The patterns and possible causes of global geographical variation in the body size of the greater horseshoe bat (Rhinolophus ferrumequinum)

Abstract

Aim Geographical variations in endotherm body size (e.g. Bergmann's rule/James's rule and Allen's rule) have long been tested. However, the patterns and causes of geographical variation in body size within bat species, especially within widespread hibernating species, are little known. Here, we evaluated the possible causes of geographical size variation patterns in the greater horseshoe bat (Rhinolophus ferrumequinum), a bat species widely distributed across the Palearctic. Location Palearctic. Methods We collected body size data (body mass and forearm length) from 1,172 adult bats via direct measurements or from the literature. We used high‐resolution environmental data for the sampled sites. We applied multiple linear regressions and an information‐theoretic approach on separate female and male datasets to estimate the support for various hypotheses. Results Temperature and latitude failed to predict body mass in both females and males. The best model showed that populations with longer forearms in both sexes were associated with higher mean temperatures (in the warmest quarter) and lower mean temperatures (in the coldest quarter). The independent contribution of these temperature parameters to forearm length in both sexes was higher than that of all other variables. Main conclusion The observed relationship between temperature and body mass was not consistent with James's rule, and thus failed to support the heat conservation hypothesis. Our results are consistent with the predictions of Allen's rule and indicated that direct heat dissipation from the wing may be the most likely mechanism underlying geographical variation in forearm length. We suggest that the evaluation of the relative importance of multiple causal mechanisms may improve our understanding of patterns of geographical variation in endotherms.

Global patterns of functional trait variation along aridity gradients in bats

“…While the relationship between bat body size and aridity has received limited attention in bats, the relationship with temperature has been extensively investigated, with various outcomes either confirming, refuting or contrasting Bergmann’s rule (e.g. intraspecific: Jiang et al., 2019; Penone et al., 2018; interspecific: Safi et al., 2013). The divergence from Bergmann’s rule in endotherms has been associated with size‐independent adaptations to cold or warm climates (Medina et al., 2007), such as the ability to hibernate in bats.…”

Allometry reveals trade-offs between Bergmann’s and Allen’s rules, and different avian adaptive strategies for thermoregulation

“…For the last 150 years, an array of evidence has accumulated that Bergmann’s and Allen’s rules reliably link phenotypic variation with geographic and temporal distribution across populations 9 – 13 and species 14 – 18 . Accordingly, body sizes tend to decrease 9 , 10 , 14 , 15 and relative appendage sizes tend to increase 13 , 16 – 18 with the environmental temperature.…”

The Potential to Encode Detailed Information About Parasites in the Acoustic Signals of Chinese Horseshoe Bats (Rhinolophus sinicus)

“…The competing models were ranked using differences in AICc scores ( AICc; Supplementary Tables 1, 2). Models with AIC scores within two of the best models were considered to have strong support (Supplementary Tables 1, 2) (Jiang et al, 2019). We finally performed model averaging and obtained modelaveraged parameter estimates and 95% confidence intervals (95% CIs) for all variables included in strongly supported models (Tables 1, 2) using the function "model.avg" in the R package "MuMIn" (Grueber et al, 2011;Barton, 2015).…”