Evolution Of Populations Flashcards
What adapts and evolves
Individuals do not adapt or evolve
POPULATIONS adapt and evolve
Micro evolution
Change in allele frequencies in a population
Requires inherited traits, genetic variability
Sources of genetic variation
Gene mutations
Chromosomal mutations
Sexual reproduction
Rapid reproduction
Gene mutations
Only gamete mutations passed on Point mutations- sickle Maybe silent- no change amino acid Maybe neutral no change in pheno (introns or amino acid change no difference) Can be beneficial or deadly
Chromosomal mutations
Change loci
Duplication of genes (cross over error, adds to available genes)
Transposable elements
Large changes harmful but few extra copies can be good to take on new function
Transposable elements
Transposons move
Retrotransposons leave a copy at original position and move= more copies or genes
Could be good to have extra for new functions
Sexual reproduction genetic variation
Crossing over
Independent assortment
Fertilization, 2^n possible gamete chromosome combos
Hardy Weinberg principle
Detects microevolution of particular genes
Determines what gene frequencies would be if no evolution (null hypothesis)
Compare null with data
Null supported- no evolution
Not supported- evolution
Population
All individuals of a species in an area that reproduce together
Gene pool
All copies of every allele at every locus in all individuals of a population
Fixed gene
All alleles of a gene are the same in the gene pool
Frequency 100%
Genotype percentage of population formula
Individuals/ total population=%
Dominant allele frequency
homozygous dominant x2 + # heterozygous
Recessive allele frequency
homozygous recessive x2 + # heterozygous
P
Frequency or dominant
Q
Frequency of recessive
Formulas for frequency
Hardy Weinberg formulas
P+Q= 1
P^2 + 2pq + q^2 = 1
Null hypothesis no evolution
F of alleles remains constant from gen to gen
Mating completely random and all allele combinations must survive equally well
So use multiplication rule of probability to predict % of genotypes of offspring
P^2
Frequency of homo dom
Q^2
Frequency or homo recessive
2pq
Frequency or hetero
Conditions for hardy Weinberg equilibrium
No mutations Random mating No natural selection Extremely large population No gene flow into or out of population (Immigration in, emigration out)
Causes of evolution
Natural selection
Genetic drift
Chance events cause random change in allele frequency
Small population maximizes effects (may decrease genetic variation)
Founder effect
New population states by few individuals
Fewer alleles, different % than main population
Bottle neck effect
Population nearly wiped out
Few reminding individuals have limited gene pool
Population may recover but genetic variation only recovers very slowly without immigration
Bottle neck effect example
Florida panther separate subspecies for 100 yrs
Population dropped under 50
Inbreeding Increased incidence of disorders
Founder effect example
Bighorn sheep
Island population
20 founders to 650
Genetic variation significantly less
Gene flow
Alleles move into or out of population Individuals move ( Immigration Emigration) Gamete move Increases genetic diversity Makes populations more similar Prevents speciation
