Mating systems and sexual dimorphism in marine mammals.

<p>Sexual dimorphism of males and females is quantified for 105 species of cetaceans, pinnipeds, sirenians, and the sea otter, expressed as male-minus-female length in natural log units <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004366#pone.0004366-Boness1" target="_blank">[17]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004366#pone.0004366-Trites1" target="_blank">[30]</a>. Territorial and harem systems that involve intense male-male competition and spatial aggregation of females have male-female dimorphism greater than about 0.15 (dashed line) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004366#pone.0004366-Weckerly1" target="_blank">[31]</a>. <i>Maiacetus inuus</i> falls in the group of ‘dispersed’ mating systems with limited aggregation and limited male control of mating. Both cetaceans and pinnipeds span the entire range shown here, although mating systems are known for relatively few species <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004366#pone.0004366-Connor1" target="_blank">[32]</a>.