Systematics/Phytogeography / Taxonomie/ Section
Baier, Christina , Blattner, Frank R. .
Genetic structure in and among populations of the Southeast Asian tropical ant-plants of Macaranga (Euphorbiaceae).
The genus Macaranga Thou. consists of about 300 shrub and tree species distributed from tropical West Africa to some Pacific islands in the east. Within the Southeast Asian sections of the genus a wide variety of ant-plant mutualisms exists ranging from the attraction of opportunistic ants to obligate myrmecophytism. Obligate myrmecophytes should be poor colonizers, as they always have to co-disperse with their ants, which should promote geographic isolation, ultimately resulting in separate species. Three of the Southeast Asian Macaranga sections contain obligate myrmecophytes. While two of these sections show all signs of a rapid and relatively recent radiation in the myrmecophytes, in section Winklerianae (two species) no indications for an ongoing radiation could be found.
We here compare population genetic parameters of M. winkleri, (obligate myrmecophyte of the non-radiating section) and M. tanarius (non-myrmecophyte) with myrmecophytes and non-myrmecophytes of the two radiated Macaranga sections, using chloroplast and nuclear microsatellite markers.
First data from M. tanarius and M. winkleri indicate high genetic diversity within populations, but low differentiation among populations. So far, no obvious differences in population genetic parameters became apparent between these myrmecophytic and non-myrmecophytic species, which indicates that the populations of both species are effectively connected and form a metapopulation. Although M. winkleri always has to co-disperse with their specific ants, primary forest is not a migration barrier for this species, whereas for M. tanarius it is. This might counterbalance the differences expected between these two species.
In the next step we will compare these data with data of the obligate myrmecophytes of the rapidly radiating species groups. A more pronounced genetic structuring among populations of these species would indicate restricted geneflow and, thus, a much stronger isolation of remote populations, which is the first prerequisite for allopatric speciation.
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1 - Institute of Plant Genetics and Crop Research (IPK), Taxonomy & Evol. Biology, Gatersleben, D-06466, Germany
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM