unit one - evolution Flashcards
what is evolution?
the changes in the organism over generations as a result of genomic variations
what is natural selection?
the non-random increase in the frequency of DNA sequences that increase survival and the non-random reduction in the frequency of deleterious sequences
what is stabilising selection?
an average phenotype is selected fr and extremes of the phenotype range are selected against
what is directional selection?
one extreme of the phenotype range is selected for
what is disruptive selection?
two or more phenotypes are selected for
natural selection
more rapid in prokaryotes
what can prokaryotes do?
prokaryotes can exchange genetic material horizontally, resulting in faster evolutionary change than in organisms that only use vertical transfer
what is horizontal gene transfer?
where genes are transferred between individuals in the same generation
what is vertical gene transfer?
where 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 are isolation barriers?
prevent gene flow between sub-populations during speciation
what ate geographical barriers?
lead to allopatric speciation and behavioural or ecological barriers lead to sympatric speciation
what is a species?
a group of organisms capable of interbreeding and producing fertile offspring, and which does not normally bread with other groups
