Takayama, Koji , López, Patricio , Kohl, Gudrun , Greimler, Josef , König, Christiane , Baeza, Marcelo , Ruiz, Eduardo , Crawford, Daniel , Peñailillo, Patricio , Gatica, Alejandro , Letelier, Luis , Novoa, Patricio , Tremetsberger, Karin , Novak, Johannes , Stuessy, Tod .
Evolution and genetic diversity of endemic plants in the Juan Fernandez Archipelago, Chile, revealed by AFLPs and microsatellites.
Oceanic islands are valuable natural laboratories of plant evolution, and they have long fascinated evolutionary biologists. In particular, numerous investigations have focused on processes of speciation in island endemic plants. Cladogenesis (also known as adaptive radiation in an island context) has been a well described speciation process in oceanic islands. From a single ancestor, several lines of speciation develop rapidly by selection within markedly different ecological zones. A contrasting process of speciation is anagenesis (phyletic speciation), whereby an initial founder population simply changes through time without further specific differentiation. It is proposed that the distribution of genetic variation within and among endemic species will be in relation to these processes of speciation along with population size, breeding systems and immigration time. In anagenetically derived species, genetic variation within populations increases with time, but interpopulational genetic variation remains low due to gene flow and recombination. In cladogenetically derived species, in contrast, genetic variation among populations (or species) will be high, correlating with strong ecological divergence, but genetic variation within populations will be low. These two different modes of speciation, therefore, not only lead to very different levels of specific diversity, but also different genetic consequences. To test these ideas, we examined on endemic species of the Juan Fernandez (Robinson Crusoe) Archipelago, located 681 kms west of continental Chile, which consists of two islands of equal size (50 km2) but of different ages (4 million years for Masatierra and 1-2 million years for Masafuera). We investigated genetic variation with AFLP and microsatellite markers of populations within anagenetically derived species of Myrceugenia and Drimys, and cladogenetically derived species of Erigeron and Robinsonia. Congruent to predictions, both markers revealed weak populational differentiation in the anagenetically derived species within each island, but clear genetic segregation among species in the cladogenetically derived species. Genetic differentiation between populations on the two islands was found in two endemic species, Drimys confertifolia and Erigeron fernandezianus. The former species contains higher levels of genetic diversity within populations in the older island (Masatierra), whereas the latter species shows more variation in the younger island (Masafuera). These results suggest that the process of speciation and time of immigration have both influenced levels of genetic variation within endemic species of the Juan Fernandez Archipelago.
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1 - University of Vienna, Systematic and Evolutionary Botany, Rennweg 14, Vienna, Austria
2 - Universidad de Concepción, Botánica, Concepción, Chile
3 - University Of Kansas, Department Of Ecology And Evolutionary Biology, 1200 Sunnyside Avenue, Haworth Hall, Lawrence, KS, 66045-7534, USA
4 - Universidad de Talca, Instituto de Biología Vegetal y Biotecnología, Talca, Chile
5 - Universidad de La Serena, Biología, La Serena, Chile
6 - Universidad Nacional Autónoma de Mexico, Centro de Investigaciones en Ecosistemas, Michoacán, Mexico
7 - Corporación Nacional Forestal, Jardín Botánico de Viña del Mar, Viña del Mar, Chile
8 - University of Natural Resources and Life Sciences, Integrative Biology and Biodiversity Research, Vienna, Austria
9 - University of Veterinary Medicine, Applied Botany and Pharmacognosy, Vienna, Austria
Presentation Type: Oral Paper:Papers for Topics
Location: Franklin B/Hyatt
Date: Monday, July 9th, 2012
Time: 11:30 AM