All flashcards
Flashcard 1: Which statement is correct: individuals evolve or populations evolve?
Answer: Populations evolve; individuals do not. Evolution requires changes in population gene frequencies.
Flashcard 2: What is meant by adaptation occurring over generations?
Answer: Beneficial alleles increase in frequency across generations. Requires multiple generations for allele frequency changes.
Flashcard 3: What is an allele frequency?
Answer: The proportion of a specific allele among all alleles in a population. Measures relative abundance of genetic variants.
Flashcard 4: What is directional selection?
Answer: Selection favors one extreme phenotype, shifting the population mean. Moves population toward one extreme of trait distribution.
Flashcard 5: What is stabilizing selection?
Answer: Selection favors intermediate phenotypes, reducing variation. Maintains population average by eliminating extremes.
Flashcard 6: What is disruptive selection?
Answer: Selection favors both extremes over intermediates. Splits population into two distinct forms.
Flashcard 7: What is sexual selection?
Answer: Selection for traits that increase mating success. Enhances reproduction through mate choice or competition.
Flashcard 8: What is artificial selection?
Answer: Human-directed breeding that changes trait frequencies. Similar to natural selection but human-controlled.
Flashcard 9: What is an example of a selective agent: predator, mutation, or mitosis?
Answer: Predator. Environmental factors that cause differential survival.
Flashcard 10: What does it mean to say selection is environment-dependent?
Answer: A trait can be beneficial in one environment and harmful in another. Selection's effectiveness depends on environmental context.
Flashcard 11: What is selective pressure?
Answer: An environmental factor that influences survival or reproduction. Determines which traits provide survival advantage.
Flashcard 12: What process can create new combinations of existing alleles during meiosis?
Answer: Recombination (crossing over and independent assortment). Shuffles existing alleles into new combinations.
Flashcard 13: What is the ultimate source of new alleles in a population?
Answer: Mutation. Creates new variants for selection to act upon.
Flashcard 14: What is differential reproduction?
Answer: Individuals with certain traits leave more offspring than others. Key mechanism driving evolutionary change over time.
Flashcard 15: What is heritability in the context of selection?
Answer: The ability of a trait to be passed genetically to offspring. Determines if traits can respond to selection pressure.
Flashcard 16: What is genetic variation?
Answer: Differences in alleles among individuals in a population. Provides raw material for natural selection to act upon.
Flashcard 17: Which condition is required for natural selection to occur: heritable variation or acquired traits?
Answer: Heritable variation. Traits must be genetically passed to offspring for selection.
Flashcard 18: What is an evolutionary trade-off?
Answer: A benefit in one function comes with a cost in another. Optimization in one trait may reduce another trait.
Flashcard 19: What is a constraint on adaptation?
Answer: A limit on evolution due to genetics, development, or history. Physical or historical limits on evolutionary change.
Flashcard 20: What is genetic drift?
Answer: Random changes in allele frequencies, strongest in small populations. Non-selective evolutionary force affecting all populations.
Flashcard 21: What is the founder effect?
Answer: Genetic drift when a new population is started by few individuals. Reduces genetic diversity in new populations.
Flashcard 22: What is the bottleneck effect?
Answer: Genetic drift after a population size is drastically reduced. Severe population reduction causes random allele loss.
Flashcard 23: What is gene flow?
Answer: Movement of alleles between populations via migration and mating. Homogenizes allele frequencies between populations.
Flashcard 24: What is meant by evolution acting on genotypes?
Answer: Allele frequencies in a population change across generations. Evolution changes genetic composition over time.
Flashcard 25: What is meant by selection acting on phenotypes?
Answer: Selection favors observable traits that affect survival or reproduction. Selection acts on visible traits, not directly on genes.
Flashcard 26: What is the unit of evolution: individual organism or population?
Answer: Population. Evolution occurs at the population level, not individual.
Flashcard 27: What is fitness in the context of natural selection?
Answer: Relative reproductive success in a given environment. Measures how many offspring an individual produces.
Flashcard 28: Identify the missing requirement for natural selection: variation, heritability, or equal reproduction?
Answer: Unequal reproductive success (differential reproduction). Differential reproduction is essential for selection.
Flashcard 29: What is natural selection?
Answer: Differential survival and reproduction due to heritable variation. Individuals with better traits survive and reproduce more.
Flashcard 30: What is an adaptation in evolutionary biology?
Answer: A heritable trait that increases fitness in a specific environment. Must enhance survival/reproduction and be passed to offspring.