An examination of color, diameter, and shape in the Pitcher Plant, Sarracenia purpurea.

Abstract

Natural selection is a fundamental component of evolution in which nature selects for individuals with phenotypes that make them more fit for their environment. We tested this concept by determining whether the phenotypic traits of the most reproductively fit individuals are more abundant within their poulation. Using 100 Sarracenia purpurea (pitcher plants), we measured color variation, opening diameter, and width to height ratio of 400 pitcher leaves in order to determine correlations between the fitness and phenotypic variation within the sample population. We hypothesized that pitchers red in color, large in diameter and short and wide would capture more prey and thus exist in higher frequency. We found that there was no significant correlation between frequencies of individuals with each of the phenotypic variables; color, opening diameters, and width to height ratio, and their corresponding fitness. Thus, we found no evidence for natural selection acting on this population, and concluded that genetic drift has been the major evolutionary process acting on the frequency of these phenotypes.