Tiago Gomes dos Santos

Diversidade e distribuição espaço-temporal de anuros em região com pronunciada estação seca no sudeste do Brasil

Anthropic activities have deeply changed natural environments and constantly affected the diversity and distribution of anurans. This study aimed to investigate the following questions: (1) What is the frogs composition in a pasture region with a pronounced seasonal climate in extreme northwest of the state of Sao Paulo? (2) How are adults and tadpoles of the species distributed temporally and spatially? (3) Is species richness correlated to descriptors of reproductive habitats heterogeneity? In the study site 20 anuran species were recorded, distributed in 11 genus of four families: Leptodactylidae (9), Hylidae (8), Microhylidae (2) and Bufonidae (1). From these, Chaunus schneideri (Werner, 1894), Physalaemus centralis Bokermann, 1962 and Physalaemus fuscomaculatus (Steindachner, 1864) were recorded only by tadpoles collection, whereas Dendropsophus minutus (Peters, 1872) and Leptodactylus labyrinthicus (Spix, 1824) occurred only in water bodies next to the studied ones. The recorded species are known by their ample geographic distribution and for colonizing disturbed areas in other localities. There was no correlation between species richness and structural complexity of water bodies. However, the greater richness was recorded in temporary water bodies that kept water more than six months throughout the year. The temporary ponds of unstable hydroperiod were colonized initially by leptodactylids, while the permanent or temporary ponds were colonized by hylids. The vocalization and reproductive activity of most species were restricted to the warm and rainy period of the year, a typical pattern of communities in the tropical seasonal regions. Five species [Chaunus schneideri, Dendropsophus nanus (Boulenger, 1889), Hypsiboas albopunctatus Spix, 1824, Leptodactylus podicipinus (Cope, 1862) and Pseudopaludicola aff. saltica (Cope, 1887)] vocalized during the dry and rainy seasons, but only C. schneideri and H. albopunctatus reproduced during the dry season. The weak spatial and temporal segregation, recorded to adults and tadpoles, is not enough to explain reproductive isolation among species. Other factors, like acoustic segregation and calling site segregation, may have major importance to explain species coexistence. Climatic severity (wide and pronounced dry season, unpredictability and inconstancy of rains in the beginning of the rainy season), along with the high level of natural habitat being converted in cultivated areas are, probably, the factors responsible for the predominance of species typical from disturbed areas.

An austral anuran assemblage in the Neotropics: seasonal occurrence correlated with photoperiod

The study describes habitat use and temporal occurrence of calling males for an austral anuran assemblage in the Neotropics, southern Brazil. Three study sites (S1 – a permanent river and a stream, S2 – a dam and backwater, S3 – two permanent ponds periodically connected) were sampled between August 2005 and July 2006. The site S3 presented the richest and most diverse assemblage and habitat use within studied sites, and was partitioned by species groups. Richness and abundance of calling males for overall assemblage were seasonal, concentrated in spring and summer and correlated with photoperiod. Temperature, rainfall and air humidity were not correlated with the richness and abundance of calling males. Photoperiod also explained the calling seasons when species were analyzed individually. Habitat use and temporal occurrence were complementary in the partitioning of breeding resources, explaining species coexistence.

Influence of the environmental heterogeneity of breeding ponds on anuran assemblages from southeastern Brazil

We hypothesized that the environmental heterogeneity of breeding ponds influences the species composition and species richness of anuran assemblages from southeastern Brazil, because it provides humidity, shelter, and breeding microhabitats for anuran species, which can result in an increasing number of species in a given habitat. To begin, we tested whether the occurrence of anuran species in each breeding pond is different from a null model of random placement of species in those ponds. We then performed two tests to evaluate which of the five environmental descriptors of breeding ponds influence (1) the species composition and (2) species richness. Species composition of the 38 breeding ponds was correlated with number of edge types, number of plant types along the edges of the breeding ponds, and the hydroperiod. Neither the percentage of vegetation cover on the water’s surface nor the size of the breeding ponds were correlated with species composition. Only the number of edge types was correlated wit...

Anurans of a seasonally dry tropical forest: Morro do Diabo State Park, São Paulo state, Brazil

We studied the richness and composition of the anuran assemblage of Morro do Diabo State Park, the major remnant of Mesophytic Semideciduous Forest in the state of São Paulo, Brazil, through hypothesis tests. From September 2005 to March 2007 we recorded 28 anuran species, comprising a mix of Atlantic, Cerrado and South American widespread species, usually considered tolerant to anthropic modifications. The low richness of species and reproductive modes, the predominance of habitat generalist species, and the high similarity with Cerrado areas can be explained by the climatic seasonality of the studied area (a pronounced dry season), as well as its large distance from centres of anuran diversification, such as the coastal mountains of the wet Atlantic Forest.

