干旱区生态环境知识资源中心

AimInvestigation of the geographical origin of Senecio and the colonization of the Palaearctic including the relationship of life-history strategy and elevational distribution in the source area and the colonized area.

LocationWorldwide with a focus on the Afrotropic and the Palaearctic.

MethodsSampling focused on adding species from the Afrotropic to existing datasets of Senecio. Two nuclear markers and three chloroplast markers were amplified and sequenced. Maximum likelihood and Bayesian inference were used to infer phylogeny, divergence times, biogeographical history and life-history strategy evolution.

ResultsSenecio originated most likely during the Mid to Late Miocene in western southern Africa (WSA). Colonization of the Palaearctic probably started from two different areas. One lineage of mostly annual lowland species seems to have originated in WSA, whereas the other lineage of perennial mountain species originated in mountainous areas of eastern southern Africa or tropical/subtropical East Africa.

Main conclusionsSenecio evolved in arid or semi-arid regions in WSA during a period of ongoing aridification and broad-scale biome changes at the onset of a winter rainfall regime in the Greater Cape Floristic Region. Life-history strategy and elevational distribution of the two Palaearctic lineages did not change between the source areas and the colonized areas.