Estruturação filogenética e diversificação de lagartos amazônicos

Abstract

The phylogenetic base of lizard communities in the Brazilian Amazon was explored at three spatial scales (geological structure, endemic areas and river banks) and at the intraspecific level, in order to understand: how the communities are structured phylogenetically, what are the processes underlying the observed structural patterns, how the communities are phylogenetically related and whether the rivers could have acted as a barrier causing divergence and / or delimiting the distribution intraspecific lineages of lizards. In the geological structures, the Amazonian Sedimentary Basin and the Guianas Shield showed a phylogenetically clustered pattern, indicating that most of the lineages present in these places diversified in the region where they occur; in the Brazilian Shield, the observed pattern was phylogenetic dispersion, indicating that the region was colonized by many lineages that do not occur in other regions of the Brazilian Amazon. In the areas of endemism, the communities presented distinct patterns of phylogenetic structuring (clustering, dispersion and random), indicating that on this scale the communities were structured both by ecological and historical processes. On the banks of rivers, most communities showed a phylogenetic dispersion pattern, indicating that they were structured predominantly by competition; only one community presented a phylogenetically clustered pattern, indicating that environmental filters were more important in their structuring. Phylogenetic relationships between communities indicate that the Amazonian Sedimentary Basin has a greater share of ancestral lineages with the Brazilian Shield and a greater share of recent lineages with the Guiana Shield. The relationship between the areas of endemism shows an ancestral break between the northwest (Imeri and Napo) and the rest of the Amazon; as well as Tapajós and Rondônia phylogenetically more distant from all other areas of endemism, mainly in the sharing of more recent lineages. For the oldest structure of the river banks, an east-west break pattern was recovered, followed by a north-south break. In addition, for the most recent structure, the lineages that occur on the opposite banks of the same river are phylogenetically more related to each other than with the lineages that occur on the banks of other rivers; except for the Trombetas and Jatapu rivers. These results show that different rivers seem to have acted as diversifying barriers or distribution limits for different species, reflecting the complexity of the Amazonian landscape and the intrinsic characteristics of each species; thus, a pattern of diversification that can be generalized to all lizards in the Amazon cannot be inferred. Finally, although it was not the objective of this study, it was observed the existence of potential species not yet described and species already described but with occurrence records not yet described in the literature for the sampled region, reinforcing how underestimated it is and how much there is to learn about the diversity of lizards in the Brazilian Amazon.