期刊
CANADIAN JOURNAL OF ZOOLOGY
卷 92, 期 1, 页码 19-31出版社
CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS
DOI: 10.1139/cjz-2013-0106
关键词
Mirounga leonina; southern elephant seal; Otaria byronia; southern sea lion; allometric growth; cranium; morphometry; growth rate; pinniped
类别
资金
- Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET)
- Agencia Nacional de Promocion Cientifica y Tecnologica (ANPCyT) [PICT 0143, PICT 1798]
- Vizcaino of CONICET [PIP 1054]
- UNLu CDD-CD [281-09]
The southern elephant seal (Mirounga leonina (L., 1758)) is one of the most dimorphic mammals, but sexual dimorphism in its skull ontogeny is poorly known. We study ontogeny of sexual dimorphism by the allometric relationships between 21 measurements and its geometric mean. Based on 66 specimens (36 females, 30 males), the bivariate and multivariate analyses indicated that both approaches were congruent in most variables. We detected that sexual dimorphism was reached mostly by sexual shape differences in the ontogenetic trajectories of males and females. Twenty-four percent of variables were associated with intercept differences (pup size proportions), while 57% of variables were associated with slope intersexual differences (relative growth rates). Contrarily, sexual dimorphism was also achieved by size differences in adult stages (19% of variables), as males exhibited an extension of their common ontogenetic trajectories. Secondary growth spurt in males was detected for few variables. Our comparison with analogous data collected from southern sea lions (Otaria byronia (de Blainville, 1820)) indicated that in both species, sexual dimorphism was mostly associated with an enhanced ability to defend territories, which was linked to the polygynic behavior. However, discrepancies between both ontogenetic patterns of dimorphism were associated with interspecific differences in their life cycles.
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