Allele dynamics and populations Flashcards
When did H. sapiens and neanderthal interbreed?
100,000 years ago
What is a population?
Individuals that live ‘close’ together that interact and may exchange genes
What is a locus?
A point on a gene
What is an allele?
A variant of a gene
What is a gene pool?
The set of alleles of all genes present in a population
What is a homozygote?
A diploid individual that has 2 identical alleles
What is a heterozygote?
A diploid individual that has 2 different alleles
How do you work out the allele/gene frequency in haploids?
Population N Number of copies of alleles n1/n2 Allele frequencies n1/N and n2/N n1+n2=N n1/N + n2/N = 1
How do you work out the allele/gene frequency in diploids?
Total number of alleles is 2N
Allele frequencies n1/2N and n2/2N
n1/2N + n2/2N = 1
n1+n2=1
What is a genotype?
The genetic constitution of an individual
What is a single nucleotide polymorphism?
2 alleles which differ by a nucleotide at a specific location
What is haplotype?
A group of alleles in an organism that are inherited together from a single parent.
Describe an advantageous gene substitution
Either quickly lost or fixed
Little polymorphism
Describe a neutral gene substitution
Changes slowly
Transient polymorphism
Describe a deleterious gene substitution
Short
Less likely to get fixed
Describe an over-dominant (heterozygote advantage) gene substitution
Seldom fixed
Maintain polymorphism over long evolutionary time
What is the law of segregation?
In diploids, two alleles, each with an identical likelihood of being passed on
What is the law of independent assortment?
Alleles at separate loci are passed on independently of each other
Name some segregation distorters
Genetic elements
Meiotic drivers
Name some post-segregation distorters
Genomic elements that reduce the frequency of non-carriers
What is genetic linkage of genes?
2 genes wouldn’t be inherited independently if they were on the same chromosome
What is genetic hitchhiking?
When an allele changes frequency because it’s near another gene that is undergoing a selective sweep
What is a selective sweep?
When a new beneficial mutation becomes fixed
What are some of the main characteristics of selective sweeps?
Eliminates diversity in the region of the genome that is close to the selected gene
Excess high-frequency derived alleles
Creates linkage disequilibrium
Increases differentiation between populations
Rapidly decays over time
