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 survival and the non-random reduction in the frequency of deleterious sequences
what are the types of selection
stabilising, directional, disruptive
what happens in stabilising selection
an average phenotype is selected for and extremes of the phenotype range are selected against
what happens in directional selection
one extreme of the phenotype range is selected for
what happens in disruptive selection
two or more phenotypes are selected for
what is horizontal gene transfer
where genes are transferred between individuals of the same generation
in what group of organisms is natural selection more rapid
prokaryotes
what allows prokaryotes to achieve faster evolutionary change
they can exchange genetic material horizontally
what is vertical gene transfer
genes are transferred from parent to offspring as a result of sexual or asexual reproduction
what is speciation
the generation of new biological species by evolution (as a result of isolation, mutation and selection)
what is a species
a group of organisms capable of interbreeding and producing fertile offspring, and which does not usually breed with other groups
what is the importance of isolation barriers
preventing gene flow between sub-populations during speciation
what are the types of barriers that result in allopatric speciation
geographical
what are the types of barriers that result in sympatric speciation
behavioural, ecological
