Lefebvre Louis, Marino Lori, Sol Daniel, Lemieux-Lefebvre Sébastien, Arshad Saima
Department of Biology, McGill University, Montréal, Canada.
Brain Behav Evol. 2006;68(4):218-28. doi: 10.1159/000094359. Epub 2006 Jun 30.
Previous work on primates and birds suggests that large brains require longer periods of juvenile growth, leading to reproductive constraints due to delayed maturation. However, longevity is often extended in large-brained species, possibly compensating for delayed maturation. We examined the relationship between brain size and life history periods in cetaceans, a large-brained mammalian order that has been largely ignored. We looked at males and females of twenty-five species of Odontocetes, using independent contrasts and multiple regressions to disentangle possible phylogenetic effects and inter-correlations among life history traits. We corrected all variables for body size allometry and separated life span into adult and juvenile periods. For females and both sexes combined, gestation, time to sexual maturity, time as an adult and life span were all positively associated with residual brain size in simple regressions; in multiple regressions, maximum life span and time as an adult were the best predictors of brain size. Males showed few significant trends. Our results suggest that brain size has co-evolved with extended life history periods in Odontocetes, as it has in primates and birds, and that a lengthened adult period could have been an important component of encephalization in cetaceans.
先前对灵长类动物和鸟类的研究表明，大脑体积较大需要更长的幼年生长时期，这会因成熟延迟而导致繁殖受限。然而，大脑体积较大的物种寿命往往更长，这可能弥补了成熟延迟的影响。我们研究了鲸类动物的大脑大小与生活史时期之间的关系，鲸类是一种大脑体积较大的哺乳动物目，但在很大程度上被忽视了。我们观察了25种齿鲸的雄性和雌性，使用独立对比和多元回归来梳理可能的系统发育效应以及生活史特征之间的相互关系。我们对所有变量进行了体型异速生长校正，并将寿命分为成年期和幼年期。在简单回归中，对于雌性以及雌雄两性综合来看，妊娠期、性成熟时间、成年时间和寿命均与剩余大脑大小呈正相关；在多元回归中，最大寿命和成年时间是大脑大小的最佳预测指标。雄性则几乎没有显著趋势。我们的研究结果表明，与灵长类动物和鸟类一样，鲸类动物的大脑大小与延长的生活史时期共同进化，并且成年期延长可能是鲸类动物脑化的一个重要组成部分。
