When are pathogen dynamics likely to reflect host population genetic structure?

Abstract

Does the structure and connectivity of host populations influence the dynamics and evolution of their pathogens? This topical question is the essence of research investigating the ecology of a Pteropus fruit bat and its zoonotic Nipah virus (NiV) published by Olival et al. in this issue of Molecular Ecology. Questioned less overtly, but nonetheless implicit to the study, is “what are the mechanisms underpinning intraspecific host–pathogen congruence (IHPC) of genetic structure?”. Olival et al. investigated the phylogeographical structure of Pteropus medius and NiV isolates across Bangladesh, from areas inside and outside of the Nipah belt—an area where most human spillover events occur. A high degree of host panmixia was discovered, with some population differentiation east of the Nipah belt. NiV genetic structure was congruent with the host. The authors attributed the panmixia and structuring, respectively, to (a) the highly vagile nature of P. medius, and (b) possible differences between bioregions within and outside the Nipah belt. Other potential explanatory mechanisms were acknowledged, including hybridization and transmission mode. This study makes a valuable contribution to a growing body of literature examining IHPC. This has implications not only for pathogen spillover to humans and domestic animals, but more generally for thinking about the mechanisms that underlie patterns of host and pathogen genetic associations.

Parasites as conservation tools

“…Otolith microchemistry uses chemical signatures from bones in the ears of fishes to identify probable geographic origin; this technique is accurate but requires expensive instrumentation (Pracheil et al, 2014;Walther & Limburg, 2012). Results of studies in which otoliths and parasite assemblages were used are highly correlative, allowing use of cost-effective parasite identification to screen large numbers of fishes (Catalano et al, 2014;Pracheil et al, 2014).…”

“…Directly transmitted host‐specific parasites can have evolutionary histories similar to those of their host and thus are most useful for assessing species invasions (Biek, Drummond, et al., 2006; Carver & Lunn, 2020; Jackson & Charleston, 2004) (Figure 2). Parasites transmitted vertically from parent to offspring have demographic histories reflecting that of the host if transmission occurs equally from both parents (Wilfert & Jiggins, 2014).…”

“…For example, genetic information from nematodes infecting Hawaiian stream fishes reflects the hypothesized history of introductions of their non‐native host across the archipelago (Gagne et al., 2018). Discordance between host and parasite evolutionary histories can complicate inferences of host evolution from that of the parasite (Carver & Lunn, 2020; du Toit et al., 2013; Gagne et al., 2015; Olival et al., 2020). Ultimately, consideration of parasite biology is important when selecting parasites as proxies of invasive species history.…”

Ever-increasing viral diversity associated with the red imported fire ant Solenopsis invicta (Formicidae: Hymenoptera)

“…Figure S1). Interestingly, while Ascunce, Yang (18) suggested an introduction event from California into Taiwan, the virus recovery from Taiwan clustered with those from Mississippi and Florida, suggesting that other more recent introductions may have occurred (64,65).…”

Combining host genetic structure and serology to investigate rabies-related lyssaviruses in the greater mouse-eared bat (Myotis myotis)

“…The spread of viruses across the home range of bat populations has already been described for other pathogens, including lyssaviruses, henipaviruses, coronaviruses and astroviruses (Halczok et al, 2017;Leopardi et al, 2016;Olival et al, 2020;Peel, Sargan, et al, 2013). Unfortunately, the lack of viral characterization in this bat species prevented us to compare the geographical structuring of LYSVs and Myotis myotis , which could help to explain the role of this bat in the dispersal and evolution of EBLV-1 (Carver & Lunn, 2020;Olival et al, 2020). Challenges in the detection of bat viruses are not peculiar to our study or to LYSVs, but are likely related with low prevalence and short shedding period of viruses in these animals and, more generally, in wildlife (Wilkinson & Hayman, 2017).…”