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Data from: Vascularization underlies differences in sexually selected skin coloration in a wild primate

DeLacey, Patricia1

Published May 22, 2023 on Dryad. https://doi.org/10.5061/dryad.sqv9s4n7p

Data files

Abstract

Male reproductive competition can select for condition-dependent, conspicuous traits that signal some aspect of fighting ability and facilitate assessment of potential rivals. However, the underlying mechanisms that link the signal to a male’s current condition are difficult to investigate in wild populations. In this study, we used digital photographs and chest skin samples to investigate mechanisms of a visual signal used in male competition in a wild primate, the red chest patch in geladas (Theropithecus gelada) in the Simien Mountains National Park, Ethiopia. We analyzed photographs collected during natural and anesthetized conditions to understand variability in male and female chest redness, and we used chest skin biopsies to explore sex differences in gene expression. Male and female geladas showed similar average redness, but males exhibited a wider within-individual range in redness under natural conditions. These sex differences were reflected at the molecular level, with 10.5% of genes exhibiting significant sex differences in expression. Subadult males exhibited intermediate expression patterns between adult males and females, pointing to mechanisms underlying the development of the red chest patch. We found that genes more highly expressed in males were associated with blood vessel development and maintenance but not with androgen or estrogen activity. Together, our results suggest male gelada redness variability is driven by increased blood vessel branching in the chest skin, providing a potential link between male chest redness and current condition as increased blood circulation to exposed skin could lead to heat loss in the cold, high-altitude environment of geladas.