Human influence on brown trout juvenile body size during metapopulation expansion

• Published in: Biology Letters
• Main Authors: Aulus Giacosa, Lucie, Guéraud, François, Gaudin, Philippe, Buoro, Mathieu, Aymes, Jean-Christophe, Labonne, Jacques, VIGNON, Matthias
• Other Authors: Ecologie Comportementale et Biologie des Populations de Poissons (ECOBIOP), Université de Pau et des Pays de l'Adour (UPPA)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), French Polar Institute, Universite de Pau et des Pays de l'Adour - E2S, INRAE
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: ecology; evolution; systems biology; ecosystems; dispersal; density dependence; brown trout; subantarctic; invasion biology; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Kerguelen; Kerguelen Islands
• Online Access: https://hal.archives-ouvertes.fr/hal-03420470; https://hal.archives-ouvertes.fr/hal-03420470/document; https://hal.archives-ouvertes.fr/hal-03420470/file/2021_AulusGiacosa_BiologyLetters.pdf; https://doi.org/10.1098/rsbl.2021.0366

International audience Change in body size can be driven by social (density) and non-social (environmental and spatial variation) factors. In expanding metapopulations, spatial sorting by means of dispersal on the expansion front can further drive the evolution of body size. However, human intervention can dramatically affect these founder effects. Using long-term monitoring of the colonization of the remote Kerguelen islands by brown trout, a facultative anadromous salmonid, we analyse body size variation in 32 naturally founded and 10 human-introduced populations over 57 years. In naturally founded populations, we find that spatial sorting promotes slow positive changes in body size on the expansion front, then that body size decreases as populations get older and local density increases. This pattern is, however, completely different in human-introduced populations, where body size remains constant or even increases as populations get older. The present findings confirm that changes in body size can be affected by metapopulation expansion, but that human influence, even in very remote environments, can fully alter this process.