Both candidate gene and neutral genetic diversity correlate with parasite resistance in female Mediterranean mouflon

Elodie Portanier,Christian Itty,Gilles Bourgoin,Jocelyn Poissant,Maxime Galan,Jeanne Duhayer,Marie-Thérèse Poirel,Mathieu Garel,Daniel Maillard,Slimania Benabed,Sébastien Devillard

doi:10.1186/s12898-019-0228-x

Abstract

BackgroundParasite infections can have substantial impacts on population dynamics and are accordingly a key challenge for wild population management. Here we studied genetic mechanisms driving parasite resistance in a large herbivore through a comprehensive approach combining measurements of neutral (16 microsatellites) and adaptive (MHC DRB1 exon 2) genetic diversity and two types of gastrointestinal parasites (nematodes and coccidia).ResultsWhile accounting for other extrinsic and intrinsic predictors known to impact parasite load, we show that both neutral genetic diversity and DRB1 are associated with resistance to gastrointestinal nematodes. Intermediate levels of multi-locus heterozygosity maximized nematodes resistance, suggesting that both in- and outbreeding depression might occur in the population. DRB1 heterozygosity and specific alleles effects were detected, suggesting the occurrence of heterozygote advantage, rare-allele effects and/or fluctuating selection. On the contrary, no association was detected between genetic diversity and resistance to coccidia, indicating that different parasite classes are impacted by different genetic drivers.ConclusionsThis study provides important insights for large herbivores and wild sheep pathogen management, and in particular suggests that factors likely to impact genetic diversity and allelic frequencies, including global changes, are also expected to impact parasite resistance.

Highlights

Parasite infections can have substantial impacts on population dynamics and are a key challenge for wild population management
For the candidate gene approach, we focused on major histocompatibility complex (MHC) DRB1 class II gene, known to encode for binding proteins presenting extracellular antigens to T-lymphocytes [80] and to be linked to parasite resistance in sheep and mammals
The positive impact of genetic diversity on parasite resistance detected emphasizes the importance of promoting genetic diversity and preventing inbreeding in populations

Summary

Introduction

Parasite infections can have substantial impacts on population dynamics and are a key challenge for wild population management. Parasites are an important component of ecosystems and can have substantial impacts on host fitness and population dynamics. While parasitism causes significant economic losses in animal production around the world (e.g. gastrointestinal nematodes (GINs)) [10, 11], in wild populations its impact on individual and population. The influence of genetics on parasite resistance is mediated by other extrinsic and intrinsic factors such as population density, environmental conditions, age, sex and body condition [18, 20,21,22,23]. In the current context of habitat fragmentation [24, 25] impacting population sizes, gene flow and genetic diversity [26,27,28] and of climate change

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Discussion

Conclusion