types of natural selection Flashcards
draw a normal distribution curve
from notes
when is continuous data received ?
when the data is polygenic (many genes) and is influenced by the environment
when do we get categoric data ?
when it is controlled by only 1 gene
what is stabilising selection ?
selection against both extremes
draw the stabilising slection graph/ curve
from notes
what happens to the mode in a stabilising selection ?
mode stays the same
in what kind of environment does stabilising selection occur ?
in an unchanging environment
what kind of organisms are favoured and which are not ?
very high and very low are not favoured because they are least likely to survive
- we get more of the average organism ( the mode ) as modal traits have the selective advantage
what happens to the standard deviation in a stabilising selection ?
the standard deviation is smaller as individuals with the extreme trait decrease
what is meant by a directional selection ?
selection against an extreme
what happens to the mode in a directional selection ?
the mode changes direction
in what kind of environment does directional selection occur in ?
occurs in a changing environment
i.e when there is competition
what happens in directional selection ?
one of the extremes is favoured as it has the selective advantage
- usually the one with the bigger peak
draw the graph for directional selection
from notes
