Podcast
Questions and Answers
What is a gene pool?
What is a gene pool?
Natural selection acts directly on genotypes.
Natural selection acts directly on genotypes.
False
Who proposed the theory that individuals inherit traits acquired during their lifetime?
Who proposed the theory that individuals inherit traits acquired during their lifetime?
Lamarck
The change in populations over time is known as __________.
The change in populations over time is known as __________.
Signup and view all the answers
Match the following terms with their definitions:
Match the following terms with their definitions:
Signup and view all the answers
Why don't dominant alleles completely eliminate recessive alleles in a population?
Why don't dominant alleles completely eliminate recessive alleles in a population?
Signup and view all the answers
Evolution can be observed in a single generation.
Evolution can be observed in a single generation.
Signup and view all the answers
What does the term 'fitness' refer to in the context of population genetics?
What does the term 'fitness' refer to in the context of population genetics?
Signup and view all the answers
Which of the following conditions is NOT required for Hardy-Weinberg equilibrium?
Which of the following conditions is NOT required for Hardy-Weinberg equilibrium?
Signup and view all the answers
The Hardy-Weinberg principle states that allele frequencies change over time if specific conditions are met.
The Hardy-Weinberg principle states that allele frequencies change over time if specific conditions are met.
Signup and view all the answers
What is the effect of genetic drift in small populations?
What is the effect of genetic drift in small populations?
Signup and view all the answers
The _____ effect occurs when a small group of individuals becomes isolated from a larger population.
The _____ effect occurs when a small group of individuals becomes isolated from a larger population.
Signup and view all the answers
Which of the following is NOT an agent of evolutionary change?
Which of the following is NOT an agent of evolutionary change?
Signup and view all the answers
Match the definitions with their corresponding concepts:
Match the definitions with their corresponding concepts:
Signup and view all the answers
In non-random mating, individuals prefer mates based on their genetic traits.
In non-random mating, individuals prefer mates based on their genetic traits.
Signup and view all the answers
What happens to allele frequencies when one or more Hardy-Weinberg assumptions are violated?
What happens to allele frequencies when one or more Hardy-Weinberg assumptions are violated?
Signup and view all the answers
What is the effect of gene flow on populations over time?
What is the effect of gene flow on populations over time?
Signup and view all the answers
Disruptive selection eliminates both extremes from a phenotypic array.
Disruptive selection eliminates both extremes from a phenotypic array.
Signup and view all the answers
What must exist among individuals for natural selection to occur?
What must exist among individuals for natural selection to occur?
Signup and view all the answers
In the Hardy-Weinberg principle, the sum of the frequencies of the two alleles must equal _____ .
In the Hardy-Weinberg principle, the sum of the frequencies of the two alleles must equal _____ .
Signup and view all the answers
Match the type of selection with its description:
Match the type of selection with its description:
Signup and view all the answers
What is an example of heterozygote advantage?
What is an example of heterozygote advantage?
Signup and view all the answers
Natural selection is the process that leads to evolution as the outcome.
Natural selection is the process that leads to evolution as the outcome.
Signup and view all the answers
Gene flow can occur via migration of _____ individuals or gametes.
Gene flow can occur via migration of _____ individuals or gametes.
Signup and view all the answers
In the Hardy-Weinberg equilibrium equation, what does the term $p^2$ represent?
In the Hardy-Weinberg equilibrium equation, what does the term $p^2$ represent?
Signup and view all the answers
The sum of allele frequencies in a population always equals 1.
The sum of allele frequencies in a population always equals 1.
Signup and view all the answers
If allele frequency q is 0.25, what is the frequency of allele p?
If allele frequency q is 0.25, what is the frequency of allele p?
Signup and view all the answers
In the Hardy-Weinberg model, the expected frequency of genotype Aa is given by ______.
In the Hardy-Weinberg model, the expected frequency of genotype Aa is given by ______.
Signup and view all the answers
What is the expected frequency of genotype aa if p = 0.5 and q = 0.5?
What is the expected frequency of genotype aa if p = 0.5 and q = 0.5?
Signup and view all the answers
If observed genotypic frequencies are significantly different from expected frequencies, evolution is not occurring.
If observed genotypic frequencies are significantly different from expected frequencies, evolution is not occurring.
Signup and view all the answers
What role does the Chi-square test play in evaluating Hardy-Weinberg equilibrium?
What role does the Chi-square test play in evaluating Hardy-Weinberg equilibrium?
Signup and view all the answers
What does a chi-squared value greater than the table threshold indicate in terms of evolutionary change?
What does a chi-squared value greater than the table threshold indicate in terms of evolutionary change?
Signup and view all the answers
All individuals in a population have the same genes which leads to identical traits.
All individuals in a population have the same genes which leads to identical traits.
Signup and view all the answers
What is the fundamental concept behind Hardy-Weinberg equilibrium?
What is the fundamental concept behind Hardy-Weinberg equilibrium?
Signup and view all the answers
In a population, alleles that produce successful phenotypes tend to ________ in frequency over time.
In a population, alleles that produce successful phenotypes tend to ________ in frequency over time.
Signup and view all the answers
Match the following scenarios with their potential outcomes:
Match the following scenarios with their potential outcomes:
Signup and view all the answers
What is the total observed population size in the flower study?
What is the total observed population size in the flower study?
Signup and view all the answers
The allele frequency for pink flowers in the study is 0.2.
The allele frequency for pink flowers in the study is 0.2.
Signup and view all the answers
Calculate the expected frequency of white flowers if the total population is 120 and the allele frequency for white is 0.2.
Calculate the expected frequency of white flowers if the total population is 120 and the allele frequency for white is 0.2.
