Ecological and Evolutionary Consequences
I tested for two potential consequences of the 2018/19 extreme wind event—one ecological and one evolutionary. I began by investigating the demographic (ecological) consequences of the 2018/19 extreme wind event. First, I used an LMM with year as a main effect and patch as a random effect to estimate gall density in June 2019 (i.e. the generation after the extreme event). I then used a Levene’s test to compare spatial variation in gall density among years.
I next moved on to the potential evolutionary consequences of the 2018/19 wind event. Because galls tend to change size from June to the following May (but reaction norms are parallel; Weis and Gorman 1990), I began by calculating the difference in gall size between the 2018/19 generation measured in May 2019 and the 2019/20 generation measured in June 2019 (i.e. the 5th and 6th generations). I then standardized this trait change, and used standardized trait change as the response variable in a LM with selection coefficients as the main effect.
Note that in all above analyses I carried error associated with selection estimates forward into subsequent analyses by weighting those analyses by the inverse of the standard error associated with each estimate. All analyses were conducted in R using the ‘lme4’ (Bates et al. 2015) and ‘car’ (Fox and Weisberg 2011) packages.