Levels of selection
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What are the 6 levels of selection?
• Genes • Traits - can evolve independently of genes • Individuals • Population - regulation of numbers • Species - rates of speciation • Higher taxonomic levels - more successful lineages predominate
What did Wayne Edwards suggest with regards to animal dispersion and social behaviour?
• Populations regulate their size in order to survive lean periods • e.g spontaneous abortion in high density populations of rodents
What are epidietic displays?
Ideas that displays such as the dawn chorus can assess the population size
How did Maynard-Smith counter the views of Wayne Edwards?
• believed model was not evolutionarily stable - populations regulated by increase/decrease in births/deaths in response to lack of resources
Describe the idea of “group selection”
The idea that the fittest groups cooperate and out-compete more selfish groups
What is function & effect?
Idea that why a trait has been evolved/maintained by evolution must be explained
What explanation is there for the ‘Bruce effect’ in rodents?
With arrival of new males infanticide is very common so spontaneous abortion avoids unnecessary reproductive effort
Define indirect fitness
Reproductive success of your relatives and the continuation of your genes
What is Hamilton’s rule?
That an organism will be ‘altruistic’ if the benefit outweighs the cost when adjusted by the coefficient of relatedness (r)
How does the Hamilton’s rule explain behaviour in social insects?
Social insects are diplo-haploid (males are haploid) and therefore relatedness between sisters is higher than between offspring
What usually defines altruism between non-relatives?
It is reciprocal
What is NeoDarwinism?
Seeing evolution as mostly changes in gene frequency
Define kinship selection
Idea that worker ants provide more of a benefit down to reproductive members of the colony, developed by Darwin
What is Hamilton’s equation for kinship selection?
-c (deductive fitness) + br (benefit to recipient) > 0 Then behaviour is favoured by natural selection
What are the 4 mechanisms of inclusive fitness
mutual benefit: c<0 b>0 selfishness: c<0 b<0 altruism: c>0 b>0 spite: c>0 b<0
What is relatedness?
Measures genetic similarity relative to the population average
What is the greenbeard effect?
• If a single gene encodes a detectable marker and helpfullness to the marker then the gene is more likely to be passed on
What are the 3 mechanisms for kin selection?
• Limited dispersal - if relatives are in close area, positive acts are more likely to be advantageous to relatives • Kin selection - ability to identify relatives • Greenbeard effect