Gene duplications and deletions in the Poeciliidae. Gene duplications and deletion in the Poeciliidae

During vertebrate evolution, complex organs have evolved several times. It has been hypothesized that gene duplications can drive the evolution of new complex traits. However, testing this prediction consistently poses a challenge because the emergence of a new complex trait is relatively rare. Here, we test the hypothesis that gene duplications are associated with complex trait evolution in the livebearing fish family Poeciliidae. In this family, a placenta has evolved nine times independently, allowing for the study of genomic convergence in association with placenta evolution. We show that different instances of placenta evolution are not associated with gene duplications in the same genes, nor in genes with a similar biological function. However, we do find an association with placenta evolution and loss-of-function mutations within genes involved in certain developmental pathways, specifically the calcineurin-NFAT signaling cascade and the BMP signaling pathway. We hypothesize that removing a copy of some previously duplicated genes that are a result of the teleost-specific genome duplication can influence these developmental pathways in some tissues, while other tissues are not affected by the deletion, thereby allowing to circumvent deleterious pleiotropic effects that would normally accompany such a deletion.