Genomic heterozygosity is associated with parasite abundance, but the effects are not mediated by host condition

Abstract

Whether, when, and how genetic diversity buffers individuals and populations against infectious disease risk is a critical and open question for understanding wildlife disease and zoonotic disease risk. Several, but not all, studies have found negative relationships between infection and heterozygosity in wildlife. Since they can host multiple zoonotic infections, we sampled a population of wild deer mice ( Peromyscus maniculatus ), sequenced their genomes, and examined their fecal samples for coccidia and nematode eggs. We analyzed coccidia infection status, abundance, and coinfection status in relation to per-locus and per-individual measures of heterozygosity, as well as identified SNPs associated with infection status. Since heterozygosity might affect host condition, and condition is known to affect immunity, it was included as a co-variate in the per-individual analyses and as response variable in relation to heterozygosity. Not only did coccidia-infected individuals have lower levels of genome-wide per-locus diversity across all metrics, but we found an inverse relationship between genomic diversity and severity of coccidia infection. We also found weaker evidence that coinfected individuals had lower levels of private allelic variation than all other groups. In the per-individual analyses, relationships between heterozygosity and infection were marginal but followed the same negative trends. Condition was negatively correlated with infection, but was not associated with heterozygosity, suggesting that effects of heterozygosity on infection were not mediated by host condition in this system. Association tests identified multiple loci involved in the inflammatory response, with a particular role for NF-κB signaling, supporting previous work on the genetic basis of coccidia resistance. Taken together, we find that increased genome-wide neutral diversity, the presence of specific genetic variants, and improved condition positively impact infection status. Our results underscore the importance of considering host genomic variation as a buffer against infection, especially in systems that can harbor zoonotic diseases. Supplementary Information The online version contains supplementary material available at 10.1007/s10682-022-10175-8.

Demographic and genetic impacts of powdery mildew in a young oak cohort

“…We can notice, however, that the seedlings with lowest heterozygosity values (PHt inferior to 0.235) were often dead at the end of the experiment, leading to a slight increase of this statistic at the end of the experiment for most families in both exposures. Although a slight effect of multilocus heterozygosity at SSRs was detected on growth traits in Q. robur (Vranckx et al 2014b, less than 5% of total variation explained), and in other species with different reproductive strategies (Cole et al 2016 in Aspen;Stilwell et al 2003 in Castanea dentata), a better resistance or tolerance to pathogen infection for heterozygotes has not been established for plants, contrary to animals (e.g., Budischak et al 2023). Specifically, oaks have generally large populations with a low inbreeding of their seedlings (Gerzabek et al 2020), a genetic context for which HFC is not expected (Slate et al 2004).…”