Biology subjects

Brandao, R. A.

Publications and source records attributed to Brandao, R. A..

3 recordsLinked to original sources

bioRxiv2025

Thermophysiology or resource availability: What shapes the post-flooding abundance of lizard species across artificial islands in a Neotropical biome?

Global warming has led to increased flooding events, causing significant habitat fragmentation and affecting species distribution in tropical ecosystems. This study investigates the postflooding abundance of lizard species across artificially created islands in the Cerrado biome, focusing on the roles of thermophysiological traits and resource availability. We conducted a comprehensive survey, recording 560 individual lizards representing 13 species from eight families, and used generalized additive models to assess the impact of mean field-active body temperature and net primary productivity on lizard abundance. Our results indicate that a rise in mean field-active body temperature significantly correlates with reduced lizard abundance, supporting the physiological tolerance hypothesis. This finding points out the critical importance of thermoregulation for ectotherm survival in the face of climate change. Conversely, resource availability, measured through net primary productivity, showed no significant effect on lizard abundance. These findings bring to light the vulnerability of lizard populations to thermal stress and emphasize the necessity for conservation strategies that prioritize the creation of thermal refuges and improve habitat connectivity to mitigate the impacts of rising temperatures. By integrating species traits into macroecological analyses, our study offers valuable insights for biodiversity conservation in fragmented landscapes. Future research should explore diverse ecosystems to validate these findings, thereby informing effective conservation planning and ensuring the resilience of ectotherm populations in altered environments.

ecology↗

bioRxiv2024

How do body size and habitat fragmentation influence extinction in lizards? A long-term case study on artificial islands in the Brazilian Cerrado

Habitat fragmentation is known to cause extinctions and species turnover, but the factors that allow some species to persist while others become locally extinct are not well understood. Landscape flooding following the construction of hydroelectric dams causes a particularly dramatic form of fragmentation disturbance, where former terrestrial habitats become aquatic and former hilltops become land-bridge islands. As such, reservoir land-bridge islands have become a successful model for accessing the impacts of fragmentation on biodiversity. We used the lizard community, to assess species sensitivity to habitat structural change during land-bridge island formation. We monitored the lizard community for 23 years before, during, and after the flooding of the Serra da Mesa Dam reservoir. Over the course of our study, the diversity of the lizard community on land-bridge islands and mainland sites along the shores of the newly formed reservoir declined from 19 to six species. We found that in Serra da Mesa islands, lizards with large body sizes (e.g., Teiidae and Tropiduridae) decreased in abundance along the flooding process, thereby increasing their extinction risk. In contrast, we found a high abundance of small-bodied lizards (Gekkonidae, Gymnophthalmidae, Scincidae, and Sphaerodactylidae) on Serra da Mesa islands. Richness on the islands declined dramatically, resulting in communities currently with one highly abundant species, Gymnodactylus amarali. For the sake of biodiversity conservation, island or fragment sizes must be considered for maintaining a reasonable number of species and our characterization of the local extinction patterns may provide relevant information to mitigate wildlife depletion due to habitat fragmentation.

ecology↗

bioRxiv2022

Group dynamics and habitat use of the Giant Otter, Pteronura brasiliensis (Zimmermann, 1780), in seasonally flooded forest in the Araguaia River, Central Brazil: A 10-years study.

We carried out monthly surveys of the giant otter population between 2010 and 2020 in a study area comprised of 1,500 hectares of igapo flooded forest with oxbow lakes in the Cantao region of central Brazil. We recorded 16-32 resident adults in the study area each year, distributed in 4-8 groups. Resident groups exhibited extensive home range overlap, with each group using several lakes and larger lakes used in rotation by up to six groups. Dens and campsites were also shared by multiple groups, but lakes were used by only one group at a time, and encounters between groups were very rare. 24 adult otters were observed to join an existing group. Some individuals changed groups multiple times. Resident adult turnover was high. Each year an average of 36% of resident adults were new immigrants, and 72% of groups left the area within two years. Resident groups had, on average, one litter every three years, and annual cub production showed high variability and a negative correlation to the number of new immigrants in the area. No pairs of giant otters reproduced successfully during the study. Groups of three otters formed through the recruitment of an adult individual by an existing pair and reproduced as successfully as larger groups. Group dynamics and territorial behavior in the Cantao flooded forest ecosystem, where optimal giant otter habitat is continuous in all directions, were found to be different from that reported in areas composed of patchy (isolated oxbow lakes) or linear (rivers) habitat. This suggest that giant otter social and territorial behavior is plastic and adapts to the spatial characteristics of the habitat.

animal behavior and cognition↗