In Atlantic salmon, space use of potential breeders stabilises population dynamics and shapes sexual selection

• Main Author: Bouchard, Colin
• Other Authors: Ecologie Comportementale et Biologie des Populations de Poissons (ECOBIOP), Institut National de la Recherche Agronomique (INRA)-Université de Pau et des Pays de l'Adour (UPPA), Université de Pau et des Pays de l'Adour, Agnes Bardonnet, Cedric Tentelier (co-directeur)
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2018
• Subjects: habitat fragmentation; mature parr; mating system; breeding sites; Atlantic salmon; sexual network; sexual competition; social competition; spatial aggregation; stock-recruitment; fragmentation de l’habitat; habitats de reproduction; saumon Atlantique; système d’appariement; réseau sexuel; stock-recrutement; Agrégation spatiale; compétition sexuelle; compétition sociale; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDV.BA]Life Sciences [q-bio]/Animal biology; Salmo salar
• Online Access: https://hal.science/tel-02292776; https://hal.science/tel-02292776v2/document; https://hal.science/tel-02292776v2/file/Bouchard.pdf

Habitat fragmentation and reduction in the availability of suitable habitats are significant threats to ecosystems in particularly for freshwater ones. For instance, accessibility, availability, and quality of breeding sites of Atlantic salmon, \textit{Salmo salar}, can be restricting in some rivers due to human activities and dams. Such threats may affect distribution of potential breeders because after their up-river migration, salmon females distribute within available breeding sites. Spatial distribution of females determines the spatial distribution of breeder males. Dominant males try to monopolise several females, whereas subordinate males adopt a sneaky behaviour. Access to females by males depends on the spatial distribution of females and on males' displacements within a river. The spatial distribution of females generates the spatial distribution of juveniles, aggregating them at some breeding sites. The latter aggregation of juveniles may raise the density-dependent mortality with potential consequences on population dynamics. The thesis aims to assess how space use of potential breeders, namely mature individuals able to spawn or fertilise eggs, influence population dynamics and sexual selection.I combined different approaches and different temporal and spatial scales to potential effects of space use of potential breeders. Time series of stock (deposited eggs) and of recruitment (juveniles) for the salmon population of the Nivelle River were combined with measures of spatial aggregation of nests. The effects of displacements and spatial distribution of potential breeders on their participation in reproduction were tested through inferring the sexual network of the population.I found that spatial aggregation of nests improved the recruitment variability but did not affect the average recruitment. The spatial aggregation of nests resulting from female aggregation was also linked to the number of effective breeders through a U-shaped curve. Such relationships suggested mate monopolization dependent on ...