Empirical modelling of trait selection by partitioning selection into direct selection and selection that is mediated by interspecific interactions

6 Trait selection has received considerable attention in the pursuit to understand niche-based community 7 assembly processes and to generate ecological predictions. To further advance the study of trait selection, 8 a conceptual statistical model is presented that outlines and discuss the possibilities of i) estimating the 9 effect of interspecific interactions on traits rather than just testing weather selection has had an effect on 10 the observed trait distributions, ii) discriminating between environmental filtering and niche partitioning 11 processes and estimate the characteristic features and importance of both processes, and iii) predicting the 12 effect of environmental changes and gradients on trait selection. To achieve these goals a number of 13 necessary assumptions have to be specified and these assumptions are discussed and assessed. Simulated 14 plant cover data from a simple uniform environment was successfully fitted to the model and the results 15 indicates that it is possible to partition direct population growth and population growth that is mediated by 16 interspecific interaction. The data requirements of the model are modest, i.e. time series data on plant 17 species abundance and a species – trait matrix. Consequently, the model concept may be used to model 18 trait selection, including the effect of interspecific interactions, in many existing plant ecological datasets. 19