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Viviparous placentotrophy in reptiles and the parent–offspring conflict
Author(s) -
Blackburn Daniel G.
Publication year - 2015
Publication title -
journal of experimental zoology part b: molecular and developmental evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.823
H-Index - 63
eISSN - 1552-5015
pISSN - 1552-5007
DOI - 10.1002/jez.b.22624
Subject(s) - offspring , biology , lizard , nutrient , pregnancy , parental investment , parent–offspring conflict , embryo transfer , embryo , in ovo , fetus , zoology , ecology , genetics
In placentotrophic viviparous reptiles, pregnant females deliver nutrients to their developing fetuses by diverse morphological specializations that reflect independent evolutionary origins. A survey of these specializations reveals a major emphasis on histotrophy (uterine secretion and fetal absorption) rather than hemotrophy (transfer between maternal and fetal blood streams). Of available hypotheses for the prevalence of histotrophic transfer, the most promising derives insights from the theoretical parent–offspring conflict over nutrient investment. I suggest that histotrophy gives pregnant females greater control over nutrient synthesis, storage, and delivery than hemotrophic transfer, reflecting maternal preeminence in any potential parent–offspring competition over nutrient investment. One lizard species shows invasive ovo‐implantation and direct contact between fetal tissues and maternal blood vessels, potentially conferring control over nutrient transfer to the embryo. Future research on squamates will benefit from application of parent–offspring conflict theory to the transition from incipient to substantial matrotrophy, as well as by testing theory‐derived predictions on both facultatively and highly placentotrophic forms. J. Exp. Zool. (Mol. Dev. Evol.) 324B: 532–548, 2015 . © 2015 Wiley Periodicals, Inc.