An analysis of similarity returns a statistic (R) based on a Bray-Curtis dissimilarity measure, which considers the difference of the mean ranks between and within groups. Most values fall between 0 and 1; 1 is the most dissimilar. Significance is assessed by comparing the observed value of R to the permutation distribution of R (33). Again, because of multiple comparisons, a Bonferroni correction was made such that α = 0.005 (31) . We then used stepwise (backward) logistic regression with binomial errors to assess the association between infection prevalence and vegetative characteristics.