Riverine barrier and aridity effects on taxonomic, phylogenetic and functional diversities of lizard assemblages from a semi‐arid region

Abstract

Aim: Disentangling historical and ecological effects on different components of species diversity is key to understanding the assembly and maintenance of communities over space and time. Historical factors may be stronger predictors of the community composition at regional scales, while ecological factors may be more important predictors at local scales. Here, we evaluate multiple biodiversity dimensions to investigate riverine barrier and aridity effects on the assembly and structure of lizard assemblages.Location: Semi-arid region of northeastern Brazil. Taxon: Lacertilia (lizards).Methods: We used data describing 63 lizard assemblages from Caatinga habitats to investigate the effects of a riverine barrier and eight environmental gradients on estimates of taxonomic, phylogenetic and functional diversity. At the regional scale, we compared communities between the banks of the SFr, assuming that differences could emerge from regionally interrupted dispersal in some of the sampled species.At local scales, we evaluated the patterns of phylogenetic and functional structure of the lizard assemblages from Caatinga, and investigated the influence of aridity-related gradients on species richness, taxonomic, phylogenetic and functional diversity.Results: Lizard assemblages were regionally structured by the SFr acting as a barrier to 47% of the species sampled. We detected phylogenetic signal in 88% of the functional traits. Lizard assemblages were phylogenetic and functionally overdispersed.Moreover, we detected evidence of aridity gradients intensifying the overdispersion of phylogenies and functional traits.Main conclusions: Lizard assemblages showed high variation at both regional and local scales. Riverine barriers played a stronger role as a historical factor structuring assemblages on a regional scale. The interaction of historical constraints with competition enhanced by aridity on a local scale may play a role in structuring lizard assemblages across multiple scales.

Determinants of resource use in lizard assemblages from the semiarid Caatinga, Brazil

“…Recognizably, the effects of historical factors are stronger over phylogenetically more diverse lizard assemblages (Vitt et al, 1999, 2003). These results are supported by the presence of phylogenetic signal in 88% (7 of 8) of the functional traits and by the phylogenetic and functional overdispersion of the Caatinga lizard assemblages (Gonçalves‐Sousa et al, 2022). Results obtained by sampling biotic assemblages in natural environments reflect current consequences of the interaction of historical and ecological effects that have led to ecological differences between species (Vitt et al, 1999).…”

“…Recognizably, the effects of historical factors are stronger over phylogenetically more diverse lizard assemblages (Vitt et al, 1999(Vitt et al, , 2003. These results are supported by the presence of phylogenetic signal in 88% (7 of 8) of the functional traits and by the phylogenetic and functional overdispersion of the Caatinga lizard assemblages (Gonçalves-Sousa et al, 2022). Results…”

“…Currently, more than half of the Caatinga areas have been deforested, and it is known that the intensification of land use and consequent degradation of natural habitats negatively affects species richness and number of functional groups (Berriozabal‐Islas et al, 2017; Flynn et al, 2009). In addition to the irreparable loss of species, changes in habitats lead to patterns of distribution of functional traits and overdispersed evolutionary histories (Gonçalves‐Sousa et al, 2022). Arid and semiarid habitats cover about one third of land surface of the world (Wickens, 1998).…”

“…The soils of Casa Nova are sandy, influenced by Paleo quaternary dunes on the banks of the São Francisco River, the most important river of the Brazilian semiarid region. The São Francisco river is an important historical factor for lizard assemblage structure at regional scale (Gonçalves‐Sousa et al, 2022; Recoder & Rodrigues, 2020). The north of the São Francisco River represents the most severe subregion of the Brazilian semiarid region.…”

“…, 2022). The most abundant species were common in the four assemblages studied and correspond to four of the five species with the largest distribution in the Caatinga(Gonçalves-Sousa et al, 2022). These four species are either generalists in the use of microhabitat (T. hispidus and A. pyrrhogularis) or use very abundant microhabitats, such as rock outcrops (P. pollicaris and T. semitaeniatus).…”