Biology Graphs: Polygenic Traits
By L Chapman
Polygenic traits are controlled by many genes and result in gradations where each gene loci has an additive effect. What this means to a biologist is that if 10 gene loci are turned on the plant might be 20 cm tall. If 5 gene loci are turned on the plant might be 10 cm tall. Skin color and height in humans are polygenic and therefore humans come in all colors and heights.
What human height has the most number of individuals?
What is the mean of the data? What is the mode of this data? What is the median of this data?
What shape does the curve have and what does that say for the number of very short and very tall people in the world?
Extension: Birth weight in humans is a bell shaped curve because there is biological risk in being too small or too large at birth. The average birth weight is around 7 pounds. Draw what that graph might look like. Be sure to set up your graph with reasonable limits. Is there such a thing as a zero pound baby?