TREMETSBERGER, KARIN, TOD STUESSY*, ROSE SAMUEL, AND CARLOS BAEZA. Department of Higher Plant Systematics and Evolution, Institute of Botany, University of Vienna, Vienna A-1030, Austria; Departamento de Botanica, Universidad de Concepcion, Concepcion, Chile. - High levels of genetic variation and multiple origins for newly established populations of Hypochaeris tenuifolia (Asteraceae) on Volcan Lonquimay, Chile.
As with newly formed oceanic islands, new volcanic areas on continents
also provide an opportunity to examine populational phenomena during
arrival and early establishment of plant species. Of special interest
is the degree of genetic variance in these early colonizers, as they
contain genetic resources that fuel, in part, future populational
differentiation and eventual speciation. It is predicted that new
populations in open ash fields should (1) result from limited numbers
of propagules from geographically adjacent areas, and (2) contain
reduced genetic variation in comparison with source populations.
Hypochaeris tenuifolia (Asteraceae), confined to high elevation
volcanic peaks (1750-2400m) along the southern Andes between 35-39
degrees S, was selected to test these predictions. A new volcanic
cone, La Navidad, erupted on the flank of Volcan Lonquimay, Chile, on
25 Dec 1988, spreading lava and ash along well documented routes.
During 1999 and 2000, we analyzed using AFLP markers 11 populations
(20-30 plants in each) of H. tenuifolia in two transects on Volcan
Lonquimay, including newly ashed slopes and undisturbed Auraucaria
forests, and compared these data with those from 30 additional
populations throughout the range of the species. The results show a
surprisingly high level of genetic variance in pioneer populations as
well as connections to many different source areas. It appears that
biological attributes of species, in this case dispersal capability,
can be more important than biogeographic parsimony in defining genetic
characteristics of colonizing species in island-like habitats.
Key words: AFLP, biogeography, Chile, genetic variation, Hypochaeris, volcanoes