Colour-assortative mating among populations ofTropheus moorii, a cichlid fish from Lake Tanganyika, East Africa

Abstract

The species flocks of cichlid fishes in the East African Lakes Tanganyika, Malawi and Victoria are prime examples of adaptive radiation and explosive speciation. Several hundreds of endemic species have evolved in each of the lakes over the past several thousands to a few millions years. Sexual selection via colourassortative mating has often been proposed as a probable causal factor for initiating and maintaining reproductive isolation. Here, we report the consequences of human-mediated admixis among differentially coloured populations of the endemic cichlid fish Tropheus moorii from several localities that have accidentally been put in sympatry in a small harbour bay in the very south of Lake Tanganyika. We analysed the phenotypes (coloration) and genotypes (mitochondrial control region and five microsatellite loci) of almost 500 individuals, sampled over 3 consecutive years. Maximum-likelihood-based parenthood analyses and Bayesian inference of population structure revealed that significantly more juveniles are the product of within-colour-morph matings than could be expected under the assumption of random mating. Our results clearly indicate a marked degree of assortative mating with respect to the different colour morphs. Therefore, we postulate that sexual selection based on social interactions and female mate choice has played an important role in the formation and maintenance of the different colour morphs in Tropheus, and is probably common in other maternally mouthbrooding cichlids as well.

CSF-1 Receptor Signaling in Myeloid Cells

“…In zebrafish, kit and csf1r play critical roles in the development of different neural crest -derived pigment cell types-kit for melanocytes (Parichy et al 1999) and csf1r for xanthophores (Parichy et al 2000;Parichy and Turner 2003)-and it is likely that the gene duplications were driven by selection for pigment cell innovations important for speciation (Fig. 1B) (Braasch et al 2006;Salzburger et al 2006). …”

Testing the stages model in the adaptive radiation of cichlid fishes in East African Lake Tanganyika

“…To investigate gut length, we removed the entire alimentary canal ('gut') from the anus to the posterior end of the stomach and measured its length to the nearest millimetre. In order to evaluate body coloration, we adopted and modified an existing colour-scoring scheme for cichlids [41].…”

Identification and Characterization of Gene Expression Involved in the Coloration of Cichlid Fish Using Microarray and qRT-PCR Approaches

“…Sexual selection has been proposed as an important mechanism in their speciation. This has been demonstrated by field observations Salzburger et al 2006;Elmer et al 2009b) and complementary mate choice experiments in the laboratory (Barlow et al 1977(Barlow et al , 1990Knight et al 1998;Seehausen et al 1999). More specifically, ecological evidence that sexual selection plays a role in speciation came from the inferred breakdown of visual reproductive barriers under monochromatic light conditions or in turbid waters (Seehausen et al 1997;Seehausen et al 2008).…”