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 tempe...