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Vascularization underlies differences in sexually selected skin coloration in a wild primate
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  • Patricia DeLacey,
  • Sharmi Sen,
  • India A. Schneider-Crease,
  • Kenneth Chiou,
  • Alemayehu Lemma,
  • Ferehiwot Ayele,
  • Abebaw Haile,
  • Amy Lu,
  • Thore J. Bergman,
  • Jacinta C. Beehner,
  • Noah Snyder-Mackler
Patricia DeLacey
University of Michigan

Corresponding Author:pdelacey@umich.edu

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Sharmi Sen
University of Michigan
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India A. Schneider-Crease
Arizona State University
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Kenneth Chiou
Arizona State University
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Alemayehu Lemma
Addis Ababa University
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Ferehiwot Ayele
Addis Ababa University
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Abebaw Haile
Ethiopian Wildlife Conservation Authority
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Amy Lu
Stony Brook University
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Thore J. Bergman
University of Michigan
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Jacinta C. Beehner
University of Michigan
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Noah Snyder-Mackler
Arizona State University
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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, often requiring invasive experimental manipulation. Here, we use 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). We analyzed photographs collected during natural (n=144) and anesthetized conditions (n=38) to understand variability in male and female chest redness, and we used chest skin biopsies (n=38) 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 gene expression patters 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.
11 Jan 2023Submitted to Molecular Ecology
13 Jan 2023Submission Checks Completed
13 Jan 2023Assigned to Editor
13 Jan 2023Review(s) Completed, Editorial Evaluation Pending
18 Jan 2023Reviewer(s) Assigned
20 Mar 2023Editorial Decision: Revise Minor
19 Apr 20231st Revision Received
24 Apr 2023Submission Checks Completed
24 Apr 2023Assigned to Editor
24 Apr 2023Review(s) Completed, Editorial Evaluation Pending
12 May 2023Editorial Decision: Accept