In northern environments, the period of access to high-quality forage is limited, exerting strong selective pressure to optimize the timing of parturition. We analysed timing and variation in moose (Alces alces) parturition dates of 555 females at 18 study sites across 12° of latitude (56-68° N, 1350 km) in Sweden. We found evidence for a spatial match of parturition timing to vegetation onset, but no evidence that moose adjust parturition to vegetation onset in a given year. We found a breakpoint at 64° N. Despite adaptation across latitudes, temporal divergences occurred. Females below 64° N calved after vegetation onset and females above 64° N calved before. Here, parturition before vegetation onset might be a strategy to optimize forage utilization time with the very short growing season. Highly seasonal environments such as at higher latitudes may make it advantageous to adapt parturition towards long-term climatic patterns by matching the most favourable period. Given the direction of temporal divergence, our study suggests that climate change may have less of an impact on moose parturition at northern latitudes than southern latitudes.

中文翻译：

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沿横向梯度的大草食动物差异中分娩时机的发散和植被的开始。

在北部环境中，获得优质草料的时间有限，从而施加了强大的选择性压力以优化分娩时机。我们分析了瑞典12个纬度（56-68°N，1350 km）的18个研究地点的555名雌性驼鹿（Alces alces）分娩日期的时间和变化。我们发现分娩时机与植被发作在空间上匹配的证据，但没有证据表明驼鹿在给定年份中会调整分娩与植被发作的关系。我们在64°N处发现了一个断点。尽管跨纬度进行了适应，但仍发生了时间差异。植被开始后，在64°N以下的雌性会cal割，而之前在64°N以上的雌性会先ved裂。在这里，在植被开始生长之前就进行分娩可能是优化草料利用时间的一种策略。高度季节性的环境（例如在较高纬度的环境）可能有利于通过匹配最有利的时期使分娩适应长期的气候模式。考虑到时间差异的方向，我们的研究表明，气候变化对北部纬度的驼鹿分娩的影响可能小于南部纬度。