Data from: Relaxed trait covariance in interspecific cichlid hybrids predicts morphological diversity in adaptive radiations

The process of adaptive radiation involves multiple events of speciation
in short succession, associated with ecological diversification.
Understanding this process requires identifying the origins of heritable
phenotypic variation that allows adaptive radiation to progress.
Hybridization is one source of genetic and morphological variation that
may spur adaptive radiation. We experimentally explored the potential role
of hybridization in facilitating the onset of adaptive radiation. We
generated first- and second-generation hybrids of four species of African
cichlid fish, extant relatives of the putative ancestors of the adaptive
radiations of Lakes Victoria and Malawi. We compared patterns in hybrid
morphological variation with the variation in the lake radiations. We show
that significant fractions of the interspecific morphological variation
and the major trajectories in morphospace that characterize whole
radiations can be generated in second-generation hybrids. Furthermore, we
show that covariation between traits is relaxed in second-generation
hybrids, which may facilitate adaptive diversification. These results
support the idea that hybridization can provide the heritable phenotypic
diversity necessary to initiate adaptive radiation.