Pectoral fin morphology of batoid fishes (Chondrichthyes: Batoidea): Explaining phylogenetic variation with geometric morphometrics

Franklin, Oliver; Palmer, Colin; Dyke, Gareth J.

doi:10.1002/jmor.20294

Cited by 22 publications

(46 citation statements)

References 75 publications

(102 reference statements)

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“…Batoids (rays, skates, guitarfishes and sawfishes) are cartilaginous fishes characterized by dorso-ventrally flattened bodies, with expanded pectoral fins fused to the cranium that form a disc ranging in shape from round to rhomboidal (Aschliman et al, 2012;Franklin et al, 2014;Nakamura et al, 2015). Most rays and all skates use their pectoral fins to swim and can be placed into a continuum between undulatory and oscillatory, based on the number of kinematic waves present on the wing during steady locomotion (Rosenberger, 2001).…”

Section: Introductionmentioning

confidence: 99%

Batoid locomotion: effects of speed on pectoral fin deformation in the little skate, Leucoraja erinacea

Santo

Blevins

Lauder

2017

Journal of Experimental Biology

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Most batoids have a unique swimming mode in which thrust is generated by either oscillating or undulating expanded pectoral fins that form a disc. Only one previous study of the freshwater stingray has quantified three-dimensional motions of the wing, and no comparable data are available for marine batoid species that may differ considerably in their mode of locomotion. Here, we investigate threedimensional kinematics of the pectoral wing of the little skate, Leucoraja erinacea, swimming steadily at two speeds [1 and 2 body lengths (BL) s]. We measured the motion of nine points in three dimensions during wing oscillation and determined that there are significant differences in movement amplitude among wing locations, as well as significant differences as speed increases in body angle, wing beat frequency and speed of the traveling wave on the wing. In addition, we analyzed differences in wing curvature with swimming speed. At 1 BL s −1 , the pectoral wing is convex in shape during the downstroke along the medio-lateral fin midline, but at 2 BL s −1 the pectoral fin at this location cups into the flow, indicating active curvature control and fin stiffening. Wing kinematics of the little skate differed considerably from previous work on the freshwater stingray, which does not show active cupping of the whole fin on the downstroke.

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Section: Introductionmentioning

confidence: 99%

Batoid locomotion: effects of speed on pectoral fin deformation in the little skate, Leucoraja erinacea

Santo

Blevins

Lauder

2017

Journal of Experimental Biology

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“…Batoids are characterized by dorso-ventrally flattened bodies, greatly enlarged pectoral fins, and in many species, a long whip-like tail. Propulsion in most of these forms is achieved through undulations (e.g., most skates and sting rays) or oscillations (e.g., eagle rays) of the widened pectoral fins [122–124], which provides a functional context for the loss of the caudal fin when compared to most other chondrichthyans that use a caudal fin-based propulsion. The paired fins do not account for much of the disparity in fin configurations: absence of the pelvic fins is limited to representatives of a single order of extinct chondrichthyans, the Eugeneodontiformes.…”

Section: Discussionmentioning

confidence: 99%

Fin modules: an evolutionary perspective on appendage disparity in basal vertebrates

2017

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BackgroundFishes are extremely speciose and also highly disparate in their fin configurations, more specifically in the number of fins present as well as their structure, shape, and size. How they achieved this remarkable disparity is difficult to explain in the absence of any comprehensive overview of the evolutionary history of fish appendages. Fin modularity could provide an explanation for both the observed disparity in fin configurations and the sequential appearance of new fins. Modularity is considered as an important prerequisite for the evolvability of living systems, enabling individual modules to be optimized without interfering with others. Similarities in developmental patterns between some of the fins already suggest that they form developmental modules during ontogeny. At a macroevolutionary scale, these developmental modules could act as evolutionary units of change and contribute to the disparity in fin configurations. This study addresses fin disparity in a phylogenetic perspective, while focusing on the presence/absence and number of each of the median and paired fins.ResultsPatterns of fin morphological disparity were assessed by mapping fin characters on a new phylogenetic supertree of fish orders. Among agnathans, disparity in fin configurations results from the sequential appearance of novel fins forming various combinations. Both median and paired fins would have appeared first as elongated ribbon-like structures, which were the precursors for more constricted appendages. Among chondrichthyans, disparity in fin configurations relates mostly to median fin losses. Among actinopterygians, fin disparity involves fin losses, the addition of novel fins (e.g., the adipose fin), and coordinated duplications of the dorsal and anal fins. Furthermore, some pairs of fins, notably the dorsal/anal and pectoral/pelvic fins, show non-independence in their character distribution, supporting expectations based on developmental and morphological evidence that these fin pairs form evolutionary modules.ConclusionsOur results suggest that the pectoral/pelvic fins and the dorsal/anal fins form two distinct evolutionary modules, and that the latter is nested within a more inclusive median fins module. Because the modularity hypotheses that we are testing are also supported by developmental and variational data, this constitutes a striking example linking developmental, variational, and evolutionary modules.Electronic supplementary materialThe online version of this article (doi:10.1186/s12915-017-0370-x) contains supplementary material, which is available to authorized users.

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“…The fossil record of batoids extends to the Lower Jurassic (Maisey, 2012). The pectoral fins are connected to the antorbital process of the cranium and are generally greatly enlarged to the point of frequently being referred to as wings (Franklin, Palmer, & Dyke, 2014;Rosenberger, 2001;Schaefer & Summers, 2005). Again, the pectoral and pelvic fins are always present in batoids.…”

Section: Heteropetalus and Chondrenchelyiformes Or Two Dorsal Fins Amentioning

confidence: 99%

A critical appraisal of appendage disparity and homology in fishes

2019

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Fishes are both extremely diverse and morphologically disparate. Part of this disparity can be observed in the numerous possible fin configurations that may differ in terms of the number of fins as well as fin shapes, sizes and relative positions on the body. Here, we thoroughly review the major patterns of disparity in fin configurations for each major group of fishes and discuss how median and paired fin homologies have been interpreted over time. When taking into account the entire span of fish diversity, including both extant and fossil taxa, the disparity in fin morphologies greatly complicates inferring homologies for individual fins. Given the phylogenetic scope of this review, structural and topological criteria appear to be the most useful indicators of fin identity. We further suggest that it may be advantageous to consider some of these fin homologies as nested within the larger framework of homologous fin‐forming morphogenetic fields. We also discuss scenarios of appendage evolution and suggest that modularity may have played a key role in appendage disparification. Fin modules re‐expressed within the boundaries of fin‐forming fields could explain how some fins may have evolved numerous times independently in separate lineages (e.g., adipose fin), or how new fins may have evolved over time (e.g., anterior and posterior dorsal fins, pectoral and pelvic fins). We favour an evolutionary scenario whereby median appendages appeared from a unique field of competence first positioned throughout the dorsal and ventral midlines, which was then redeployed laterally leading to paired appendages.

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Pectoral fin morphology of batoid fishes (Chondrichthyes: Batoidea): Explaining phylogenetic variation with geometric morphometrics

Cited by 22 publications

References 75 publications

Batoid locomotion: effects of speed on pectoral fin deformation in the little skate, Leucoraja erinacea

Batoid locomotion: effects of speed on pectoral fin deformation in the little skate, Leucoraja erinacea

Fin modules: an evolutionary perspective on appendage disparity in basal vertebrates

A critical appraisal of appendage disparity and homology in fishes

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