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Body forms in sharks (Chondrichthyes: Elasmobranchii) and their functional, ecological, and evolutionary implications
Zoology ( IF 1.6 ) Pub Date : 2020-06-01 , DOI: 10.1016/j.zool.2020.125799
Phillip C Sternes 1 , Kenshu Shimada 2
Affiliation  

Sharks are among the oldest vertebrate lineages in which their success has been attributed to their diversity in body shape and locomotor design. In this study, we investigated the diversity of body forms in extant sharks using landmark-based geometric morphometric analyses on nearly all the known (ca. 470) extant sharks. We ran three different analyses: the 'full body,' 'precaudal body,' and 'caudal fin' analyses. Our study suggests that there are two basic body forms in sharks, a 'shallow-bodied' form (Group A) and 'deep-bodied' form (Group B), where all sharks essentially have one basic caudal fin design of a heterocercal tail despite some specializations. We found that swimming modes in sharks are highly correlated with body forms where Group A sharks are predominantly anguilliform swimmers and Group B sharks are represented by carangiform and thunniform swimmers. The majority of Group A sharks are found to be benthic whereas pelagic forms are relatively common among Group B sharks. Each of the two superorders of sharks, Squalomorphii and Galeomorphii, must have gone through complex evolutionary history where each superorder contains both Group A sharks and Group B sharks, possibly involving parallel evolution from one group to the other or at least one episode of evolutionary reversal.

中文翻译:

鲨鱼(软骨鱼类:Elasmobranchii)的身体形态及其功能、生态和进化意义

鲨鱼是最古老的脊椎动物谱系之一,它们的成功归功于它们在身体形状和运动设计方面的多样性。在这项研究中,我们对几乎所有已知(约 470 只)现存鲨鱼使用基于地标的几何形态测量分析,调查了现存鲨鱼身体形态的多样性。我们进行了三种不同的分析:“全身”、“前体”和“尾鳍”分析。我们的研究表明,鲨鱼有两种基本的体型,“浅体”形式(A 组)和“深体”形式(B 组),其中所有鲨鱼基本上都有一个基本的异尾鳍尾鳍设计尽管有一些专业。我们发现鲨鱼的游泳模式与体型高度相关,其中 A 组鲨鱼主要是鳗鱼形游泳者,B 组鲨鱼以卡兰吉形和鲱鱼形游泳者为代表。大多数 A 组鲨鱼被发现是底栖的,而 B 组鲨鱼中的中上层鲨鱼则相对常见。鲨鱼的两个超级目 Squalomorphii 和 Galeomorphii 中的每一个都必须经历复杂的进化历史,其中每个超级目都包含 A 组鲨鱼和 B 组鲨鱼,可能涉及从一组到另一组的平行进化或至少一次进化逆转.
更新日期:2020-06-01
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