Topic 7B:Populations and Evolution Flashcards
What does the Hardy-Weinberg principle state?
The Hardy-Weinberg principle states that allele frequencies in a population will remain constant from one generation to the next in the absence of evolutionary influences (e.g., mutation, natural selection, genetic drift, migration).
What are the conditions required for the Hardy-Weinberg equilibrium?
The conditions include: no mutation, random mating, no natural selection, large population size, and no migration.
What is the Hardy-Weinberg equation?
The Hardy-Weinberg equation is:
p^2 + 2pq + q^2 = 1
p^2 =dominant homozygous frequency (AA)
2pq =heterozygous frequency (Aa)
q^2 =recessive homozygous frequency (aa)
How can the Hardy-Weinberg equation be used to calculate allele frequencies?
The equation can be rearranged to solve for allele frequencies:
If genotype frequencies are known, allele frequencies can be calculated by taking the square root of (for the recessive allele frequency). p² + 2pq + q² = 1.
What is genetic variation in a population?
Genetic variation refers to the differences in alleles and genotypes within a population, which contribute to diversity in traits.
What is natural selection?
Natural selection is the process by which individuals with advantageous traits are more likely to survive, reproduce, and pass those traits to the next generation.
What are the stages of natural selection?
The stages of natural selection are:
~Variation in traits within a population
~Selection pressure (e.g., predators, climate)
~Survival of individuals with advantageous traits
~Reproduction and passing on advantageous traits to offspring
What is directional selection?
Directional selection occurs when one extreme phenotype is favored, leading to a shift in the population’s trait distribution toward that phenotype.
What is disruptive selection?
Disruptive selection occurs when both extreme phenotypes are favored, and individuals with intermediate phenotypes are selected against, potentially leading to two distinct groups in the population.
What is a stabilizing selection?
Stabilizing selection favors the intermediate phenotype, reducing variation in the population and maintaining a stable trait distribution.
What is speciation?
Speciation is the process by which new species are formed due to reproductive isolation and genetic divergence.
What is the difference between allopatric and sympatric speciation?
Allopatric speciation occurs when a population is geographically isolated, leading to genetic divergence and the formation of new species. Sympatric speciation occurs when a new species evolves within the same geographical area, often due to behavioral or ecological factors
What is genetic drift?
Genetic drift is a random change in allele frequencies within a population, which can occur in small populations due to chance events rather than natural selection.
How does the bottleneck effect contribute to genetic drift?
The bottleneck effect occurs when a population’s size is drastically reduced, leading to a loss of genetic diversity and random changes in allele frequencies.
What is the founder effect in genetic drift?
The founder effect occurs when a small group of individuals establishes a new population, leading to a reduced genetic diversity and different allele frequencies compared to the original population.
What is the purpose of the Hardy-Weinberg Equation?
To calculate allele and genotype frequencies in a population under Hardy-Weinberg equilibrium.
What is Hardy-Weinberg Equilibrium?
The condition under which allele frequencies in a population do not change from generation to generation, assuming no evolutionary forces act on the population.
What is Genetic Variation?
The differences in alleles and genotypes among individuals in a population, contributing to diversity in traits and the potential for evolution.
What is Allopatric Speciation?
Speciation that occurs when a population is geographically isolated, leading to reproductive isolation and genetic divergence.
What is Sympatric Speciation?
Speciation that occurs without geographic isolation, often due to ecological or behavioral factors that prevent gene flow within the population.
What is the Bottleneck Effect?
A form of genetic drift that occurs when a population undergoes a drastic reduction in size, leading to a loss of genetic diversity.
