Abstracts (first author)
The effect of habitat on plant diversification: a macroevolutionary approach
The close relationship between plants and their habitats is a research subject of long-standing interest. However, the macroevolutionary patterns of this association are still unclear. For instance, it is not known whether habitat conditions affect the diversification of plant lineages. Moreover, few studies have investigated if ecological conservatism is a general phenomenon with comparable patterns across habitats and lineages. Here we present an analysis of habitat evolution in Saxifragales, an angiosperm clade exhibiting diverse morphologies and habitats. Using well-resolved phylogenies built with a super-matrix approach and habitat data for ~1000 taxa (50% of the group) we investigate a) The pattern of habitat evolution: the most likely ancestral habitat and the rates of transition across the different classes of habitats b) The association between diversification rates and habitat, determining if the speciousness of certain lineages is related to their habitat; or, if on the contrary, certain habitats are linked to higher extinction rates c) Ecological conservatism across lineages and habitats: if the adaptation to certain habitats constrains diversification into other environments, and whether the constrains are equivalent for different habitats Our results show that from a forest-inhabiting ancestor, the Saxifragales have transitioned into a variety of environments. Some of these habitat shifts appear to have triggered bursts of diversification. Seemingly harsh environments, such as rock cliffs and the tundra, are linked to high diversity and have been occupied and abandoned repeatedly throughout evolution. Conversely, deserts contain only ancient, species-poor lineages, and the transition into an aquatic medium seems irreversible. This indicates that although adaptation to extreme conditions can lead to evolutionary cul-de-sacs, this phenomenon is complex and very dependent on as-yet unknown underlying physiological and morphological changes.