Biology Flashcards: Explain Adaptation Through Selection

What this deck covers

This deck focuses on Explain Adaptation Through Selection, giving you a quick way to review the definitions, rules, and examples that matter most for Biology.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: What is differential reproduction?

Answer: Individuals with certain traits leave more offspring than others. Key mechanism driving evolutionary change over time.

Flashcard 2: Which statement is correct: individuals evolve or populations evolve?

Answer: Populations evolve; individuals do not. Evolution requires changes in population gene frequencies.

Flashcard 3: What does it mean to say selection works on existing variation?

Answer: Selection increases or decreases alleles already present in a population. Selection cannot create new variants, only choose among existing.

Flashcard 4: Identify the error: "Giraffes grew longer necks because they needed to reach leaves." What is wrong?

Answer: It is teleological; selection favors heritable variation, not need. Implies purpose; evolution has no foresight or goals.

Flashcard 5: Which option best completes the statement: selection acts on phenotype but changes  ?

Answer: Allele frequencies (genotypes) in the population. Selection affects phenotype but evolution changes genotype.

Flashcard 6: 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 7: 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 8: Which option describes antibiotic resistance correctly: adaptation in bacteria or acquired immunity in individuals?

Answer: Adaptation in bacterial populations via selection for resistance alleles. Resistance alleles increase frequency through selection.

Flashcard 9: 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 10: What is convergent evolution?

Answer: Independent evolution of similar traits in similar environments. Same environmental pressures produce similar solutions.

Flashcard 11: What is sexual selection?

Answer: Selection for traits that increase mating success. Enhances reproduction through mate choice or competition.

Flashcard 12: What is the bottleneck effect?

Answer: Genetic drift after a population size is drastically reduced. Severe population reduction causes random allele loss.

Flashcard 13: What is the founder effect?

Answer: Genetic drift when a new population is started by few individuals. Reduces genetic diversity in new populations.

Flashcard 14: Identify the correct sequence: mutation then selection, or selection then mutation?

Answer: Mutation then selection. Variation must exist before selection can act.

Flashcard 15: Identify the best explanation for increased dark moth frequency after pollution darkened trees.

Answer: Directional selection favored better-camouflaged dark moths. Industrial melanism demonstrates selection favoring camouflage.

Flashcard 16: What is meant by "selection over generations" in a population?

Answer: Repeated differential reproduction shifts allele frequencies over time. Cumulative effect of selection across multiple generations.

Flashcard 17: What is stabilizing selection?

Answer: Selection favors intermediate phenotypes, reducing variation. Maintains population average by eliminating extremes.

Flashcard 18: What is meant by adaptation being non-random?

Answer: Selection consistently increases alleles that raise fitness. Selection systematically favors beneficial traits.

Flashcard 19: What is meant by evolution acting on genotypes?

Answer: Allele frequencies in a population change across generations. Evolution changes genetic composition over time.

Flashcard 20: What is directional selection?

Answer: Selection favors one extreme phenotype, shifting the population mean. Moves population toward one extreme of trait distribution.

Flashcard 21: What is the unit of evolution: individual organism or population?

Answer: Population. Evolution occurs at the population level, not individual.

Flashcard 22: What is genetic variation?

Answer: Differences in alleles among individuals in a population. Provides raw material for natural selection to act upon.

Flashcard 23: 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 24: What is meant by adaptation occurring over generations?

Answer: Beneficial alleles increase in frequency across generations. Requires multiple generations for allele frequency changes.

Flashcard 25: What is artificial selection?

Answer: Human-directed breeding that changes trait frequencies. Similar to natural selection but human-controlled.

Flashcard 26: What is genetic drift?

Answer: Random changes in allele frequencies, strongest in small populations. Non-selective evolutionary force affecting all populations.

Flashcard 27: What is an analogous structure?

Answer: A similar function trait that evolved independently, not from common ancestry. Function is similar but evolutionary origin differs.

Flashcard 28: What is the key difference between acclimation and adaptation?

Answer: Acclimation is individual and temporary; adaptation is heritable and population-level. Acclimation is phenotypic plasticity; adaptation is genetic.

Flashcard 29: Choose the correct outcome: if a trait reduces predation and is heritable, what happens over generations?

Answer: Its allele frequency tends to increase in the population. Beneficial heritable traits increase in frequency.

Flashcard 30: 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 31: 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 32: Which option best explains why a beneficial trait can still disappear by chance in a small population?

Answer: Genetic drift can override selection in small populations. Random sampling effects stronger than weak selection.

Flashcard 33: What is the ultimate source of new alleles in a population?

Answer: Mutation. Creates new variants for selection to act upon.

Flashcard 34: What is natural selection?

Answer: Differential survival and reproduction due to heritable variation. Individuals with better traits survive and reproduce more.

Flashcard 35: What is selective pressure?

Answer: An environmental factor that influences survival or reproduction. Determines which traits provide survival advantage.

Flashcard 36: 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 37: What is disruptive selection?

Answer: Selection favors both extremes over intermediates. Splits population into two distinct forms.

Flashcard 38: What is meant by "survival of the fittest" in biology?

Answer: Those with higher fitness leave more viable offspring. Fitness means reproductive success, not physical strength.

Flashcard 39: What is selective pressure?

Answer: An environmental factor that influences survival or reproduction. Determines which traits provide survival advantage.

Flashcard 40: 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 41: What is meant by mutations being random with respect to need?

Answer: Mutations do not occur because an organism needs them. Mutations occur regardless of environmental benefit.

Flashcard 42: Identify the correct definition of homologous structures as evidence of adaptation and descent.

Answer: Similar structures due to common ancestry, sometimes modified by selection. Inherited from ancestors, may be modified by selection.

Flashcard 43: What is gene flow?

Answer: Movement of alleles between populations via migration and mating. Homogenizes allele frequencies between populations.

Flashcard 44: What is an example of a selective agent: predator, mutation, or mitosis?

Answer: Predator. Environmental factors that cause differential survival.

Flashcard 45: 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 46: 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 47: 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.

Flashcard 48: Choose the correct statement: "Individuals adapt to the environment during their lifetime." True or false?

Answer: False; populations adapt across generations via selection. Individual change is not evolutionary adaptation.

Flashcard 49: What is an adaptationist error to avoid when explaining traits?

Answer: Assuming every trait is an adaptation shaped by selection. Many traits result from drift, constraints, or trade-offs.

Flashcard 50: Identify the best prediction: when a new predator appears, what changes first, phenotypes or allele frequencies?

Answer: Phenotypes are selected first; allele frequencies change across generations. Phenotypic selection precedes genetic frequency changes.

Flashcard 51: What is a polymorphism?

Answer: The presence of two or more common phenotypes in a population. Maintained by balancing selection or environmental variation.