Lecture 18- Quantitative Genetics and Heritability
Heritability – Common Errors
1. People think of heritability as a FIXED characteristic – It is not fixed!
- It is a quantity that you measure in a particular population at a given time and it can change.
-what happens to heritability is the variability of the environment changes?
Even if the variation of the genes stays the same, if the amount of variation from the environment
changes then heritability will change
Example: Skin Colour among Caucasians in Vancouver:
- There a variation in skin tone depending on the amount of time you spend under the sun
- In the winter, there is barely any sunlight so everyone will look the same no environmental
variation so heritability is high offspring and parents look alike.
- In the summer however, the sun comes out so there is variation from the environment caused
by how much sun exposure a person gets. So the environmental variation is high heritability
- This is also the case for a trait that occurs during development and stays the same way after.
1. ERROR- if everyone in a population has the same trait then that trait is highly heritable eg: having a
nose. If there is NO VARIATION in the trait then IT IS NOT HERITABLE.
2. ERROR- Heritability is a fixed value for a particular