Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
12 Cards in this Set
- Front
- Back
|
Sources of physical conflict |
- Defend access to resources - mate or food territory e.g red deer stags - Determine social rank - Confused ownership by intruder - Most likely and most intense when resources are defendable - Polygynyous systems where intense sexual selection on males for access to females favours weaponry . |
|
|
Why are lethal fights rare? How does Hawk-Dove model explain this? |
Hawk-dove model - be a hawk (fight) or be a dove (display rather than fight) ESS is a mixture when average payoffs are equal, as each does best when rare due to frequency-dependent selection. - If all doves, mutant hawk soon spread as alway beats doves (+50). - If all hawks, mutant dove soon spread as retreats and gains greater payoff, while hawks have 50% chance of injury each fight. - Higher cost of injury, lower ESS frequency of hawks will be. |
|
|
Fatal fights do occur - limitations of model (but this is heuristic, illustrates general evolutionary principle of ESS and freq-dep) (simplified verison of fighting and display) |
More than two strategies, vary with strength Encounters non-random Displays involve assessment of fighting potential, individuals will vary their tactics from contest to contest. |
|
|
So when is hawk a ESS? |
When current resource value is greater than cost of fighting Risk more if current resource value greater than future resource value. |
|
|
In which taxa are lethal fights common? |
- Short-lived arthropods e.g fig wasp males fight for a female in the same fruit using large mandibles. - 10% of musk ox males die from fights for females. |
|
|
Cant 2006 - what increases probability of subordinates fighting with dominant paper wasps? |
- Value of nest increases - Reproductive share of subordinate is lower (less to gain from becoming dominant) |
|
|
3 factors determining outcome of fights |
1. Asymmetry in RHP - best fighter wins, why ownership in first place. 2. Payoff asymmetry -- if current resource value greater for one, prepared to fight harder e.g subordinate paper wasps more likely to fight if reproductive share was lower. 3. Convention - follow simple rule of thumb to settle disputes early and low cost. |
|
|
Sequential Assessment Model - indirectly assess RHP through signals |
Contests process of information gathering with each 'bout' of fight to gain sample of relative strength; one certainty high enough, giving-up point. Longer duration if more closely matched in RHP as takes longer to assess the strongest. |
|
|
Sequential assessment in red deer stags (Clutton-Brock 1979) |
Assess fighting ability by roaring and parallel walks, only escalating to physical conflict when equally matched. Lethal fighting rare, when very costly when it occurs (20% permanently injured) Roaring good signal of fighting ability as indicates size and physical condition |
|
|
Davies (1978) - assessment in common toads using croak pitch |
Males more likely to try displace males when high-pitched croaks were played, and less likely when low-pitched croaks played (indicates larger size and fighting ability) Not only assessment though as still fewer attacks at large frogs - strength of defenders kick also important |
|
|
What keeps signals of strength honest? |
1. Handicap principle - displaying individuals must be high quality as they can afford to display the handicap. 2. Socially-imposed costs by faking |
|
|
Tibbets (2004) - paper wasp facial marking manipulation |
- Those with manipulated markings above their actual status were subject to 6x more aggregation than unmanipulated controls. - Suggests social cost of cheating that maintains honesty of badge. |
