9.4 types of selection Flashcards
what is selection?
process by which organisms that are better adapted to their environment tend to breed & survive
what does a polygene characteristic mean?
charactistic is controlled by 1+ gene
when does directional selection occur?
during environmental changes
what individuals do directional selection select for?
phenotype more suited to environmental pressure
towards which direction will the distribution curve shift towards when a specific allele is selected for?
towards their direction
describe the environment when stabilising selection occurs.
stable & unchanging
which individuals are selected against in stabilising selection?
both extremes
how will the curve change during stabilising selection?
narrowing of curve
give an example of anatomical adaptation.
short ears & thick fur in arctic foxes
give an example of physiological adaptation.
kangaroos oxidise fat to produce water in dry desert
what are physiological adaptations related to?
chemical reactions
give an example of behavioural adaptation.
migration
what is the founder effect?
reduction in genetic variation
when a small preset of a large population is used to establish a new colony
what is a genetic drift?
variation in genotypes in a small population because of the chance disappearance of particular genes
(because individuals die / do not reproduce)
what is genetic bottleneck?
extreme example of genetic drift (when size of population is severely reduced)
-> population is decimated & on,he small, random assortment of survivors remain
