Evolution of litter size in North America’s most common small mammal: an informatics-based approach
Evolution of litter size in North America’s most common small mammal: an informatics-based approach
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DOI：
10.1093/jmammal/gyz057
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发表时间：
2019-04
影响因子：
1.7
通讯作者：
Bryan S. McLean;N. Barve;J. Flenniken;R. Guralnick
中科院分区：
文献类型：
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作者：
Bryan S. McLean;N. Barve;J. Flenniken;R. Guralnick
确定哺乳动物生活史变化的环境和生态驱动因素对于有效监测这些分类群对全球变化的反应至关重要。研究了地理分布广泛的北美鹿鼠（Peromyscus maniculatus）的整体生活史特征（窝产仔数）与气候的关系。利用从数字化博物馆标本和小型哺乳动物普查记录（跨越一个多世纪的2000次观测）收集的马齿虎胚胎计数的时空综合数据集，我们模拟了产仔数与短期和长期气候变量的关系，并测试了产仔数随近期气候变化的变化。马齿苋的窝产仔数与无霜期的长度相关，表明前者的性状可能在一定程度上是对每年繁殖机会数量的非生物或资源驱动限制的反应。在某些模型中，短期气候变量（繁殖期间的温度和降水）是产仔数的显著预测因子；然而，除无霜期日数外，所有短期和长期气候变量都增加了边际预测能力。进一步的分析证实了在大多数季节性地区的年龄结构繁殖，在那里，母亲的体型和产仔数在一年内都会减少，尽管母亲的体型本身不能很好地预测这些种群的产仔数。我们还发现，随着时间的推移，在已知的无霜期制度（1980年前和1980年后），马齿苋的产仔量在统计上显著下降，正如预测的那样，如果更长的无霜期增加了该物种的终身繁殖机会，尽管需要更多的工作来证实这一趋势并确定潜在的机制。我们的研究完善了气候对马齿虎生活史影响的理解，并重申了数字化标本数据在帮助解决哺乳动物生活史和气候变化响应中悬而未决的问题方面的巨大潜力。
Determining the environmental and ecological drivers of variation in mammalian life histories is essential for effectively monitoring responses of these taxa to global change. We investigated relationships between climate and an integral life history trait (litter size) in the geographically widespread North American deer mouse (Peromyscus maniculatus). Using a spatiotemporally comprehensive data set of P. maniculatus embryo counts assembled from digitized museum specimens and small mammal census records (> 2,000 observations spanning more than a century), we modeled the associations of litter size with short- and long-term climate variables, and tested for shifts in litter size in response to recent climate change. Litter size in P. maniculatus was correlated with length of the frost-free period, suggesting the former trait may have evolved partly as a response to abiotic or resource-driven constraints on the number of annual breeding opportunities. Short-term climate variables (temperature and precipitation during breeding) were significant predictors of litter size in some models; however, all short-and long-term climate variables other than number of frost-free days added marginal predictive power. Further analyses confirmed age-structured breeding in the most seasonal regions, where maternal body sizes and litter sizes both decrease within a year, although maternal body size itself was poorly predictive of litter size in these populations. We also found a statistically significant decrease in P. maniculatus litter size through time and across known frost-free period regimes (pre- and post-1980), as predicted if longer frost-free periods are increasing lifetime breeding opportunities in this species, although more work is required to confirm this trend and identify underlying mechanisms. Our study refines understanding of climate impacts on P. maniculatus life history and reiterates the great potential of digitized specimen data to help address outstanding questions in mammalian life history and climate change response.