Contrasting patterns of RUNX2 repeat variations are associated with palate shape in phyllostomid bats and New World primates.

Establishing the genetic basis that underlies craniofacial variability in natural populations is one of the main topics of evolutionary and developmental studies. One of the genes associated with mammal craniofacial variability is RUNX2, and in the present study we investigated the association between craniofacial length and width and RUNX2 across New World bats (Phyllostomidae) and primates (Catarrhini and Platyrrhini). Our results showed contrasting patterns of association between the glutamate/alanine ratios (Q/A ratio) and palate shape in these highly diverse groups. In phyllostomid bats, we found an association between shorter/broader faces and increase of the Q/A ratio. In New World monkeys (NWM) there was a positive correlation of increasing Q/A ratios to more elongated faces. Our findings reinforced the role of the Q/A ratio as a flexible genetic mechanism that would rapidly change the time of skull ossification throughout development. However, we propose a scenario in which the influence of this genetic adjustment system is indirect. The Q/A ratio would not lead to a specific phenotype, but throughout the history of a lineage, would act along with evolutionary constraints, as well as other genes, as a facilitator for adaptive morphological changes.

Oxytocin and arginine vasopressin systems in the domestication process

Abstract Domestication is of unquestionable importance to the technological revolution that has given rise to modern human societies. In this study, we analyzed the DNA and protein sequences of six genes of the oxytocin and arginine vasopressin systems (OXT-OXTR; AVP-AVPR1a, AVPR1b and AVPR2) in 40 placental mammals. These systems play an important role in the control of physiology and behavior. According to our analyses, neutrality does not explain the pattern of molecular evolution found in some of these genes. We observed specific sites under positive selection in AVPR1b (ω = 1.429, p = 0.001) and AVPR2 (ω= 1.49, p = 0.001), suggesting that they could be involved in behavior and physiological changes, including those related to the domestication process. Furthermore, AVPR1a, which plays a role in social behavior, is under relaxed selective constraint in domesticated species. These results provide new insights into the nature of the domestication process and its impact on the OXT-AVP system.

Progesterone Response Element Variation in the OXTR Promoter Region and Paternal Care in New World Monkeys.

Paternal care is a complex social behavior common in primate species with socially monogamous mating systems and twin births. Evolutionary causes and consequences of such behavior are not well understood, nor are their neuroendocrine and genetic bases. However, the neuropeptide oxytocin (OXT) and its receptor (OXTR) are associated with parental care in mammalian lineages. Here we investigated the interspecific variation in the number of progesterone response elements (PREs) in the OXTR promoter region of 32 primate species, correlating genetic data with behavior, social systems, and ecological/life-history parameters, while controlling for phylogeny. We verified that PREs are only present in New World monkeys and that PRE number is significantly correlated with the presence of paternal care in this branch. We suggest that PRE number could be an essential part of the genetic repertoire that allowed the emergence of taxon-specific complex social behaviors, such as paternal care in marmosets and tamarins.