Data from: Climate change and temporal trends in body size: the case of rodents

A reduction in body size has been proposed as the third universal ecological response to global warming, after species distributional shifts and phenological changes. However, some recent studies raise doubts about the validity of this pattern, in particular for endotherms. Within this context, here we analyzed data on body mass (mb) for 17 rodent species, covering (at least) the last six decades, together with data on temperature change and basal metabolic rate (BMR) for each species. We found that: 1) ten species (58.8%) showed no significant changes in mb, while the remaining seven species (41.2%) decreased their size during the 20th century; 2) phylogenetic generalized linear mixed models indicate that there is a significant and negative effect of the year of collection on mb; 3) the correlation coefficient between mb and the year of collection (ryear) was not correlated with species mean mb, species distributional range, the length of the time series, or the change in ambient temperature; and 4) the correlation between ryear and (residual) BMR was significant (and negative) only for species that do not use torpor. In summary, our results suggest that reductions in mb are common among rodents, but we were unable to identify a clear cause behind these changes (e.g. some results support the energetic argument behind the Bergmann rule but other do not). We concluded that with less than 0.5% of the extant (known) rodent species analyzed to date, we still are far from reaching a clear understanding of current patterns of variation in body size that are associated with global environmental change for this group.

体型缩小被提出为继物种分布范围转移与物候变化之后，应对全球变暖的第三种全球性生态响应。然而近期多项研究对该模式的有效性提出了质疑，尤其针对内温动物（endotherms）。在此研究背景下，本研究针对17种啮齿类物种的体重（body mass, mb）数据展开分析，数据跨度至少覆盖过去60年，同时纳入各物种的温度变化与基础代谢率（basal metabolic rate, BMR）数据。本研究结果显示：1）10个物种（占比58.8%）的体重未出现显著变化，剩余7个物种（占比41.2%）在20世纪期间出现体型缩小；2）系统发育广义线性混合模型（phylogenetic generalized linear mixed models）表明，采集年份对体重存在显著负向影响；3）体重与采集年份的相关系数（ryear）与物种平均体重、物种分布范围、时间序列长度或环境温度变化均无显著相关性；4）仅在不使用蛰伏（torpor）的物种中，ryear与（残差）基础代谢率（BMR）的相关性显著（且为负相关）。综上，本研究结果表明，啮齿类中普遍存在体重缩小的现象，但我们尚未明确这类变化的明确诱因——例如部分结果支持伯格曼法则（Bergmann rule）背后的能量代谢假说，其余结果则不支持该假说。本研究总结道，截至目前仅对不足0.5%的现存（已发现）啮齿类物种开展了相关分析，我们仍远未明确该类群与全球环境变化相关的体型变化当前模式。