All flashcards
Flashcard 1: What process reshuffles existing alleles to create new trait combinations?
Answer: Genetic recombination during sexual reproduction. Meiosis and fertilization mix parental genes.
Flashcard 2: What does fitness mean in evolutionary biology?
Answer: Relative reproductive success in a specific environment. Not strength or speed, but reproductive output.
Flashcard 3: Identify the correct explanation link: why does trait variation matter for selection?
Answer: Selection can only change populations when individuals differ in traits. No variation means no differential survival or reproduction.
Flashcard 4: Choose the best conclusion: antibiotic use kills most bacteria; a few resistant survive.
Answer: Resistance increases in the bacterial population. Survivors reproduce, passing resistance genes to offspring.
Flashcard 5: Identify the population outcome: a new predator makes bright coloration easier to spot.
Answer: Bright coloration decreases in frequency over generations. Predation pressure selects against conspicuous individuals.
Flashcard 6: Identify the population outcome: drought favors deeper roots in plants over time.
Answer: Average root depth increases in the population. Shallow-rooted plants die more, shifting the trait distribution.
Flashcard 7: Which option best describes disruptive selection?
Answer: Both extreme traits are favored over the intermediate. Can split populations into two distinct forms.
Flashcard 8: Which option best describes directional selection?
Answer: One extreme trait is favored, shifting the population average. Pushes trait distribution toward one end.
Flashcard 9: Which option best describes stabilizing selection?
Answer: Intermediate traits are favored; extremes are selected against. Reduces variation by eliminating both extremes.
Flashcard 10: What is gene flow?
Answer: Movement of alleles into or out of a population by migration. Immigrants bring new alleles; emigrants remove them.
Flashcard 11: Identify the correct claim: selection acts on individuals or populations?
Answer: Selection acts on individuals; populations change over generations. Individuals die or reproduce; their traits accumulate in populations.
Flashcard 12: Identify the most direct source of new genetic variation in a population.
Answer: Mutations. DNA copying errors create new alleles and traits.
Flashcard 13: What is gene flow?
Answer: Movement of alleles into or out of a population via migration. Migration spreads genetic variation between populations.
Flashcard 14: What is genetic drift?
Answer: Random change in allele frequencies, strongest in small populations. Sampling error causes random fluctuations in gene pools.
Flashcard 15: Which process changes trait frequencies because of chance rather than advantage: genetic drift or natural selection?
Answer: Genetic drift. Drift is random; selection favors beneficial traits.
Flashcard 16: Which statement best connects trait variation to selection: variation affects survival, or survival creates variation?
Answer: Variation affects survival and reproduction. Selection acts on existing variation, doesn't create it.
Flashcard 17: Identify the population outcome if a heritable trait increases survival in the current environment.
Answer: That trait becomes more common over generations. Selection increases frequency of beneficial heritable traits.
Flashcard 18: Identify the population outcome if a trait is beneficial but not heritable (for example, a learned behavior).
Answer: No consistent increase in that trait frequency across generations. Without inheritance, beneficial traits die with the individual.
Flashcard 19: Which type of selection is shown when one extreme trait value is favored and the mean shifts?
Answer: Directional selection. Population shifts toward the favored extreme value.
Flashcard 20: Which type of selection is shown when intermediate trait values are favored and extremes are selected against?
Answer: Stabilizing selection. Average individuals have highest fitness.
Flashcard 21: Identify the best claim: individuals evolve or populations evolve over time?
Answer: Populations evolve over time. Individuals don't evolve; their traits are fixed at birth.
Flashcard 22: Identify the most likely outcome if a new predator appears and darker coloration improves camouflage and is heritable.
Answer: Frequency of darker coloration increases in the population. Better camouflage increases survival, spreading the trait.
Flashcard 23: Which evidence best supports selection on a trait: more offspring from one variant or equal offspring from all variants?
Answer: More offspring from one heritable variant. Differential reproduction is the mechanism of selection.
Flashcard 24: What is fitness in biology?
Answer: Relative reproductive success in a given environment. Higher fitness means more offspring survive to reproduce.
Flashcard 25: What is an adaptation?
Answer: A heritable trait that increases fitness in a specific environment. Adaptations evolve because they improve survival and reproduction.
Flashcard 26: Which condition is required for natural selection to change a population: heritable or nonheritable variation?
Answer: Heritable variation. Only genetic traits can be passed on and selected for.
Flashcard 27: What does it mean for a trait to be heritable?
Answer: It can be passed from parents to offspring through genes. Genetic inheritance allows traits to persist across generations.
Flashcard 28: What is natural selection?
Answer: Differential survival and reproduction based on heritable traits. Organisms with favorable traits survive and reproduce more successfully.
Flashcard 29: What is a population outcome in evolution by natural selection?
Answer: A change in trait frequencies in a population over generations. Natural selection causes advantageous traits to become more common.
Flashcard 30: What is trait variation in a population?
Answer: Differences in a trait among individuals of the same species. Variation is the raw material for natural selection to act upon.