Fluctuating Asymmetry of Antlers of White-tailed Deer (Odocoileus virginianus) in Relation to Yearling Antler Expression

Abstract

Fluctuating asymmetry is a measure of differences in bilateral traits within individuals and has been linked to heterozygosity, an individual’s ability to cope with environmental stresses, and mate choice. Many studies have suggested that fluctuating asymmetry could be a signaling trait for intrasexual interactions and for sexual selection in cervid species. Additionally antler characteristics throughout life have been shown to be smaller in bucks that were spike-antlered as yearlings than in bucks that were fork-antlered as yearlings. Here the asymmetry of main beam length, total normal tine length, total abnormal tine length, total tine length, gross Boone and Crockett scores, antler weight, and main beam circumference are compared for the first 4 sets of antlers for 144 bucks born between 1973 and 1990 at the Donnie Harmel Research Facility at the Kerr Wildlife Management Area. Comparisons were performed using Levene’s test and linear regression to test if bucks that were spike-antlered as yearlings are more asymmetric throughout life than bucks that were fork-antlered (3 or more points) as yearlings. Significant differences were found for variance in asymmetries based on deer age, yearling antler type and the interaction of yearling antler type and deer age. No difference was found in the regression slopes of variance in asymmetries versus deer age between yearling antler types. Bucks that were fork-antlered as yearlings had a smaller variance in asymmetry than bucks that were spike-antlered as yearlings. The age of bucks also played a role in asymmetry differences, with 1-year old deer having the largest variance in asymmetry of antler traits for both antler types. These results suggest bucks that were spike-antlered as yearlings may be less heterozygous than bucks that were fork-antlered as yearlings, and thus asymmetry in antler traits may function in signaling.