Skip to main content

Advertisement

Table 1 Coverage of key concepts and misconceptions about genetic drift in the GeDI and the Ferrets module

From: Observing populations and testing predictions about genetic drift in a computer simulation improves college students’ conceptual understanding

Key concepts GeDI Item Ferrets workbook Ferrets simulations
1. Random sampling error happens every generation, which can result in random changes in allele frequency that is called genetic drift
 a. Genetic drift results from random sampling error  
 b. Random sampling occurs each generation in all finite populations 16  
 c. Random sampling can result in random changes in allelic, phenotypic, and/or genotypic frequency  
2. Random sampling error tends to cause a loss of genetic variation within populations, which in turn increases the level of genetic differentiation among populations
 a. The processes leading to genetic drift tend to cause a loss of genetic variation within populations over many generations 3, 13
 b. Decreasing genetic variation within populations usually increases genetic differentiation among populations   
3. The magnitude of the effect of random sampling error from one generation to the next depends on the population size. The effect is greater when populations have a small effective size, but generally small or undetectable when effective population size is large
 a. The effects of genetic drift are larger when the population is smaller 1
 b. Founding and bottlenecking events are two situations in which the effects of genetic drift are greater because the effective population size is rapidly reduced 10
4. In populations with small effective sizes, genetic drift can overwhelm the effects of natural selection, mutation, and migration; therefore, an allele that is increasing in frequency due to selection might decrease in frequency some generations due to genetic drift
 a. Other evolutionary mechanisms, such as natural selection, mutation, and migration act simultaneously with genetic drift    
 b. The processes leading to genetic drift can overwhelm the effects of other evolutionary mechanisms 15   
 c. Random sampling error can result in populations that perpetuate deleterious alleles or traits 4   
Misconceptions
 About sampling error
  1. Random sampling error only results in fixation or loss    
  2. Genetic drift is unpredictable because it has a random component 7  
  3. Genetic drift only occurs in small populations, because random sampling error does not occur in large populations  
 Confusing genetic drift with natural selection
  4. Genetic drift is natural selection/adaptation/acclimation to the environment that may result from a need to survive 5, 6, 8  
  5. Genetic drift only occurs when natural selection cannot or is not occurring    
  6. Genetic drift is not evolution because it does not lead to directional change that increases fitness 2  
  7. Natural selection is always most powerful mechanism of evolution, and it is the primary agent of evolutionary change 9, 12, 17, 20   
 Confusing genetic drift with evolutionary processes other than natural selection
  8. Genetic drift is random mutation 14, 19, 22   
  9. Genetic drift is speciation    
  10. Genetic drift is gene flow or migration 11, 18, 21   
 Limiting when genetic drift occurs
  11. Genetic drift results only from an isolated event, often a catastrophe   
  1. These key concepts are considered necessary for understanding genetic drift (Price et al. 2014), and the misconceptions are those that undergraduates frequently have about genetic drift (Andrews et al. 2012). We indicate whether each key concept or misconception was explicitly covered in the text of the printed workbook and/or addressed in the onscreen simulations of the Ferrets module