Ecological plasticity by morphological design reduces costs of subordination: influence on species distribution

We studied the feeding behaviour of two subordinate tit species (Parus spp. ) in two competitive contexts: feeding solitarily versus feeding in the pre sence of the dominant great tit. Considering ecological plasticity as the w ithin-species component of mean behavioural performance associated with dif ferent morphologies in different species, we test the hypothesis that subor dinate species with morphological designs allowing a greater ecological pla sticity (e.g. blue tit whose hindlimb morphology is modified for greater le g flexion) may gain an advantage against subordinate species with a less pl astic design (e.g. crested tit whose hindlimb morphology is modified for ai d in leg extension) in a competitive context. Our results demonstrate that the blue tit has greater foraging abilities than the crested tit, as the fo rmer is able to modify its feeding behaviour in the presence of the dominan t great tit significantly more than the crested tit. In light of these resu lts we propose that some subordinate species can take advantage of their gr eater ecological plasticity against another less plastic, subordinate speci es, suggesting that ecological plasticity due to morphological design is a way of reducing costs of subordination as well as a novel, alternative mech anism explaining species distribution.