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Population Genetics - Coggle Diagram
Population Genetics
Definitions
population genetics
- genetic analysis
- @ population level
gene pool
- sum total of ALL genes
- in pop
- @ particular time
allele frequency
- proportion of particular allele
- in pop
- @ particular time
genome
- all DNA in individual
- entire genetic makeup
Hardy-Weinberg
equation
assumptions
-
-
individuals = DIPLOID
- trait inherited in normal Mendelian way
differential selection NOT
taking place
- 1 genotype more likely to survive than other
-
NO migration
- loss/gain individuals can affect equilibrium
-
-
-
-
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Selection
STABALISING
SELECTION
-
in stable unchanging environment
- selection favour = STATUS QUO
most traits shows normal distribution
- eg height, mass
- most average
- fewer @ extremes
-
-
selection pressures can change over time
- eg with more modern medicine
- low + high weight babies more likely survive
- stabilising selection pressure reduced
-
DIRECTIONAL
SELECTION
-
-
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pesticide resistance in insects+rats
- resistance caused by mutation
- individuals w/ mutation MORE LIKELY to survive
antibiotic resistance in bacteria
ANTIBIOTICS SELECTION PRESSURE
- now over 95% strains of staphylococcus aureus resistant to penicillin
- caused by random mutation:
- produces enzyme breaks down P
- lead change cell wall structure prevent entry P
- associated with EVIRONMENTAL CHANGE
- leads to EVOLUNTIONARY CHANGE over time
POLYMORPHISM
-
-
-
examples
- human blood groups
- eye colour
- banding in snails
-
-
only selection against GENETIC VARIATION
- that is significant
- in terms of evolutionary change
- in population
- over time
-
artificial selection
- particular traits in dog accelerated
- by selective breeding
Species
D: group of individuals of common ancestry normally capable of interbreeding to produce fertile offspring
-
Speciation
D: formation of new species from existing ones
- New species reproductively isolated from other species
occurs in 2 ways
-
DIFFERENT FORMS of DIRECTIONAL SELECTION takes place
- populations become so different
- remain reproductively isolated
allopatric speciation
- initial geographical separation
- then genetic divergence