Evolution of placentotrophy: using viviparous sharks as a model to understand vertebrate placental evolution

Buddle, Alice L., Van Dyke, James U., Thompson, Michael B., Simpfendorfer, Colin A., and Whittington, Camilla M. (2019) Evolution of placentotrophy: using viviparous sharks as a model to understand vertebrate placental evolution. Marine and Freshwater Research, 70 (7). pp. 908-924.

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Reproducing sharks must provide their offspring with an adequate supply of nutrients to complete embryonic development. In oviparous (egg-laying) sharks, offspring develop outside the mother, and all the nutrients required for embryonic growth are contained in the egg yolk. Conversely, in viviparous (live-bearing) sharks, embryonic development is completed inside the mother, providing offspring with the opportunity to receive supplementary embryonic nourishment, known as matrotrophy. Viviparous sharks exhibit nearly all forms of matrotrophy known in vertebrates, including a yolk-sac placenta, which involves several significant ontogenetic modifications to fetal and maternal tissues. The selective pressures that have driven the evolution of complex placentas in some shark species, but not in others, are unresolved. Herein we review the mechanisms of reproductive allocation and placental diversity in sharks, and consider the application of both adaptive and conflict hypotheses for the evolution of placental nutrient provisioning. Both have likely played roles in placental evolution in sharks, perhaps at different times in evolutionary history. Finally, we recommend sharks as an outstanding model system to investigate the evolution of placentas and mechanisms for fetal nutrition during pregnancy in vertebrates.

Item ID: 59963
Item Type: Article (Research - C1)
ISSN: 1448-6059
Keywords: Chondrichthyes, matrotrophy, uterus, viviparity, yolk sac placenta
Funders: Australian Research Council (ARC), University of Sydney, L'Oreal-UNESCO
Projects and Grants: ARC Discovery Project Grant DP180103370
Date Deposited: 24 Jul 2019 07:46
FoR Codes: 31 BIOLOGICAL SCIENCES > 3104 Evolutionary biology > 310404 Evolution of developmental systems @ 50%
31 BIOLOGICAL SCIENCES > 3109 Zoology > 310911 Animal structure and function @ 50%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 100%
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