Resource partitioning in Sarracenia purpurea based on pitcher color.

Abstract

Resource partitioning is found in situations where two or more species have divided the use of essential resources in order to avoid competition. In some environments, such as bogs, where nitrogen is extremely limiting, plants like Sarracenia purpurea, the purple pitcher plant, have evolved modified leaves that acquire nitrogen through the capture and digestions of insects. Unlike most plants, whose leaves look identical and have the single function of carbon capture, pitchers have the dual function of both carbon and nitrogen capture and vary remarkably in green and red color. It is possible that pitchers on an individual plant exhibit color polymorphism as a mechanism to partition prey resources and maximize prey capture. We hypothesized that pitchers that were more similar in color would capture more similar types of prey than pitchers of more different color on the same plant. We sampled and analyzed prey of three pitchers (two of similar and one of different color) from 25 S. purpurea plants at Mud Lake Bog in Cheboygan, MI. We found that there is no evidence of a relationship between color difference in pitchers on the same plant and differences in types of prey captured. Our results did show however, that pitchers of bigger hoods tend to capture flying insects while smaller hoods favor capture of crawling insects, inferring that there may be a mechanism of resource partitioning through variation of hood sizes.