Changes in environmental factors, such as sun exposure, soil type, and proximity to human activities, result in variation in pitcher morphology (length and capacity).
Variation in pitcher morphology are correlated with changes in insect yield.
Despite the lack of direct correlation between insect yield and environmental factors, the effects of habitat on morphology result in changes in insect yield.
Therefore, changes in insect yield may be attributed to environmental factors, but only through changes in morphology.