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

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.

Spatial aggregation in small spring-fed tributaries leads to a potential metapopulation structure in a parasitic fish leech

“…2009; Dharmarajan et al . 2016) or at large spatial scales (on the order of 100–1000 km) (McCoy et al . 2003).…”

Prevalence and diversity of piroplasms and ticks in young raccoons and an association of Babesia sensu stricto infections with splenomegaly

“…The tick species found on our young raccoons from Minnesota are commonly reported on raccoons (Dennis et al 1994; Ouellette et al 1997; Hersh et al 2012). Ixodes texanus was the most common and abundant tick found on the raccoons which was expected as this species is found on host's year-around and is assumed to be acquired within the nests of their vertebrate hosts (Sonenshine, 1993; Dharmarajan et al 2016). This tick species has a widespread distribution in the USA (Eastern and Midwestern USA, California, and Alaska and likely many states in between) (Ouellette et al 1997; Gabriel et al 2009; Durden et al 2016).…”

High levels of inbreeding with spatial and host‐associated structure in lice of an endangered freshwater seal

“…Spatial population‐genetic differentiation in host‐specific parasites is expected to be influenced by the dispersal patterns of their host species, but spatial structuring can be either weaker or stronger than in the hosts (Cole & Viney, 2019; Dharmarajan et al, 2016; Mazé‐Guilmo et al, 2016; McCoy et al, 2005; Sweet et al, 2020). Weaker differentiation is expected if the parasite species also utilizes intermediate hosts or other host species, has a large effective population size in relation to its host, or if it has a complex life cycle with a highly dispersive life stage (Blasco‐Costa & Poulin, 2013; DiBlasi et al, 2018; Solórzano‐García et al, 2021).…”

“…Spatial population-genetic differentiation in host-specific parasites is expected to be influenced by the dispersal patterns of their host species, but spatial structuring can be either weaker or stronger than in the hosts (Cole & Viney, 2019;Dharmarajan et al, 2016;Mazé-Guilmo et al, 2016;McCoy et al, 2005;Sweet et al, 2020) et al, 2016).…”