Data fishes

Data of the 57 fish species used in this study, including male body mass (in g), combined testes mass (in g), the presence or absence of hormonal induction of sperm production, sperm number (in billions), total sperm length (in µm), average-path sperm velocity (in µm/s), sperm longevity (in s), female body mass (in g), egg diameter (in mm), egg number (in thousands), the type of spawning water, spawning site, and mating system

Phylogeny frogs

Phylogenetic reconstruction for the 130 anurans used in this stud

Phylogeny fishes

Phylogenetic reconstruction for the 57 fishes used in this stud

Data frogs

Data of the 130 anuran species used in this study, including spawning site occurrence of foam nesting, mating system/amplexus, oviposition substrate site, oviposition type, egg capsule consistency, water type, male body mass (in g), combined testes mass (in mg), total sperm length (in µm), sperm head length (in µm), sperm flagellum length (in µm), sperm number (in million), female snout-vent length (in mm), clutch size, and egg diameter (in mm). OD in the references refers to own data

Species, latitude (°), samplings, average snout vent length (SVL: mm), brain size (mm3) and volume of different brain regions (mm3), age at sexual maturity (years), longevity (mean; years), sperm length (μm), testes mass (mg) and egg size (mm).

Species, latitude (°), samplings, average snout vent length (SVL: mm), brain size (mm3) and volume of different brain regions (mm3), age at sexual maturity (years), longevity (mean; years), sperm length (μm), testes mass (mg) and egg size (mm)

Cerebellum size is positively correlated with geographic distribution range in anurans: Supplementary Material

<p>The ‘cognitive buffer’ hypothesis predicts that the costs of relatively large brains are compensated for later in life by the increased benefits of large brains providing a higher chance of survival under changing environments through flexible behaviors in the animal kingdom. Thus, animals that live in a larger range (with a higher probability of environmental variation) are expected to have larger brains than those that live in a restricted geographic range. Here, to test the prediction of the ‘cognitive buffer’ hypothesis that larger brains should be expected to occur in species living in geographic ranges of larger size, we analyze the relationship between the size of the geographic range and brain size and the size of various brain regions among 42 species of anurans using phylogenetic comparative methods. The results show that there is no correlation between relative brain size and size of the species’ geographic range when correcting for phylogenetic effects and body size. Our findings suggest that the effects of the cognitive buffer and the energetic constraints on brains result in non-significant variation in overall brain size. However, the geographic range is positively correlated with cerebellum size, but not with optic tecta, suggesting that species distributed in a wider geographic range do not exhibit larger optic tecta that provide behavioral flexibility to allow for an early escape from potential predators and discover new food resources in unpredictable environments.</p