SREL Reprint #3355

Genetic co-structuring in host-parasite systems: Empirical data from raccoons and raccoon ticks

Guha Dharmarajan1,2, James C. Beasley1,3, William S. Beatty1,4, Zachary H. Olson1,5, Jennifer A. Fike1,6,
and Olin E. Rhodes Jr.1,7

1Department of Forestry and Natural Resources, Purdue University, West Lafayette, Indiana 47907 USA 2Department of Biological Sciences, Indian Institute of Science Education and Research – Kolkata,
Mohanpur, West Bengal 741246 India
3Savannah River Ecology Laboratory, Warnell School of Forestry and Natural Resources,
University of Georgia, Drawer E, Aiken, South Carolina 29802 USA
4Alaska Science Center, United States Geological Survey, Anchorage, Alaska 99508 USA
5University of New England, Biddeford, Maine 04005 USA
6Fort Collins Science Center, Fort Collins, Colorado 80526 USA
7Savannah River Ecology Laboratory, Odum School of Ecology, University of Georgia,
Drawer E, Aiken, South Carolina 29802 USA

Abstract: Many aspects of parasite biology critically depend on their hosts, and understanding how host-parasite populations are co-structured can help improve our understanding of the ecology of parasites, their hosts, and host-parasite interactions. This study utilized genetic data collected from raccoons (Procyon lotor), and a specialist parasite, the raccoon tick (Ixodes texanus), to test for genetic co-structuring of host-parasite populations at both landscape and host scales. At the landscape scale, our analyses revealed a significant correlation between genetic and geographic distance matrices (i.e., isolation by distance) in ticks, but not their hosts. While there are several mechanisms that could lead to a stronger pattern of isolation by distance in tick vs. raccoon datasets, our analyses suggest that at least one reason for the above pattern is the substantial increase in statistical power (due to the ≈8-fold increase in sample size) afforded by sampling parasites. Host-scale analyses indicated higher relatedness between ticks sampled from related vs. unrelated raccoons trapped within the same habitat patch, a pattern likely driven by increased contact rates between related hosts. By utilizing fine-scale genetic data from both parasites and hosts, our analyses help improve our understanding of epidemiology and host ecology.

Keywords: animal movement; disease ecology; ectoparasite; kin structure; mesocarnivore; microsatellite; parasite; spatial structure; Upper Wabash River Basin

SREL Reprint #3355

Dharmarajan, G., J. C. Beasley, W. S. Beatty, Z. H. Olson, J. A. Fike, and O. E. Rhodes Jr. 2016. Genetic co-structuring in host-parasite systems: Empirical data from raccoons and raccoon ticks. Ecosphere 7(3): e01269.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).