Response of a cold water adapted species to environmental changes : phenotypic plasticity and divergence in early life-history traits of arctic charr (Salvelinus alpinus) Southernmost populations

• Main Author: Mari, Lisandrina
• Other Authors: Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Institut National de la Recherche Agronomique (INRA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry ), Université Grenoble Alpes, Jean Guillard, Émilien Lasne
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2019
• Subjects: Global change; Fish; Temperature; Local adaptation; Phenotypic plasticity; Sediment; Changement global; Poisson; Température; Adaptation locale; Plasticité phénotypique; Sédiments; [SDV.SA]Life Sciences [q-bio]/Agricultural sciences; Arctic charr; Climate change; Salvelinus alpinus
• Online Access: https://theses.hal.science/tel-03574289; https://theses.hal.science/tel-03574289/document; https://theses.hal.science/tel-03574289/file/MARI_2019_archivage.pdf

In a warming climate, the capacity of species to adopt effective strategies to cope with temperature increase will be key to their persistence in hostile environments. Furthermore, elevated temperatures are likely to modulate the effects of other environmental pressures on biota.The Arctic charr (Salvelinus alpinus) is a cold water adapted stenotherm, found essentially below the Arctic circle. In Europe, the Southernmost edge of its native distribution range is located in the Alps where the species remained following the glacier retreat after the last glaciation. As alpine and peri-alpine lakes are deemed particularly vulnerable to warming, these isolated populations can be considered as sentinels of climate change and constitute an interesting study system to investigate i) local adaptation to thermal habitat and ii) population response to multiple environmental stressors.Using a common garden experimental design, we first reared embryos originating from four lakes along an altitudinal gradient to an optimum temperature (5°C) or to a temperature close to the thermal tolerance limit of arctic charr embryos (8.5°C). We measured fitness-related traits in hatched larvae and at near emergence and investigated the evolutionary processes underlying population divergence using a QST-FST approach. Results revealed contrasted thermal reaction norms with effects of temperature affecting survival, body size and timing of hatching, that reflected genetic divergence among populations. However, pairwise population comparisons showed that quantitative trait divergence could often be explained by drift and homogenous selection. Results also indicated that neutral genetic diversity was relatively high, but adaptive potential to warming was limited in populations managed by supportive breeding, suggesting a negative effect of local management practices on populations.A second study investigated the combined effects of temperature and fine sediment, a stressor that affects strongly oxygen availability and habitat quality of ...