3 Influences over evolutionary pathways
- heritable genetic variation
- changes in allele freq (via. ev forces)
- environment
4 evolutionary forces
o Mutation:
o Random genetic drift:
o Gene flow
o Natural selection
principals of mutation
- makes variation,
- changes at a relativly slow rate
- Weak ev force
principals of RGD
- deletes variation (within pop)
- increases diversity b/w pops
- greater change in smaller pop
Principals of gene flow
mixes variation, counteracts drift (inc pop + inc similarity- homogenising)
principals of NS
selects variation, is directional
in RGD what happens when smaller pop
, smaller pop is quicker fixed/lost
what is RGD inversely proportional to
population (1/2Ne)
why did RGD influence early humans
small pops
principals of founder effect
- type of RGD
reduce genetic diversity within population and increase diversity between populations
DIFF b/w migration + gene flow
• Migration = movement, gene flow= movement + mating
explain sex specific differences in RGD
patriocality= women move to men
= moving group less diverse (b/w pop) but more diverse w/in
= holding group more difference b/w + more sim within
evidence that shows patrilocal movement
mitochondrial similar (bc women are moving)
what are the 2 measures of fitness (reproductive success)
- Viability (survival, mortality)
* Fertility
what is the only adaptive force
NS
What does ROChange of NS depend on
- mode of expression (dom/rec)
2. selection strength + initial allele frequ
how does ROC with mode of expression
Dom= multiple genotype express phenotype // speed increase is greater
how does ROC with strength of selection + initial allele freq
- High intial freq= more likely to be fixed
* Stronger selection= quicker selection
what is balancing selection
heterozygote advantage
- • Maintaining selection even if deleterious
what does the CCR5 gene do
- In human genome= mutation
* Variation where no HIV receptor
why isn’t CCR5 gene prevalent in countries its needed
- initial freq too low
how can CCR5 be maladaptive
CCR5 deficiency= increase risk of west nile virus
why is expected replacement rate (aa change) not followed for variation
Rate for silent change is actually higher (deleterious effect of replacement taken into account as a selective pressure)
