Fluctuating asymmetry and the South American sea lion ( Otaria byronia) and El Nino

The South American sea lion (Otaria byronia) was exposed to substantial environmental stress as a result of the 1997--98 El Nino events. It has been shown that less fit organisms exhibit higher mortality rates during stressful conditions and their fitness can be affected by improper morphological development. One indicator of abnormal development is fluctuating asymmetry (FA), which occurs when asymmetrical individuals fluctuate around a population's normal state of bilateral symmetry. This study compared FA in sea lions in Peru that were exposed to the 1997--98 El Nino events to those that were not. It was found that the Peruvian male canines, sexually selected characters and Peruvian female mandibular characters contained higher degrees of FA compared to males and females from the Control population. This study also showed a higher degree of FA in the canines and mandibular characters of Peruvian males compared to those characters in the Peruvian females.