Elevational replacement, higher tropical mountain passes and isolated sky islands: untangling neutral and adaptive processes driving radiation of Andean Apocynaceae

DFG: OrthoTAX 1991, Taxon-OMICs

The mountain systems in South America are biodiversity hotspots. Several Andean mountain floras are among the most diverse, evolutionary most active and species-richest systems worldwide. Here, we follow a clade-centered perspective to ask specifically about the contribution of adaptive and neutral processes in the evolution of diversity in these systems. We study the Orthosiinae clade of the dogbane family (Hundsgiftgewächse, Apocynaceae) using phylogenomics, comparative methods and integrative taxonomy to reveal the net contributions of these processes in species diversification. We (1) estimate the number of species combining morphological studies and coalescence analysis of target-enriched genomic data (Hyb-Seq) of Orthosiinae specimens harbored in museums and herbaria around the world. Time-calibrated species trees are used to (2) estimate rates of flower size evolution and their correlation to species diversification rates. Spatial analyses of species occurrences and niche modelling will be used to (3) identify the frequency of allopatric speciation events, the ecological preferences of (sister) species, and the elevational pattern of species replacement (current and historical). Integrating the genomic, phenotypic, ecologic and spatial perspectives on species in this clade, we (4) estimate tempo, mode and impact of neutral and adaptive evolution in the radiation of Andean Orthosiinae. This will contribute to our understanding of interactions among drivers of species diversification in South America.