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Collar DC, Tremaine S, Harrington RC, Beckett HT, Friedman M. Mosaic adaptive peak shifts underlie body shape diversification in pelagiarian fishes (Acanthomorpha: Percomorpha). Biol J Linn Soc Lond 2022. [DOI: 10.1093/biolinnean/blac096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Extreme body elongation in fishes is a major evolutionary transformation that extends the boundaries of morphological diversity and alters aspects of function, behaviour and ecology. Prior studies have identified features of the cranial and axial skeleton that characterize elongate fishes, but a lack of detailed reconstructions of anatomical evolution has limited inferences about factors that underlie major shifts in body shape. In this study, we fitted multi-peak adaptive (Ornstein–Uhlenbeck) evolutionary models to species body shape and anatomical dimensions in Pelagiaria, a radiation of open-ocean fishes whose species span a continuum from deep bodied to highly elongate. We inferred an ancestral fusiform adaptive peak that is retained by several major pelagiarian lineages (e.g. Scombridae) and found robust support for multiple transitions to deep-bodied optima (in the families Stromateidae, Bramidae and Caristiidae) and elongate-bodied optima (within Trichiuroidei), including two instances of sequential shifts towards increasingly elongate optima that followed distinct paths of anatomical evolution. Within Trichiuridae, initial increases in head length and the number of vertebrae were followed by changes in head and vertebral shape. Within an elongate-bodied subclade of taxa traditionally identified as ‘gempylids’, changes in head and vertebral shape and in the number of precaudal vertebrae preceded an increase in the number of caudal vertebrae. Altogether, this mosaic of anatomical peak shifts suggests that body shape transformations were associated with differing selective demands and developmental changes.
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Affiliation(s)
- David C Collar
- Department of Organismal and Environmental Biology, Christopher Newport University , Newport News, VA , USA
| | - Samantha Tremaine
- Department of Organismal and Environmental Biology, Christopher Newport University , Newport News, VA , USA
| | - Richard C Harrington
- Department of Ecology and Evolutionary Biology, Yale University , New Haven, CT , USA
| | - Hermione T Beckett
- Department of Earth Sciences, University of Oxford , Oxford , UK
- Department of Biology, King’s High School for Girls , Warwick , UK
| | - Matt Friedman
- Museum of Paleontology, University of Michigan , Ann Arbor, MI , USA
- Department of Earth and Environmental Sciences, University of Michigan , Ann Arbor, MI , USA
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