Parasite species richness in hoofed mammals

Student Rachel Mercaldo, who participated in summer 2013, chose a mapping study for her project. She worked with mentors Patrick Stephens and John Gittleman to map ungulate parasite richness worldwide. The abstract from her summer project is below.

Abstract. The effect of host traits, individual parasite biology, and phylogeny on parasite species richness (PSR) was studied in ungulates.  To correct for differences in sampling effort among host species, in addition to using residuals of PSR on sampling effort, three non-parametric estimators of PSR were employed for analyses of the 22 best studied species.  Data for a wide variety of host traits were obtained from a published species level data base of mammalian traits (PanTHERIA) and tested for correlations with PSR. Data on the biological traits of parasites were obtained from a variety of literature sources and used to determine if the correlates of PSR are influenced by parasite type (e.g., bacterial, viral) or parasite transmission mode. To account for the influence of phylogeny, multivariate analyses were conducted using phylogenetic GLM. Of the 27 host traits considered, only geographical range area and litter size were found to be consistent correlates of variation in PSR.  The type of parasite was also significant, with factors influencing PSR varying for different parasite types, but not transmission mode.  Analyses also showed a strong influence of the latitude and longitude where host species occur on PSR, as well as the temperature, rainfall, and human population density within a host species range.  Future work will focus using spatially explicit models to determine whether the latter results reflect spatial autocorrelation or the influence of environmental variables on PSR.

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