Lack of evidence for coevolution between oxytocin receptor N-terminal variants and monogamy in placental mammals

• Published in: Hormones and behavior 2023-11, Vol.156, p.105437, Article 105437
• Main Authors: Cerrito, Paola, Spear, Jeffrey K.
• Format: Article
• Language: English
• Subjects: Alloparental care; Animals; Eutheria - metabolism; Female; Humans; Mammals - genetics; Mammals - metabolism; Oxytocin; Oxytocin - genetics; Oxytocin - metabolism; Oxytocin receptor; Phylogeny; Placenta - metabolism; Placental mammals; Pregnancy; Primates - genetics; Primates - metabolism; Receptors, Oxytocin - genetics; Receptors, Oxytocin - metabolism
• ISSN: 0018-506X; 1095-6867; 1095-6867
• DOI: 10.1016/j.yhbeh.2023.105437

Oxytocin (OXT) is a neurohypophyseal hormone that influences a wide range of affiliative behaviors, such as pair-bonding and infant care, across mammals. The effects of OXT depend significantly on an adequate interaction with its receptor, OXTR. OXTR belongs to the G-protein coupled receptor family. The extracellular N-terminal domain of OXTR interacts with the linear C-terminal tail of OXT and is required for OXT binding. Across mammalian species there is a genetic diversity in OXTR terminal sequence. Previous work on primates has shown an association between OXTR phylogeny and monogamy. However, it is not clear whether this variation coevolved with either mating system (monogamy) or infant care behaviors (such as allomaternal care). Here, we take a phylogenetic comparative and evolutionary modeling approach across a wide range of placental mammals (n = 60) to test whether OXTR N-terminal variants co-evolved with either monogamy or allomaternal care behaviors. Our results indicate that the diversity in OXTR N-terminal region is unlikely to provide the underlying genetic bases for variation in mating system and/or allomaternal behavior as we find no evidence for co-evolution between protein sequence and affiliative behaviors. Hence, the role played by OXT in influencing affiliative behaviors is unlikely to be mediated by the genetic diversity of its receptor. •Oxytocin is known to mediate affiliative behavior. Its action is mediated via its receptor (OXTR).•Across mammals there is considerable variation in OXTR sequence.•It is not known whether this variation is correlated with monogamy and/or parental behavior.•We show that there is no evidence for correlated evolution between OXTR and allomaternal care.•We also show that there is minimal evidence for correlated evolution between OXTR and monogamy.