The role of spatial and temporal descriptors for neotropical tadpole communities in southern Brazil

We evaluated tadpole communities of temporary and permanent ponds, in order to understand how community richness varies monthly in a subtropical humid climate, to interpret the community structure in relation to biotic and abiotic environmental variables related to the temporary and permanent ponds. The study site was the Pró-Mata Research and Nature Conservation Center, a private reserve in southern Brazil. The climate is classified as Temperate Superhumid, with no dry season. We sampled three temporary and three permanent ponds. We compared the richness of tadpole assemblages of permanent and temporary ponds through individual-based rarefaction curves, and tested for possible differences using a MANOVA test. Tadpole richness was related to temporal environmental descriptors through General Regression Model. Relationships between the tadpole assemblages and possible predictors of their spatial variation were measured using a partial Canonical Correspondence Analysis. Analysis of rarefaction curves indicated higher expected richness for the temporary ponds. The mean values of richness were significantly different between the two hydroperiods across all months. Monthly richness showed the same tendency of variation for both pond types. Only temperature was related to tadpole richness. The pCCA analysis was significant. The most important predictors on the first pCCA axis were vegetation cover, conductivity, depth, and predator diversity. In this study, vegetation cover, conductivity, predator diversity, and water depth explained the spatial variation of tadpoles between ponds, with tadpole richness and diversity being higher in temporary than in permanent ponds. Our results suggest that different spatial-seasonal patterns operating in temporary and permanent ponds are related to maintaining the species diversity of pond-breeding anurans.

Climatic variables and altitude as predictors of anuran species richness and number of reproductive modes in Brazil

Because anuran species are highly dependent on environmental variables, we hypothesized that anuran species richness and the number of reproductive modes from different Brazilian localities vary according to climatic and altitudinal variables. Published data were compiled from 36 Brazilian localities and climatic and altitudinal data were extracted from an available database. A partial redundancy analysis (pRDA) showed that 23.5% of the data sets variation was explained by climatic and altitudinal data, while the remaining 76.5% remained unexplained. This analysis suggests that other factors not analysed herein may also be important for predicting anuran species richness and the number of reproductive modes in Brazil. Altitude and total annual rainfall were positively correlated with anuran species richness and the number of reproductive modes, and total annual rainfall was strongly associated with these two biotic variables in the triplot of pRDA. The positive association of total annual rainfall and the negative association of the concentration of annual rainfall were already expected based on physiological and reproductive requirements of anurans. On the other hand, temperature was not associated with richness or the number of reproductive modes.

Mamíferos do campus da Universidade Federal de Santa Maria, Rio Grande do Sul, Brasil

Universidade Estadual Paulista Instituto de Biociencias Programa de Pos-Graduacao em Ciencias Biologicas (Zoologia)

Extension of the geographical distribution of two anuran species for Rio Grande do Sul State, Brazil, with comments on natural history

We record for the first time Crossodactylus schmidti (Anura: Hylodidae) and Proceratophrys avelinoi (Anura: Cycloramphidae) from Rio Grande do Sul State, Brazil, based on individuals captured in an area of Mesophytic Semideciduous Forest, the Parque Estadual do Turvo, located in the northwest region of the state. These records extend the geographical range for both species in about 60 km from the nearest known locality, the Municipality of San Vicente, Misiones, Argentina. We provide a characterization of the calling site used by males of Crossodactylus schmidti, and we also determined the niche breadth of P. avelinoi regarding to the use of water bodies.

SIMILARITIES IN CALLING SITE AND ADVERTISEMENT CALL AMONG ANURAN AMPHIBIANS IN SOUTHEASTERN BRAZIL1

Abstract We hypothesized that species that overlap in calling sites partition the acoustic space, whereas those that segregate calling sites overlap in the acoustic space. Most of the 12 analyzed species (75%; n = 9 species) were generalists with respect to at least one of the calling site variables, a characteristic of species living in unpredictable or human-altered habitats. In most water bodies, segregation in calling sites occurred as a result of low species richness in the communities. Higher overlaps in calling sites were observed among species that called from the ground or while floating in water than among those that called perched on vegetation, probably due to differences in the use of two- versus three-dimensional spaces. As a result of the analysis of similarity among advertisement call features, we observed higher segregation among species that called on the ground or floating on water than perched on vegetation. For those species, differences in advertisement calls seem to explain their coexistence.

Spatial and temporal distribution of tadpole assemblages (Amphibia‚ Anura) in a seasonal dry tropical forest of southeastern Brazil

We determined spatial and temporal distribution of tadpoles in 11 breeding habitats from Morro do Diabo State Park (MDSP), southeastern Brazil. Breeding habitats occupancy by tadpoles was tested to be different from a null model of random placement of species. We also tested whether tadpole occupancy in a given breeding habitat is organized according to different ecomorphological guilds, and we analyzed spatial partitioning of tadpoles among breeding habitats through similarity analysis. For temporal analysis we analyzed temporal partitioning of tadpole monthly occurrence also using similarity analysis, and assessed what climatic variable better predicts tadpole temporal occurrence in the MDSP, through regression analysis. Among tadpoles from 19 anuran species, distribution was different from a null model, but co-occurrence patterns among the breeding habitats did not differ among different guilds. However, breeding habitats with similar hydroperiods had similar species composition, which may be related to the reproduction patterns of species. Among the three climatic variables analyzed (rainfall, temperature, and photoperiod), temporal occurrence of monthly tadpole richness and abundance was correlated with temperature and rainfall. Most species were found only during the rainy season months, and overlap occurred within three groups of species. Thus, temporal distribution does not seem to be an important mechanism in species segregation at the MDSP, where the dry season is pronounced. In this case, spatial partitioning tends to be more important for species coexistence.