Covariance in species diversity and facilitation among non-interactive parasite taxa: all against the host

• Published in: Parasitology 2005-10, Vol.131 (4), p.557-568
• Main Authors: KRASNOV, B. R., MOUILLOT, D., KHOKHLOVA, I. S., SHENBROT, G. I., POULIN, R.
• Format: Article
• Language: English
• Subjects: Animals; Anoplura; Biodiversity; Biological and medical sciences; Community organizations; covariance; Ectoparasites; Ectoparasitic Infestations - immunology; Ectoparasitic Infestations - parasitology; Endoparasites; Fundamental and applied biological sciences. Psychology; General aspects; General aspects and techniques. Study of several systematic groups. Models; helminths; Host-Parasite Interactions - immunology; Host-Parasite Interactions - physiology; host-parasite relationships; Immunocompetence - immunology; Immunocompromised Host; Invertebrates; Ixodidae; lice; Mammalia; Mesostigmata; Mites; Mites - classification; Mites - growth & development; Organisms; parasite communities; parasite facilitation; Parasites; Phthiraptera - classification; Phthiraptera - growth & development; Phylogeny; Rodentia; rodents; Siphonaptera; Siphonaptera - classification; Siphonaptera - growth & development; Species diversity; Species richness; Species Specificity; Studies; Taxa; taxonomic distinctness; ticks; Ticks - classification; Ticks - growth & development; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution
• ISSN: 0031-1820; 1469-8161
• DOI: 10.1017/S0031182005007912

Different parasite taxa exploit different host resources and are often unlikely to interact directly. It is unclear, however, whether the diversity of any given parasite taxon is indirectly influenced by that of other parasite taxa on the same host. Some components of host immune defences may operate simultaneously against all kinds of parasites, whereas investment by the host in specific defences against one type of parasite may come at the expense of defence against other parasites. We investigated the relationships between the species diversity of 4 higher taxa of ectoparasites (fleas, sucking lice, mesostigmatid mites, and ixodid ticks), and between the species richness of ectoparasites and endoparasitic helminths, across different species of rodent hosts. Our analyses used 2 measures of species diversity, species richness and taxonomic distinctness, and controlled for the potentially confounding effects of sampling effort and phylogenetic relationships among host species. We found positive pairwise correlations between the species richness of fleas, mites and ticks; however, there was no association between species richness of any of these 3 groups and that of lice. We also found a strong positive relationship between the taxonomic distinctness of ecto- and endoparasite assemblages across host species. These results suggest the existence of a process of apparent facilitation among unrelated taxa in the organization of parasite communities. We propose explanations based on host immune responses, involving acquired cross-resistance to infection and interspecific variation in immunocompetence among hosts, to account for these patterns.