Pettersen Amanda K, Feiner Nathalie, Noble Daniel W A, While Geoffrey M, Uller Tobias, Cornwallis Charlie K
Department of Biology, Lund University, Lund, Sweden.
School of Life and Environmental Sciences, The University of Sydney, Sydney, Australia.
Evol Lett. 2023 Jul 26;7(5):351-360. doi: 10.1093/evlett/qrad031. eCollection 2023 Oct.
Live birth is a key innovation that has evolved from egg-laying ancestors over 100 times in reptiles. However, egg-laying lizards and snakes can have preferred body temperatures that are lethal to developing embryos, which should select against prolonged 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 their embryos. We find that the same response occurs in both live-bearing and egg-laying species, despite the latter only retaining embryos during the early stages of development. Importantly, phylogenetic reconstructions suggest this thermoregulatory behavior in gravid females evolved in egg-laying species prior to the evolution of live birth. Maternal thermoregulatory behavior, therefore, bypasses the constraints imposed by a slowly evolving thermal physiology and has likely been a key facilitator in the repeated transition to live birth.
胎生是一项关键的创新，它在爬行动物中已从产卵祖先那里进化而来100多次。然而，产卵蜥蜴和蛇可能具有对发育中的胚胎致命的偏好体温，这应该会选择避免长时间保留卵。在这里，我们证明了母体与后代之间的热不匹配在有鳞目系统发育中广泛存在。这种不匹配通过怀孕雌性将体温调节到其胚胎的最适温度来解决。我们发现，无论是胎生物种还是卵生物种都会出现相同的反应，尽管后者仅在发育早期保留胚胎。重要的是，系统发育重建表明，怀孕雌性的这种体温调节行为在胎生进化之前就在卵生物种中演化出来了。因此，母体体温调节行为绕过了缓慢演化的热生理学所带来的限制，并且很可能是反复向胎生转变的关键促进因素。
