Intraspecific variation in thermal tolerance and acclimation capacity in brook trout (Salvelinus fontinalis): physiological implications for climate change.
Cold-water fishes are becoming increasingly vulnerable as changing thermal conditions threaten their future sustainability. Thermal stress and habitat loss from increasing water temperatures are expected to impact population viability, particularly for inland populations with limited adaptive resources. Although the long-term persistence of cold-adapted species will depend on their ability to cope with and adapt to changing thermal conditions, very little is known about the scope and variation of thermal tolerance within and among conspecific populations and evolutionary lineages. We studied the upper thermal tolerance and capacity for acclimation in three captive populations of brook trout (Salvelinus fontinalis) from different ancestral thermal environments. Populations differed in their upper thermal tolerance and capacity for acclimation, consistent with their ancestry: the northernmost strain (Lake Nipigon) had the lowest thermal tolerance, while the strain with the most southern ancestry (Hill's Lake) had the highest thermal tolerance. Standard metabolic rate increased following acclimation to warm temperatures, but the response to acclimation varied among strains, suggesting that climatic warming may have differential effects across populations. Swimming performance varied among strains and among acclimation temperatures, but strains responded in a similar way to temperature acclimation. To explore potential physiological mechanisms underlying intraspecific differences in thermal tolerance, we quantified inducible and constitutive heat shock proteins (HSP70 and HSC70, respectively). HSPs were associated with variation in thermal tolerance among strains and acclimation temperatures; HSP70 in cardiac and white muscle tissues exhibited similar patterns, whereas expression in hepatic tissue varied among acclimation temperatures but not strains. Taken together, these results suggest that populations of brook trout will vary in their ability to cope with a changing climate.
Environmental and Life Sciences Graduate Program, Trent University, Peterborough, Ontario K9J 7B8, Canada; 2Department of Biology, Trent University, Peterborough, Ontario K9J 7B8, Canada; 3Department of Biology, Mount Allison University, Sackville, New Brunswick E4L 1G7, Canada; 4Wildlife Conservation Society Canada, Trent University, Peterborough, Ontario K9J 7B8, Canada; 5Ontario Ministry of Natural Resources, Trent University, Peterborough, Ontario K9J 7B8, Canada.
Bradley C
BC
Stitt
Gary
G
Burness
Kirsten A
KA
Burgomaster
Suzanne
S
Currie
Jenni L
JL
McDermid
Chris C
CC
Wilson
D000064:Acclimatization; D000818:Animals; D001481:Basal Metabolism; D002980:Climate; D057231:Climate Change; D003247:Conservation of Natural Resources; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D005843:Geography; D050883:HSC70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D018869:Heat-Shock Response; D006358:Hot Temperature; D009928:Organ Specificity; D013045:Species Specificity; D013550:Swimming; D014337:Trout / Q000235:genetics / Q000502:physiology*
D029941:Fish Proteins; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins