title: Adaptation and acclimation of traits associated with swimming capacity in Lake Whitefish (coregonus clupeaformis) ecotypes.
abstract: Improved performance in a given ecological niche can occur through local adaptation, phenotypic plasticity, or a combination of these mechanisms. Evaluating the relative importance of these two mechanisms is needed to better understand the cause of intra specific polymorphism. In this study, we reared populations of Lake Whitefish (Coregonus clupeaformis) representing the'normal' (benthic form) and the 'dwarf' (derived limnetic form) ecotypes in two different conditions (control and swim-training) to test the relative importance of adaptation and acclimation in the differentiation of traits related to swimming capacity. The dwarf whitefish is a more active swimmer than the normal ecotype, and also has a higher capacity for aerobic energy production in the swimming musculature. We hypothesized that dwarf fish would show changes in morphological and physiological traits consistent with reductions in the energetic costs of swimming and maintenance metabolism.
  
  
  
  We found differences in traits predicted to decrease the costs of prolonged swimming and standard metabolic rate and allow for a more active lifestyle in dwarf whitefish. Dwarf whitefish evolved a more streamlined body shape, predicted to lead to a decreased drag, and a smaller brain, which may decrease their standard metabolic rate. Contrary to predictions, we also found evidence of acclimation in liver size and metabolic enzyme activities.
  
  
  
  Results support the view that local adaptation has contributed to the genetically-based divergence of traits associated with swimming activity. Presence of post-zygotic barriers limiting gene flow between these ecotype pairs may have favoured repeated local adaptation to the limnetic niches.
authors: Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada. uni.mlaporte@gmail.com.|Department of Biology, Saint Mary's University, Halifax, NS, Canada. uni.mlaporte@gmail.com.|School of Medicine, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia. uni.mlaporte@gmail.com.
authors: Martin
authors: 0000-0002-0622-123X
authors: M
authors: Laporte
authors: Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada.|Department of Biology, Saint Mary's University, Halifax, NS, Canada.
authors: Anne C
authors: AC
authors: Dalziel
authors: Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada.|Department of Biology, Saint Mary's University, Halifax, NS, Canada.|School of Medicine, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia.
authors: Nicolas
authors: N
authors: Martin
authors: Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Canada.
authors: Louis
authors: L
authors: Bernatchez
mesh_terms: D000064:Acclimatization; D000818:Animals; D005075:Biological Evolution; D060146:Ecotype; D004734:Energy Metabolism; D005260:Female; D051456:Gene Flow; D008297:Male; D012487:Salmonidae / Q000033:anatomy & histology / Q000235:genetics* / Q000502:physiology*; D013550:Swimming
keywords: Ecophysiology; Geometric morphometrics; Local adaptation; Parallel evolution; Phenotypic plasticity; Salmonidae; Speciation; Swimming cost