Sexual selection 2- Week 3, part 5- Choice for indirect benefits (handicap principle). Flashcards
What will this set of flashcards be about?
What can this type of benefit be explained through?
Another type of indirect benefits females get from being choosy.
Handicap principle.
In what species, do females all prefer the same male after watching them?
Due to this, what will happen (issue)?
Give an example.
Grouse.
Genetic variation among males will be depleted.
Females prefer males with long-tailed- will spread over many generations- reduces variation among males.
Continuation from variation depleting:
So what will a difference in males like conditions now come from?
Give an example of this.
What is the lex paradox?
Environmental- not genetic sources.
Long tails- now apart of design of species- whether or not he lost it in an accident for example.
Genetic variation reduced among males due to female choosiness- why do females females carry on preferring the trait?
To understand why females still remain choosy, what do we have to resort to?
What is the handicap principle best at explaining?
Handicap principle.
Why they stay choosy.
Lions- handicap principle:
What do male lions have to live with?
What does a mane do?
What happens if males get older?
What do males do in the hottest months?
What is there an interaction between?
What is a big mane to them?
Manes in summer.
Insulates males- prevents heat leaving.
Manes get darker- keeps more heat.
Decrease their food intake- big meals causes them to overheat- avoiding getting hot.
Mane colour + temperature.
Handicap- makes it hard to maintain temperature, eat + damages sperm production (testes overheat).
Handicap theory/principle:
What can males traits be?
Who can cope with this successfully?
What cant low quality individuals do?
Read the example- do not need to memorise this bit.
Not only indicators but handicaps.
High quality males.
Fake handicaps- are honest handicaps.
Imagine a male lion that was really struggling to eat, hunt and fight off other males he would not be able to get by with a big bushy mane because it is too much of a burden for him- But the males who can walk around in the hot African sun which causes them to overheat and can still outperform other males and keep themselves well nourished and produce enough sperm to fertilise females much have a quality (underlying aspect) that other males do not have- Therefore females should pay attention to whether or not they have a big bushy mane and there is some evidence that they do.
Handicap theory/principle:
What do females prefer?
What happens if traits are heritable?
What must traits be?
What will eventually happen?
Males with costly traits- shows males can survive despite them- shows quality.
Passed onto offspring.
Costly- or can be mimicked by low quality males- will lose predictive value.
Lose interest in manes.
Give another example of a handicap theory/principle in a species.
Why is it a handicap?
Widowbirds- long tailed males.
Declines their health (takes energy + stops them feeding effectively).
Original handicap principle- Survival handicap (Zahavi handicap):
What is this?
What does this state?
What does a possession of handicap do?
What happens to the males?
What does this run into?
Different version of the handicap.
All males express a handicap trait.
Impairs survival.
All males suffer burden of trait- high quality males cope better.
Lek paradox problem.
Condition dependent handicap:
What does the condition dependent handicap state?
What are high quality males able to do?
What else does the trait tell the female?
All males try to display a trait.
Grow the trait larger (and less affected by costs).
Other things like whether they function well in their environment.
Revealing handicap:
What do all males do?
Give an example.
What does it do?
Why is this honest?
Grow the trait- reveals a hidden quality.
All males can grow long tails- those that lack genes which allow them to be healthy will have bad tails (holey).
Indicates something (e.g. health)
Because there is a correlation between trait + underlying quality.
Continuation from the revealing handicap:
What can these ideas be extended to?
What is honest and cannot be faked?
Behaviours like courtship dances- all males can do it- only high quality males will do it properly.
Handicaps.
Hamilton-Zuk theory:
What does this theory state?
What does it lead to?
What do parasites do?
GO ON THE SLIDES AND GO THROUGH THE ANIMATION ABOUT IT, FROM SLIDE 19 to 22.
Animals evolve resistance to parasites and parasites evolve new ways to exploit hosts.
Arms race- between parasites + their hosts.
Live off you- makes it hard to stay well nourished- affects health.
Continuation from the Hamilton-Zuk theory:
What happens to those who can resist parasites?
Do parasites become better at exploiting hosts?
Who evolve more quickly?
What is this often called?
What does it solve?
Healthier- leave more descendants- resistant gene will spread.
Yes.
Parasites- reproduce quicker (many times a day).
Red queen type of process.
Paradox of the lek- genes vary depending on how things are going in arms race.
Continuation from the Hamilton-Zuk theory:
What does male condition (e.g. ornament size/quality) depend on?
As parasites and hosts co-evolve, what can this maintain?
What has the Hamilton-Zuk theory attracted?
Resistance to parasites currently affecting the population.
Genetic variability among males.
A lot of research attention.
