School of Zoology, University of Tasmania, Hobart, Tasmania, Australia.
PLoS One. 2012;7(7):e41835. doi: 10.1371/journal.pone.0041835. Epub 2012 Jul 26.
The evolution of matrotrophy (i.e., direct supply of nutrients by the mother during gestation) may be associated with high maternal energy availability during gestation. However, we lack knowledge about the selective advantages of matrotrophic viviparity (live-bearing) in reptiles. In reptiles, the interaction between body temperature and food intake affect maternal net energy gain. In the present study, we examined the effects of basking and food availability (2 by 2 factorial design) during gestation on offspring phenotype in a matrotrophic viviparous lizard (Pseudemoia entrecasteauxii). Subsequently, we investigated if the maternal effects were context-dependent using offspring growth rate as an indicator of the adaptive significance of matrotrophy. Offspring were exposed either to the same thermal conditions as their mothers experienced or to thermal conditions different from those experienced by their mothers. We provide the first evidence that an interaction between maternal thermal and maternal food conditions during gestation strongly affects offspring phenotype, including date of birth, body size and performance ability, which affect offspring fitness. Offspring growth rate was dependent on offspring thermal conditions, but was not influenced by maternal effects or offspring sex. Matrotrophic viviparity provided gravid females with the means to enhance offspring fitness through greater energetic input to offspring when conditions allowed it (i.e., extended basking opportunity with high food availability). Therefore, we suggest that selective advantages of matrotrophic viviparity in P. entrecasteauxii may be associated with high maternal energy availability during gestation.
营养质（即母体在妊娠期间直接供给营养物质）的进化可能与妊娠期间母体的高能量供应有关。然而，我们对爬行动物中营养质胎生（活体生产）的选择优势知之甚少。在爬行动物中，体温和食物摄入之间的相互作用会影响母体的净能量收益。在本研究中，我们研究了妊娠期间（2×2 析因设计）晒太阳和食物可获得性对营养质胎生蜥蜴（Pseudemoia entrecasteauxii）后代表型的影响。随后，我们通过将后代生长率作为营养质胎生适应性意义的指标，来研究母体效应是否依赖于环境。后代暴露于与母亲经历相同的热条件或与母亲经历不同的热条件。我们提供了第一个证据，证明妊娠期间母体热和母体食物条件之间的相互作用强烈影响后代的表型，包括出生日期、体型和表现能力，这些都影响后代的适应性。后代的生长率取决于后代的热条件，但不受母体效应或后代性别影响。营养质胎生使怀孕的雌性能够在条件允许时（即延长有高食物可获得性的晒太阳机会），通过向后代投入更多的能量来提高后代的适应性。因此，我们认为，P. entrecasteauxii 中营养质胎生的选择优势可能与妊娠期间母体的高能量供应有关。
