L3-4 Flashcards
What is the effect on variation for mutation, gene flow, drift, natural selection
mut: increases
gf: increase
drift: decrease
ns: up/down
is mutation a weak or strong evolutionary force and why
weak
- Mutation alone can change frequencies but only over long period of time
what is RGD
- Allele frequ. change due to chance – Sampling variation
what does RGD do to 2 populations, compared to gene flow
make them genetically different , gf counteracts and homogenises
explain the relationship of RGD between effect magnitude and population number
- Magnitude is inversely proportional to N (Size of pop important)
o Low pop= larger effect of RGD
o High pop= less effect of RGD
what is the process of natural selection
• The change in allele frequency within a population from one generation to the next, resulting from differences in the ability of different phenotype to produce surviving offspring.
what is the measure of natural selction
• Fitness (reproductive success): viability (survival, mortality) and fertility
what is the result of natural selection
• Genotypes with higher fitness increase in frequency (changes in allele frequency)
components for natural selection to occur
variation
heritablity
compeittion
differential reproduction
heritability formula
- Total variation= f (genes, environment)
* H= VarianceG /VarianceG+VarianceE (proportion of the total variance that is due to genetic variation)
what is directional change
phenotypic characters shifts in one direction
what is the speed of directional change influenced by
- Starting allele freq prior to selective pressure (low= slower than higher)
- Expression (recessive= longer to increase in pop
what is stabilising selection
- Outlier phenotypes= disadvantagous // favoured to centre middle
- If higher fitness is centre= removal of outliers or extremes
what is balancing selection and what does it promote
Heterozygote advantage
• Promoting polymorphism
what does deviation of HW mean
evolutionary forces at play
formula for allele freq (from pop number)
[# heterozygotes+ 2(# homozygotes)]/2n
Allele Frequency > (Expected) Genotype Frequency
- Find allele freq via [# heterozygotes+ 2(# homozygotes)]/2n
- Work out genotypes via: p2=, q2=, 2pq=
- (Working out P = 1-q)
(Expected) Genotype Frequency > # Individuals
- Genotype frequency (i.e. p2) x n
Chi- Square Test:
- χ2 = Σ(observed-expected)2/expected
most suitable environment for respiratory pathogens
high pop density
most suitable environment for fecal-oral pathogens
contaminated water
most suitable environment for vector pathogens
temp, conditions suitable for vector
what factors have influenced disease over time in humans
agriculture trade migration sanitation treatment
decribe HG vs agriculture in predisposition to disease
• Mobile groups (HGs) = low population density, no domesticated animals (limited vector contact/ animal-human transmission) or likely contaminate water sources
- Increased population density (build-up of waste), particular farming methods (stagnant water), vectors (rodents, mosquitoes)
- Increased pathogen exposure ‘crowd diseases’, transmission from animal reservoirs, vectors
Did the onset of agriculture increase the effect of Malaria?
- Some aspects of agriculture likely to have increased vector reservoirs also coinciding with increased human (host) populations in settled areas
- More vector= more likelihood of transmission + increase population= accelerated malaria
- Although already existed before onset of agricultural practices
ways disease can impact darwinian fitness
- Survival
• Death inutero= (zero fitness for fetus? Parents)
• Death before reproductive maturity or in reproductive years - Growth & Development
• Competition for resources within body
• Destruction of parts of body or diminished capacity to use resources effectively - Mating
• Stigma
• Reduced attractiveness or behaviourally unappealing
• Social shunning & isolation - Child Rearing
• Infertility
• Impairment of capacity to raise children successfully
