All flashcards
Flashcard 1: Identify the best interpretation when a beneficial trait increases after an environmental change.
Answer: Natural selection favored that trait in the new environment. The trait provides survival or reproductive advantage.
Flashcard 2: Identify the best interpretation when a harmful trait decreases steadily over many generations.
Answer: Selection acted against that trait. Individuals with the trait had lower survival or reproduction.
Flashcard 3: Which option best explains a new trait appearing, then slowly increasing over generations?
Answer: A mutation arose and was favored by selection. New genetic variation can spread if it provides an advantage.
Flashcard 4: Identify the trait with the greatest increase: A goes from 10% to 40%, B from 30% to 50%.
Answer: Trait A (increase of 30%). Compare absolute changes: A increased by 30% points vs B's 20%.
Flashcard 5: Find the change in frequency: a trait is 0.20 at Gen 1 and 0.35 at Gen 6.
Answer: Increase of 0.15. Subtract initial from final frequency: 0.35−0.20=0.15.
Flashcard 6: Identify the correct conclusion if a model shows higher survival for one trait and its frequency increases.
Answer: That trait has higher fitness in that environment. Better survival leads to increased frequency over generations.
Flashcard 7: What is the term for a change in trait frequencies in a population across generations?
Answer: Evolution. Heritable traits change in frequency over successive generations.
Flashcard 8: What is the term for the proportion of individuals with a trait in a population?
Answer: Trait frequency. Measures how common a trait is relative to the whole population.
Flashcard 9: What does a flat (horizontal) trait frequency line over time indicate?
Answer: The trait frequency is not changing over time. The trait proportion remains constant across generations.
Flashcard 10: What does it mean if a trait frequency line slopes downward over time?
Answer: The trait is becoming less common in the population. Fewer individuals have the trait each generation.
Flashcard 11: What does it mean if a trait frequency line slopes upward over time?
Answer: The trait is becoming more common in the population. More individuals inherit or develop the trait each generation.
Flashcard 12: What does the x-axis usually represent in a graph showing population trait changes?
Answer: Time (generations, years, or breeding seasons). Tracks how traits change across multiple reproductive cycles.
Flashcard 13: What does the y-axis usually represent in a graph of trait frequency over time?
Answer: Trait frequency (often percent or proportion) in the population. Shows what proportion of the population has the trait at each time point.
Flashcard 14: Identify the selection type if a graph shows two peaks forming over time from one original peak.
Answer: Disruptive selection. One peak splits into two distinct peaks.
Flashcard 15: What is the average rate of change per generation if frequency goes from 0.10 to 0.30 in 4 generations?
Answer: 0.05 per generation. Rate = change/time = (0.30−0.10)/4.
Flashcard 16: What is the change in frequency if a trait rises from 0.20 to 0.50 over the time shown?
Answer: 0.30. Change = final - initial = 0.50−0.20.
Flashcard 17: What is the percent frequency if an allele frequency is 0.65 on a graph?
Answer: 65%. Multiply by 100 to convert to percent.
Flashcard 18: What does it suggest if a trait frequency changes rapidly right after an environmental change on a timeline?
Answer: New selective pressure is acting. Environmental change drives selection.
Flashcard 19: What does it indicate if two trait lines cross, where trait A decreases as trait B increases?
Answer: The population is shifting from trait A to trait B. One trait replaces another over time.
Flashcard 20: What does it mean if an allele is lost on a graph (frequency reaches 0.00)?
Answer: That allele is no longer in the population. Lost means 0% frequency, extinct from population.
Flashcard 21: Which interpretation is correct if a model shows survivors have a trait value closer to one extreme?
Answer: Selection favored that extreme trait value. Survivors show which traits were advantageous.
Flashcard 22: What is the allele frequency if 30 of 100 alleles in a sample are allele A?
Answer: 0.30. Frequency = count/total = 30/100.
Flashcard 23: What does the x-axis usually represent on a graph of population trait change over time?
Answer: Time (generations or years). Time is the independent variable when tracking changes.
Flashcard 24: What does it mean if a trait becomes fixed on a graph (frequency reaches 1.00)?
Answer: All individuals carry that allele/trait version. Fixed means 100% frequency in population.
Flashcard 25: What does the y-axis usually represent on a graph showing a trait changing in a population?
Answer: Trait frequency or average trait value. Shows how common a trait is or its average value.
Flashcard 26: What does a graph showing cyclical ups and downs in a trait frequency over time most likely indicate?
Answer: Changing conditions or frequency-dependent selection. Fluctuating selection pressures cause cycles.
Flashcard 27: What does an increase in allele frequency over time on a graph indicate about that allele?
Answer: It is becoming more common in the population. Higher frequency means more individuals carry it.
Flashcard 28: What does a flat line for trait frequency over many generations most directly indicate?
Answer: No net change in trait frequency (stable). Flat line means the trait isn't changing.
Flashcard 29: Which term describes a trait change where the population mean shifts toward one extreme over time?
Answer: Directional selection. Population shifts toward one extreme value.
Flashcard 30: Which term describes a trait change where both extremes increase and the middle decreases over time?
Answer: Disruptive selection. Selection against intermediate values.