Population divergence and speciation in Hypochaeris (Asteraceae, Cichorieae) from

K. TREMETSBERGER; P. LOPEZ; T. F. STUESSY; E. URTUBEY; C. M. BAEZA

Bariloche

Congreso; VI Southern Connection Congress; 2010

Universidad

The c. 40 morphologically diverse South American species of the perennial herb Hypochaeris havediversified in the Pleistocene. They have colonized large portions of the continent and grow in a diversearray of habitats. AFLP analysis has revealed phyletic assemblages within the South American radiation.The species contained in the same phyletic assemblage also occur in the same biogeographic provincesof South America. We are interested in the potentially important factors that have driven recentspeciation within biogeographic regions, including divergent ecological preferences of the species (nichedifferentiation), changes in the reproductive system, and karyotypic changes. Ecological adaptation issuggested as a driver of speciation in the young phyletic assemblage containing H. apargioides, H.gayana, and H. spathulata. The species show parapatric distributions and divergent ecologicalpreferences in Chile and Argentina suggestive of adaptive radiation. Self-compatibility evolved fromself-incompatibility within several phyletic assemblages suggesting that inbreeding could have promoted speciation. Autopolyploidization is seen at the infraspecific level in several species. In H. incana from the Patagonian and Subantarctic region, the tetraploids show different ecological preferences than their diploid progenitors suggesting that autopolyploidization could be the starting point for a new round of diversification.H. incana from the Patagonian and Subantarctic region, the tetraploids show different ecological preferences than their diploid progenitors suggesting that autopolyploidization could be the starting point for a new round of diversification.