Variation in Scrotal Color Among Widely Distributed Vervet Monkey Populations (Chlorocebus Aethiops Pygerythrus and Chlorocebus Aethiops Sabaeus). Issue 7 (19th April 2013)

• Record Type: Journal Article
• Authors: CRAMER, JENNIFER DANZY; GAETANO, TEGAN; GRAY, JOSEPH P.; GROBLER, PAUL; LORENZ, JOSEPH G.; FREIMER, NELSON B.; SCHMITT, CHRISTOPHER A.; TURNER, TRUDY R.; Higham, James P.; Semple, Stuart
• Is Part Of: American journal of primatology. Volume 75:Issue 7(2013:Jul.)
• Page Start: 752
• Page End: 762
• Publication Date: 2013-04-19
• Subjects: Primates -- Periodicals; Primates -- Périodiques; 599.8
• DOI: 10.1002/ajp.22156
• Languages: English
• ISSNs: 0275-2565

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <sec id="ajp22156-sec-0001" sec-type="section"> <p>Vervet monkeys (<italic>Chlorocebus aethiops</italic>) exhibit bright blue scrotal skin which may function to mediate social interactions by acting as a socio‐sexual signal. Previous research on scrotal coloration among vervet monkeys was limited to experimental work on captive <italic>Ch. a. sabaeus</italic>, the least colorful vervet subspecies, and two field studies of the more colorful <italic>Ch. a. pygerythrus</italic>. In a study of free‐ranging and captive vervet monkeys in South Africa (<italic>Ch. pygerythrus</italic>), West Africa (<italic>Ch. a. sabaeus</italic>) and the Caribbean (<italic>Ch. a. sabaeus</italic>), we examined scrotal color variation across geographically distant subspecies. We provide an exploration of how digital photographs may be used to quantify and analyze blue and green skin coloration by examining the blue–yellow opponency channel and luminance channel as color measures. We found that that at all ages the scrotal color of <italic>Ch. a. pygerythrus</italic> males was always bluer and darker than that of <italic>Ch. a. sabaeus</italic> males. Among <italic>Ch. a. pygerythrus</italic> scrotal color becomes bluer and lightens with increasing age, while the color of <italic>Ch. a. sabaeus</italic> males also lightens, but becomes less blue with increasing age. We suggest that color variation is related to maturation and may function as an age‐related signal among <italic>Ch. a. pygerythrus</italic> and <italic>Ch. a. sabaeus</italic>. We also found color was related to three morphological features among adults. For <italic>Ch. a. pygerythrus</italic>, higher body weight is associated with more blue color and longer canine length is associated with lighter color. Lighter color was associated with longer body lengths among <italic>Ch. a. sabaeus</italic>. Future studies focused on color variation within age classes are needed to examine the potential signal content of color in this species. Am. J. Primatol. 75:752–762, 2013. © 2013 Wiley Periodicals, Inc.</p> </sec> </abstract>