The complexity and diversity of insect galls have been heavily researched with continuous debate on what possible factors affect their formation and diversity. Galls are plant growths that are induced by other organisms such as gall wasps and are highly specialized to act as larval cavities (Krishnamurthy 1984). There are various types of galls, and the specific type we researched was leaf, stem, and twig galls. Leaf galls appear on the petioles or leaf blades and most commonly appear on the upper the upper or lower leaf surface where as stem and twig galls are slight swellings or large knot-like growths restricted to the twigs and stems of the host plant (Wawrzynaski, Hahn, Ascerno 2005).
In Lafayette Community Park, we measured the circumference (3. 5-4 ft. up) of 25 Oak trees. For each tree we counted the number of galls and the number of different types of galls found on 50 leaves and stems of one tree limb. We also measured the distance to the closest neighboring tree. This data collection was repeated by 7 pairs of classmates to accumulate data for a total of 175 Oak trees. We expect there to be a linear relationship between the relative size of the Oak trees and the number and diversity of galls found. A linear regression was done to analyze the data in order to determine the number and diversity of Oak tree galls varies depending on tree size and the distance between the nearest neighboring tree.
Four regression analyses were conducted for both our individual pairs collected data (figures 1-4) and for the cumulated class data (figures 5-8). The results from each the full and reduced data sets were then compared. For our pairs collected data alone out of the four measured variables, the number of galls vs. tree circumference (p-value 0. 000) and distance to the nearest neighboring tree (p-value 0. 014) were statistically significant. Our r2 values showed there to be little relationship between the two variables being compared for each data set, with the highest r2 value being 57. 13% for the total number of galls found vs. tree circumference. As for the to...