and this method enabled us to identify a case of biotic exclusion where the habit generalist D. albiventris is excluded by the presence of the specialist D. aurita. The morphometric analyses show that a degree of shape discrimination occurs between the species, strengthened by allometric differences, which possibly allowed them to occupy marginally different feeding niches supplemented by behavioral shift in contact areas. Overlap in skull morphology is shown between sympatric and allopatric specimens and a significant, but weak, shift in shape occurs only in D. aurita in sympatric areas. This could be a residual evidence of a higher past competition between both species, when contact zones were possibly larger than today. Therefore, the specialist D. aurita acts a biotic barrier to D. albiventris when niche diversity is not available for coexistence. On the other hand, when there is niche diversification (e.g. habitat mosaic), both species are capable to coexist with a minimal competitive effect on the morphology of D. aurita.

Local randomness, vegetation type and dispersal drive bird and mammal's diversity in a tropical South American region

How dispersal, environmental filters, and local extinctions affect species diversity depends on the species requirements for habitat, dispersal limitations, and abundance. Few studies have been able to properly separate these processes and to show how they affect the beta diversity patterns for multiple organisms. We investigated how the composition of birds and mammals changed along geographical and environmental gradients in an environmentally complex South American region. Using mantel tests and a null model approach we disentangled the effects of dispersal, environment, and stochastic processes in the species beta diversities. The similarity on species composition was negatively associated with the geographical distance separating areas for both groups. The changes in bird species composition likely resulted from their dispersal limitation over large geographical regions. In contrast, the composition of mammals in a given area was a partially random subset of the regional species pool, to some extent, filtered by the vegetation. Small communities tended to have more variable species composition, whereas dispersal limited birds showed a stronger distance-decay pattern. Neither local randomness nor dispersal limitation prevented species from being filtered by the environment. Other groups are likely to show similar patterns depending on their dispersal abilities, environmental requirements and community size.

The taxonomic status of Myotis levis levis and Myotis levis dinellii (Mammalia: Chiroptera: Vespertilionidae)

Investigating the Myotis levis complex is important for understanding the taxonomic status of the two subspecies currently recognized in it: Myotis levis levis (I. Geoffroy, 1824) and M. levis dinellii Thomas, 1902. Both M. levis levis and M. levis dinellii have been recently observed in sympatry in Argentina. This finding suggests that these populations might in fact correspond to distinct species rather than subspecies, as they have traditionally been designated. By using a multivariate morphometric approach, we demonstrate that M. l. levis has secondary sexual dimorphism in several measurements, with females being larger than males; sexual dimorphism was not detected in M. levis dinellii. However, we found morphometric differences between the two taxa. These differences exceeded those documented for other Neotropical Myotis. Based on their sympatry, morphological, and morphometrical differences, we propose a change in the status of both subspecies to M. levis and M. dinellii.