Analysis of a Monarch Butterfly Research Report

Analysis of a Monarch Butterfly Research Report

David Bell

HCS438

July 5, 2010

Keith Harris PhD

Analysis of a Monarch Butterfly Research Report

Statistics are a critical part of performing research studies. Researchers make use of a variety of statistical analyses to analyze data and make meaningful conclusions. Examining an example of a research study is an effective way to understand how such analyses are used in the research process. The following paper is an analysis of a study conducted to analyze the correlation between the virulence of parasites in monarch butterflies and the host plant that monarch caterpillars feed on.

Research and Statistical Procedures

Researchers in this study of the effect of the host plant on parasite virulence performed a controlled experiment in which monarch caterpillars were divided into eight groups. Researchers inoculated four groups of caterpillars with different parasite spores derived from cloning. These four groups were then divided into eight with half of each fed with the Asclepias incarnata species of milkweed and half with the Asclepias curassavica species of milkweed. The remaining two groups consisted of a control group raised on each species of milkweed without parasite inoculation (de Roode, Pedersen, Hunter, & Altizer, 2008). The use of two control groups ensured that effects on lifespan in the experiment were the result of the host plant’s effect on parasites. Butterflies in the control groups should have statistically similar longevity, which indicates that the differences in lifespan are not the direct result of the food source.

The variables of interest in the monarch study were the type of host plant for the caterpillars and the virulence of parasites. The explanatory variable in the experiment is the species of host plant. Although both species of plant are similar in size, Asclepias curassavica contains much higher concentrations of toxins than Asclepias incarnata (de Roode, et al.,...