Interpret Evolutionary Trend Data - Biology

1. What is the term for a change in allele frequencies due to random sampling in small populations?

   Genetic drift. Random sampling effects are strongest in small populations.

2. If two populations show increasing genetic divergence and decreasing hybrid fertility, what conclusion fits?

   Reproductive isolation is increasing toward speciation. Genetic differences and breeding barriers are developing.

3. If allele frequency changes from $p=0.40$ to $p=0.55$ across generations, what occurred?

   Evolution occurred (allele frequencies changed). Allele frequency change indicates evolutionary change.

4. If allele frequencies change rapidly after a storm drastically reduces population size, what cause fits?

   Bottleneck effect (genetic drift). Sudden population reduction causes random changes.

5. What is the term for a trait that is favored because it increases mating success in data trends?

   Sexual selection. Traits evolve to increase reproductive opportunities.

6. What is the term for long periods of little change punctuated by rapid change in the fossil record?

   Punctuated equilibrium. Rapid change alternates with periods of stasis.

7. Which option best defines an evolutionary trend in a dataset?

   A consistent change in trait or allele frequency across generations. Patterns show directional change over time in populations.

8. What relationship must allele frequencies satisfy at a two-allele locus when computed from data?

   $p+q=1$. Two allele frequencies must sum to one.

9. If male ornament size increases while survival decreases but mating success increases, what selection fits?

   Sexual selection. Ornaments increase mating despite survival costs.

10. If two populations become more genetically similar after migration between them, which mechanism fits?

    Gene flow. Migration makes populations more genetically similar.

11. What is the Hardy–Weinberg equation for expected genotype frequencies from allele frequencies?

    $p^2+2pq+q^2=1$. Expected frequencies from allele probabilities.

12. What is the term for movement of alleles between populations that can reduce differences?

    Gene flow. Migration transfers alleles between populations.

13. What is the term for traits evolving in unrelated lineages due to similar selection pressures?

    Convergent evolution. Similar environments produce similar traits independently.

14. Which type of selection favors extremes and can produce a bimodal distribution?

    Disruptive selection. Both extreme phenotypes are favored over intermediates.

15. Which equation gives allele frequency $q$ for allele $a$ from genotype counts $AA, Aa, aa$?

    $q=\frac{2aa+Aa}{2N}$. Counts both homozygotes and half the heterozygotes.

16. What is the term for speciation caused by geographic isolation, often inferred from range data?

    Allopatric speciation. Geographic barriers separate populations, preventing gene flow.

17. If genotype counts are $AA=36$, $Aa=48$, $aa=16$, what is $q$ for allele $a$?

    $q=0.40$. Calculate from $(32+24)/200 = 0.40$.

18. What is the definition of fitness when interpreting selection from survival or reproduction data?

    Relative reproductive success in a specific environment. Measured by survival and reproductive output.

19. If $p=0.70$ and $q=0.30$, what is the expected heterozygote frequency under equilibrium?

    $2pq=0.42$. Two times the product of allele frequencies.

20. What is the term for evolution of similar traits due to shared ancestry, not similar pressures?

    Homology. Similarities arise from common evolutionary origin.

21. What is the term for a gradual change within a lineage over time as seen in fossil sequences?

    Anagenesis. Single lineage changes gradually over time.

22. What is the term for a split in one lineage into two or more lineages shown in phylogenetic data?

    Speciation. One lineage splits into multiple separate lineages.

23. What is the term for selection that favors different phenotypes in different environments?

    Diversifying selection. Different environments select for different traits.

24. What is the term for random change in allele frequencies that is strongest in small populations?

    Genetic drift. Random sampling effects vary inversely with population size.

25. What is the definition of allele frequency used when interpreting evolutionary data?

    Proportion of a specific allele among all alleles at a locus. Calculated from total alleles in the population.

26. Which statement indicates that a population is evolving in terms of population genetics?

    Allele frequencies change from one generation to the next. Evolution is defined by changing allele frequencies.

27. Which option best interprets a consistent increase in antibiotic-resistant bacteria after treatment?

    Natural selection increased resistance allele frequency. Antibiotic creates selective pressure favoring resistance.

28. What is the definition of adaptation as inferred from evolutionary trend data?

    Heritable trait that increases fitness in a given environment. Inherited traits that improve survival or reproduction.

29. Which option lists the five Hardy–Weinberg conditions used to interpret equilibrium from data?

    Large population, random mating, no mutation, no migration, no selection. Requirements for stable allele frequencies over time.

