The evolution of underwater flight: The redistribution of pectoral fin rays, in manta rays and their relatives (Myliobatidae)
The evolution of underwater flight: The redistribution of pectoral fin rays, in manta rays and their relatives (Myliobatidae)
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DOI：
10.1002/jmor.20837
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发表时间：
2018-08-01
影响因子：
1.5
通讯作者：
Crow, Karen D.
中科院分区：
文献类型：
--
作者：
Hall, Kayla C.;Hundt, Peter J.;Crow, Karen D.
鳐鱼是扁平软骨鱼的一个多样化分支，主要出现在底栖海洋生境中。鳐鱼和鳐鱼通常使用其灵活的胸鳍通过波动性游泳来进食和推进。然而，鳐鱼科和裸鳐科有两组鳐鱼采用了中上层或底栖浮游生活方式，并利用振荡游泳。蝠鲼进化出了头叶，即为进食而优化的前部延伸附肢，而它们的胸鳍则表现出一些变化，这些变化可能与通过振荡飞行进行远洋巡航的功能优化有关。在这里，我们使用以下方法在进化背景下检查蝙蝠胸鳍鳍条分布的变化和鳍条发育的个体发生时间：射线照相、计算机断层扫描、解剖以及透明和染色的标本。我们提出了一个表征胸鳍条分布变化的指数。虽然波动性游泳者表现出对称性或轻微的前偏，但我们发现鳍条的分布发生后移，这种分布出现在与振荡性游泳相关的两个不同谱系中。波状和振荡游泳者在鳍条分布方面占据不重叠的形态空间，说明振荡游泳者胸鳍的显着重塑。此外，我们描述了 Myliobatidae 前胸鳍的衍生骨骼特征，该特征可能与振荡游泳的优化有关。通过检查具有明确关节点的鳍条分布，我们能够推断出与远洋环境入侵相关的进化趋势和身体计划重塑。最后，我们发现，小鳐鱼、圆黄貂鱼和牛鼻鳐的鳍条数量和分布在发育早期就已确定，这表明出生或孵化后标本的鳍条数量具有代表性，因此在物种之间具有可比性。
Batoids are a diverse clade of flat cartilaginous fishes that occur primarily in benthic marine habitats. The skates and rays typically use their flexible pectoral fins for feeding and propulsion via undulatory swimming. However, two groups of rays have adopted a pelagic or bentho-pelagic lifestyle and utilize oscillatory swimmingthe Myliobatidae and Gymnuridae. The myliobatids have evolved cephalic lobes, anteriorly extended appendages that are optimized for feeding, while their pectoral fins exhibit several modifications that likely arose in association with functional optimization of pelagic cruising via oscillatory flight. Here, we examine variation in fin ray distribution and ontogenetic timing of fin ray development in batoid pectoral fins in an evolutionary context using the following methods: radiography, computed tomography, dissections, and cleared and stained specimens. We propose an index for characterizing variation in the distribution of pectoral fin rays. While undulatory swimmers exhibit symmetry or slight anterior bias, we found a posterior shift in the distribution of fin rays that arose in two distinct lineages in association with oscillatory swimming. Undulatory and oscillatory swimmers occupy nonoverlapping morphospace with respect to fin ray distribution illustrating significant remodeling of pectoral fins in oscillatory swimmers. Further, we describe a derived skeletal feature in anterior pectoral fins of the Myliobatidae that is likely associated with optimization of oscillatory swimming. By examining the distribution of fin rays with clearly defined articulation points, we were able to infer evolutionary trends and body plan remodeling associated with invasion of the pelagic environment. Finally, we found that the number and distribution of fin rays is set early in development in the little skate, round stingray, and cownose ray, suggesting that fin ray counts from specimens after birth or hatching are representative of adults and therefore comparable among species.