Interpret phenotype data to distinguish continuous and discontinuous variation, then identify the genetic and environmental factors that explain the observed pattern in Cambridge…
Within a population, the variation for one characteristic is usually the result of genetic and environmental causes.
A study was carried out to investigate the effect of treating infected chickens with extracts from a plant, Bidens pilosa.
B pilosa is used in traditional medicine for the treatment of some infectious diseases. - Three populations, each containing 25 chickens infected with Eimeria were observed. - The body mass of each chicken was measured at the start of the study. - Each population was given a different treatment for 56 days: - standard diet with no B. pilosa extract - standard diet with low dose of B. pilosa extract - standard diet with high dose of B. pilosa extract. - The body mass of each chicken was measured at the end of the study and the gain in body mass over the 56 days was calculated. - The mean gain in body mass was calculated for each population. The results are shown in Table 3.1.
Table 3.1
A statistical analysis of the results of the study of these three populations confirmed that there was a significant difference in mean gain in body mass between low dose B. pilosa and high dose B. Pilosa extract treatments.
Sketch on Fig. 3.1 curves to show the pattern of variation for gain in body mass in chickens treated with low dose B. pilosa extract and in chickens treated with high dose B. pilosa extract.
Label one curve 'low dose' and the other curve 'high dose'.
Fig. 3.1