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.Fil: Ferraz, Tiago. Universidade Federal do Rio Grande do Sul; Brasil. Universidade de Sao Paulo; BrasilFil: Rossoni, Daniela M.. Universidade de Sao Paulo; BrasilFil: Althoff, Sérgio L.. Universidade Regional de Blumenau; BrasilFil: Pissinatti, Alcides. Universidade Federal da Bahia; BrasilFil: Paixão Cortês, Vanessa R.. Centro de Primatologia do Rio de Janeiro; BrasilFil: Bortolini, María Cátira. Universidade Federal do Rio Grande do Sul; BrasilFil: González José, Rolando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Ciencias Sociales y Humanas; ArgentinaFil: Marroig, Gabriel. Universidade de Sao Paulo; BrasilFil: Salzano, Francisco M.. Universidade Federal do Rio Grande do Sul; BrasilFil: Gonçalves, Gislene L.. Universidad de Tarapacá de Arica; Chile. Universidade Federal do Rio Grande do Sul; BrasilFil: Hünemeier, Tábita. Universidade de Sao Paulo; Brasi
