SEXUAL DIFFERENCES IN MORPHOLOGY AND NICHE UTILIZATION IN AN AQUATIC SNAKE, ACROCHORDUS-ARAFURAE
SEXUAL DIFFERENCES IN MORPHOLOGY AND NICHE UTILIZATION IN AN AQUATIC SNAKE, ACROCHORDUS-ARAFURAE
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DOI：
10.1007/bf00377632
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发表时间：
1986-01-01
期刊：
影响因子：
2.7
通讯作者：
SHINE, R
中科院分区：
文献类型：
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作者：
SHINE, R
白头蛇是澳大利亚热带地区体型较大(可达2米)、体型较重的蛇。在成年的体型、体重/长度比和身体比例(相对的头和尾的长度)上，性别的二形性是明显的。甚至在新生儿中也存在二形性。这种二态进化的两个假设是(1)性别选择或(2)性别适应不同的生态位。性选择的假说与蛇性二态身体大小的一般趋势是一致的，并准确地预测了对于花纹夜蛾来说，较大的性别(雌性)是繁殖成功率随着身体大小增加最强烈的。然而，性别选择并不能解释相对头部大小的性别差异。适应特定性别生态位的假说预测了栖息地和/或猎物的差异。我观察到雄性和雌性阿拉弗罗非鱼在猎物类型、猎物大小和栖息地利用(浅水和深水)方面存在重大差异。因此，相对头部大小的性别差异归因于生态原因，而不是性选择。尽管如此，性别之间的竞争不需要被援引为这种性格差异的选择性优势。考虑到性别选择在大小、栖息地或行为上的预先存在的差异，将这些差异解释为两性之间的独立适应，以增加觅食成功，这是更简约的。来自系统发育上遥远的分类群的另外三种水生蛇物种的数据表明，在食物习性、觅食地点和摄食形态上的性别二型性在蛇中普遍存在。
Filesnakes (Acrochordus arafurae) are large (to 2 m), heavy-bodied snakes of tropical Australia. Sexual dimorphism is evident in adult body sizes, weight/length ratios, and body proportions (relative head and tail lengths). Dimorphism is present even in neonates. Two hypotheses for the evolution of such dimorphism are (1) sexual selection or (2) adaptation of the sexes to different ecological niches. The hypothesis of sexual selection is consistent with general trends of sexually dimorphic body sizes in snakes, and accurately predicts, for A. arafurae, that the larger sex (female) is the one in which reproductive success increases most strongly with increasing body size. However, the sexual dimorphism in relative head sizes is not explicable by sexual selection. The hypothesis of adaptation to sex-specific niches predicts differences in habitats and/or prey. I observed major differences between male and female A. arafurae in prey types, prey sizes and habitat utilization (shallow versus deep water). Hence, the sexual dimorphism in relative head sizes is attributed to ecological causes rather than sexual selection. Nonetheless, competition between the sexes need not be invoked as the selective advantage of this character divergence. It is more parsimonious to interpret these differences as independent adaptations of each sex to increase foraging success, given pre-existing sexually-selected diferences in size, habitat or behavior. Data for three other aquatic snake species, from phylogenetically distant taxa, suggest that sexual dimorphism in food habits, foraging sites and feeding morphology, is widespread in snakes.