Contest-Combat Competition (intro + risks and benefits)- Week 2, part 2. Flashcards
What are the different types of intrasexual competition mechanisms?
1) Contest competition (aka combat)- males fight or have contests- decides who will have access to females.
2) Alternative strategies- used to avoid combat.
3) Scramble competition.
4) Endurance rivalry.
5) Post-compulatory mechanisms.
Contest competition:
What do males engage in?
Why do they do this?
What does selection favour?
Give 4 examples.
Essentially, does it favour things which will make them successful?
Direct combat or other physical contests.
To gain access to females.
Favours large size, strength, weaponry (e.g. horns), agility (fighting effectively) etc.
Yes.
What does contest competition lead to?
Give an example.
How does sexual selection work?
Evolution of differences in males and females.
Example- Seal- males are huge, females are small- need it to fight for females- bigger = more successful.
Strongest- wins contest- mates with female- leaves more descendants- next generation will be like him, bigger and stronger.
As being bigger helps males gain access to multiple females, what does this lead to?
Evolution of difference in size between males and females- Size of difference reflects the intensity of competition over evolutionary time.
What is an important determinant of success in fights?
Is this how weaponry evolves?
Size of weaponry.
Yes- those with largest weapons are more successful and leave more descendants- passed through generations.
What is weaponry an example of?
Why is it called convergent evolution?
Convergent evolution.
Because different species converged on the same solution.
Do males with no weaponry still fight?
What do baboons have?
What do those who are highly ranked do?
Why do the males compete with each other?
Yes.
Dominance hierarchy.
Highly ranked- can boss others around + mate with more females (leave more descendants).
For position in the hierarchy.
What is one interesting things that happens to baboons?
What happens when females cannot conceive?
Competition becomes intense when females are fertile and can conceive offspring.
There is no fighting.
Can fighting get switched on and off?
Do some animals die after fighting?
Yes- switched on in breeding season- off when there is not.
Yes- animals do not hold back for the good of the species.
In terms of proximate causations, what is turning this behaviour on and off?
Hormones.
Risks and benefits:
Why do males take extreme risks that could result in their deaths?
Explain.
Because of effective polygyny.
Males have more to win when competing with other males and more to lose (not successful= do not reproduce).
Is reproductive success a major component of fitness?
When are males more willing to take extreme risks?
Have males evolved to take extreme risks in order to be successful?
Do males also compete for stuff that will get them access to females like territory?
Yes.
When the variation in male reproductive success is greater than females- they compete for stuff that will get them access to females like territory.
Yes.
Yes.
Definition of risk:
In behavioural ecology, what does risk mean?
Why is engaging in combat risky?
What do animals vary in?
Explain.
Variance in outcomes.
Outcomes are highly variable- You could win and leave lots of descendants or die.
Risk-sensitivity- some are do not mind taking risks (risk-prone) and some do not want to (risk-averse).
Continuation with definition of risk:
Give an example of an animal which is really variable.
Has this led to extreme sexual dimorphism in elephant seals?
Elephant seals- Males fight a lot and females don’t and just give birth.
Yes.
What is there no difference between (from the POV of evolution)?
What can still happen even if they end up with the tendency to fight (inherit it)?
Leaving no offspring (not fighting) and being dead- Both don’t leave descendants.
They can still lose- most males lose.
