Causal factors and time in formation of areas of endemism for land planarians in the Atlantic Forest

Here, we discovered areas of endemism (AoE) for land planarians (Geoplaninae) and tested the influence of the past climate in the formation of AoEs in the southeastern AF in Brazil.

Location

Southeastern Atlantic Forest, Brazil.

Materials and Methods

We used 1888 records of 371 species in Endemicity Analysis and Geographic Interpolation of Endemism to uncover AoEs. We also carried out a species distribution modelling (SDM) of three genera to see the suitability regions where they were distributed during Mid-Pliocene, Last Interglacial Maximum, Last Glacial Maximum and present time. Finally, we inferred a molecular phylogeny of Geoplaninae aiming to estimate divergence times of the taxa to test the relative influence of more recent climatic fluctuations in the speciations.

Results

We delimited 15 robust AoEs. SDM corroborates past climate altered some genera distribution. However, results of the phylogenetic analysis resulted in time estimation older than Pleistocene climatic fluctuations for more recent speciations. These endemic patterns could be explained through processes of reduction and expansion of suitability areas but in older times as generally reported in the literature. Geological events that formed mountains, sedimentary basins and major rivers are integrated with climate to explain high endemism and diversification.

Main Conclusions

Planarians have shown to be an optimal model for fine-scale studies of AoE and diversification in AF. Pleistocene climatic fluctuations seem to have not been responsible for their diversification, but older climatic changes with geological events seem to have influenced their speciations and the present-day high levels of endemism. In the future, robust phylogenies with more comprehensive sampling integrated with palaeoecological models will help to understand the diversification of the AF.