PT  - JOURNAL ARTICLE
AU  - Amanda K. Pettersen
AU  - Nathalie Feiner
AU  - Daniel W.A. Noble
AU  - Geoffrey M. While
AU  - Tobias Uller
AU  - Charlie K. Cornwallis
TI  - Maternal behavioural thermoregulation facilitated evolutionary transitions from egg laying to live birth
AID  - 10.1101/2021.02.07.430163
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2021.02.07.430163
4099  - http://biorxiv.org/content/early/2022/08/02/2021.02.07.430163.short
4100  - http://biorxiv.org/content/early/2022/08/02/2021.02.07.430163.full
AB  - Live birth is a key innovation that has evolved from egg laying ancestors over 100 times in reptiles. However, egg-laying lizards and snakes often possess preferred body temperatures that are lethal to developing embryos, which should select against egg retention. Here, we demonstrate that thermal mismatches between mothers and offspring are widespread across the squamate phylogeny. This mismatch is resolved by gravid females adjusting their body temperature towards the thermal optimum of embryos. Importantly, phylogenetic reconstructions suggest this thermoregulatory behaviour evolved in egg-laying species prior to the evolution of live birth. Maternal thermoregulatory behaviour therefore bypasses the constraints imposed by a slowly evolving thermal physiology and has likely been a key facilitator in the repeated transitions to live birth.Competing Interest StatementThe authors have declared no competing interest.