Lecture 9: Human and animal Flashcards
What is the term for a behaviour where both participants benefit?
What about if only you benefit?
Only they benefit?
No one benefits?
Mutualism
Selfishness
Altruism
Spite
What is the main problem of group living?
Free-riders. For example, a vervet monkey that doesn’t produce its share of alarm share. According to natural selection, free riders should prosper. However, they tend not to, so its the central problem of sociobiology according to Wilson.
Describe the different levels of selection
Selection of groups: Wynne-Edwards did a study on animal dispersion in relation to social behaviour and found that animals modify their behaviour for the good of the group, for example, controlling population density or competition of resources. Therefore a group of animals are more likely to survive and the selfish individuals wouldn’t. This makes theoretical sense.
Selection of individuals: Williams researched adaptation and natural selection and found that selfish individuals take more than their fair share of resources and therefore have increased fitness, over time the whole group would become selfish, conditions aren’t likely to favour the group over the individual.
Selection of genes: Gene are immortal coils whereas bodies are impermanent so a selfish gene is more likely to spread through the group.
Does the selfish gene lead to selfish animals?
No, selfishness and altruism are both widely spread throughout the population. Examples of altruism: Parental care, sharing food, alarm calls and alliances.
Discuss relatedness/gene’s point of view
In diploid species, a gene has a 50% chance of being passed on to an offspring. Animals can act in a certain way to ensure that their genes are passed on or their relatives have a greater chance of survival, e.g. ants. Siblings have 0.5 relatedness, grandchildren 0.25 and cousins 0.125.
What is Hamilton’s rule?
An altruistic gene would spread if rB>C where r=relatedness, B=benefit and C=cost. It would also spread if rB-C>0. Or if B/C>r donor to own offspring/r donor to recipient’s offspring.
What did Hoogland 1983 find about alarm calls in prairie dogs?
They are more likely to produce an alarm call if close relatives are in the social group.
What is Hamilton’s rule?
The idea that it’s more beneficial for brothers to have the same polyandrous female, this is quite common in nature, especially with native hens. It’s more beneficial as selection could favour them however it wouldn’t for unrelated polyandrous couples. Also, there is an increased chance for reproductive success and more chance for their genes to be passed on in comparison to monogamous couples.
Define kin selection
When a (disadvantageous) characteristic spreads through the population, like altruism, because of increased survival of those who are genetically related.
Define relatedness
The probability that individuals share a rare gene that is identical by descent. Kin selection favours these genes over those that aren’t identical by descent.
Describe the cooperation of social insects
They cooperate by having sterile worker castes, however this is a Darwinian problem as it goes against natural selection. This cooperation is a form of eusociality, there’s a reproductive division of labour, cooperative care of young and overlapping generations. The insects repeatedly evolve independently.
Social insects are also called superorganisms, compare these to individual organisms
Individuals: Organs, foraging, reproduction, defence.
Superorganisms: Caste system, workers, queens, soldiers
Individuals: Germ line and soma
Super: Queens and workers
Individuals: Information sharing, functional dependency, immune system
Super: Nervous system, need each other to survive, rejection of invaders.
Describe the lifestyle of hymenopteron
The queen hibernates in the winter, then she forages, the she starts nest initiation, she then produces workers and develops the colony, mating then occurs, the males die and the queen is left to hibernate again.
Describe how you work out relatedness
Describe the relatedness/haplodiploidy of hymenoptera
Make a flow chart and follow the lines, each split, divides the relatedness by half (except for haplodiploids).
Sisters are related to each other by 0.75 but are related to their brothers 0.25. They are related to their daughters 0.5 and nephews 0.375.
How did eusociality evolve?
Because natural selection favours the sister’s involvement in her mother’s reproduction rather than her own as sisters are more related to each other than daughters. Perhaps haplodiploids have a genetic predisposition for eusociality, however this is too simplistic. Perhaps because of ecological constraints, for example, so they could defend their young from parasites by building a nest.
