Parasite and host contributions to the taxonomic, phylogenetic, and functional beta diversity of small mammalian hosts' flea faunas: A case study with data from four continents

The taxonomic, phylogenetic, and functional beta diversity (BD_tax, BD_phy, and BD_fun, respectively) of flea faunas across host species, in seven continental sections from four continents, was partitioned into species (=flea) and local (=host) contributions. We asked (a) whether the same flea or host species contributed similarly to taxonomic, phylogenetic, and functional beta diversity within each continental section; (b) which flea and host traits drove their contributions to BD_tax, BD_phy, and BD_fun; and (c) whether the effects of these traits on flea and host contributions differed between continental sections. Although different fleas and hosts contributed differently to each beta diversity facet, contributions of the same species to BD_tax, BD_phy, and BD_fun were similar. The heterogeneity between flea faunas, harbored by different host species, was mainly due to the variation in flea species composition, with the distribution of phylogenetic lineages and functional attributes playing lesser roles. The host contributions to BD_phy and BD_fun were driven by phylogenetic and functional similarities between flea species. The relationships between flea traits and their contributions to BD_tax, BD_phy, and BD_fun were weak (if at all), whereas host contributions were mainly associated with the structure of flea faunas in terms of species richness, with the effect of functional host traits being weaker. The main geographic differences in flea and host contributions to BD_tax, BD_phy, and BD_fun were differential associations between these contributions and flea and host functional traits. We concluded that the between-host heterogeneity of flea faunas was driven by the interplay of ecological and historical processes.