Effect of sexual activity on male survivorship after infection with P. entomophila. Kaplan-Meier plots of survivorship of sexually active (■) and virgin males (□) from BRB (A), LH (B) and CS (C) populations. The experiment was done in two independent blocks and 40 males were infected in each Block × Treatment × Population combination. Data was analysed using two models- model1: that includes block as random factor (using R package ‘coxme’ ) and model2: that does not include block as random factor (using R package ‘coxphw’ ; for details see statistical analysis section in materials and methods). No significant block effects were detected and thus block was eliminated as a factor and data from the two blocks were pooled for further analysis. When infected with P. entomophila, sexually active males survived significantly better than virgin males in all the populations (all p < 0.0001, Cox proportion regression analysis). None of the sham infected flies (―――) died over the course of the observation. While we did have mated and virgin sham infected controls, we represent both of them with a single line in the figure for simplicity.
Gupta et al. BMC Evolutionary Biology 2013 13:185 doi:10.1186/1471-2148-13-185