Mutations, Genetic Drift and Molecular Evolution Flashcards
What are the results of migration?
movement of individuals causing gene flow. reduces genetic variation. can be maladaptive
what are the results of mutation?
increases genetic variation. very rare but is the source of new alleles.
what are the results of genetic drift?
large effect in small population. allele frequencies can go up or down by chance
what is a bottleneck?
sharp reduction in population size, extreme form of genetic drift
what is the founder effect?
when a few individuals start a new population - can lose genetic variation
what is non-random mating?
individuals choose a partner can increase/decrease certain phenotypes
what are the results of inbreeding?
increases frequency of homozygotes, this can lead to deleterious recessive mutation and inbreeding depression
what are the 3 fates of a mutation?
fixation, maintained, eliminated
how are species genetically isolated?
mutations can arise and get fixed in different species
what is genetic divergence?
how long a species has been genetically isolated
what is the molecular clock?
correlation of time and genetic divergence
how can the rate of the molecular clock vary?
attributed to intensity of selection. rates can vary from gene to gene
what is genetic drift?
change of allele frequencies by chance
what can be the result of genetic drift in small populations?
can prevent natural selection
what is Ne?
effective population size
what is effective population size?
size of an idealized population with the same genetic properties as observed in the real population
what are the properties of an idealized population?
- equal reproducing sex ratio
- low variance in family size
- constant population size over generations
why might the effective population size be smaller than the census?
number of males and females reproducing may differ eg a small of males could be reproducing as compared to females
why would there still be an unequal contribution of genetics?
even with a 1:1 sex ratio some individuals will have more offspring than others
when is genetic drift stronger?
- bottleneck is severe
- bottleneck is protracted
why is genetic variation important?
fuel for evolution
what are some types of mutation?
single base pair changes. substitution. point mutation. insertions/deletions - indels. gene duplication. slippage. chromosomal mutations
what are SNPs?
when a single nucleotide base changes to a different base
what is the role of a triplet?
codes for amino acids
what a synonymous mutations?
change in DNA but no change of amino acid. silent.
what are non-synonymous mutations?
causes a change in the amino acid coded for
how is an SNP represented in an alignment?
where there is a different letter
how is an indel mutation represented in an alignment?
by lines
how is a slippage mutation represented in an alignment?
a simple repeating pattern is change
what is a slippage mutation?
in a repetition pattern the polymerase can slip resulting in addition or subtraction`
what are the outcomes of gene duplication?
- retain original function
- become pseudogenes (inactive)
- mutate (gain new function)
what are the different types of chromosomal mutations?
paracentric inversion. reciprocal translocation. fusion. fission.
what do fusion and fission mutations change?
the chromosomal number
what are the different types of polyploidy?
autopolyploidy and allopolyploidy
where does molecular evolution occur?
at the DNA
what is positive selection?
new mutation = advantageous. increases in frequency. substitutes old form
what is negative selection?
disadvantageous mutation is eradicated
what is a neutral mutation?
determined by genetic drift. frequency of mutation rises and falls.
what is the neutral theory?
- majority of mutations have no effect on fitness
- genetic drift not natural selection drives molecular evolution
what are the predictions from neutral theory?
- molecular clock
- rate of substituion
what is the molecular clock?
- genes evolve at a constant rate.
- genetic divergence proportional to divergence time
what are the different hypothesis
- generation time hypothesis
- metabolic rate hypothesis
- DNA repair efficiency hypothesis
what is rate of substitution in neutral theory?
less constrained –> evolve more quickly. more constrained –> more deleterious.
