L2 - Natural Selection & Biological Fitness Flashcards
What is evolution (simple)?
Descent with modification
What is evolution (complex)?
Changes in the properties of populations that transcend the lifetime of a single individual
What are the stages of natural selection?
There is variation in traits e.g. some beetles are green, and some are brown. There is differential reproduction e.g. green beetles get eaten by birds and survive to reproduce less often than brown beetles do. There is heredity e.g. the surviving brown beetles have brown bay beetles because this trait has a genetic basis. End result - if this process continues, eventually, all individuals in the population will be brown.
What is biological fitness?
A genotype’s fitness includes its ability to survive, find a mate, produce offspring - ultimately leave its genes in the next generation
What is Kin selection?
Evolutionary strategy that favours the reproductive success of an organism’s relatives.
What does Hamilton’s theory of kin selection predict?
It predicts that altruistic behaviours will be favoured by selection if the costs of performing the behaviour are less than the benefits to the receiver whilst considering the coefficient of relatedness between actor and recipient
Hamilton’s theory of kin selection equation?
c<b*r
c = fitness cost to the actor
b = the sum benefits to recipients affected by the behaviour
r = the average coefficient of relatedness between the actor and recipients
What does a genotype’s fitness include?
Its ability to survive, find a mate, produce offsprings - and ultimately leave its genes in the next generation
What is the haplo-diploid system - cooperative behaviour between related individuals
There are no sex chromosomes in most species of bees and ants. Females develop from fertilised eggs and are thus diploid. Males develop from unfertilised eggs and are haploid ; they have no fathers.
What is the naturalistic fallacy?
Idea that what is found in nature is good
How does infanticide occur?
One male units (polygyny : single male monopolises multiple females). Males compete for access to females. Infanticide following takeovers
On what level does natural selection act on?
Individuals and/or genes
What decreases the chance of encountering a threat?
Grouping this was theorised by William Hamilton and observed in sheep
What is the selfish herd hypothesis?
Observed in sheep where they protect themselves by trying to get into the centre when trying to avoid a predator. Individuals at the centre have the highest chance of survival
Define altruism?
Giving up something yourself for the sake of someone else
What did Hamilton say about Altruism?
You should see altruism only occur if cost of giving is less than benefit whilst considering the relatedness between individuals
What does migration in monkeys cause?
Spread of genotypic diversity
What does multilevel selection consider?
Social environment, it is not group selection
What is multilevel selection not for?
The good of the group or species except social insects and beas
How much DNA is shared in drone bees?
75% related, inclusive fitness not group selection, maximising genes passed on
What is an example or infanticide and why does it occur?
In male baboons, removal of offspring so that the offsprings mother is available to be a mate. This is a reproductive strategy allowing male to sire offspring passing on its genes. These males have more genes in the next generation. This occurs due to a takeover where a male from a all male unit takes over a male from a one male unit. As a result they may kill offspring from the prior male.
What is a counter strategy to infanticide due to male takeover?
Fake sexual swellings which falsely indicate fertility
