Cichlid
diversity in Lake Tanganyika
I am interested in diversification at the population level, including
incipient speciation. In the early stages of divergence, environmental,
ecological and behavioral factors are far more important than postzygotic
mechanisms for maintaining and driving differentiation. Studies of
population structure, mating systems and mate preferences can yield
information on how diversification is launched or, in other cases,
prevented.
Cichlid fishes of the African Rift Lakes are excellent model systems
for this kind of research, because they are closely related to each
other, but highly diversified in morphological, ecological and behavioral
respects. My group is studying the phylogenetic relationship among
cichlid species in Lake Tanganyika, as well as the population genetic
structure and mating systems of different species in the southern
part of Lake Tanganyika.
One particularly interesting case is represented by the color morphs
of the genus Tropheus in Lake Tanganyika (see figure to the
right), which have a common ancestor about 800,000 years ago. The
absence of sexual dimorphism and the establishment of temporary pair
bonds for spawning distinguishes Tropheus from other colorful
cichlids, whose biology is more consistent with the action of strong
sexual selection. We study the evolution of the extant wealth of color
variants in Tropheus by investigating the mating system, the
role of color variation in mating behavior, and the genetic structure
of populations and color morphs.
Past and current group members are:
Bernd Egger (PhD), Eva Eigner (Ms), Beate Obermüller (Ms), Caroline
Hermann (Ms), Karin Mattersdorfer (Ms), Bernd Steinwender (Ms), and
Stephan
Koblmüller (Postdoc).
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Sympatric
speciation in brood parasitic indigobrids
As a Postdoc in Michael Sorenson's lab at Boston University, I joined
his research on speciation in a group of African finches, the indigobirds.
Indigobirds (genus Vidua) are obligate, but benign, brood parasites
with strict specificity to particular host species. The parasitic
chicks mimic the mouth markings of their hosts and learn the host
song, which they later on use as a mate recognition cue. Mating is
assortative among associates of the same host, and females
lay their eggs into nests of the same species that they were raised
by. Host switches result in immediate reproductive isolation between
birds reared by novel hosts and their former conspecifics, thus setting
the stage for rapid sympatric speciation. Although the extant indigobird
species are of very recent origin, genetic data confirm the reproductive
isolation between associates of different hosts.
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Genetic analysis of grapevine
cultivars
In my PhD work at the Center for Applied
Genetics, Universität für Bodenkultur Wien, I used microsatellite
markers to build a database for the identification of grapevine and
rootstock cultivars. Based on the cultivar's genotypes, I reconstructed
ancient crosses that gave rise to some of our extant cultivars. The
genetic contribution of local wild vines to European grapevine cultivars
was inferred from the genetic structure of grapevines from different
wine producing regions.
from Sefc et al. 1998, Theor. Appl.
Genet. 97 |
