Unit 1.7 Evolution Flashcards
What is evolution?
The changes in organisms over generations as a result of genomic variations
What is natural selection?
The non-random increase in frequency of DNA sequences that increase the chances of survival of the organism and the non-random reduction in the frequency of deleterious sequences
What is stabilising selection?
where the average phenotype is selected for and extremes of the phenotype range are selected against
What happens in directional selection?
of of the extremes of a phenotype is selected for and the average and opposite extreme phenotype are selected against.
What happens during disruptive selection
Both of the extreme phenotypes are selected for and the average phenotype is selected against.
What is horizontal gene transfer?
Horizontal gene transfer is where genes are transferred between individuals of the same generation.
What is vertical gene transfer?
Where genes are transferred from a parent to offspring as a result of sexual or asexual reproduction
What does horizontal gene transfer allow prokaryotes to do?
Allows them to adapt to their environment more rapidly as evolutionary change occurs at much higher rates than organisms that use exclusively vertical gene transfer
What is speciation?
Speciation is the generation of a new biological species by evolution as a result of isolation, mutation and selection
What is a species?
A group of organisms that is capable of interbreeding to produce fertile offspring, and which does not normally breed with other groups
What role do isolation barriers play in speciation?
Isolation barriers prevent gene flow between sub-populations during speciation
What causes allopatric speciation?
Geographical isolation barriers
What causes sympatric speciation?
Behavioural or ecological isolation barriers
