Host repertoire
We investigated the effects of host environment and phylogeny on the
host repertoire of the parasites. Host repertoires were quantified as
mean pairwise distance (MPD) and mean nearest taxon distance (MNTD) of
host species to investigate ancient and recent evolutionary
relationships respectively (Clark & Clegg 2017). We calculate MPD and
MNTD from functional-phylogenetic distance (FPDist) matrices.These matrices are derived from functional (FDist) and phylogenetic
(PDist) distance matrices of the host species infected by each parasite
species. We inferred the FDist matrices from the host niche dendrograms
and the PDist matrices from the host phylogenetic trees and scaled the
matrices by dividing the values through the respective maximum distance.
We accounted for uncertainty in the host niche/tree topology by drawing
random samples of dendrograms/trees every time we calculated FPDist =
(aPDistp + (1 -
a)FDistp)1/p (Cadotte et al.2013) with p = 2 to calculate Euclidean distances (see Cadotte et
al. 2013; Burbrink et al. 2017; Clark & Clegg 2017). Finally,
we applied 100 incremental increases from 0 to 1 to the weighting
parameter a . We calculated FPDist through the functionFPDist in the R package funphylocom v1.1 (Walker
2014). For the null model (NM3), we generated null
distributions by randomly redistributing the labels of the FPDist
matrices resulting from 1000 random draws from FDist and PDist matrices.
We calculated MPD, MNTD, and 1000 null estimates through the functionsmpd , mntd , and taxaShuffle in the R packagepicante v1.8.2 (Kembel et al. 2010). For interpretation of
the FPDist plots, we followed Cadotte et al. (2013).