Odum School of Ecology, University of Georgia, United States
Abstract: Parasites incur fitness costs on their hosts, and hosts manage these costs using a wide range of strategies. These strategies can be studied by observing host life history, the changes an individual undergoes during its lifetime. Among life history traits, those associated with reproduction and growth represent a major axis of variation, and these traits can be summarized along an organismal pace-of-life continuum.We propose that large-scale data on organismal pace of life can be used to predict and explain the risk of parasitism hosts may face at a global scale. In order to study this phenomenon using existing datasets, we suggest using parasite species richness as a measure of the pressure that a host may experience from parasites over its lifetime. Furthermore, we predict that patterns for macroparasites (helminths, arthropods) and microparasites (viruses, bacteria, protozoa) may differ due to differences in parasite life history strategies and detection biases. For tractability, we restricted this analysis to mammalian hosts to control for taxonomic differences and to take advantage of existing data on parasites in mammalian hosts.
We used CLOVER, an aggregate of multiple databases that record host-parasite association records, to estimate parasite species richness. Life history characteristics were gathered from existing life history databases such as PanTHERIA which includes data on traits such as max longevity, age at first reproduction, and litter sizes. Life history metrics such as generation time and mean sexual reproductive rate will also be calculated using life table data from the COMADRE database. Using these data, we used Boosted Regression Trees to predict parasite species richness according to host life history traits. The results of this analysis allowed for detection of patterns between host life history and parasite species richness in total and across parasite types.
Preliminary results show that patterns in parasite species richness are difficult to detect for all parasites, but that microparasite and macroparasite species richness may show contrasting patterns. Along a fast-slow pace-of-life continuum, we find that macroparasite species richness is greater in slower pace-of-life compared to faster pace-of-life hosts, but microparasite species richness shows the opposite effect; microparasite species richness is greater in host species with traits associated with a faster pace-of-life. Host life history can be predictive of parasite species richness and be used to study determinants of host susceptibility to novel parasites, helping to inform the zoonotic potential of parasites in wildlife or livestock hosts.
