Placentation and maternal investment in mammals

Capellini, I., Venditti, C. ORCID: https://orcid.org/0000-0002-6776-2355 and Barton, R. A. (2011) Placentation and maternal investment in mammals. American Naturalist, 177 (1). pp. 86-98. ISSN 0003-0147 doi: 10.1086/657435

Abstract/Summary

The mammalian placenta exhibits striking interspecific morphological variation, yet the implications of such diversity for reproductive strategies and fetal development remain obscure. More invasive hemochorial placentas, in which fetal tissues directly contact the maternal blood supply, are believed to facilitate nutrient transfer, resulting in higher fetal growth rates, and to be a state of relative fetal advantage in the evolution of maternal-offspring conflict. The extent of interdigitation between maternal and fetal tissues has received less attention than invasiveness but is also potentially important because it influences the surface area for exchange. We show that although increased placental invasiveness and interdigitation are both associated with shorter gestations, interdigitation is the key variable. Gestation times associated with highly interdigitated labyrinthine placentas are 44% of those associated with less interdigitated villous and trabecular placentas. There is, however, no relationship between placental traits and neonatal body and brain size. Hence, species with more interdigitated placentas produce neonates of similar body and brain size but in less than half the time. We suggest that the effects of placental interdigitation on growth rates and the way that these are traded off against gestation length may be promising avenues for understanding the evolutionary dynamics of parentoffspring conflict. Keywords: placenta, parent-offspring conflict, life history, brain evolution, reproductive strategies, gestation.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/29057
Identification Number/DOI	10.1086/657435
Refereed	Yes
Divisions	Life Sciences > School of Biological Sciences > Ecology and Evolutionary Biology
Uncontrolled Keywords	Keywords: placenta, parent-offspring conflict, life history, brain evolution, reproductive strategies, gestation.
Publisher	University of Chicago Press
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