Intraspecific variation in the skull morphology of the black caiman Melanosuchus niger (Alligatoridae, Caimaninae)
Intraspecific variation in the skull morphology of the black caiman Melanosuchus niger (Alligatoridae, Caimaninae)
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DOI：
10.1111/azo.12045
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发表时间：
2015-01-01
期刊：
影响因子：
1.2
通讯作者：
Desojo, Julia B.
中科院分区：
文献类型：
--
作者：
Foth, Christian;Bona, Paula;Desojo, Julia B.
尼日尔是广泛分布于南美洲北方地区的一种鳄目动物。本种是生态学、遗传学和形态学研究的焦点。然而，形态学研究一般仅限于南美鳄类现存种间变异的检查。在这里，我们提出的第一个研究种内变异的头骨M。尼日尔使用二维几何形态测量方法。对52个性别不同的个体的颅骨进行了分析，以量化形状变化，并将观察到的形状变化分配给不同类型的种内变异，即个体发育变异和性二型。该物种的大部分变异是在吻长、头骨深度、眼眶大小和眶后区宽度方面的个体发育变异。这些变化与咬合力表现相关，可能与饮食变化相关。然而，与以前的功能研究的比较表明，个体发育过程中的功能适应似乎主要限于postrostral区域，而喙形状的变化更相关的饮食变化。此外，M.尼日尔显示出两性异形，这主要与大小有关。非大小相关的性二型性的存在必须在未来的检查中进行测试。
Melanosuchus niger is a caimanine alligatorid widely distributed in the northern region of South America. This species has been the focus of several ecological, genetic and morphological studies. However, morphological studies have generally been limited to examination of interspecific variation among extant species of South American crocodylians. Here, we present the first study of intraspecific variation in the skull of M. niger using a two-dimensional geometric morphometric approach. The crania of 52 sexed individuals varying in size were analysed to quantify shape variation and to assign observed shape changes to different types of intraspecific variation, that is, ontogenetic variation and sexual dimorphism. Most of the variation in this species is ontogenetic variation in snout length, skull depth, orbit size and the width of the postorbital region. These changes are correlated with bite force performance and probably dietary changes. However, a comparison with previous functional studies reveals that functional adaptations during ontogeny seem to be primarily restricted to the postrostral region, whereas rostral shape changes are more related to dietary shifts. Furthermore, the skulls of M. niger exhibit a sexual dimorphism, which is primarily sizerelated. The presence of non-size-related sexual dimorphism has to be tested in future examinations.