Conservatism of host specificity in parasites


  • David Mouillot,

  • Boris R. Krasnov,

  • Georgy I. Shenbrot,

  • Kevin J. Gaston,

  • Robert Poulin

D. Mouillot ( and K. J. Gaston, Biodiversity and Macroecology Group, Dept of Animal and Plant Sciences, Univ. of Sheffield, Sheffield S10 2TN, UK (present address of D. M.: UMR CNRS-UMII 5119 Ecosystemes Lagunaires, Univ. of Montpellier II, CC093, FR-34095 Montpellier Cedex 5, France). – B. R. Krasnov and G. I. Shenbrot, Ramon Science Center and Mitrani Dept of Desert Ecology, Jacob Blaustein Inst. for Desert Research, Ben-Gurion Univ. of the Negev, P.O. Box 194, Mizpe Ramon IL-80600, Israel. – R. Poulin, Dept of Zoology, Univ. of Otago, P.O. Box 56, Dunedin, New Zealand.


As information becomes available for many groups of organisms a general pattern of phylogenetic conservatism in ecological characters or morphological traits is now widely recognized. Conversely, conservatism of external ecological attributes throughout a lineage is still a contentious theme in ecology. Moreover, the studies exploring this topic have focused on free-living organisms, and have ignored parasites. The main external ecological attribute of parasite species is certainly their host specificity, which is a key determinant of both their range size and local abundance. We address the subject of conservatism and predictability of host specificity using 2 large databases concerning, respectively, ectoparasites and endoparasites. We found a significant positive relationship between the numbers of host species infested by flea sister species. Moreover, this result was consistent whether we used sympatric or allopatric flea species, suggesting no influence of the mode of speciation on this conservatism of specificity. Additionally, our results showed that congeneric helminth species have more similar host taxonomic diversities than expected by chance, although this conservatism is due mostly to trematodes. Whilst there is evidence of conservatism, the moderate levels preclude robust prediction of host specificity for one species based on that of closely related species.