How quickly can populations adapt to
climate change?
Chris Wilson
Aquatic Research and Monitoring Section
Ontario Ministry of Natural Resources and Forestry
Adapting to a changing climate
• adaptation to climate change
largely focused on economic
and environmental impacts
• ecological repercussions and
impacts on Ontario’s biodiversity
are expected to be significant
and permanent (www.eco.on.ca)
• Ontario action plan includes
conserving biodiversity and
supporting resilient ecosystems
• key question: adaptive potential
of wild species and populations
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How do species react to change?
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•
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behavioural response
phenotypic plasticity
migration
adaptation
x population extirpation
x species extinction
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Climate change challenges for coldwater species
• climate change models
predict significant
warming for Ontario
• coldwater species
expected to be hit
hardest
• ability to cope (shortterm) and/or adapt
(long-term)?
– local populations
– species-wide
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Climate change challenges for coldwater species
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Lake trout as a coldwater specialist
• common below 8ºC;
• optimal range between 8
to 12ºC
• [O2] >6 mg/L (<4 = lethal)
(Plumb & Blanchfield, 2009)
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Systems and populations under stress
• O2 depletion already a concern
• effect of longer stratification
interval?
(Wilson and Evans 2010)
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Climate model predictions
• lake stratification: earlier
onset, stronger gradients,
and longer duration
 temperature + O2 habitat
squeeze
 loss of habitat
 change in reproductive
timing?
 impacts on juvenile
survival; reduced
recruitment
 increased population
vulnerability
(Ficke et al., 2007)
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Regional habitat projections for lake trout
(Minns et al. 2009)
• increasing
temperatures (IPCC
A2 scenario)
• regional changes for
lake trout habitat
and productivity
• how will populations
respond?
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How quickly can populations adapt?
• adaptive ability of population
– population size (N and Ne)
– range in expression of adaptive
characters
– standing genetic resources
– “genetic architecture” and
heritability of traits under selection
• strength of selective pressures
(Naish and Hard 2008)
– magnitude and variance
– duration; time frame relative to
generation time
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Important traits for selection
• Life history
– growth rate
– age at maturity
– size at maturity
– fecundity
– (asymptotic size)
• Ecology
– place in food web
– feeding strategy
– habitat usage
• Physiology / metabolism
– temperature tolerance
– oxygen requirements /
consumption
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Similar thermal performance among lake trout
populations
Thermal Tolerance
Metabolic Scope
• acclimation temperature
(environment) had much
stronger effect than ancestry
(population) on thermal
performance
• reduced energy budget at
highest temperature (19°C)
• no significant differences in
thermal tolerance or
metabolic scope
• genetic constraints on
species-level response
(Kelly et al. 2014)
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Hot times for
brook trout?
Range considerations
Status concerns in New
England
Range contraction
(Meisner 1990)
Projected change in
distribution (Chu et al
2005)
Predicted Species Range Shifts
Habitat suitability for
brook trout in Canada
in:
a) 2005
b) 2020
c) 2050
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Thermal physiology and adaptive potential
of brook trout populations
• variation among wild
populations + hatchery strains
 fitness differences
• scope for activity
– thermal stress
– oxygen stress
– physiological performance
within ‘metabolic envelope’
 scope for adaptation
(photo credit: S. D’Amelio)
(B. Stitt M.Sc., C. Cook M.Sc.)
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Findings and new research questions
• responses to increased summer temperatures
– delayed spawning; phenological plasticity
– [02] challenge > temperature
• limited scope for rapid adaptive response
• assisted migration (facilitated gene flow)
– lake trout: unlikely to increase adaptive responses
– brook trout: potential benefit but needs more testing
• epigenetic mechanisms for rapid adaptive responses?
– controlled breeding crosses:
– testing heritability of thermal tolerance from acclimation
– gene expression in offspring; transgenerational inheritance
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Canada’s aquatic biodiversity: a global treasure
• Canada’s unique
global standing and
biological wealth
• responsibilities for
sustainable
management
– stewardship
– sustainable
resource use
– may require new
approaches
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