Signup and view all the answers
The Hardy-Weinberg principle uses __________ to calculate expected genotype frequencies.
The Hardy-Weinberg principle uses __________ to calculate expected genotype frequencies.
Signup and view all the answers
Match the following components with their definitions related to allele frequencies:
Match the following components with their definitions related to allele frequencies:
Signup and view all the answers
What is the expected number of red flowers if the population size is 120 and the allele frequency for red is 0.8?
What is the expected number of red flowers if the population size is 120 and the allele frequency for red is 0.8?
Signup and view all the answers
If observed genotypic frequencies are not significantly different from expected frequencies, evolution is occurring.
If observed genotypic frequencies are not significantly different from expected frequencies, evolution is occurring.
Signup and view all the answers
What test can be used to evaluate if a population is in Hardy-Weinberg equilibrium?
What test can be used to evaluate if a population is in Hardy-Weinberg equilibrium?
Signup and view all the answers
Study Notes
Population Genetics: Hardy-Weinberg Theorem
- Population: A group of organisms of the same species that occur in the same area and can interbreed to produce fertile offspring.
- Gene pool: The sum of all alleles at all gene loci of all individuals in a population.
- Species: A group of organisms that can interbreed with each other and produce fertile offspring.
- Evolution: The change in populations over time. Populations evolve; individuals do not. (Requires at least 2 generations to observe evolution.)
How Evolution Happens (Darwin/Wallace)
- Natural Selection:
- Gene variation causes variability in traits.
- Some individuals have inherited traits allowing more surviving offspring than others without those traits.
- Populations gradually include more individuals with advantageous characteristics.
- Natural selection acts directly on phenotypes and indirectly on genotypes.
- Fitness: the number of surviving offspring an individual produces for the next generation (relative measure). Selection favors phenotypes with the greatest fitness.
Darwin vs Lamarck
- Lamarck: Individuals accumulate changes during their lifetime that are advantageous and pass these traits to their offspring. Traits acquired during an individual's life are passed on.
- Darwin: Individuals are born with either advantageous or disadvantageous traits. Traits that are advantageous are passed on.
Population Genetics
- Fuses evolutionary biology with genetics of populations, investigating evolutionary change due to natural selection and other factors.
- Hardy-Weinberg Principle (1908):
- If certain conditions are met, frequencies of alleles in a population remain constant from generation to generation.
- If this principle is met (allele frequencies do not change across generations), genotypes are in Hardy-Weinberg Equilibrium (HWE). HWE means evolution is not occurring.
Conditions Required for HWE
- Infinitely large population to avoid genetic drift (change in allele frequencies due to chance).
- Random mating with respect to traits/alleles.
- No new mutations at the gene locus.
- No immigration or emigration (no gene flow).
- No selection: all genotypes have equal reproductive success.
Genetic Drift
- Frequencies of alleles may change by chance alone.
- Particularly important in small populations.
- Founder effect: Few individuals found a new population - small allelic pool.
- Bottleneck effect: drastic reduction in population size causing a smaller gene pool.
Non-random Mating & Mutation
- Assortative mating: Individuals mate with similar phenotypes (e.g., blue with blue).
- Mutation: Changes to the genetic code. May cause a change in phenotype. Mutation rates are typically low.
Gene Flow/Migration
- Movement of alleles among populations.
- Alleles move through individual or gamete migration (e.g., pollen).
- Reduction in variation across populations over time.
- Can increase or decrease population fitness depending on alleles introduced.
Selection
- Disruptive selection: Eliminates intermediate types.
- Directional selection: Eliminates one extreme phenotype.
- Stabilizing selection: Eliminates both extremes for a phenotypic array.
Natural Selection (Examples)
- Adaptive melanism: Variation in coloration related to environment. (e.g., pocket mice on lava rocks).
- Heterozygote advantage: Heterozygotes are favored over homozygotes (e.g., sickle cell anemia with malaria resistance).
Artificial Selection
- Human-exerted selection (e.g., dog breeds, agriculture).
Hardy-Weinberg Rule: Calculating Allele Frequencies
- Analyzing frequencies of alleles in successive generations to predict allele frequencies.
- If conditions for HWE are met, you can predict the frequency of alleles in a population.
- Two alleles at one locus: A and a. Allele frequencies designated as p (dominant) and q (recessive). Sum of p and q must always equal 1 (p+q=1).
Hardy-Weinberg Rule: Calculating Allele Frequencies (continued)
- Possible genotypes are: AA (homozygous dominant), Aa (heterozygous), and aa (homozygous recessive)
- In algebraic terms: p² + 2pq + q² = 1
- Frequency of genotype AA = p²
- Frequency of genotype aa = q²
- Frequency of genotype Aa = 2pq
Further Hardy-Weinberg Examples
- Illustrates calculating allele and genotypic frequencies using actual data from a population.
More Practice (Stepwise work)
- Step-by-step calculations to illustrate how to solve Hardy-Weinberg problems, using MC1R gene as an example
Hardy-Weinberg Practice.
- Illustrates chi-square test to analyze whether a population is in HWE.
Further notes on Variation and Population Capacity.
- All populations have capacity to increase, but not indefinitely.
- Competition for resources.
- Alleles that produce successful phenotypes will increase.
- Change leads to increased fitness and adaptation.
Outputs
- Lists exercises related to Hardy-Weinberg equilibrium and simulation of evolutionary change.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your understanding of the Hardy-Weinberg theorem and the principles of population genetics. This quiz covers key concepts such as gene pools, species definitions, and the mechanisms of evolution including natural selection. Boost your knowledge of how populations evolve over time.
