Filogeografia e demografia histórica de lagartixas-rabo-de-nabo Thecadactylus rapicauda e T.solimoensis (Squamata: Phyllodactylidae)

Abstract

Phylogeographic studies associated with ecological analyzes have become important tools to understand how historical changes in the landscape have acted in the diversification of cryptic species in megadiverse regions, such as the Neotropical regions. We present an integrative approach between phylogeography and species distribution models (SDM) to investigate the potential historical and ecological agents that govern the phylogeographic and demographic dynamics of Thecadactylus rapicauda and T.solimoensis, cryptic nocturnal geckos, distributed throughout the Amazon. We used data from mitochondrial and nuclear gene sequences and geographic data from taxa to delimit the evolutionary units within these species of geckos. We employ molecular dating, coalescent demographic analysis and niche modeling to infer patterns of lineage differentiation in space and time, and we assess the degree of niche overlap between T. rapicauda and T. solimoensis. Despite being sister species, these geckos have very different histories of diversification. In T. rapicauda, distributed in the eastern portion of the Amazon, Pleistocene climatic fluctuations and the dynamics of establishing rivers, were responsible for greater phylogeographic structuring, and populations that do not share haplotypes. Pleistocene climate instability was also responsible for a slight demographic decline in populations. The estimated paleomodels show moments of adequacy transitions between periods and which may be related to the demographic retraction. On the other hand, in T. solimoensis, whose distribution is centered in the western portion, the greater climatic stability in the Quaternary that occurred in the region, influenced the low phylogeographic structure, with the sharing of haplotypes among the populations. In the estimated paleodistribution scenarios, it is evident that the stability of vegetation during periods of moderate climatic transitions in the region, favored the demographic stability recovered in T. solimoensis. Finally, the low niche conservatism found between the two species indicates that ecological divergence along with diversification events associated with the evolution of the landscape and climatic conditions are responsible for the cryptic diversity between species. The high genetic distances of populations in both species and the hypothesis of a possible Trans-Andean clade reinforce the need for more detailed investigations on the limits between species and future taxonomic studies.