Local adaptation in brown trout early life-history traits: implications for climate change adaptability

Abstract

Knowledge of local adaptation and adaptive potential of natural populations is becoming increasingly relevant due to anthropogenic changes in the environment, such as climate change. The concern is that populations will be negatively affected by increasing temperatures without the capacity to adapt. Temperature-related adaptability in traits related to phenology and early life history are expected to be particularly important in salmonid fishes. We focused on the latter and investigated whether four populations of brown trout (Salmo trutta) are locally adapted in early life-history traits. These populations spawn in rivers that experience different temperature conditions during the time of incubation of eggs and embryos. They were reared in a common-garden experiment at three different temperatures. Quantitative genetic differentiation (Q ST ) exceeded neutral molecular differentiation (F ST ) for two traits, indicating local adaptation. A temperature effect was observed for three traits. However, this effect varied among populations due to locally adapted reaction norms, corresponding to the temperature regimes experienced by the populations in their native environments. Additive genetic variance and heritable variation in phenotypic plasticity suggest that although increasing temperatures are likely to affect some populations negatively, they may have the potential to adapt to changing temperature regimes.

Old wine in new bottles: reaction norms in salmonid fishes

“…Coupled with this variability was the observation that quantitative trait differentiation (Q ST ) exceeded neutral molecular differentiation (F ST ) for body length at two different developmental stages (alevin, swim-up). As documented by Haugen and Vllestad (2000) for grayling, Jensen et al (2008) found evidence of genetic variability in plasticity among individuals within populations, as indicated by significant sire  temperature interactions. They further supported their conclusion that population differences in reaction norms were a consequence of natural selection by arguing for potentially adaptive responses by alevin length and growth rate to temperatures that the populations were most likely to experience in the wild.…”

An assessment of the spatial scale of local adaptation in brown trout (Salmo trutta L.): footprints of selection at microsatellite DNA loci

“…Factors such as temperature may vary considerably among and within rivers at smaller geographical scales and may represent potent selection regimes (Jensen et al, 2008). However, information at this geographical scale was not available for all sampled localities.…”

“…Recently, the development of statistical and conceptual frameworks such as the Q ST -F ST approach (Merilä and Crnokrak, 2001) has enabled more rigorous testing of selection and local adaptation at the phenotypic level among salmonid populations (Koskinen et al, 2002;Perry et al, 2005;Jensen et al, 2008). Moreover, the revolutionizing developments in the genomic sciences have led to the generation of vast amounts of molecular resources available in silico, which can readily be used for identification of suitable genetic markers (Bouck and Vision, 2007).…”

Adaptive capacity: from assessment to action in coastal social-ecological systems

“…In ecological systems, short-term adaptive strategies usually refer to acclimation to a new (or temporary) environmental state; acclimation may draw on phenotypic plasticity, habitat diversity, or short-term behavioral responses (Stillman 2003). If an environmental stressor or shift continues, long-term adaptive strategies depend on evolutionary responses at the species level or migration strategies (leaving the area for better suited habitats; Jensen et al 2008, Chown et al 2010, Ekstrom et al 2015. Social communities may cope with change in the short term through social networks, informal arrangements, alternative income generating activities, or financial remittances from overseas family members (Adger 2003, Adger et al 2007).…”