unit 1 KA7 - evolution Flashcards
what is evolution
evolution is the changes in organisms over generations as a result of genomic variations
what is natural selection
natural selection is the non-random increase in frequency of DNA sequences that increase survival and the non-random reduction in the frequency of deleterious sequences
what are the three types of natural selection
- stabilizing
- directional
- disruptive
describe stabilizing selection
in stabilizing selection, an average phenotype is selected for and extremes of the phenotype range 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
what is horizontal gene transfer
horizontal gene transfer is where genes are transferred between individuals in the same generation
is natural selection more rapid in prokaryotes or eukaryotes
prokaryotes
why is natural selection more rapid in prokaryotes
because prokaryotes can exchange genetic material horizontally, resulting in faster evolutionary change than in organisms that only use vertical transfer
what is vertical gene transfer
this 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
why are isolation barriers important
they prevent gene flow between sub-populations during speciation
which type of barriers lead to allopatric speciation
geographical
which type of isolation barriers lead to sympatric speciation
ecological or behavioural
