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.