All flashcards
Flashcard 1: Calculate expected heterozygote frequency when p=0.60 and q=0.40.
Answer: 2pq=0.48. 2pq=2(0.60)(0.40)=0.48
Flashcard 2: What is heterozygote advantage?
Answer: Heterozygotes have highest fitness, maintaining both alleles. Balancing selection maintains genetic diversity.
Flashcard 3: Identify the Hardy–Weinberg condition: what must be true about mutation?
Answer: No mutations occur. Mutations would change allele frequencies over time.
Flashcard 4: Identify the Hardy–Weinberg condition: what must be true about mating?
Answer: Mating is random. Prevents preferential mating patterns that alter genotype frequencies.
Flashcard 5: Identify the Hardy–Weinberg condition: what must be true about population size?
Answer: Population is very large (minimizes genetic drift). Large populations reduce random sampling effects.
Flashcard 6: Which Hardy–Weinberg genotype frequency corresponds to homozygous recessive?
Answer: q2. Frequency of aa genotype in Hardy-Weinberg equilibrium.
Flashcard 7: Which Hardy–Weinberg genotype frequency corresponds to heterozygotes?
Answer: 2pq. Frequency of Aa genotype; factor of 2 accounts for both combinations.
Flashcard 8: State the Hardy–Weinberg allele frequency equation for two alleles.
Answer: p+q=1. The two allele frequencies must sum to 1.
Flashcard 9: Identify the formula for allele frequency p from genotype counts AA, Aa, aa in N individuals.
Answer: p=2N2AA+Aa. Counts each homozygote twice and heterozygote once for allele A.
Flashcard 10: What is mutation as an evolutionary mechanism?
Answer: Source of new alleles via DNA sequence changes. Introduces novel alleles but usually at low rates.
Flashcard 11: What does it mean if allele frequency changes across generations in a dataset?
Answer: Evolution is occurring in that population. Frequency changes indicate evolutionary forces are acting.
Flashcard 12: What is the gene pool of a population?
Answer: All alleles present in the population. The collective genetic variation available for evolution.
Flashcard 13: Identify the allele frequency change if p shifts from 0.50 to 0.62 in one generation.
Answer: Δp=0.12. Δp=0.62−0.50=0.12
Flashcard 14: Calculate expected carrier (heterozygote) frequency when q=0.10 and p=0.90.
Answer: 2pq=0.18. 2pq=2(0.90)(0.10)=0.18
Flashcard 15: Calculate p if q=0.30 for a two-allele locus under Hardy–Weinberg notation.
Answer: p=0.70. Since p+q=1, then p=1−0.30=0.70
Flashcard 16: Which inference is supported if a phenotype is rare and has higher fitness specifically because it is rare?
Answer: Negative frequency-dependent selection. Rare phenotypes gain advantage specifically from their rarity.
Flashcard 17: Which inference is supported if a harmful allele persists because heterozygotes have higher fitness?
Answer: Balancing selection via heterozygote advantage. Heterozygote advantage maintains harmful alleles in populations.
Flashcard 18: Which inference is supported if a beneficial allele rises quickly in frequency after an environmental change?
Answer: Positive selection increased the allele’s frequency. Rapid increase after environmental change indicates adaptive advantage.
Flashcard 19: What is the key population-level evidence that a trait is heritable?
Answer: Trait variation correlates between parents and offspring. Parent-offspring correlation indicates genetic basis for the trait.
Flashcard 20: What is a selective pressure in the context of population data?
Answer: Environmental factor that causes differential survival or reproduction. Environmental factors create fitness differences between phenotypes.
Flashcard 21: Identify the strongest evidence for natural selection in population data across generations.
Answer: Consistent allele frequency change correlated with a selective pressure. Correlation between selection pressure and frequency change indicates causation.
Flashcard 22: Choose the best selection pattern if extremes decline and intermediate phenotypes become most common.
Answer: Stabilizing selection. Intermediate optimization indicates selection against extremes.
Flashcard 23: Choose the best selection pattern if both extremes increase while intermediates decrease in frequency.
Answer: Disruptive selection. Both extremes increasing indicates selection against intermediate forms.
Flashcard 24: Choose the best selection pattern if the mean phenotype increases steadily across generations.
Answer: Directional selection. Consistent shift toward one extreme indicates directional selection.
Flashcard 25: Choose the best evolutionary mechanism if allele frequencies become more similar between two populations over time.
Answer: Gene flow. Migration homogenizes allele frequencies between populations over time.
Flashcard 26: Choose the best evolutionary mechanism if a new island population has unusual allele frequencies from few founders.
Answer: Genetic drift (founder effect). Few founding individuals create non-representative gene pools.
Flashcard 27: Choose the best evolutionary mechanism if allele frequencies change randomly after a population crash.
Answer: Genetic drift (bottleneck effect). Population crashes cause random allele loss through sampling effects.
Flashcard 28: What is frequency-dependent selection?
Answer: Fitness depends on how common or rare a phenotype is. Selection strength varies with phenotype abundance in population.
Flashcard 29: What is nonrandom mating and how does it affect genotype frequencies?
Answer: Mate choice/inbreeding changes genotype frequencies, not allele frequencies directly. Affects Hardy-Weinberg genotype predictions without changing allele frequencies.
Flashcard 30: What is natural selection in terms of population data?
Answer: Nonrandom allele frequency change due to differential survival/reproduction. Fitness differences cause predictable frequency changes.