Functional and phylogenetic diversity

Functional and phylogenetic diversities are different dimensions of the biodiversity and fundamental to test the hypothesis that Caatinga vegetation near roads will exhibit decreased taxonomic, functional and phylogenetic diversity compared to Caatinga vegetation far from roads. In order to analyze functional diversity, four indexes were used: functional richness (FRic), functional evenness (FEve), functional divergence (FDiv) (Villéger et al. , 2008) and functional dispersion (FDis) (Laliberté & Legendre, 2010). Functional richness represents the amount of functional space filled by the community, while functional evenness quantifies the regularity that the functional space is filled by the species, weighing their abundances. Functional divergence can be understood as the distribution of the abundance occupied by the species within the volume of the functional space so that the divergence is low when the most abundant species is close to the center of the amplitude of the functional traits and high when this species has extreme trait values. Finally, functional dispersion refers to the average distance of one species in the multidimensional functional space for the centroid of all species.
We calculated these indices for all species sampled considering the characteristics related to tolerance/resistance strategies for herbivory deterrence: resprouting abilities, succulence with spines, urticancy/toxicity and annuals. For the woody component, calculations were made considering the following functional traits: resprouting abilitiy, urticancy/toxicity, succulents, nitrogen fixers, life form, endozoochory, maximum diameter (cm) and maximum height (m). For the non-woody component (herbaceous-sub-shrub), the functional traits considered were resprouting ability, annuals (therophytes), urticancy/toxicity, succulents, nitrogen fixers, life form and relative coverage of each species. All functional diversity indexes were calculated in R statistical environment (R Development Core Team, 2015), using the methods, scripts (Villéger et al. , 2008) and the functions of the FD package (Laliberté & Legendre, 2010).
Phylogenetic diversity was calculated by the sum of the phylogenetic distance between species in each community using the PD (phylogenetic diversity) index provided by the Phylocom 4.2 program (Webb et al. , 2011) and its standardized measure (standardized effect size - SESPD) calculated through ’picante’ package (Kembel, 2015) in R statistical environment (R Development Core Team, 2015). The phylogeny used was constructed in the same way as the phylogenetic structure described in the next section.
To investigate the effect of disturbance near roads on variation in community functional and phylogenetic diversity, we tested the calculated indices statistically. We used Shapiro-Wilk test to verify normality of the data. We performed an ANOVA for the data with normal distribution and the Kruskal-Wallis test for distribution-free data (Zar, 1996).