Hypothesis 2: Differences in trait spaces are explained by different species contribution
Our second goal was to characterise the contribution of each species to the island’s trait space. If there is convergence of all islands’ trait space with variations according to the ontogenetic state, we expected that species contribution will be minimal in mature islands (Tenerife, La Gomera, and Gran Canaria), and larger both in young (La Palma and El Hierro) and senescent (Fuerteventura and Lanzarote) islands.
We expressed the contribution of each individual species to the functional hypervolume of each island using the functional species contribution metric, calculated using the BAT functionkernel.contribution and the “neighbor” approach. Contribution is a measure of the functional rarity (Violle et al. 2017; Carmona et al. 2017), which allows mapping the impact of each species to the richness component of the functional diversity (i.e. the volume of the island’s trait space). The distribution of the contribution values was then represented as a density plot for each island.