The allometry between secondary sexual traits and body size is nonlinear among cervids

Abstract

Allometric relationships between sexually selected traits and bodysize have been extensively studied in recent decades.While sexually selected traits generally display positive allometry, a few recent reports have suggested that allometric relationships are not always linear. In male cervids, having both long antlers and large size provides benefits in terms of increased mating success. However, such attributes are costly to growand maintain, and these costsmight constrain antler length fromincreasing at the same rate as bodymass in larger species if the quantity of energy that males can extract fromtheir environment is limiting.We tested for possible nonlinearity in the relationship between antler size and body mass (on a log-log scale) among 31 cervids and found clear deviation from linearity in the allometry of antler length. Antler length increased linearly until a male body mass threshold at approximately 110 kg. Beyond this threshold, antler length did not change with increasing mass. We discuss this evidence of nonlinear allometry in the light of life-history theory and stress the importance of testing for nonlinearity when studying allometric relationships. © 2014 The Author(s) Published by the Royal Society. All rights reserved.