Population Genetics Flashcards
Population genetics
Genetic structure of a population
Gene pool
Members of a species can interbreed and produce fertile offspring, all the alleles of a population from which the next generation could be drawn
Hardy Weinberg principle is used to describe ____________
Non-evolving populations
Deviations from hardy Weinberg result in __________
Evolution
5 assumptions of hardy Weinberg
1 large population 2 no migration 3 no net mutations 4 random mating 5 no natural selection
The gene pool of a non revolving population remains _____________ over multiple generations
Constant
The hardy Weinberg equation
1.0 = p^2 + 2pq + q^2
P^2 is AA
2pq is Aa
q^2 is aa
Why is genetic variation important
Potential for change in genetic structure
How does genetic structure change?
Changes in allele frequencies and/or genotype frequencies through time
Mutation
Spontaneous change in DNA
Migration
Individuals move into population
Natural selection
Certain genotype produce more offspring
Genetic drift
Genetic change by chance alone
Non random mating
Mating combines alleles into genotypes
Causes of micro evolution
Mutation, gene flow, genetic drift, non random mating, natural selection
What is the only source of new alleles in a species
Mutation
Factors that cause genetic drift
Bottleneck event, founder event
Bottleneck effect
A drastic reduction in population, reduced genetic variation, smaller population may not be able to adapt to new selection pressures
Founder effect
Occurs when a new colony is started by a few members of the original population, reduced genetic variation, may lead to speciation
Stabilizing selection
Favors intermediate over extreme phenotypes, maintains the average
Directional selection
Selects for one of the extremes
Disruptive selection
Selects against the mean for both extremes
Genetic recombination
Source of most genetic differences between individuals in a population
Co evolution
Often occurs between parasite and host and flowers and their pollinators
mtDNA
Often used in systematic; in enteral, no recombination, uniparental inheritance
Microsatellites
Tandem repeats, genotyping and population structure
Single nucleotide polymorphisms (SNPs)
Single base pair changes
cpDNA
Often used in systematic; in general, no recombination, uniparental inheritance
Transposable elements
Mobile DNA elements dispersed throughout the genome
Allozymes
Variations of proteins; population structure
RAPDs
Short segments of arbitrary sequences: genotyping
RFLPs
Variants in DNA exposed by cutting with restriction enzymes; genotyping, population structure
AFLPs
After digest with restriction enzymes, a subset of DNA fragments are selected for PCR amplification; genotyping
Molecular markers
A sequence of DNA or protein that can be screened to reveal key attributes of its state or composition and thus used to reveal genetic variation
Four major molecular techniques are commonly applied to reveal genetic variation
Polymerase chain reaction (pcr) electrophoresis, hybridization and DNA sequencing
Nuclear DNA
Diploid; bilateral inherited; recombination occur; can be viewed as a huge ocean of largely nongenic DNA with some tens of thousands of genes and gene clusters scattered around like small islands
Chloroplast DNA
Haploid; usually maternally inherited in angiosperms and paternally inherited in gymnosperms; is packed with genes and thus resembles the streamlined configuration of its Cyanobacteria ancestral genome
Mitochondrial DNA
Haploid; typically maternally inherited
Polymerase chain reaction (PCR)
A procedure used to amplify a specific sequence of DNA
Electrophoresis
Technique for separating the components of a mixture of charged molecules in an electric field within a gel or other support
Sequencing
The process of determining the order of the nucleotide bases along a DNA strand
Codominant marker
A marker in which both alleles are expressed, thus heterozygous individuals can be distinguished from either homozygous state
Dominant marker
A marker shows dominant inheritance with homozygous dominant individuals indistinguishable from heterozygous individuals
Where are micro-satellites found
In the non-coding region
How can micro satellites mutate
DNA polymerase slippage, unequal crossing over
Stepwise mutation model
When SSRs mutate, they gain or lose only one repeat
