Size and ornamentation often predict the outcome of
male–male contests in species in which these traits are
larger or more exaggerated in males (Andersson 1994).
Most studies of intrasexual selection have examined traits
that show male-biased dimorphism because these are expected
a priori to be targets of sexual selection. However,
traits that are monomorphic or are more exaggerated in
females may also play a role in male–male contests
(Maklakov et al. 2004; e.g. Legrand & Morse 2000; Prenter
et al. 2003; Kraaijeveld et al. 2004). In several species of arthropods
in which females are larger than males, larger
size is advantageous in male contest competition (Fairbairn
& Preziosi 1994; Kraushaar & Blanckenhorn 2002;
Prenter et al. 2003; Maklakov et al. 2004). In contrast, in
yellow-pine chipmunks, Tamias amoenus, one of relatively
few mammals with female-biased sexual size dimorphism