Newell, M. A. | bioRxiv Science

bioRxiv2024

Asymptomatic infection and antibody prevalence to co-occurring avian influenza viruses vary substantially between sympatric seabird species following H5N1 outbreaks

Emerging infectious diseases are of major concern to animal and human health. Recent emergence of high pathogenicity avian influenza virus (HPAIV) (H5N1 clade 2.3.4.4b) led to substantial global mortality across a range of host species. Co-occurring species showed marked differences in mortality, generating an urgent need for better epidemiological understanding within affected populations. We therefore tested for antibodies, indicative of previous exposure and recovery, and for active viral infection in apparently healthy individuals (n=350) across five co-occurring seabird species on the Isle of May, Scotland, during 2023, following H5N1 HPAIV associated mortality in the preceding summer. Antibody prevalence to AIV subtypes varied substantially between species, ranging from 1.1% in European shags (Gulosus aristotelis) (to H5) to 78.7% in black-legged kittiwakes (Rissa tridactyla) (to H16 or both H13 and H16), and between 31-41% for three auk species (H5, H16 or both). At least 20.4% of auks had antibodies to an as yet unidentified subtype, suggesting further subtypes circulating in the population. We found low levels of active, but asymptomatic, AIV infection in individuals (1.6-4.5%), but excluded this as H5N1. Our results emphasise the importance of testing healthy individuals to understand the prevalence of co-circulating AIV subtypes in wild populations, and the potential for future reassortment events which could alter virus behaviour and impact.

ecology↗

bioRxiv2022

Components of micro-evolutionary and phenotypic change in seasonal migration versus residence in a wild population

Dissecting joint micro-evolutionary and plastic responses to environmental perturbations fundamentally requires quantifying interacting components of genetic and environmental variation underlying expression of key traits. This ambition is particularly challenging for phenotypically discrete traits where multiscale decompositions are required to handle non-linear transformations of underlying genetic and environmental variation into phenotypic variation, especially when effects have to be estimated from incomplete field observations. We devised a novel joint multistate capture-recapture and quantitative genetic animal model, and fitted this model to full-annual-cycle resighting data from partially migratory European shags (Gulosus aristotelis) to estimate key components of genetic, environmental and phenotypic variance in the ecologically critical discrete trait of seasonal migration versus residence. We demonstrate non-trivial additive genetic variance in latent liability for migration, resulting in estimated micro-evolutionary responses following two episodes of strong survival selection. Yet, underlying additive genetic effects interacted with substantial permanent individual and temporary environmental effects to generate complex non-additive effects, causing large intrinsic gene-by-environment interaction variance in phenotypic expression. Our findings reveal how temporal dynamics of seasonal migration result from combinations of instantaneous micro-evolution and within-individual phenotypic inertia, and highlight how plastic phenotypic variation could expose cryptic genetic variation underlying discrete traits to complex forms of selection.

evolutionary biology↗