Early-life history traits and dispersal of Anguillids : toward a bio-evolutive approach

• Main Author: Réveillac, Elodie
• Other Authors: LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Université de La Rochelle, Eric Feunteun
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2008
• Subjects: Early-life history traits; dispersal; Anguillid eels; otolith; traits d'histoire de vie larvaire; dispersion; anguilles; otolithe; [SDV.EE]Life Sciences [q-bio]/Ecology; environment; Indian; European eel
• Online Access: https://theses.hal.science/tel-00561952; https://theses.hal.science/tel-00561952/document; https://theses.hal.science/tel-00561952/file/Manuscrit_de_thA_se_ER.pdf

Among life-history processes that contribute to life-histories diversity, dispersal is probably the most important one involved in both species persistence and evolution. It grants escapement from competition and unfavourable conditions, permits to keep connections between isolated populations, and enlarges or displace distribution areas by exploration of the environment. Anguillid eels are famous fish species for the huge dispersal capacities of their leaf-like transparent larvae. These leptocephali can indeed cross thousands to hundreds of kilometres to reach coastal, estuarine or freshwater growth habitats from which adults escape to return to natal waters in tropical areas to spawn and die. This migration loop is thought to have first occurred entirely in tropical marine waters and progressively enlarged toward temperate areas for growth. This work examined the larval dispersal capacities of eels through the study of larval traits (e.g. larval duration, metabolic rate) and their contribution to the evolution of the genus through speciation along with range expansion. Emphasis was made on three species among which the tropical Mozambican eel Anguilla mossambica is the most ancient species and is endemic to the southwestern Indian Ocean; the giant mottled eel A. marmorata is the most widespread species but also the most genetically structured one; and the temperate European eel A. anguilla is the youngest species and displays the highest dispersal capacities. Plasticity of traits was proposed to have generated the observed larval life-histories diversity, which, supported by environmental conditions could have favoured specific range expansion. However, intraspecific dispersal elasticity displayed limits that might have induced temporal and/or spatial segregation of migration loops that subsequently formed new species. Nevertheless, the huge variability of dispersal capacities recorded in each species evidenced a high potential of resilience in face of environmental changes. This is proposed to have supported ...