Overall this suggests that vivparity evolution cannot be separated from squamate lineage diversification. Further, exploring patterns by simulations of a binary trait also showed a similar association with palaeoclimate. Here led by Hans Recknagel in his interdisciplinary PhD studentship, we showed that stable and long-lasting cold climatic conditions are correlated with transitions to viviparity across squamates. Interestingly, this correlation of parity mode and palaeoclimate is mirrored by background diversification rate in squamates. Also many studies have examined particular species groups but we have lacked the data so far to estimate a time tree in context of climate. However this is challenging to disentangle correlation from causation, and response from cause. It has long been argued that the origin of viviparity is related to cold climatic conditions. Therefore, our results suggest that pre-established regulatory networks are repeatedly recruited for viviparity and that these are shared at deep evolutionary scales.Ī collaboration between evolutionary biology and Geography for reconstruction of palaeoclimate. Our comparison to seven independent origins of viviparity in mammals, squamates, and fish showed that genes active in pregnancy were related to immunity, tissue remodelling, and blood vessel generation. Natural selection on these parity mode genes was evident genome-wide. Angiogenesis, vascular endothelial growth, and adrenoreceptor pathways were enriched in the viviparous female reproductive tissue, while pathways for transforming growth factor were enriched in the oviparous.
Viviparity involved more genes and complex gene networks than did oviparity. In these lizards, parity trait genes were associated with progesterone-binding functions and enriched for tissue remodelling and immune system pathways. Here we leveraged natural hybridisations between oviparous and viviparous common lizards ( Zootoca vivipara) to describe the functional genes and genetic architecture of parity mode and its key traits, eggshell and gestation length, and compared our findings across vertebrates. However, the genetic basis of these parity modes has never been resolved and consequently its convergence across evolutionary scales is currently unknown. ElmerĪll amniotes reproduce either by egg-laying (oviparity), which is ancestral to vertebrates, or by live-bearing (viviparity), which has evolved many times independently.
The functional genetic architecture of egg-laying and live-bearing reproduction in common lizards
Our paper on the genetic basis of parity mode is now published.
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