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Published June 29, 2022 | Published + Supplemental Material
Journal Article Open

Decoding the dynamics of dental distributions: insights from shark demography and dispersal

Abstract

Shark teeth are one of the most abundant vertebrate fossils, and because tooth size generally correlates with body size, their accumulations document the size structure of populations. Understanding how ecological and environmental processes influence size structure, and how this extends to influence these dental distributions, may offer a window into the ecological and environmental dynamics of past and present shark populations. Here, we examine the dental distributions of sand tigers, including extant Carcharias taurus and extinct Striatolamia macrota, to reconstruct the size structure for a contemporary locality and four Eocene localities. We compare empirical distributions against expectations from a population simulation to gain insight into potential governing ecological processes. Specifically, we investigate the influence of dispersal flexibility to and from protected nurseries. We show that changing the flexibility of initial dispersal of juveniles from the nursery and annual migration of adults to the nursery explains a large amount of dental distribution variability. Our framework predicts dispersal strategies of an extant sand tiger population, and supports nurseries as important components of sand tiger life history in both extant and Eocene populations. These results suggest nursery protection may be vital for shark conservation with increasing anthropogenic impacts and climate change.

Additional Information

© 2022 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. Manuscript received 26/04/2022. Manuscript accepted 06/06/2022. Published online 29/06/2022. Published in print 29/06/2022. This research would not be possible without the support of many individuals. We thank the curators and collection managers for their help and access to collect the empirical data: K. Shepherd and M. Currie at the Canadian Museum of Nature, P. Holroyd at the University of California Museum of Paleontology, L. Skibinski at Paleontological Research Institute, T. Mörs at the Swedish Natural History Museum, A. Henrici at the Carnegie Museum of Natural History, and C. Flis at the Whiteside Natural History Museum. We are grateful to D. Fox for access to data from the 2012 Carcarias taurus tagging season as part of his research programme at Delaware State University. Our research benefited from conversations with M. Clementz, P. Holroyd, D. Jablonski and S. Kidwell over the years. We also thank two anonymous referees for valuable comments and feedback that greatly improved our manuscript. Thank you to Christina Spence Morgan for scientific illustration on figures 1 and 2. This research was funded in part by the National Science Foundation (OPP1842049) and University of Chicago T.C. Chamberlin Fellowship to S.L.K.; Mellon Mayes Undergraduate Fellowship at University of Chicago, National Science Foundation Graduate Research Fellowship, and NASA Emerging Worlds grant no. (18 − EW182 − 0084) to S.Z.; Austrian Science Fund (FWF) [P 33820] to J.K. For the purpose of open access, J.K. has applied a CC BY public copyright licence to any Author. Field research to collect shark teeth on Banks Island, Canada was supported by National Science Foundation grant no. ARC0804627 to J.J.E. Data accessibility. Raw data for empirical tooth distributions are provided in the Dryad repository at https://doi.org/10.6071/M3RT05. Simulation code is available in the public GitHub repository https://github.com/jdyeakel/sharks_bodysize. The data are provided in electronic supplementary material [48]. We declare we have no competing interests.

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Published - rspb.2022.0808.pdf

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Additional details

Created:
August 22, 2023
Modified:
October 23, 2023