Topic 7: Evolution Flashcards
What is the definition of natural selection?
Natural selection is the:
non-random INCREASE in frequency of DNA sequences that increase survival
ALSO
non-random REDUCTION in frequency of deleterious sequences
Changes in phenotype frequency arise as a result of what?
Stabilising, directional and disruptive selection
What happens in stabilising selection?
An average phenotype is selected for and extremes of the phenotype range are selected against
What happens to the mean phenotype over generations in stabilising selection?
The mean phenotype is on changed over generations
What happens in directional selection?
One extreme of the phenotype ranges selected for
What happens to the mean phenotype in directional selection?
The mean phenotype moves towards an extreme
What happens in disruptive selection?
Two or more phenotypes are selected for
What happens to the phenotypes in disruptive selection?
Individuals close to the mean phenotype are selected against, causing the population to have two distinct phenotypes and fewer with the mean
Natural selection is more rapid in which organism?
Prokaryotes
How can genes be transferred?
Horizontally or vertically
What is horizontal gene transfer?
Horizontal gene transfer is where genes are transferred between individuals in the same generation
What is vertical gene transfer?
Vertical gene transfer is where genes are transferred from parents to offspring as a result of sexual or asexual reproduction
How do prokaryotes have faster evolutionary change?
Prokaryotes can exchange genetic material horizontally resulting in faster evolutionary change than organisms that only use vertical transfer
