House sparrows do not exhibit a preference for the scent of potential partners with different MHC-I diversity and genetic distances

Abstract

MHC genes play a fundamental role in immune recognition of pathogens and parasites. Therefore, females may increase offspring heterozygosity and genetic diversity by selecting males with genetically compatible or heterozygous MHC. In birds, several studies suggest that MHC genes play a role in mate choice, and recent evidence suggests that olfaction may play a role in the MHC-II discrimination. However, whether olfaction is involved in MHC-I discrimination in birds remains unknown. Previous studies indicate that house sparrow females with low allelic diversity prefer males with higher diversity in MHC-I alleles. Here, we directly explored whether female and male house sparrows (Passer domesticus) could estimate by scent MHC-I diversity and/or dissimilarity of potential partners. Our results show that neither females nor males exhibit a preference related to MHC-I diversity or dissimilarity of potential partners, suggesting that MHC-I is not detected through olfaction. Further studies are needed to understand the mechanisms responsible for mate discrimination based on MHC-I in birds.

A Gull Species Recognizes MHC-II Diversity and Dissimilarity Using Odor Cues

“…While blue petrels and song sparrows were shown to discriminate MHC-II characteristics using odor cues (Leclaire et al 2017;Grieves et al 2019), house sparrows did not discriminate MHC-I characteristics using olfaction (Amo et al 2022). To estimate the taxonomic range of olfactory assessment of MHC in birds, more avian taxa need to be studied.…”