Divergent color signals from homologous unfeathered ornaments in two congeneric grouse

• Published in: Ecology and evolution Vol. 9; no. 20; pp. 11833 - 11847
• Main Authors: Gould, Geoffrey M., Carter, Gerald G., Augustine, Jacqueline K.
• Format: Journal Article
• Language: English
• Published: Bognor Regis John Wiley & Sons, Inc 01.10.2019; John Wiley and Sons Inc; Wiley
• Subjects: Age; Animal reproduction; Body parts; character displacement; Chickens; Color; Dependence; Esophagus; Homology; honest signaling; Lek behavior; lek‐mating grouse; Males; Mate selection; Original Research; Plumage; Poultry; Properties (attributes); signal divergence; Signaling; skin color; spectrometry; Success; Visual aspects; Visual signals; Wildfowl; United States > US; Ohio
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.5687

Color‐based visual signals are important aspects of communication throughout the animal kingdom. Individuals evaluate color to obtain information about age and condition and to behave accordingly. Birds display a variety of striking, conspicuous colors and make ideal subjects for the study of color signaling. While most studies of avian color focus on plumage, bare unfeathered body parts also display a wide range of color signals. Mate choice and intrasexual competitive interactions are easily observed in lekking grouse, which also signal with prominent unfeathered color patches. Most male grouse have one pair of colorful bare part ornaments (combs), and males of several species also have inflatable air sacs in their throat. Previous studies have mostly focused on comb color and size, but little is known about the signaling role of air sac color. We measured comb size and the color properties of combs and air sacs in the Lesser and Greater Prairie‐Chickens (Tympanuchus pallidicinctus and T. cupido, respectively), and investigated whether these properties varied with age and mass. We found that mass predicted color properties of air sacs and that age predicted comb size in the Greater Prairie‐Chicken, suggesting that these ornaments indicate condition dependence. No conclusive relationships between color and age or size were detected in the Lesser Prairie‐Chicken. Color properties of both ornaments differed between the two species. Further research is needed to determine mechanisms that link condition to color and whether the information advertised by color signals from these ornaments is intended for males, females, or both. We measured comb size and the color properties of combs and air sacs in wild caught Lesser and Greater Prairie‐Chickens (Tympanuchus pallidicinctus and T. cupido, respectively), and investigated whether these properties varied with age and mass. We found that mass predicted color properties of air sacs and that age predicted comb size in the Greater Prairie‐Chicken, but no conclusive relationships between ornament color and age or size were detected in the Lesser Prairie‐Chicken. Our findings suggest the occurrence of a past episode of character displacement, possibly as a means of discouraging hybridization, between these recently diverged congeneric species.