Reflectance characteristics are correlated with male condition in a population of threespine stickleback (Gasterosteus aculeatus) that has lost the species typical nuptial signal

Abstract

Several populations of threespine stickleback (Gasterosteus aculeatus) on the Pacific Coast of North America remain drab during courtship and become melanic during parental care rather than adopt the species typical red signal. Male signal redness is an honest signal of male physiological condition. Here, I test the prediction that reflectance characteristics of drab males also honestly indicate male condition. I located, observed and captured nesting stickleback from Brannen Lake, British Columbia, Canada. I measured reflectance characteristics of each male’s signal right after capture and later measured its wet weight and total length to calculate Fulton’s condition index, K. Males in better condition, higher K, had lower total reflectance (i.e. were darker) than males in poorer condition. The principals underlying honest signaling appear to be operating despite the possession of a novel nuptial signal in Brannen Lake stickleback.