Stress coping styles (focus on maternal grey seal)

Question 1

Stress – the good and the bad

Answer 1

• Stress vs distress.
• Stress is ‘normal’ (eustress)
• Eustress = motivation! Drives us to do what we need to do
• But, when does stress become distress?
• And does that threshold differ across individuals?

Question 2

Conservation/management:
policies are based on supposition that anthropogenic activities are ‘distressful’ to animals

Answer 2

• But is anthropogenic stress qualitatively or quantitatively different from natural stressors?
• Do individuals differ in ability to cope with stress?

Question 3

example: What stressors do breeding seals have

Answer 3

• Mums fighting and biting others pups
• Losing pups or pups being abandoned
• Male aggression and attempted mating
• Changes in weather patterns – reduced water availability for cooling causes clumping for example

Question 4

example: What anthropogenic stressors do breeding seals have?

Answer 4

-tourists
- hydroelectric dams
- Donna Nook also has an offshore windfarm and a military base

Question 5

Proactive-Reactive axis and Coping Styles

Answer 5

• Coping styles: suites of behavioural and physiological responses that characterise an individual’s reaction to stressors

Proactive – less flexible and less responsive to environmental stimuli

Reactive – more flexible and more responsive to environmental stimuli

Physiological basis……and the link to resting heart rate variability….

Question 6

Coping styles

Answer 6

suites of behavioural and physiological responses that characterise an individual’s reaction to stressors

e.g. a seal study on coping style studied proactive high symp and reactive high parasymp activity
(Koolhaas et al. 1999)

Question 7

Physiological impacts of coping styles: Heart rate

Answer 7

• Heart rate (HR) (in healthy individuals) represents the net interactions between vagal/parasympathetic (which reduces HR) and sympathetic (which increases HR) regulation.
• At rest: vagal regulation dominates.
• Physical activity characterised by increasing sympathetic & decreasing vagal influences.
• HR increase caused by:
  -increased sympathetic activity (mainly)
  
  • decreased parasympathetic (vagal) regulation
  • or from simultaneous changes in both regulatory systems

Question 8

There are individual differences in para/sympathetic balance at rest
differences in resting heart-rate variability (rHRV)

Answer 8

• Parasympathetic (vagal) dominance is characterised by higher HRV.
• resting heart-rate variability (rHRV), i.e while at rest
• reactive individuals have relatively high parasympathetic activity -> higher HRV
• Proactive individuals are dominated by sympathetic activity -> lower HRV

(see review by Borell et al - title in notes)

Question 9

Heart rate variability as indication of coping style

Answer 9

• Pro-active: bold, aggressive, less flexible
  high symp activity lower rHRV
• Reactive: shy, more responsive, more flexible
  high para-symp activity higher rHRV

Question 10

So what are the fitness consequences? in grey seal mothers

Answer 10

• Maternal daily mass loss rate (MDML) to indicate expenditure.
• Pup daily mass gain (PDMG) to indicate within season fitness outcomes.
• No difference in average MDML or PDMG between proactive and reactive mothers.
• Most individuals cope with day-to-day stressors.

Findings: No ‘net’ benefit to being proactive or reactive!

However:
how much individual daily mass loss in females deviated from the population average
* Reactive mothers deviate more from the sample mean for MDML and PDMG than proactive mothers.
* i.e. Reactives vary more in reproductive investment and fitness outcome

conclusion: Reactive individuals attempt phenotype-environment matching with varying success

Question 11

Reactivity: Analytical problem: Reactives don’t ‘have to’ react!

Answer 11

issue with this conclusion- reactive individuals don’t have to express their plasticity – may often act like proactive individuals

Resting HRV (pro-reactivity spectrum) only represents ‘potential to react’.

Question 12

So, how to measure actual reactivity?

Answer 12

see graphs by Koolhaas et al 2010 in notes - visualising stress coping activities in 2 dimensions

Question 13

In summary:
Individual variation in stress-coping styles is likely to have subtle but wide-ranging and profound impacts

Answer 13

on the following:
* Individual success
* Individual interactions with biotic and abiotic environment
* Population demographics
* Ecosystem interactions
* Responses to rapid environmental change (cumulative stressors)
* Differential resilience (e.g. scope for habituation, behavioural plasticity