Laterality is Universal Among Fishes but Increasingly Cryptic Among Derived Groups
Laterality is Universal Among Fishes but Increasingly Cryptic Among Derived Groups
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DOI：
10.2108/zs160196
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发表时间：
2017-08-01
影响因子：
0.9
通讯作者：
Takeuchi, Yuichi
中科院分区：
文献类型：
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作者：
Hori, Michio;Nakajima, Mifuyu;Takeuchi, Yuichi
侧化在一些脊椎动物中已经被研究过，主要是在大脑侧化和行为侧化方面，但是形态不对称性还没有被广泛研究。鱼类的不对称性最早是在坦噶尼喀湖的食鳞慈鲷中发现的，其形式是双侧二型性，即一些个体在张开嘴时向右扭转，另一些向左扭转。这种不对称性具有遗传基础，并且与侧化攻击行为相关。这随后被发现在鱼类从许多类群与不同的食性。因此，应在尽可能广泛的鱼类中研究这种形态偏侧性的普遍性。使用特定指标的下颌骨和头部倾斜的横向差异，我们发现，代表性的物种从所有60个现存的有颌鱼类（骨和软骨）具有形态偏侧。此外，我们确定了相同的偏侧无颌类（八目鳗和七鳃鳗），这表明这种特性出现在鱼类进化的早期，并一直保持在整个鱼类谱系。然而，硬骨鱼群体之间的不对称性比较显示，出乎意料的是，在遗传学上更近的群体在身体结构上具有更少的不对称性。鱼类普遍存在的侧化现象表明其具有单系起源，可能存在于脊椎动物的祖先中。生态因素，特别是捕食者与猎物之间的相互作用，可能是进化和维持二型性的关键驱动因素，也可能是导致衍生群体中不对称性的神秘趋势的原因。由于肺鱼和腔棘鱼都具有这种特征，因此四足动物很可能也继承了这种特征。我们相信，对这种形态侧化的研究将为脊椎动物的行为和感觉侧化提供新的见解。
Laterality has been studied in several vertebrates, mainly in terms of brain lateralization and behavioral laterality, but morphological asymmetry has not been extensively investigated. Asymmetry in fishes was first described in scale-eating cichlids from Lake Tanganyika, in the form of bilateral dimorphism in which some individuals, when opening their mouths, twist them to the right and others to the left. This asymmetry has a genetic basis, and is correlated with lateralized attack behaviors. This has subsequently been found in fishes from numerous taxa with various feeding habits. The generality of such morphological laterality should thus be investigated in as wide a range of fishes as possible. Using specific indicators of lateral differences in mandibles and head inclination, we find that representative species from all 60 orders of extant gnathostome fishes (both bony and cartilaginous) possess morphological laterality. Furthermore, we identify the same laterality in agnathans (hagfish and lamprey), suggesting that this trait appeared early in fish evolution and has been maintained across fish lineages. However, a comparison of asymmetry among groups of bony fishes reveals, unexpectedly, that phylogenetically more recent-groups possess less asymmetry in body structures. The universality of laterality in fishes indicates a monophyletic origin, and may have been present in the ancestors of vertebrates. Ecological factors, predatorprey interactions in particular, may be key drivers in the evolution and maintenance of dimorphism, and may also be responsible for the cryptic trend of asymmetry in derived groups. Because lung-fish and coelacanths share this trait, it is likely that tetrapods also inherited it. We believe that study of this morphological laterality will provide insights into the behavioral and sensory lateralization of vertebrates.