Craniodental mechanics and diet in Asian colobines: Morphological evidence of mature seed predation and sclerocarpy.
Craniodental mechanics and diet in Asian colobines: Morphological evidence of mature seed predation and sclerocarpy.
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DOI：
10.1002/ajpa.21213
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发表时间：
2010-05
影响因子：
2.8
通讯作者：
D. Koyabu;H. Endo
中科院分区：
文献类型：
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作者：
D. Koyabu;H. Endo
棕榈树已经被公认为袋鼠的一般饮食模式。然而，最近的生态学研究表明，在一些棕榈科动物物种中发现了广泛的食种行为。据报道，不同食籽者觅食种子的成熟度也不同。由于种子通常是受胁迫限制的，并可能提出更大的机械需求，食籽物种被预测表现出适应种子捕食的形态特征。此外，以果皮坚硬的未成熟果实种子为食的物种预计将显示出更多的前牙列杠杆作用。为了验证这些假说，我们比较了以种子为食的亚洲斗鱼(Presbytis ruicunda和Trachypithecus phayrei)与那些很少利用种子的物种(Presbytis Comata、Trachypithecus Darcurus和Semnopithecus vetulus)的头骨形态。结果表明，食种子的共生动物拥有一个咀嚼系统，在犬齿后咬合点具有增强的杠杆作用。在前牙咬合点上，硬果食性食草动物P.ruicunda也表现出明显更大的咀嚼杠杆作用，而吃成熟种子的T.phayrei在犬类和门牙上没有表现出这样的优势。这些观察结果表明，红星天牛很好地适应了利用前牙列剥离未成熟果实的抗性果皮，并获得未成熟种子的途径，而这种核果取食行为对沙棘来说可能不那么重要。我们的发现表明，斗猴独特的头骨变异可能与捕食成熟和/或未成熟的种子有关，并暗示了捕食种子对斗猴进化的重要意义。
Folivory has been accepted as the general dietary pattern for colobines. However, recent ecological studies have revealed that extensive seed eating is found in some colobine species. The ripeness of foraged seeds is also reported to differ between seed eaters. As seeds are generally stress-limited and may pose greater mechanical demands, seed-eating species are predicted to exhibit morphological features adaptive for seed predation. In addition, species that feeds on seeds from unripe fruits with hard pericarp is predicted to exhibit increased leverage for anterior dentition. To test these hypotheses, we compared the craniodental morphology of seed-eating Asian colobines (Presbytis rubicunda and Trachypithecus phayrei) with those of species that rarely exploit seeds (Presbytis comata, Trachypithecus obscurus, and Semnopithecus vetulus). The results show that the seed-eating colobines possess a masticatory system with enhanced leverage at postcanine bite points. The sclerocarpic forager P. rubicunda also exhibits markedly greater masticatory leverage at anterior dental bite points, while the mature-seed-eating T. phayrei shows no such advantage for canine and incisor use. These observations suggest that P. rubicunda is well adapted to husking the resistant pericarps of unripe fruits, using the anterior dentition and to gain access to the immature seeds, whereas such sclerocarpic feeding behavior may be less important for T. phayrei. Our findings indicate that the distinctive craniodental variations of colobines may be linked to mature and/or immature seed eating and suggest the significance of seed predation for the evolution of colobine monkeys.