Skeletal development in the heterocercal caudal fin of spotted gar (lepisosteus oculatus) and other lepisosteiformes. Issue 5 (31st January 2018)

• Record Type: Journal Article
• Authors: Desvignes, Thomas; Carey, Andrew; Braasch, Ingo; Enright, Trevor; Postlethwait, John H.
• Is Part Of: Developmental dynamics. Volume 247:Issue 5(2018)
• Page Start: 724
• Page End: 740
• Publication Date: 2018-01-31
• Subjects: Holostei -- actinopterygian -- tail -- ontogeny -- skeletogenesis -- morphology; Morphogenesis -- Periodicals; Anatomy -- Periodicals; Anatomie -- Périodiques; Biologie du développement -- Périodiques; 571.833
• DOI: 10.1002/dvdy.24617
• Languages: English
• ISSNs: 1058-8388

Abstract

Abstract : Background : The caudal fin of actinopterygians experienced substantial morphological changes during evolution. In basal actinopterygians, the caudal fin skeleton supports an asymmetrical heterocercal caudal fin, while most teleosts have a symmetrical homocercal caudal fin. The transition from the ancestral heterocercal form to the derived homocercal caudal fin remains poorly understood. Few developmental studies provide an understanding of derived and ancestral characters among basal actinopterygians. To fill this gap, we examined the development of the caudal fin of spotted gar Lepisosteus oculatus, one of only eight living species of Holostei, the sister group to the teleosts.Results : Our observations of animals from fertilization to more than a year old provide the most detailed description of the development of caudal fin skeletal elements in any Holostean species. We observed two different types of distal caudal radials replacing two transient plates of connective tissue, identifying two hypaxial ensembles separated by a space between hypurals 2 and 3. These features have not been described in any gar species, but can be observed in other gar species, and thus represent anatomical structures common to lepisosteiformes.Conclusions : The present work highlights the power and importance of ontogenic studies and provides bases for future evolutionary and morphological investigations on actinopterygians fins. Developmental Dynamics 247:724–740, 2018 . © 2018 Wiley Periodicals, Inc. Key Findings: Observations presented here provide the most detailed description of the developmental origins of caudal fin skeletal elements in any Holostean species to date. Two types of distal caudal radials replace two transient plates of connective tissue, identifying two hypaxial ensembles separated by a space between hypurals 2 and 3. These novel features have not been described in any gar species, but can be observed in published figures of other gar species, and thus represent anatomical structures common to lepisosteiformes. The present work highlights the power and importance of developmental studies, and provides the basis for future evolutionary, morphological, and functional investigations on a variety of actinopterygians.