Phenotypic variation in otolith shape of American shad across eastern North American rivers

Abstract Otolith shape analysis has been widely applied to study population structure and environmental influences in various fish species. However, research on American shad (Alosa sapidissima) otolith morphology remains scarce, despite its potential to provide insights into population differentiat...

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Main Authors: Joana Vasconcelos, Karin E. Limburg, José Luis Oterro-Ferrer, Víctor M. Tuset
Format: Article
Language:English
Published: Nature Portfolio 2025-08-01
Series:Scientific Reports
Online Access:https://doi.org/10.1038/s41598-025-14742-1
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author Joana Vasconcelos
Karin E. Limburg
José Luis Oterro-Ferrer
Víctor M. Tuset
author_facet Joana Vasconcelos
Karin E. Limburg
José Luis Oterro-Ferrer
Víctor M. Tuset
author_sort Joana Vasconcelos
collection DOAJ
description Abstract Otolith shape analysis has been widely applied to study population structure and environmental influences in various fish species. However, research on American shad (Alosa sapidissima) otolith morphology remains scarce, despite its potential to provide insights into population differentiation and environmental adaptation. This study analyses otolith contour shape from 1141 American shad collected between 2000 and 2023 across eleven large rivers from Canada to Florida. Using a wavelet transform framework based on the à trous algorithm and B3-spline wavelet, we quantified otolith shape variability and assessed its effectiveness for population discrimination. Principal Component Analysis revealed significant shape variation, with key differences in the rostrum, antirostrum, and posterior region. Wavelet analysis identified two primary otolith morphologies—upper and lower rostrum—geographically structured along a latitudinal gradient. A Multilayer Perceptron neural network successfully classified individuals with 90.9% accuracy, highlighting strong population differentiation, particularly in the St. Lawrence and Delaware rivers. Cluster analysis identified five morphotypes with distinct spatial distributions, suggesting a role for local environmental conditions in shaping otolith morphology. These findings underscore the utility of otolith shape analysis in deciphering population structure and highlight potential links between environmental variation and phenotypic plasticity in American shad.
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spelling doaj-art-a6ecc5b4e1554d8fb20cb97e277a8f882025-08-20T03:45:55ZengNature PortfolioScientific Reports2045-23222025-08-0115111510.1038/s41598-025-14742-1Phenotypic variation in otolith shape of American shad across eastern North American riversJoana Vasconcelos0Karin E. Limburg1José Luis Oterro-Ferrer2Víctor M. Tuset3Grupo en Biodiversidad y Conservación (BIOCON), ECOAQUA, Universidad de Las Palmas de Gran CanariaDepartment of Aquatic Resources, Swedish University of Agricultural ScienceBiostatech, Advice, Training and Innovation in Biostatistics (Ltd)Instituto de Oceanografía y Cambio Global, IOCAG, Universidad de Las Palmas de Gran Canaria, Unidad Asociada ULPGC-CSICAbstract Otolith shape analysis has been widely applied to study population structure and environmental influences in various fish species. However, research on American shad (Alosa sapidissima) otolith morphology remains scarce, despite its potential to provide insights into population differentiation and environmental adaptation. This study analyses otolith contour shape from 1141 American shad collected between 2000 and 2023 across eleven large rivers from Canada to Florida. Using a wavelet transform framework based on the à trous algorithm and B3-spline wavelet, we quantified otolith shape variability and assessed its effectiveness for population discrimination. Principal Component Analysis revealed significant shape variation, with key differences in the rostrum, antirostrum, and posterior region. Wavelet analysis identified two primary otolith morphologies—upper and lower rostrum—geographically structured along a latitudinal gradient. A Multilayer Perceptron neural network successfully classified individuals with 90.9% accuracy, highlighting strong population differentiation, particularly in the St. Lawrence and Delaware rivers. Cluster analysis identified five morphotypes with distinct spatial distributions, suggesting a role for local environmental conditions in shaping otolith morphology. These findings underscore the utility of otolith shape analysis in deciphering population structure and highlight potential links between environmental variation and phenotypic plasticity in American shad.https://doi.org/10.1038/s41598-025-14742-1
spellingShingle Joana Vasconcelos
Karin E. Limburg
José Luis Oterro-Ferrer
Víctor M. Tuset
Phenotypic variation in otolith shape of American shad across eastern North American rivers
Scientific Reports
title Phenotypic variation in otolith shape of American shad across eastern North American rivers
title_full Phenotypic variation in otolith shape of American shad across eastern North American rivers
title_fullStr Phenotypic variation in otolith shape of American shad across eastern North American rivers
title_full_unstemmed Phenotypic variation in otolith shape of American shad across eastern North American rivers
title_short Phenotypic variation in otolith shape of American shad across eastern North American rivers
title_sort phenotypic variation in otolith shape of american shad across eastern north american rivers
url https://doi.org/10.1038/s41598-025-14742-1
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