Evolution Flashcards
What is evolution?
The changes in organisms over generations as a result of genomic variations.
What is natural selection?
Natural selection is the non-random increase in the frequency of DNA sequences that increase survival and the non-random reduction in the frequency of deleterious sequences.
Name the three types of selection that result in changes in phenotype frequency.
Stabilising, Directional and Disruptive.
Describe stabilising selection.
In stabilising selection, an average phenotype is selected for and extremes of the phenotype are selected against.
Describe directional selection.
In directional selection, one extreme of the phenotype range is selected for.
Describe disruptive selection
In disruptive selection, two or more phenotypes are selected for.
Why is natural selection more rapid in prokaryotes?
Prokaryotes can exchange genetic material horizontally, which results in faster evolutionary change than in organisms that only use vertical transfer.
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 parent to offspring as a result of sexual or asexual reproduction.
What is speciation?
Speciation is the generation of new biological species by evolution as a result of isolation, mutation and selection.
What is a species?
A species is a group of organisms capable of interbreeding and producing fertile offspring, and which does not normally breed with other groups.
What type of speciation results from geographical barriers?
Allopatric specication.
What type of speciation results from behavioural or ecological barriers?
Sympatric speciation.
