Chapter Eighteen: Population Genetics Flashcards
…is the study of genes and genotypes in populations, and how they can change over time
Population Genetics
Population Genetics depends on the existence of genetic…
variation
….(many forms) refers to a trait that shows more than one phenotype
Polymorphism
To be considered polymorphic, rare alleles must be present at a frequency of >…
> 1%
Polymorphisms may be due to:
1. …of a region of a gene
2. …of a region of a gene
3. Change in a single… (substitution mutation) (Single-Nucleotide Polymorphism or snips)
Deletion
Duplication
nucleotide
snips represent …% of all variation in human DNA
90
To calculate allergic frequencies, it is necessary to know the…of all individuals in the population
genotypes
Equation for finding the frequency of allele:
of certain allele / #total allele
what two letters are typically used to symbolize two allelic frequencies?
p and q
…frequencies are the frequencies or proportions of the different genotypes
Genotypic
In 1908, what two people both independently proposed the conditions under which allelic and genotypic frequencies would remain constant (equilibrium)
Hardy and Weinberg
Under equilibrium, both allelic and genotypic frequencies would remain constant, and the genotypic frequencies would depend upon or could be calculated from what frequencies?
allelic frequencies
What are the five Hardy Weinberg Equilibrium Conditions?
- No mutations
- No natural selection
- No migration between populations
- Infinite population size
- Random Mating
Populations are…in Hardy-Weinberg Equilibrium and meet all 5 conditions for equilibrium
rarely
Hardy-Weinberg Equilibrium is useful to show the conditions under which allelic and genotypic frequencies will not remain constant but will…
Change
The change in allelic frequencies over time is…
microevolution
mutations may be important in providing the variation for…but is not important in directly changing allele frequencies
natural selection
…occurs when one genotype has an advantage that allows the individuals with that genotypes to survive better and leave more offspring than other genotypes
natural selection
natural selection is usually defined with…
fitness
the maximum fitness is…
1
Is a high fitness good or bad?
good
a positive selection coefficient means that natural selection works…the genotype
against
If natural selection is operating, it means that some genotypes are not leaving as many offspring and genotypic frequencies will change. This is also known as…
Microevolution
If the dominant or recessive genotype is at a selective disadvantage, the frequency of the allele producing that genotype will…overtime
decrease
Genetic variation produces a range of…, usually in a normal distribution
phenotypes
If both extremes in phenotype are selected against, …will force the phenotype to become less variable
Stabilizing Selection
If intermediate phenotypes are selected against, …produces two phenotypes
Disruptive Selection
What kind of selection occurs when two alleles are maintained in a population?
Balancing Selection
Heterozygote advantage occurs if the heterozygote has the…fitness
highest
What kind of selection occurs when individuals with a rare genotype have a higher fitness than individuals with a more common genotype?
Negative frequency-dependent selection
What kind of selection occurs when certain genotypes have an advantage over other genotypes of the same sex, with respect to reproduction?
Sexual Selection
…refers to the changes in allelic frequencies due to random/chance events
Random Genetic Drift
What kind of effect occurs when a small number of individuals found a new population?
Founder Effect
What kind of effects occur when populations that are usually large, experience temporary decreases?
Bottleneck Effects
The neutral theory of evolution believes the contribution of each gene to the overall fitness of the individual is…
small
What refers to the movement of individuals from one population to another?
Migration
As individuals move, they carry their alleles with them, this is called…
Gene flow
Mating must be…if allele frequencies are not to change
random
If mating with one genotype is preferred, the alleles making up that genotype will…
increase
What kind of mating occurs when individuals tend to mate with others with a similar phenotype?
Positive Assortative Mating
What kind of mating occurs when mating between different phenotypes is preferred?
Negative Assortative Mating
Inbreeding…refers to the decrease in fitness brought about by the production of deleterious homozygous phenotypes as a result of inbreeding
depression
