lecture 21: population genetics 1, hardy-weinberg Flashcards
achondroplasia
what can frequencies of offspring in a family cross tell us
dominant vs recessive
what can frequencies of alleles/genotypes in a population tell us
rare and common
genetic studies: comparative genomics
studies of different species and how theyre related
genetic studies: mendelian genetics
studies of the offspring in one specific family (tells about dominant or recessive)
genetic studies: population genetics
studies of the members of a population in one specific species (tells about rare and common, and allele history)
criteria for a population at harvey weinberg equilibrium
allele frequencies not changing
genotype frequencies are product of random mating and not changing
(population is not evolving)
random mating
all members throwing their alleles into a hat, each genotype made by choosing 2 gametes at random
a population at hw equilibrium
allele frequencies not changing
genotype frequencies not changing after one generation of random mating
for hw equilibrium define the allele frequencies
p is frequency of more common allele, p is frequency of less common allele
p+q=1
how long does it take random mating to get to hw equilibrium
1 generation
hemizygous
a genotype consisting of only a single copy of a particular gene in an otherwise diploid organism
x linked recessive traits
affected females are homozygous, affected males are hemizygous
what can cause evolution
genetic drift
non random mating
mutation
migration
selection
genetic drift
the change in allele frequencies due to random chance in a finite population
hw assumes a population is infinitely large such that drift doesnt occur
extreme genetic drift occurs when you have:
continuously small
bottleneck
founder effect
bottleneck
when the existing population gets much smaller (after a major catastrophe)
founder effect
a type of bottleneck where a small group from the population begins a new population
impact of genetic drift on populations
negative assortative mating
when individuals favor those opposite to them (people mating with people that have different HLA types)
positive assortative mating
when individuals favor those similar to them (deaf people are more likely to get with deaf people)
inbreeding is one of the strongest forms of positive assortative mating
impact of non random mating on populations
mutation
change in the structure of dna to generate a new allele in the population
-like de novo mutation in position 380 that causes glycine instead of arginine in achondroplasia
impact of mutations on populations
migration/gene flow
transfer of alleles from one population to another
the impact of migration on population
selection
drives the increase prevalence of traits that enhance survival or reproductive success
different types of selection
natural vs artificial
lactose tolerance/persistence
impact of selection on population
how to solve a hw problem
hw step 0: null hypothesis
hw step 1: calculate allele frequencies
hw step 2: calculate expected genotype
hw step 3: calculate chi squared
hw step 3 part 2: degrees of freedom
hw step 4: find p value
hw step 5: interpret p value
