A wide-ranging survey of Nicotonia growing in its natural environment recorded a variation in
corolla length ranging from 12mm to 47mm with a variance of 36.5. Subsequently, collected seeds
were grown in a greenhouse and it was found that the range was now very much lower with most
plants having similar corolla lengths and the variance was now only 8.4.
a) What is the heritability of corolla length?
b) After the plants had grown to maturity and formed seed, seeds were collected from plants with
either the shortest and or the longest corollas in the population and planted separately in the
greenhouse. When flowers were formed it was found that the variance of the plants with the
shortest flowers was now 4.2 while that of the flowers from the longest seeds had become 13.7
Calculate the new values for heritability in the different groups of plants and explain why this
difference may arise.
