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Evolution shapes behavior, and behavior influences
the course of evolution. I am interested in how behavior and evolutionary
processes interact in various contexts including reproduction, migration
and dispersal, ecological specialization and territoriality.
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The remarkable diversification of cichlid fishes
is ascribed to their particular breeding biology and their capacity
for ecological specialization. Sexual and natural selection shaped
morphologies and behaviors, and in turn, the resultant phenotypes
constrained, permitted or accelerated evolutionary changes.
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One focus taxon, the genus Tropheus,
occupies a narrow trophic niche in the rocky littoral of Lake Tanganyika,
Africa. Being restricted to this particular type of habitat, species
are divided into multiple separate populations along the lake shore,
with little or no gene flow across even minor habitat barriers.
This, in consequence, enabled the different populations to evolve
specific color patterns and to produce one of the most stunning
examples of intraspecific color pattern diversity. The territorial,
sexually monomorphic Tropheus communicate by means of body
color signals in both sexual and agonistic contexts, and sexual
and social selection may have affected color pattern evolution.
Allopatric color pattern diversification was in some cases, but
not always, accompanied by the evolution of color-assortative mating
preferences. Secondary contact among differentiated populations
occurred in the course of lake level fluctuations, and a few of
the extant color morphs are likely to have originated from hybridization
during such population admixtures.
Our research addresses the evolutionary history of Tropheus
populations, reproductive isolation among color morphs, social and
sexual interactions within populations, hybrid origins of color
morphs and the molecular basis of color pattern differentiation.
Putting together evidence from these different approaches, we hope
to identify the processes behind the rapid and extensive allopatric
diversification.
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Mating and breeding behaviors are highly diverse
across cichlid species. Even within Lake Tanganyika, we find mouthbrooders
and substrate breeders, uniparental, biparental and cooperative
breeders, monogamous, polygynous, polyandrous and promiscuous species,
as well as a diversity of alternative reproductive tactics such
as piracy and sneaking. Genetic parentage of broods is often found
to be at odds with the social mating system, and both intra- and
interspecific brood adoption occur. Within a species, reproductive
behavior may vary considerably across seasons or among populations.
Reproductive strategies affect how individuals can maximize their
own fitness, how reproductive success is distributed within populations,
and how sexual selection influences the evolution of populations
and species.
Our research investigates the true (genetic) parentage in cichlid
broods in a background of different social mating systems, and is
concerned with consequences on individual fitness and sexual selection.
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