Flashcards in Animal Behaviour-Co-operation between related individuals Deck (22)
What is altruism?
A behaviour that is costly to the actor with no benefit
What does the Wynne-Edwards model show?
That a group that co-operates does better than a group of selfish individuals. This is because the selfish individual over exploit a resource and die out whereas altruistic individuals share the resources and do not over exploit them
What is the problem with the Wynne-Edwards model?
Selection acts on individuals and not groups which means if a selfish individual invades an altruistic group, it will do better (basically it is not an ESS)
For co-operation to occur, what factor must outweigh what?
Benefits to the individual must outweigh the cost (e.g a prisoner is going to sell out for a bigger pay off so will need something better if they are to co-operate with other prisoners/criminals)
Why do a lot of animals show co-operation with individuals which are genetically more similar/ more related to them?
Because full fitness can be achieved (passing on all of your genes) through others such as siblings without you having offspring of your own. This is called inclusive fitness or kin selection (e.g Zoe has half of my genes. Each of her children will have half again so a quarter of mine. If she has four children, all of my genes will be passed on)
What is Hamilton's rule?
The more related the actor is to the recipient, the bigger the cost can be
How do we calculate r (relatedness) in Hamilton's rule?
r = Σ (0.5)L
where L is a generation link, sum across all possible pathways
E.g grandparents to an individual = 0.25
This is because r=1(one pathway) (0.5)^2 as it'd across two generations
Can you state the r value for offspring and full sibs, grandchildren and half sibs/nephews/nieces, great-grandchildren and cousins?
0.5= full sibs and offspring
0.25= grandchildren and half sibs, nephews and nieces
0.125= great grandchildren and cousins
So iffor example an actor died in an altruistic act to save some relatives, those genes will increase the gene pool if the acted benefited >2 full sibs or for example >8 cousins
Name a non-animal organism which co-operation increases with relatedness.
Bacteria produce more 'public goods' when around related individuals
There was uncertainty about whether discrimination cannibalism in salamanders was due to kin selection or whether sibs didn't eat eachother due to other direct benefits such as avoidance of pathogens/parasites. What was the outcome of the study?
Showed it was due to kin selection which was evident because the benefits outweighed the costs of being a discriminator. Being a discriminator (choosing not to eat sibs) was not very costly at all
Do animals which co-operate have to be social?
No, red squirrels are not but help eachother thermoregulate by communal nesting in cold weather. The females pair up. They are usually closely related
Prairie dogs call to raise awareness of a predator. (These alarm calls can be different depending on what predator is present). What is the trend of how much females and males call if there are their offspring in the group? If there are offspring of relatives? If there are no related offspring?
If their offspring are in the group, females and males call 50% of the time (so share it equally). The rates are similar if it is offspring of their relatives. If there are no related offspring present, calling still happens but at a reduced rate. Also males tend to call more than females in this last case
Why do prairie dogs still call when there are no related offspring present?
May benefit the individual by warning off the predator
How do animals recognise kin? What was shown about conflict/ antagonistic interactions of sibs raised together and those raised apart?
Odour cues (for those siblings raised apart) and learning familiarity (for those raised together). Much more conflict between sibs raised apart. Also found this in non sibs
What are 'greenbeard' genes? Can you give an example of an insect which use these?
Genes which allow recognition by other individuals and induce co-operative behaviour to one another.
E.g Fire ants attack a queen without a b allele of the GP-9 locus
Why are 'greenbeard' genes not commonly seen?
Very complex. Requires 1 gene to be involved in signal production, recognition and co-operative behaviour. Also very susceptible to cheating/faking
How did monogamous and polyandry birds show how co-operation can be dependent on mating systems?
Birds which are monogamous will produce a set of full sibs which are more likely to co-operate than a polyandrous bird which will produce many more distantly related birds that may not co-operate as much
How do Seychelles' warblers show how mating systems can influence co-operation?
Warblers can breed at a year old but a lack of suitable habitats mean that they often help relatives. Females ar more likely to help closer relatives (through feeding for example). They are also more likely to help if their mother is the dominant female doing the reproducing.
Male warblers do not help as much with offspring as they try to mate many females. Why might helpers still help less related sibs?
Indirect benefits (kin selection) is still beneficial
Breeding by subordinates in meerkats (those that are not dominant) are policed by dominant members (they may kill the offspring or evict the pregnant subordinate). Why?
It is costly for the dominant female if her helpers do not share their resources as much with her. To pay their way back into the group, meerkats allolactate (directly feed the offspring of the dominant female). It is beneficial for both members as pregnant subordinates won't survive alone
Give an example of an extreme co-operative system in eusocial insects?
Bees,wasps. Co-operative care of young, sterile workers and one queen that produces offspring, overlapping generations.