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 survival and the non-random reduction in the frequency of deleterious sequences.
describe the two types of gene transfer
Horizontal gene transfer is where genes are transferred between individuals in the same generation.
Vertical gene transfer is where genes are transferred from parent to offspring as a result of sexual or asexual reproduction.
what are the 3 types of selection?
directional, stabilising and disruptive
what is directional selection?
one extreme of the phenotype range is selected for.
what is stabilising selection?
an average phenotype is selected for and extremes of the phenotype range are selected against.
what is disruptive selection?
two or more phenotypes are selected for.
what is speciation?
formation of new biological species as a result of isolation, mutation or selection
what is a species?
a group of organisms capable of interbreeding and producing fertile offspring, and which does not normally breed with other groups.
what is allopatric speciation?
a new species is formed due to the isolation of a population by a geographical barrier
what is sympatric speciation?
a new species is formed due to the isolation of a population by either a behavioural or ecological barrier
