Metabolic growth hypothesis for the evolution of the nuchal hump in swordtail fishes

Abstract

trait was demonstrated in wild-caught X. multilineatus females, suggesting the nuchal hump could be a target of sexual selection if it developed in males in the wild. We consider the results from this study in relation to the diversity in development of the trait across species and introduce a nuchal hump metabolic growth hypothesis to help explain its function in swordtails.