This is R code for addressing the following research questions:

(1) Do species differ in their average responses to density treatments?

(2) Does seed mass explain species’ responses to increasing densities of conspecifics?

(3) Does seed mass explain species’ responses to increasing densities of both conspecifics and heterospecifics?

The present analysis is the result of a thinning experiment using natural assemblages of six closely related annual plant species in a Mediterranean Woodland in Western Australia to assess how seed mass influences the outcomes of plan-plant interactions.

All analyses were performed in R 4.2.1. Focal plant performance was assessed using survival, adult biomass, and reproductive output. In the models used to address each research question, all six species were included to enable comparisons within and among species. For each species, only one single averaged seed mass value was considered. Survival was modelled as a binary response using a binomial distribution and logit link function. Biomass was relativised as the percentage of the maximum log-transformed biomass to reduce intrinsic differences in biomass among the species and then modelled using a Gaussian distribution. To facilitate comparison across species that differ in fecundity (due to variation in seed mass), reproductive output was relativised as the percentage of the maximum reproductive effort for each species. This relative fecundity response was modelled using a negative binomial distribution and log link function. Mixed-effects models were used to account for observations nested within plots, and observations nested within species. Specifically, we used the packages lme4 and glmmTMB. All continuous explanatory variables were standardized to zero mean and unit variance before analyses.

R and R studio.