CAIE A-Level Biology A2 17.1.1 Genetic and Environmental Variation Questions

Within a population, the variation for one characteristic is usually the result of genetic and environmental causes.

Both genetic and environmental factors contribute to variation in body mass in a bird population.

One cause of variation in body mass in chickens is infection with the gut protoctist Eimeria. When fed with the same diet, infected chickens have a lower gain in body mass than healthy chickens in the same population.

Suggest one environmental factor that affects the growth and reproduction of Eimeria.