Factors affecting gestation periods in elasmobranch fishes

Gestation periods vary greatly across elasmobranch species. Differences in body size and body temperature (i.e. major determinants of metabolic rates) might explain such variation. Although temperature effects have been demonstrated for captive animals, body size effects remain undocumented. Moreove...

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Bibliographic Details
Published in:Biology open 2022-06, Vol.11 (6)
Main Authors: Tokunaga, Soma, Watanabe, Yuuki Y, Kawano, Mai, Kawabata, Yuuki
Format: Article
Language:English
Subjects:
Animals
Body size
Body temperature
Body Weight
Embryos
endothermy
Female
Fishes
Gestation
Humans
Metabolic rate
Metabolism
phylogenetic analysis
Pregnancy
scaling
Sharks
Sharks - metabolism
Size effects
Species
Temperature effects
viviparity
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Summary:Gestation periods vary greatly across elasmobranch species. Differences in body size and body temperature (i.e. major determinants of metabolic rates) might explain such variation. Although temperature effects have been demonstrated for captive animals, body size effects remain undocumented. Moreover, whether metabolic rates of mothers or those of embryos affect gestation periods remains unclear. Because biological times generally scale with mass1-β, where β is metabolic scaling exponent (0.8-0.9 in fishes), we hypothesized that elasmobranch gestation periods would scale with mass0.1-0.2. We also hypothesized that regionally endothermic species with elevated metabolic rates should have shorter gestation periods than similar-sized ectothermic species if the metabolic rates of mothers are responsible. We compiled data on gestation periods for 36 elasmobranch species to show that gestation periods scale with M0.11 and m0.17, where M and m are adult female mass and birth mass, respectively. Litter size and body temperature also affected gestation periods. Our findings suggest that the body-mass dependence of metabolic rate explains some variations in elasmobranch gestation periods. Unexpectedly, regionally endothermic sharks did not have shorter gestation periods than their ectothermic counterparts, suggesting that the metabolic rates of embryos, which are likely ectothermic in all elasmobranch species, may be responsible. This article has an associated First Person interview with the first author of the paper.
ISSN:2046-6390
2046-6390
DOI:10.1242/bio.059270