30. What is the term for speciation without geographic separation, inferred from within-range divergence?

    Sympatric speciation. Populations diverge in the same geographic area.

31. If fossil morphology stays stable for long intervals with abrupt shifts at boundaries, what pattern fits?

    Punctuated equilibrium. Stasis interrupted by rapid morphological change.

32. If $q=0.20$ at a Hardy–Weinberg locus, what is the expected frequency of $aa$?

    $q^2=0.04$. $q$ squared gives homozygous recessive frequency.

33. If observed heterozygosity is higher than expected under $2pq$, what pattern is indicated?

    Negative assortative mating or heterozygote advantage. Excess heterozygotes suggest outcrossing or advantage.

34. If observed heterozygosity is lower than expected under $2pq$, which process is most indicated?

    Non-random mating (inbreeding) or population structure. Reduced heterozygosity indicates non-random mating patterns.

35. If intermediate phenotypes decline and both extremes increase over generations, which selection fits?

    Disruptive selection. Extremes increase while intermediates decrease.

36. What is the term for a DNA sequence difference used to track evolutionary change in populations?

    Genetic marker. DNA variations help track population changes.

37. What is the term for closely related species becoming more different over time?

    Divergent evolution. Related species develop different characteristics.

38. Which type of selection favors intermediate phenotypes and reduces variation?

    Stabilizing selection. Middle values are favored, reducing trait variance.

39. If allele frequency changes are larger in a small population than a large one, what trend does this show?

    Stronger genetic drift in smaller populations. Smaller populations show larger random fluctuations.

40. Which option best interprets a molecular clock where sequence differences increase with time?

    Mutations accumulate over time at an approximately constant rate. Genetic differences accumulate steadily over time.

41. If a harmful recessive allele persists because heterozygotes have highest fitness, what mechanism is shown?

    Heterozygote advantage (balancing selection). Mixed genotype has highest fitness, maintaining both alleles.

42. What is the term for non-random mating that increases homozygosity in data trends?

    Inbreeding. Relatives mating increases homozygous genotypes.

43. What is the term for similarity in traits due to similar function, not shared ancestry?

    Analogy. Similar function evolved independently, not inheritance.

44. If a trait mean steadily increases across time points, which selection pattern is most consistent?

    Directional selection. Consistent shift in one direction indicates selection.

45. If allele frequencies cycle because rare phenotypes have higher fitness, what mechanism is indicated?

    Negative frequency-dependent selection. Rare types have advantage, preventing fixation.

46. What is the definition of phenotype frequency in a population dataset?

    Proportion of individuals expressing a particular phenotype. Observable traits expressed by individuals in a dataset.

47. If genotype counts are $AA=36$, $Aa=48$, $aa=16$, what is $p$ for allele $A$?

    $p=0.60$. Calculate from $(72+24)/200 = 0.60$.

48. If $p=0.60$ and $q=0.40$, what are expected genotype frequencies $AA, Aa, aa$?

    $AA=0.36$, $Aa=0.48$, $aa=0.16$. Use $p^2$, $2pq$, and $q^2$ formulas.

49. If a new population has allele frequencies very different from the source population at founding, what cause fits?

    Founder effect (genetic drift). Small founding group creates different frequencies.

50. What is the term for a sharp reduction in population size that changes allele frequencies by chance?

    Bottleneck effect. Dramatic population reduction causes random allele loss.

51. Which option best defines reproductive isolation when interpreting speciation evidence?

    Barriers prevent gene flow between populations. Populations cannot successfully interbreed and exchange genes.

52. Which equation gives allele frequency $p$ for allele $A$ from genotype counts $AA, Aa, aa$?

    $p=\frac{2AA+Aa}{2N}$. Counts both homozygotes and half the heterozygotes.

53. If genotype frequencies match $p^2:2pq:q^2$ and remain constant, what is the conclusion?

    Population is in Hardy–Weinberg equilibrium at that locus. Genotype frequencies match predictions and stay constant.

54. Which type of selection shifts a trait mean in one direction over time?

    Directional selection. One extreme phenotype becomes more common over time.

55. Which option best interprets a rapid rise of pesticide resistance after pesticide use begins?

    Directional selection favoring resistant individuals. Pesticide selects for resistant individuals over time.

56. What is the term for allele frequency change when a small group colonizes a new area?

    Founder effect. Small founding groups carry limited genetic diversity.

57. If trait variance decreases while the mean stays similar over time, which selection is most consistent?

    Stabilizing selection. Reduced variance with stable mean indicates stabilizing.

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