Physical constraints on thermoregulation and flight drive morphological evolution in bats
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2022-04
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Resumo
Body size and shape fundamentally determine organismal energy requirements by modulating
heat and mass exchange with the environment and the costs of locomotion,
thermoregulation, and maintenance. Ecologists have long used the physical linkage
between morphology and energy balance to explain why the body size and shape of
many organisms vary across climatic gradients, e.g., why larger endotherms are more
common in colder regions. However, few modeling exercises have aimed at investigating
this link from first principles. Body size evolution in bats contrasts with the patterns
observed in other endotherms, probably because physical constraints on flight limit
morphological adaptations. Here, we develop a biophysical model based on heat transfer
and aerodynamic principles to investigate energy constraints on morphological
evolution in bats. Our biophysical model predicts that the energy costs of thermoregulation
and flight, respectively, impose upper and lower limits on the relationship of wing
surface area to body mass (S-MR), giving rise to an optimal S-MR at which both energy
costs are minimized. A comparative analysis of 278 species of bats supports the model’s
prediction that S-MR evolves toward an optimal shape and that the strength of selection
is higher among species experiencing greater energy demands for thermoregulation
in cold climates. Our study suggests that energy costs modulate the mode of morphological
evolution in bats—hence shedding light on a long-standing debate over bats’
conformity to ecogeographical patterns observed in other mammals—and offers a procedure
for investigating complex macroecological patterns from first principles.
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Biophysical model, Bergmann’s rule, Thermoregulation, Chiroptera, Bat
Citação
RUBALCABA, Juan G. et al. Physical constraints on thermoregulation and flight drive morphological evolution in bats. Proceedings of the National Academy of Sciences of the United States of America, Washington, v. 119, n. 15, e2103745119, Apr. 2022.