Syndrome-driven diversification in a mediterranean ecosystem

摘要

Phylogenetic methods to detect lineage diversification have been traditionally used within a particular taxonomic clade, but rarely applied to detect local diversification. For understanding in situ diversification triggered by novel conditions it is necessary to focus on the time slice where such conditions occur. These new conditions may differentially affect the diversification rate of lineages with different morpho-functional syndromes. A prominent example of these processes occurs in the Mediterranean Basin, where climate arising along the Tertiary/Quaternary transition acted as an environmental filter. In this context, lineages with different syndromes (sclerophyllous and nonsclerophyllous) are hypothesized to have different local diversification rates after the rise of the Mediterranean conditions. We used macroevolutionary methods of time-dependent diversification on a calibrated local phylogeny accommodating topological and chronological uncertainty to test syndrome-driven diversification in Mediterranean shrublands from the eastern Iberian Peninsula. We found phylogenetic evidence of higher speciation associated with the nonsclerophyllous syndrome, although extinction rates were similar between syndromes. Consequently a syndrome-driven local diversification has occurred in shrublands under Mediterranean conditions. The results provide an example of how the integration of the environmental filter in a dated phylogeny may recreate the local history of lineages and help to explain assembly processes in Mediterranean ecosystems.