Rethinking Hardy–Weinberg and genetic drift in undergraduate biology

Abstract

Population genetics is often taught in introductory biology classes, starting with the Hardy-Weinberg principle (HWP) and genetic drift. Here I argue that teaching these two topics first aligns neither with current expert knowledge, nor with good pedagogy. Student difficulties with mathematics in general, and probability in particular, make population genetics difficult to teach and learn. I recommend an alternative, historically inspired ordering of population genetics topics, based on progressively increasing mathematical difficulty. This progression can facilitate just-in-time math instruction. This alternative ordering includes, but does not privilege, the HWP and genetic drift. Stochastic events whose consequences are felt within a single generation, and the deterministic accumulation of the effects of selection across multiple generations, are both taught before tackling the stochastic accumulation of the effects of accidents of sampling.

The Genetic Drift Inventory: A Tool for Measuring What Advanced Undergraduates Have Mastered about Genetic Drift

“…Imperiled populations have small effective population sizes, so the effects of random sampling are magnified (Masel, 2012). Over time, genetic drift reduces the amount of genetic variation within populations, limiting the potential for adaptive evolution (Freeman and Herron, 2004).…”

“…Genetic drift also tends to increase the genetic distinction among populations, potentially leading to evolutionarily significant units that require independent protection (Mills, 2007). Genetic drift is the theoretical framework for Kimura's highly influential neutral theory of molecular evolution, which is important for understanding many aspects of molecular biology, bioinformatics, and genetics (Masel, 2012). In paleobiology, understanding genetic drift is essential for distinguishing active macroevolutionary trends driven by natural selection from passive trends driven by random processes (Raup et al.…”

Statistic and Analytical Strategies for HLA Data

“…Dividing into two groups: We planned to observe 20 patients with gastric ulcers (patient No. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]; one group uses an effective drug ranitidine as a control, and the other group uses a lily decoction. Twenty2-digit random numbers are generated by looking up the random number form, and the random numbers are arranged from small to large, allowing us to obtain the grouping order number "R".…”

Testing validity inferences for Genetic Drift Inventory scores using Rasch modeling and item order analyses

“…Recent editions of popular high school textbooks, however, continue to include genetic drift (e.g., Miller and Levine 2017;Nowicki 2017), leaving the option to cover this topic in the hands of individual teachers, schools, or districts. While genetic drift is commonly taught in evolution courses (e.g., Masel 2012) or within evolution units of biology survey courses (e.g., The College Board 2015;Masel 2012;Urry et al 2017), it may also be taught in genetics courses (e.g., Masel 2012;Stony Brook University 2017, p. 49). Overall, while there is consensus that nonadaptive causes of evolution are an essential component of biology education, inconsistent attention to genetic drift (and other non-adaptive evolutionary concepts) in high-school and college curricula makes it difficult to determine the extent to which students are exposed to instruction on non-adaptive evolutionary processes as well as the degree to which they are able to integrate it into their mental models of evolutionary change (Nehm 2018).…”

“…The scientific community recognizes both adaptive and nonadaptive causes of evolutionary change (reviewed in Beggrow and Nehm 2012;Masel 2012). While standards and textbooks vary in the extent to which they address non-adaptive evolutionary processes, genetic drift is recognized foremost among the various-non adaptive evolutionary factors Price and Perez 2016).…”