Microevolutionary change in viscerocranial bones under congeneric sympatry in the Lake Tanganyikan cichlid genus .

Unlabelled: The endemic Lake Tanganyika cichlid genus lives at rocky shores all around the lake and comprises six species which are subdivided into about 120 morphologically similar but color-wise distinct populations. Typically, they live without a second species, but there are some regions where two or even three sister species live in sympatry. We previously showed that there are morphological differences concerning head shape, eye size and insertion of fins among populations living alone compared to those living in sympatry with a second .

Asymmetric dominance and asymmetric mate choice oppose premating isolation after allopatric divergence.

Assortative mating promotes reproductive isolation and allows allopatric speciation processes to continue in secondary contact. As mating patterns are determined by mate preferences and intrasexual competition, we investigated male-male competition and behavioral isolation in simulated secondary contact among allopatric populations. Three allopatric color morphs of the cichlid fish Tropheus were tested against each other.

Morphological distinctness despite large-scale phenotypic plasticity--analysis of wild and pond-bred juveniles of allopatric populations of Tropheus moorii.

Cichlids are an excellent model to study explosive speciation and adaptive radiation. Their evolutionary success has been attributed to their ability to undergo rapid morphological changes related to diet, and their particular breeding biology. Relatively minor changes in morphology allow for exploitation of novel food resources.

Sexual dimorphism and population divergence in the Lake Tanganyika cichlid fish genus Tropheus.

Background: With about 120 colour morphs currently assigned to six nominal species, the genus Tropheus is an ideal model to study evolutionary divergence of populations in allopatry. The morphology of Tropheus has been described as relatively static, but reproductive constraints are sexually dimorphic due to mouthbrooding in females. We analysed phenotypic variation in six populations of T.