The heritability (h²) is given as 1.0 for both, indicating that all phenotypic variation is due to genetic variation.
Misapplication to Human Races and IQ
The discussion references the misapplication of these concepts to human races, specifically IQ scores in the USA.
Mentioned are studies of post-WWII children raised in Europe, specifically children of African-American US soldiers, showing no difference in IQ scores.
Chapter 7: Genetic Drift – Isolating the Concept
Chapter 7 focuses on genetic drift.
To isolate the concept, selection and mutation are ignored.
Definition of Genetic Drift
Genetic drift is defined as the random change in allele frequencies within populations.
Along with natural selection, it is one of the most important processes affecting allele frequencies.
Random events are unpredictable and probabilistic, unlike deterministic events.
Random Change in Allele Frequency
Random change in allele frequency is likened to flipping a coin; the probability of an allele frequency increasing or decreasing is equal in any generation.
This contrasts with natural selection, where frequency changes are deterministic.
Allele Frequency Graphs
Several graphs depict allele frequency (p) over generations.
These graphs illustrate the random fluctuations in allele frequencies over time.
Fixation and Loss
Genetic drift eventually leads to one allele becoming fixed (frequency = 1) and the other being lost (frequency = 0).
Although the process is random, probabilistic predictions can be made.
Probabilistic Nature of Genetic Drift
It's impossible to predict what happens in any single generation, but overall trends can be predicted.
Eventually, one allele will be fixed, and the other will go extinct.
Start at p = 0.5
20 populations all start at p=0.5. With 9 individuals and 18 gene copies
Probability of Allele Fixation
Graphs illustrate allele frequency changes over generations in multiple populations.
Probability distributions show the likelihood of allele fixation at different time points (t = 0.1N, 0.2N, 0.5N, N, 2N generations).