Greater variability in rhesus macaque (Macaca mulatta) endocranial volume among males

dc.contributor.authorColby, Abigail
dc.contributor.authorDeCasien, Alex
dc.contributor.authorCooper, Eve
dc.contributor.authorHigham, James
dc.date.accessioned2022-03-21T17:04:10Z
dc.date.available2022-03-21T17:04:10Z
dc.date.issued2022-03
dc.description.abstractThe greater male variability hypothesis posits that males exhibit more physical and behavioral variability than females. This pattern is observed across mammalian species and is especially pronounced in sexually selected traits. Greater variability in males likely reflects some combination of evolutionary mechanisms (e.g. balancing or disruptive selection) and developmental mechanisms (e.g. sexually dimorphic developmental schedules) that produce and maintain inter-individual variability. However, research investigating this phenomenon in brain size and structure is almost exclusive to humans. To address this gap in knowledge, we investigate sex differences in variability and heritability of relative and absolute endocranial volume (ECV) in a pedigreed sample of 542 (300F/242M) rhesus macaques using generalized linear mixed models that control for pairwise relatedness (i.e. an ‘animal model’). We found that males display more variable relative ECVs (phenotypic variance: male mean=0.646 [0.578,0.693], female mean=0.503 [0.457,0.540]) and absolute ECVs (phenotypic variance: male mean=0.670 [0.598,0.717], female mean=0.533 [0.481,0.568]). These findings are consistent with research in humans and chimpanzees. However, males do not display significantly lower heritability estimates and sex differences in phenotypic variance are not driven by environmental variance for relative (heritability: female mean=0.658 [0.568,0.778], male mean=0.626 [0.522,0.809]; environmental: female mean=0.171 [0.109,0.211], male mean=0.241 [0.119,0.302]) or absolute (heritability: female mean=0.683 [0.613,0.806], male mean=0.667 [0.578,0.827]; environmental: female mean=0.168 [0.112,0.210], male mean=0.223 [0.115,0.283]) ECV. These results suggest that, in rhesus macaques, greater male variability in brain size is likely driven by balancing or disruptive selection, rather than greater susceptibility to environmental effects during their relatively extended development.en_US
dc.description.grantingagencyOtheren_US
dc.identifier.citationColby, A., DeCasien, A., Cooper, E., & Higham, J. (2022, March 23-April 1). Greater variability in rhesus macaque (Macaca mulatta) endocranial volume among males [Conference poster]. Annual Meeting of the American Association of Biological Anthropologists. https://physanth.org/meetings-and-webinars/annual-meeting-2022/en_US
dc.identifier.doihttp://dx.doi.org/10.11575/PRISM/39658
dc.identifier.urihttp://hdl.handle.net/1880/114504
dc.language.isoengen_US
dc.publisher.departmentAnthropology & Archaelogyen_US
dc.publisher.facultyArtsen_US
dc.publisher.institutionNew York Universityen_US
dc.publisher.institutionSection on Developmental Neurogenomics at the National Institute of Healthen_US
dc.publisher.institutionNew York Consortium of Evolutionary Primatologyen_US
dc.publisher.institutionUniversity of Calgaryen_US
dc.rightsUnless otherwise indicated, this material is protected by copyright and has been made available with authorization from the copyright owner. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.en_US
dc.titleGreater variability in rhesus macaque (Macaca mulatta) endocranial volume among malesen_US
dc.typeconference posteren_US
ucalgary.item.requestcopytrueen_US
ucalgary.scholar.levelGraduateen_US
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