MHC variability in an isolated wolf population in Italy

Area of Science:

• Conservation Genetics
• Immunogenetics
• Wildlife Biology

Background:

• Small, isolated populations risk extinction from low genetic diversity, impacting adaptive potential.
• The Major Histocompatibility Complex (MHC) is vital for immunity, typically exhibiting high variability due to pathogen-driven selection.
• The Italian wolf population, isolated and bottlenecked, faces potential genetic challenges.

Purpose of the Study:

• To assess the genetic variability of three MHC class II genes (DRB1, DQA1, DQB1) in the Italian wolf population.
• To investigate the impact of a recent population bottleneck and hybridization on MHC genetic diversity.
• To understand the adaptive potential of Italian wolves concerning their immune system.

Main Methods:

• Analysis of 94 Italian wolf samples for MHC class II gene variability (DRB1, DQA1, DQB1).
• Sequencing of MHC genes to identify alleles and assess selective pressures (dN/dS ratio).
• Genotyping of 12 background microsatellite loci to evaluate population structure and bottleneck effects.

Main Results:

• Italian wolves exhibit substantial MHC variability (6-9 alleles per locus), including novel alleles.
• MHC genes show signatures of historical selection but lack evidence of ongoing selection.
• Genetic variation at MHC and microsatellite loci was not significantly impacted by the recent bottleneck.
• Domestic dog MHC alleles were rare in non-admixed Italian wolves, indicating limited introgression.

Conclusions:

• The Italian wolf population retains significant MHC genetic diversity, crucial for disease resistance and adaptation.
• Despite a severe bottleneck and hybridization, deep introgression of domestic dog MHC alleles has not compromised the native wolf population's genetic integrity.
• The findings support the resilience of Italian wolf MHC diversity and their adaptive capacity.