Explain Adaptation Through Selection - Biology
- What is differential reproduction?
- Individuals with certain traits leave more offspring than others. Key mechanism driving evolutionary change over time.
- Which statement is correct: individuals evolve or populations evolve?
- Populations evolve; individuals do not. Evolution requires changes in population gene frequencies.
- What does it mean to say selection works on existing variation?
- Selection increases or decreases alleles already present in a population. Selection cannot create new variants, only choose among existing.
- Identify the error: "Giraffes grew longer necks because they needed to reach leaves." What is wrong?
- It is teleological; selection favors heritable variation, not need. Implies purpose; evolution has no foresight or goals.
- Which option best completes the statement: selection acts on phenotype but changes ______?
- Allele frequencies (genotypes) in the population. Selection affects phenotype but evolution changes genotype.
- Identify the missing requirement for natural selection: variation, heritability, or equal reproduction?
- Unequal reproductive success (differential reproduction). Differential reproduction is essential for selection.
- What is an evolutionary trade-off?
- A benefit in one function comes with a cost in another. Optimization in one trait may reduce another trait.
- Which option describes antibiotic resistance correctly: adaptation in bacteria or acquired immunity in individuals?
- Adaptation in bacterial populations via selection for resistance alleles. Resistance alleles increase frequency through selection.
- Which condition is required for natural selection to occur: heritable variation or acquired traits?
- Heritable variation. Traits must be genetically passed to offspring for selection.
- What is convergent evolution?
- Independent evolution of similar traits in similar environments. Same environmental pressures produce similar solutions.
- What is sexual selection?
- Selection for traits that increase mating success. Enhances reproduction through mate choice or competition.
- What is the bottleneck effect?
- Genetic drift after a population size is drastically reduced. Severe population reduction causes random allele loss.
- What is the founder effect?
- Genetic drift when a new population is started by few individuals. Reduces genetic diversity in new populations.
- Identify the correct sequence: mutation then selection, or selection then mutation?
- Mutation then selection. Variation must exist before selection can act.
- Identify the best explanation for increased dark moth frequency after pollution darkened trees.
- Directional selection favored better-camouflaged dark moths. Industrial melanism demonstrates selection favoring camouflage.
- What is meant by "selection over generations" in a population?
- Repeated differential reproduction shifts allele frequencies over time. Cumulative effect of selection across multiple generations.
- What is stabilizing selection?
- Selection favors intermediate phenotypes, reducing variation. Maintains population average by eliminating extremes.
- What is meant by adaptation being non-random?
- Selection consistently increases alleles that raise fitness. Selection systematically favors beneficial traits.
- What is meant by evolution acting on genotypes?
- Allele frequencies in a population change across generations. Evolution changes genetic composition over time.
- What is directional selection?
- Selection favors one extreme phenotype, shifting the population mean. Moves population toward one extreme of trait distribution.
- What is the unit of evolution: individual organism or population?
- Population. Evolution occurs at the population level, not individual.
- What is genetic variation?
- Differences in alleles among individuals in a population. Provides raw material for natural selection to act upon.
- What does it mean to say selection is environment-dependent?
- A trait can be beneficial in one environment and harmful in another. Selection's effectiveness depends on environmental context.
- What is meant by adaptation occurring over generations?
- Beneficial alleles increase in frequency across generations. Requires multiple generations for allele frequency changes.
- What is artificial selection?
- Human-directed breeding that changes trait frequencies. Similar to natural selection but human-controlled.
- What is genetic drift?
- Random changes in allele frequencies, strongest in small populations. Non-selective evolutionary force affecting all populations.
- What is an analogous structure?
- A similar function trait that evolved independently, not from common ancestry. Function is similar but evolutionary origin differs.
- What is the key difference between acclimation and adaptation?
- Acclimation is individual and temporary; adaptation is heritable and population-level. Acclimation is phenotypic plasticity; adaptation is genetic.
- Choose the correct outcome: if a trait reduces predation and is heritable, what happens over generations?
- Its allele frequency tends to increase in the population. Beneficial heritable traits increase in frequency.
- What is a constraint on adaptation?
- A limit on evolution due to genetics, development, or history. Physical or historical limits on evolutionary change.
- What is meant by selection acting on phenotypes?
- Selection favors observable traits that affect survival or reproduction. Selection acts on visible traits, not directly on genes.
- Which option best explains why a beneficial trait can still disappear by chance in a small population?
- Genetic drift can override selection in small populations. Random sampling effects stronger than weak selection.
- What is the ultimate source of new alleles in a population?
- Mutation. Creates new variants for selection to act upon.
- What is natural selection?
- Differential survival and reproduction due to heritable variation. Individuals with better traits survive and reproduce more.
- What is heritability in the context of selection?
- The ability of a trait to be passed genetically to offspring. Determines if traits can respond to selection pressure.
- What is disruptive selection?
- Selection favors both extremes over intermediates. Splits population into two distinct forms.
- What is meant by "survival of the fittest" in biology?
- Those with higher fitness leave more viable offspring. Fitness means reproductive success, not physical strength.
- What is selective pressure?
- An environmental factor that influences survival or reproduction. Determines which traits provide survival advantage.
- What is an allele frequency?
- The proportion of a specific allele among all alleles in a population. Measures relative abundance of genetic variants.
- What is meant by mutations being random with respect to need?
- Mutations do not occur because an organism needs them. Mutations occur regardless of environmental benefit.
- Identify the correct definition of homologous structures as evidence of adaptation and descent.
- Similar structures due to common ancestry, sometimes modified by selection. Inherited from ancestors, may be modified by selection.
- What is gene flow?
- Movement of alleles between populations via migration and mating. Homogenizes allele frequencies between populations.
- What is an example of a selective agent: predator, mutation, or mitosis?
- Predator. Environmental factors that cause differential survival.
- What process can create new combinations of existing alleles during meiosis?
- Recombination (crossing over and independent assortment). Shuffles existing alleles into new combinations.
- What is fitness in the context of natural selection?
- Relative reproductive success in a given environment. Measures how many offspring an individual produces.
- What is an adaptation in evolutionary biology?
- A heritable trait that increases fitness in a specific environment. Must enhance survival/reproduction and be passed to offspring.
- Choose the correct statement: "Individuals adapt to the environment during their lifetime." True or false?
- False; populations adapt across generations via selection. Individual change is not evolutionary adaptation.
- What is an adaptationist error to avoid when explaining traits?
- Assuming every trait is an adaptation shaped by selection. Many traits result from drift, constraints, or trade-offs.
- Identify the best prediction: when a new predator appears, what changes first, phenotypes or allele frequencies?
- Phenotypes are selected first; allele frequencies change across generations. Phenotypic selection precedes genetic frequency changes.
- What is a polymorphism?
- The presence of two or more common phenotypes in a population. Maintained by balancing selection or environmental variation.