Paternal nutrient provisioning during male pregnancy in the seahorse Hippocampus abdominalis

Vertebrates that incubate embryos on or within the body cavity exhibit diverse strategies to provide nutrients to developing embryos, ranging from lecithotrophy (solely yolk-provided nutrition) to substantial matrotrophy (supplemental nutrients from the mother before birth). Syngnathid fishes (seaho...

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Bibliographic Details
Published in:Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology Biochemical, systemic, and environmental physiology, 2020-09, Vol.190 (5), p.547-556
Main Authors: Skalkos, Zoe M. G., Van Dyke, James U., Whittington, Camilla M.
Format: Article
Language:English
Subjects:
Animal Physiology
Biochemistry
Biomedical and Life Sciences
Biomedicine
Dietary supplements
Eggs
Embryogenesis
Embryonic growth stage
Embryos
Gestation
Hippocampus abdominalis
Human Physiology
Hypotheses
Life Sciences
Lipids
Neonates
Nutrient content
Nutrient transport
Nutrients
Nutrition
Offspring
Original Paper
Pregnancy
Provisioning
Reproductive system
Vertebrates
Yolk
Zoology
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Summary:Vertebrates that incubate embryos on or within the body cavity exhibit diverse strategies to provide nutrients to developing embryos, ranging from lecithotrophy (solely yolk-provided nutrition) to substantial matrotrophy (supplemental nutrients from the mother before birth). Syngnathid fishes (seahorses, pipefishes and sea dragons) are the only vertebrates to exhibit male pregnancy. Therefore, they provide a unique opportunity for comparative evolutionary research, in examining pregnancy independent of the female reproductive tract. Here, we tested the hypothesis that the most complex form of syngnathid pregnancy involves nutrient transport from father to offspring. We compared the dry masses of newly fertilised Hippocampus abdominalis eggs with those of fully developed neonates to derive a patrotrophy index. The patrotrophy index of H. abdominalis was 1, indicating paternal nutrient supplementation to embryos during gestation. We also measured the lipid content of newly fertilised eggs and neonates and found that there was no significant decrease in lipid mass during embryonic development. Since lipids are likely to be the main source of energy during embryonic development, our results suggest that lipid yolk reserves being depleted by embryonic metabolism are replaced by the brooding father. The results of our study support the hypothesis that nutrient transport occurs in the most advanced form of male pregnancy in vertebrates.
ISSN:0174-1578
1432-136X
DOI:10.1007/s00360-020-01289-y