Potential responses to climate change in organisms with complex life histories: evolution and plasticity in Pacific salmon

Abstract

Salmon life histories are finely tuned to local environmental conditions, which are intimately linked to climate. We summarize the likely impacts of climate change on the physical environment of salmon in the Pacific Northwest and discuss the potential evolutionary consequences of these changes, with particular reference to Columbia River Basin spring/summer Chinook (Oncorhynchus tshawytscha) and sockeye (Oncorhynchus nerka) salmon. We discuss the possible evolutionary responses in migration and spawning date egg and juvenile growth and development rates, thermal tolerance, and disease resistance. We know little about ocean migration pathways, so cannot confidently suggest the potential changes in this life stage. Climate change might produce conflicting selection pressures in different life stages, which will interact with plastic (i.e. nongenetic) changes in various ways. To clarify these interactions, we present a conceptual model of how changing environmental conditions shift phenotypic optima and, through plastic responses, phenotype distributions, affecting the force of selection. Our predictions are tentative because we lack data on the strength of selection, heritability, and ecological and genetic linkages among many of the traits discussed here. Despite the challenges involved in experimental manipulation of species with complex life histories, such research is essential for full appreciation of the biological effects of climate change.

Run-of-River hydropower and salmonids: potential effects and perspective on future research

“…These periods of accentuated low flow in spring and summer also correspond to important times for spawning, incubating, or rearing salmonids ( Table 2). As found by studies conducted in reservoir-storage systems and in unregulated rivers, increased temperatures coinciding with low flows have the potential to change the timing of spawning migrations and interspecific interactions (e.g., Freeman et al 2001;Bendall et al 2012;Malcolm et al 2012), reduce survival of smolts before and during migrations (Nislow and Armstrong 2012), and make fish more vulnerable to pathogens (Crozier et al 2008;Mantua et al 2010). Additionally, these extended periods of low flow can reduce water quality, limit movement of nutrients and sediment, and increase competition and predation (Lake 2000;Bradford and Heinonen 2008;Walters and Post 2011).…”

Reproductive Biology of Hilsa Shad Tenualosa ilisha (Teleostei: Clupeidae) During Spawning Migration in the Shatt Al Arab River and Southern Al Hammar Marsh, Basra, Iraq

“…These differences in the spawning period of Hilsa shad populations may be due to changes in the environmental factors caused by climate change. Climate change has had a clear impact on the annual timing of life-history events of animals and plants (Bradley et al, 1999;Walther et al, 2002), such as selective pressures on the date of spawning (Crozier et al, 2008) and variations in reproductive characteristics (Barange and Perry, 2009).…”

Toward a synthetic understanding of the role of phenology in ecology and evolution

“…For example, high-altitude populations have delayed phenologies relative to their low-elevation counterparts but have been selected for faster development (a phenomenon known as countergradient variation; Conover & Schultz 1995). However, interactions between plastic and genetic changes in phenology have received little study in the context of climate change (though see Crozier et al 2008).…”