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.