Coexistence in scarcity: Small mammals and seasonality in the Caatinga

Abstract

Species coexistence involves resource partitioning, even if indirectly. These resources can fluctuate over time especially in highly seasonal environments such as Caatinga, the largest tropical-dry-forest in South America, that has a long dry season and short periods of rain. Here, we describe the diversity of small mammals in a well-preserved area of the Caatinga, quantifying richness, diversity and evenness. Our aim is to assess coexistence analysing community structure spatially (mobility and vertical use) and functionally (functional richness, evenness and divergence), evaluating the influence of seasonality on these parameters. We monthly live-trapped small mammals for five nights during one year. We recorded five small mammal species (marsupials and rodents). Capture success were higher during the dry season and the abundance of marsupials was correlated with precipitation and water balance. The most scansorial species explored the ground more than usual during the dry season. The community presents low functional richness and evenness, but high divergence and in the dry season this is emphasized. The community is spatially and functionally well structured, with well discriminated exploration of resources, but it is still impacted by the strong seasonality of the biome, reflected on the differential use of vertical strata and abundance data across seasons.