Body growth, mass at sexual maturity, and sexual dimorphism in Florida panthers (Puma concolor coryi)

Abstract

Abstract Recognizing individual variation in body growth characteristics and size at sexual maturity is of particular interest because they indicate a potential source of variance in survival and reproductive fitness. I used the Richards group of unified models method to examine body growth characteristics, mass at sexual maturity, and development of sexual size dimorphism in Florida panthers (Puma concolor coryi). A larger asymptotic body size and mass at sexual maturity in males resulted from a greater instantaneous growth rate across the life span and longer duration of growth than in females. Juvenile males attained larger body mass than female counterparts before achieving independence and sexual maturity, suggesting that a greater instantaneous growth rate developed from precopulatory intrasexual selection. Body mass growth rapidly decreased proximate to the minimum age at first conception in both sexes, suggesting that energetic costs of reproduction inhibited additional growth. Intrasexual selection among males to enhance fighting ability and promote access to a territory and mates is implicated as the cause for sexual size dimorphism, together with more direct underlying energetic costs of reproduction in females. The results provide uniform sex-specific body mass-at-age growth and mass at sexual maturity statistics for comparison with other puma populations and reference values to implement measurable criteria to evaluate trends in Florida panther population health.