Ambient temperature correlates with geographic variation in body size of least horseshoe bats

Abstract

Geographic variation in body size is common within many animal species. The causes of this pattern, however, remain largely unexplored in most vertebrate groups. Bats are widely distributed globally owing to their ability of powered flight. Most bat species encounter a variety of climatic conditions across their distribution range, making them an ideal taxon for the study of ecogeographic patterns in body size. Here, we used adult least horseshoe bats, Rhinolophus pusillus, to test whether geographic variation in body size was determined by heat conservation, heat dissipation, climatic seasonality, or primary productivity. We measured body mass and head-body length for 246 adult bats from 12 allopatric colonies in China. We quantified the ecological conditions inhabited by each colony, including mean maximum temperature of the warmest month, mean minimum temperature of the coldest month, temperature seasonality, precipitation seasonality, and annual net primary productivity (ANPP). Body mass and head-body length, 2 of the most reliable indicators of body size, exhibited marked differences between colonies. After controlling for spatial autocorrelation, the mean minimum temperature of the coldest month explained most of the variation in body size among colonies, regardless of sex. The mean maximum temperature, climatic seasonality, and ANPP had limited power in predicting body size of males or females in comparison with mean minimum temperature. These results support the heat conservation hypothesis and suggest adaptive responses of body size to cold climates in cave-dwelling bats.

Abiotic and biotic drivers of functional diversity and functional composition of bird and bat assemblages along a tropical elevation gradient

“…Moreover, small bats may have advantages in environments with high precipitation, because rain imposes additional energetic costs on bat flight due to higher thermoregulatory costs and lowered aerodynamic properties, especially for large species (Voigt et al., 2011). The differences in the responses of birds and bats to temperature might further be related to differences in their reproductive biology, because breeding birds are typically more exposed to variation in ambient temperature than cavity‐roosting bats (Carroll et al., 2018; Du et al., 2019; Rodriguez‐Durán & Soto‐Centeno, 2003; Wang et al., 2020). Together, our results reveal that multiple factors related to abiotic conditions and habitat structure affect the functional composition of bat assemblages in terms of body size and wing shape, whereas in birds these traits seem to be mainly constrained by temperature.…”

Body Size Variation in Italian Lesser Horseshoe Bats Rhinolophus hipposideros over 147 Years: Exploring the Effects of Climate Change, Urbanization and Geography

“…Either increases or decreases in bat body size are therefore valid hypotheses to explore as potential responses to climate change. Body size in Chinese Rhinolophus pusillus , for example, correlated negatively with the mean minimum temperature of the coldest month, supporting the fact that at least in that species body size is influenced by the need to preserve heat [ 14 ], although for bats no clear body size trend over time is known that might be associated with climate change. Prolonged pre-natal growth associated to higher temperatures under a climate change scenario might also lead to an increasing body size over time [ 15 ].…”