The breeding time of many species has changed over the past 2–3 decades in response to climate change. Yet it is a key reproductive trait that affects individual's parturition time and reproductive success, and thereby population dynamics. In order to predict how climate change will affect species’ viability, it is crucial to understand how species base their reproductive efforts on environmental cues. By using long-term datasets of mating behaviours and copulation dates recorded since 1996 on a semi-domesticated reindeer population, we showed that mating time occurred earlier in response to weather conditions at different key periods in their annual breeding cycle. The mating time occurred earlier following a reducing snow cover in early spring, colder minimum temperatures in the last 2 weeks of July and less precipitation in August-September. The mediated effect of a reduced snow cover in early spring on improving individuals’ pre-rut body weight through a better availability of late winter food and reduced costs of locomotion on snow would explain that mating time has occurred earlier overtime. A lower level of insect harassment caused by colder maximum temperatures in July might have caused an advance in mating time. Less precipitation in August-September also caused the mating time to occur earlier, although the direct effects of the last two weather variables were not mediated through the pre-rut body weight of individuals. As such, the causal effects of weather conditions on seasonal timing of animals are still unclear and other mechanisms than just body weight might be involved (e.g. socio-biological factors). The plastic response of reindeer mating time to climatic variability, despite supplemental feeding occurring in late April, demonstrated that environmental factors may have a greater influence on reproductive outputs than previously thought in reindeer.

中文翻译：

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驯鹿交配时间对气候变化的响应。

在过去的2-3年中，由于气候变化，许多物种的繁殖时间发生了变化。然而，它是一个重要的生殖特征，会影响个体的分娩时间和生殖成功，进而影响人口动态。为了预测气候变化将如何影响物种的生存能力，至关重要的是要了解物种如何根据环境线索进行繁殖。通过使用自1996年以来在半驯化驯鹿种群上记录的长期交配行为和交配日期数据集，我们发现交配时间是在其年度繁殖周期中不同关键时期对天气条件的响应较早发生的。交配时间较早，这是由于早春积雪减少，7月的最后两周最低温度较低以及8月至9月的降水较少。早春积雪减少通过改善冬季食物的供应和降低雪上运动的费用而改善了个体发情前体重的调节作用，这说明交配时间早于加班。7月份最高温度降低导致的昆虫骚扰程度降低，可能导致交配时间提前。虽然最后两个天气变量的直接影响没有通过个体发情前的体重来调节，但八月至九月较少的降水也导致交配时间提前。因此，天气状况对动物季节性时机的因果影响尚不清楚，可能涉及除体重以外的其他机制（例如，社会生物学因素）。驯鹿交配时间对气候变化的塑性响应，