2.6 Phylogenetic analysis
Standardized effect size measure of mean nearest taxon distance
(ses.MNTD) was used to quantify phylogenetic relationships between
closely related taxa (Webb et al., 2002).
Negative ses.MNTD value ( < 0) suggests that species are more
closely related than expected by chance (clustering), whereas positive
value ( > 0) indicates that species are less closely
related than expected by chance (over dispersion). The calculation was
implemented in the R environment (http://www.r-project.org) with the
Picante package using the null model ‘taxa.labels’ (999 randomization)
(Kembel et al., 2010).