Genomics of adaptive divergence in East African cichlid fishes

Cichlid fishes, one of the most species-rich families of vertebrates, are a textbook example of adaptive radiation and a model system in speciation research. My previous postdoc was part of a large project aiming at assessing the role of ecology and phenotypic plasticity in adaptive divergence in East African cichlid fishes.

Specifically, we investigated early stages of diversification in several lake-stream population pairs of Astatotilapia burtoni, Haplochromis stappersii, Ctenochromis horei and Pseudocrenilabrus philander. These replicated population pairs display varying levels of genetic differentiation and therefore represent a suitable empirical example of the ‘speciation continuum’. Using whole genome resequencing, we examined population demography, patterns of genomic divergence and signatures of natural selection between fish from lake and river environments (Weber et al, in preparation).

We also investigated adaptive phenotypic plasticity and reproductive barriers between lake and stream populations of Astatotilapia burtoni, using several infield experiments. Finally, we discovered a sex chromosome in a lake population of Pseudocrenilabrus philander. Interestingly, we could not detect this sex chromosome signature in a closely related river population of P. philander. (Böhne*, Weber* et al, 2019).