Individual variation and migration Dr. Steven Cooke Fish Ecology and Conservation Physiology Lab Carleton University, Ottawa Dr. Kathryn Peiman Lake Ontario Atlantic Salmon Restoration Program Coordinator, OFAH
Individual variation and migration
Dr. Steven Cooke
Fish Ecology and Conservation Physiology Lab
Carleton University, Ottawa
Dr. Kathryn Peiman
Lake Ontario Atlantic Salmon
Restoration Program
Coordinator, OFAH
Why care about individual variation?
Why care about individual variation?
• The stuff of natural selection
• Not due to age or sex
• Individual differences in:• behaviour: bold-shy; aggressive; exploratory -> personality
• physiology: metabolic rate, hormones, immunity
• morphology: feeding; movement -> resource polymorphism
• life history: life span, fecundity, age at maturity -> r vs k selection
• Feedback among categories (cause/effect)
• Genetic vs induced by the environment
• Consistent over time vs flexible
Réale et al 2010 Phil Trans Roy Soc B
Stressors affect variation
Killen et al. 2013 Trends in Ecology and Evolution
Mild stressor (differential sensitivity to stressor)
Severe stressor (single best response)
• what happens during one part of your life affects outcome during another part
• causes and consequences
Carryover effects
• feeding location in the ocean affects ability to migrate/spawn (fitness consequence of carryover effect)
• successful migrators/spawners were offshore, feeding at a lower trophic level (more –ve stable isotopes)
Sockeye salmon (British Columbia)
320 km
40 km
Final (death) Initial (near-end migration) endogenous resources carryover effect
scale, adipose scale, adipose, blood
Do successful migrators/spawners have different initial isotope values than failed migrators/spawners?
2-27 days
Do successful migrators have different initial isotope values than failed migrators?
x
No – but only 6 failures
Do successful spawners have different isotope values than failed spawners?
Males: Are isotope values related to morphology?
4.5
5
5.5
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7
-22.00 -21.00 -20.00 -19.00 -18.00
Bo
dy
dep
th a
t d
eath
(in
ches
)
δC scale initial
Carryover effect: initial values – no
Other effects
• Males: more enriched δC and δN, later capture date (scale, adipose, and blood)
• Carryover effect – assuming early arrival is good
8.50
9.00
9.50
10.00
10.50
11.00
11.50
18-Aug 20-Aug 22-Aug 24-Aug 26-Aug 28-Aug 30-Aug 01-Sep
δN
sca
le in
itia
l
Migration date
Brown trout (Denmark)
• partial migration
• migrant vs resident phenotype
• individual threshold controlled by genetics,
environment
• timing of migration within migratory phenotype
• natural variation contributes to both (body condition,
body size, growth rate)
• manipulated variation (causes of carryover effect)
• chase, food deprivation, temperature increase
• cortisol – hormone released when hypothalamic-
pituitary-interrenal axis activated; mimicking ‘stress
response’Peiman et al. 2017 Oecologia
Natural variation: the migrant vs resident phenotype
Small, poor-condition individuals were migratory
• constrained by low food availability
• empirical evidence mixed
Treatments had no effectMigratory
Resident
0
0.1
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1
0 50 100 150 200 250
Pro
po
rtio
n m
igra
ted
Migration date (Oct 26 = day 1)
control
thermal challenge
chase
food deprivation
cortisol
sham
June 15Oct 26
Stress affects migration date: cortisol treated fish migrated earlier
cortisol
Low growth-rate individuals under stress migrated earlier
Thermal stress
Food deprivation
...unexpected result!
March 16 140
150
160
170
180
190
200
-0.04 0.01 0.06 0.11 0.16
Mig
rati
on
dat
e
Specific growth rate (% day-1)
May 19
White suckers (Ontario)
• tagged fish returns (2018)
• individual consistency across years
• predictors of skip spawning (cortisol -> physiology;
morphology; timing -> behaviour; diet)
What are the
correlates of
migration timing?
Cobourg Creek
Correlates of migration timing: date of migration (behaviour) and physiology
0
50
100
150
200
250
300
350
Bas
elin
e co
rtis
ol (
ng
/ml)
May 30April 17
0
100
200
300
400
500
26-Mar 05-Apr 15-Apr 25-Apr 05-May 15-May 25-May 04-Jun 14-Jun 24-Jun
Cu
mu
lati
ve n
um
ber
Causes:-lake conditions?-contaminants?-physiology?
Consequences:-reproduction?-skip spawning?
Stressors affect variation
Killen et al. 2013 Trends in Ecology and Evolution
-food availability, distribution-density-hypoxia-water velocity-predation risk-temperature-pollutants-dehydration-refuge availability-anthropogenic noise, light
-change the amount of variation present on which natural selection can act-select for certain phenotypes
Example: low food -> high MR lose mass -> bolder -> more predation -> low fitness for high MRExample: repeated temp changes -> flexibility -> optimal conditions -> high fitness for flexibility
BC:
Steven Cooke, Michael Power, David Patterson, Scott Hinch, Matt Casselman, N’QuatquaFirst Nations, St’át’imctechnicians
Denmark:
Steven Cooke, Kim Aarstrup, Kim Birnie-Gauvin, Martin Larsen, Jon Midwood, Alex Wilson
Acknowledgements