Data from: Breeding phenology drives variation in reproductive output, reproductive costs and offspring fitness in a viviparous ectotherm

Phenological advances are a widespread response to global warming and can contribute to determine the climate vulnerability of organisms, particularly in ectothermic species which are highly dependent on ambient temperatures to complete their life cycle. Yet, the relative contribution of breeding dates and temperature conditions during gestation on fitness of females and their offspring is poorly documented in reptiles. Here, we exposed females of the common lizard Zootoca vivipara to contrasting thermal scenarios (cold versus hot treatment) during gestation and quantified effects of parturition dates and thermal treatment on life-history traits of females and their offspring for one year. Overall, our results suggest that parturition date has a greater impact than thermal conditions during gestation on life history strategies. In particular, we found positive effects of an earlier parturition date on juvenile survival, growth and recruitment suggesting that environmental dependent selection and/or differences in parental quality between early and late breeders underlie seasonal changes in offspring fitness. Yet, an earlier parturition date compromised the energetic condition of gravid females, which suggests the existence of a mother-offspring conflict regarding the optimisation of parturition dates. While numerous studies focused on the direct effects of alterations in incubation temperatures on reptile life-history traits, our results highlight the importance of considering the role of breeding phenology in assessing the short- and long-term effects of thermal developmental plasticity.物候提前是全球变暖下生物的普遍响应，可用于评估生物的气候脆弱性，尤其对于高度依赖环境温度完成生命周期的变温动物（ectothermic species）而言。然而，爬行动物中繁殖日期与妊娠期温度条件对雌性及其后代适合度（fitness）的相对贡献，目前仍鲜有研究报道。本研究将胎生蜥蜴（Zootoca vivipara）的雌性个体置于两种差异显著的妊娠期热环境（低温处理组与高温处理组）中，并量化了分娩日期与热处理对雌性及其后代为期一年的生活史特征（life-history traits）的影响。总体而言，本研究结果显示，相较于妊娠期的热环境条件，分娩日期对生活史策略的影响更为显著。具体而言，较早的分娩日期可正向影响幼体存活率、生长速度与种群补充量（recruitment），这提示环境依赖型选择，或是早、晚繁殖个体间的亲本质量差异，是后代适合度随季节变化的内在机制。但较早的分娩日期会降低怀卵雌性的能量状态，这表明在分娩日期的优化过程中存在母子冲突（mother-offspring conflict）。尽管已有大量研究聚焦于孵化温度改变对爬行动物生活史特征的直接影响，但本研究结果强调，在评估温度发育可塑性（thermal developmental plasticity）的短期与长期效应时，需充分考虑繁殖物候（breeding phenology）的作用。