Evolutionary genetics of naturally and sexually selected traits in cichlid fishes

In my PhD thesis I use cichlid fishes as model system to study the evolutionary
genetics of naturally and sexually selected traits. Several traits of cichlid fishes such as; the pharyngeal jaw apparatus, haplochromine maternal mouthbrooding, egg-spots and color polymorphisms have been proposed as evolutionary key innovations. Key innovations are described as novel traits that allow its bearer to exploit new ecological niches, and are considered as one of the possible causes leading to an adaptive radiation. Furthermore, these traits could (partly) be responsible for the evolutionary success of cichlid lineages.
Besides these key innovations, other adaptive traits could also have increased the fitness of an individual and subsequently spread within a population. These adaptive traits can be of a morphological, behavioral as well as physiological kind and are eminent candidates to study the genetic basis of adaptation and diversification.
Furthermore, they can be used to determine the role of natural and/or sexual selection in adaptive processes.
In my doctoral work I studied the molecular evolutionary genetics of candidate gene families that are associated with either key innovations or other adaptations in cichlids or specific lineages thereof. The goal was to get a better understanding of the sequence evolution and type of selection (i.e., neutral, purifying or positive selection) acting upon genes that are involved in evolutionary important traits. Furthermore, functional implications of these loci can then be validated by means of e.g., expression assays.
The goal of the second part of my thesis was to unravel the genetic basis of a particular adaptation: the thick-lipped phenotype observed in multiple cichlid lineages. Here, the aim was to generate a candidate gene list of loci that are putatively involved in the evolution of this particular adaptation. In conclusion, the results of my doctoral thesis provide valuable insights into the
molecular evolutionary genetics of three specific gene families and offers exciting
new insights into the genetic basis of one specific convergent adaptive trait: the thicklipped
phenotype observed in both African and Nicaraguan species.