molecular evolution Flashcards
define natural selection
the effects of a Wide range of factors on the frequency of heritable changes in a species
what is the main source of heritable changes in a species
genetic variation
what are genetic variants affected by? (4)
selection
mutation
migration
genetic drift
describe selection
confer a POSITIVE change
e.g. resistance to disease
describe mutation
where variation in a genome arises
frequency depends on selection
describe migration
movement of people from a different population resulting in new pools of variants
aka as admixture
describe genetic drift
how the frequency of a variant changes in a population due to chance
what is sequence conservation
DNA sequence needed for survival of an organism doesn’t show much evidence of variation
- most variants selected against and have strong deleterious effects
explain the sequence conservation in genes
high conservation = coding regions
intermediate conservation = promoter, 5’ UTR, 3’ UTR., terminator
low = introns, 3rd base codons, terminator
use of sequence conservation?
- cross species comparison for evolutionary profile
- cross species allows to identify important regions of gene and its protein
- can concentrate on areas that appear important in novel genes
importance of phylogenetic?
observe DNA sequences
reconstruct evolutionary histories
learn about evolutionary processes
develop better evolutionary models
what are phylogenetic trees?
to illustrate relatedness of diff species/strains
distance between two entities = similarity
link between infectious disease and phylogenetics
HIV contaminated Polio vaccine in africa
was disproven to be linked to chimpanzee and SARS
