The use of comparative phylogeographic and ecologic modeling to disentangle interacting evolutionary processes in contrasting clades: the example of Malagasy mouse lemurs (Microcebus) and woolly lemurs (Avahi)

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Identifying drivers of speciation and their relative importance is key to understanding the diversification and distribution of species. These drivers range from large-scale geomorphological processes such as mountain and river formation to small-scale mechanisms like intra-specific ecological plasticity, habitat choice, or colonization potential. Although species diversity is likely the result of complex interactions among speciation drivers, these have only rarely been studied in an integrative way due to the lack of appropriate model species and regions. In this still ongoing DFG-funded project, we surveyed and sampled mouse and woolly lemurs of the genera Microcebus and Avahi in a region encompassing multiple inter-river-systems in northeastern Madagascar. Both genera differ significantly in size, ecology and patterns of species diversity, and form ideal models to study the importance and interaction of various drivers of speciation. Within the ongoing funding period we are making use of geomorphological reconstructions of river basins and some first RADseq-based genomic analyses in order to establish the species diversity and distribution of these nocturnal lemur taxa in the study region and to assess for some selected species the effects of rivers, altitude, and paleoclimatic oscillations on genetic structure. However, the full completion of the project will not be possible within the first funding period due to an unforeseeable and COVID-related 1-year delay in field work. Therefore, we will need this 1-year extension to determine the role and interaction of these factors and integrate them with new modelling results on the ecological plasticity of all species and a reliable inference of the temporal context of gene flow across the study region for a full reconstruction of the diversification processes in both genera. Together with previous findings, these analyses will paint a comprehensive picture of lemur speciation in the study region and identify how it was differentially shaped by the interaction of extrinsic and intrinsic factors in the ecologically contrasting mouse and woolly lemurs. In addition, our findings will provide guidelines for conservation stakeholders and policy makers for informed conservation decisions.