For neither heat nor water conservation: Body size variation in Atlantic Forest frogs does not follow a general mechanism

• Published in: Journal of biogeography 2022-03, Vol.49 (3), p.460-468
• Main Authors: Servino, Leonardo Matheus, Verdade, Vanessa Kruth, Sawaya, Ricardo J.
• Format: Article
• Language: English
• Subjects: Amphibia; Amphibians; Atlantic forest; Bergmann's rule; Biogeography; Body size; Climate change; Evapotranspiration; Forest conservation; Frogs; Heat; Hypotheses; macroecology; Phylogeny; size; Variation; Water availability; Water conservation
• ISSN: 0305-0270; 1365-2699
• DOI: 10.1111/jbi.14309

Aim Animal body size is recurrently associated with climate. Bergmann's rule proposes that larger endotherms inhabit higher latitudes because higher latitudes are generally colder, and larger body sizes promote heat conservation. However, body size variation of ectotherms has been associated with other climatic variables as anurans in drier environments reach larger sizes for water conservation. We tested whether body size variation of anuran amphibians can be explained by the heat conservation or water conservation hypotheses. Location Brazilian Atlantic Forest. Taxon Anuran amphibians. Methods We selected anurans from different phylogenetic groups. The size was defined by snout‐vent length (SVL) and stoutness. We implemented spatial regressions including morphological dimensions and variables describing temperature and water availability. Results Only Haddadus binotatus had SVL size negatively associated with temperature, in accordance with the heat conservation hypothesis (HCH). Itapotihyla langsdorffii had SVL positively associated with temperature, contrary to the HCH. Cycloramphus eleutherodactylus had SVL negatively associated with potential evapotranspiration, in accordance with the water conservation hypothesis (WCH). Thoropa miliaris+T. taophora and Ischnocnema guentheri showed no associations between SVL and climate. Stoutness was poorly associated with climate, with a negative relationship found only in Rhinella crucifer+R. ornata in accordance with the WCH. Main conclusions The heat conservation and water conservation hypotheses do not offer general explanations for the body size variation in anurans from the Brazilian Atlantic Forest. Natural history, functional and ecological traits are more likely to affect anuran body size and they should be considered in posterior analyses.