Individual variation: Personality 2 Flashcards
Examples of laboratory studies on personality in non-human species
Personality in beadlet anenome
(Mark Briffa, Julie Greenaway)
bold/shy study of anenomes – each individual squirted with water and timed until they reopened - variation was observed
Plasticity and consistency study of hermit crabs
(Mark Briffa et al.)
crabs were turned upside down on hand and timed to see how long they take tore-emerge from their shell
Field studies of personality?
Field studies are much harder to conduct, many confounding factors and little evidence of efficacy at present
e.g. semi-wild studies conducted on tits (birds) and how they responded to changes in appearance of their nesting boxes
the introduction of novel items to bird boxes tested bold/shy behaviour
Field study: Wild grey seals: male activity budget
same patterns were observed in different generations
Some were more alert than others but this did not appear to impact mating success
Field study: pup-check behaviour in wild grey seals in an undisturbed situation
repeatability in CID observed same patterns seen in different years and between different colonies
Field study: pup-check behaviour in disturbed situation
Vigilance behaviour when disturbed: Experimental test:– Introducing ‘Rocky’ the cam bot
-The vehicle (‘Rocky’) was parked next to individual females for 5 mins to allow them to acclimatize
-Then the vehicle plays a wolf call then 2 mins silence then wolf call 2mins and wolf call 2mins wait
( this is a natural novel stimulus as there are no wolves in UK)
Onboard camera was used to record mother pup check behaviour
CID observed between diff females - some more alert than others
the test was repeated 2 times, once in early lactation and once late in lactation (near weaning age)
Evolutionary and ecological consequences of personalities
– Constraint or adaptive? E.g. individual with lower basal metabolism->less active
- personality may limit plasticity? CID suggests limitations
- An evolutionary constraint? based on morphology etc.
- Life history trade-offs? Behaviour beneficial in some life stages and not others
- Fitness consequences of personality?
- Personality-environment interactions?
» (see level 3 ATEEB)
Are personalities adaptive or constraining?
– Why not just respond optimally to each circumstance?
– Why ‘tie’ different behavioural traits together? E.g. Bold + aggressive/Shy + less aggressive
- From an adaptive perspective, the evolution of animal personalities is still a mystery, a more flexible structure of behaviour should provide a selective advantage.
- Many researchers view personalities as resulting from constraints imposed by the architecture of behaviour rather than as adaptive.
- Can personality affect survival & success?
Behavioural ‘spill-over’ example
Example: Pre-copulatory sexual cannibalism in spiders
(Arnqvist & Henriksson 1997, Johnson & Sih 2005)
- female spiders benefit from being aggressive in early life – they catch more food, grow bigger and therefore have higher fecundity (produce more eggs) but that hyper aggressiveness carries over into the reproductive phase of their life often resulting in them cannibalising potential mates before their eggs can be fertilised - which seems maladaptive
*female spiders differ in cannibalistic tendency
* eat potential mates before mating, risk unfertilized clutches.
– hypothesis: behavioural spillovers across contexts: a behaviour from an earlier stage of life history/suited to a different situation being expressed when it is not beneficial – Suggests limited plasticity
Are personalities adaptive: Stickleback study (Bell 2005)
Methods: Fish taken from 2 geographically adjacent populations:
1 – Navarro River- subject to predation. 2 – Putah Creek, fewer predators (Fish under high and low predation)
Behavioural assays:
– (1) Boldness under risk
– (2) Aggression
Tested facing another fish through a glass jar (similar to fighting fish study) observing if they approached or attempted to attack another fish
Predictions:
* constraint hypothesis: +ve correlation across populations & across individuals within populations
* adaptive hypothesis = may not see same correlations between behaviours in different population
Results:
* Navarro River; +ve correlation - subject to predation. (black dot)
* Putah Creek: no correlation - fewer predators (white dot)
Suggesting links between boldness and aggression are adaptive.
Are personalities adaptive? Wild study example: bighorn ewes (Ovis canadensis) (Reale et al. 2000)
utilised a docility index in response to handling
Individuals are captured yearly for weighing, monitoring and attaching biotelemetry devices.
Reale et al. Got handlers to fill in a questionnaire after each individual describing how they responded to handling from this docility was estimated for each individual each year (individual tags identify them)
Outcome:
– indices at repeated captures were consistent (CIDs)
– not affected by reproductive status (new mothers or experienced etc.), age or body mass
– Bold ewes reproduced earlier & had higher weaning success– i.e.: related to fitness differences
first offspring raised: bolder individuals reproduce earlier
weaning success: bolder individuals more successful
If this is true why aren’t all ewes bold to be successful mothers?
Why are population variations in personality maintained?
Cost and benefits of different personality types
Shy vs. Bold? Cost-benefit trade-offs
Example: Fish boldness in farmed Roach and how this related to the probability of being predated
- Behavioural types differ in cost-benefit trade-off?
- Example: Hulthén. et al. (2017)– Roach (Rutilus rutilus)– Predator: cormorants (Phalacrocorax carbo).
- Bolder fish more susceptible to cormorant predation cf. shy fish
- (PIT tag experiment)
‘Personalities’ as different adaptive solutions to life’s challenges?
traditional view was that there was one phenotypic fitness peak we now believe that there are usually multiple peaks of fitness interacting
But, how do ‘personalities’ develop?
Nature vs. Nurture? (Groothius & Trillmich 2011)
- Is personality heritable or defined by life phases?
- Not enough studies following full lifetimes
Example of full lifetime study: inbred mice
Environmental influences emerging during development contribute to individual differences in structural brain plasticity and behaviour, even among genetically identical animals
Example: Freund et al. 2013– 40 inbred mice
each mouse had a pit tag and pit loggers were located around the inclosure to record where the mice went and how often they roamed.
Found that more exploratory individuals became more exploratory as they aged. Greater neurogenesis seen in exploratory individuals suggesting higher plasticity.
Thinking more broadly…
Personalities (or more generally inter-individual variation)
Personalities (or more generally inter-individual variation) likely impacts:
– Movement and space use
– Habitat selection
– Mate choice and reproductive success
– Physiological differences (e.g. metabolic rate)
– Stress response
– Disease/Parasite exposure & susceptibility
* Importance in conservation & management (Merrick & Koprowski 2017)
– Detection probability and capture success
– Harvest success and population implications
– Effects of anthropogenic disturbance
– Wildlife control and invasive species
– Reintroduction, translocation, and captivity .
(More thinking about IIV in level 3 ‘ATEEB)
