Wetter climates select for higher immune gene diversity in resident, but not migratory, songbirds

O’Connor, Emily; Hasselquist, Dennis; Nilsson, Jan‐Åke; Westerdahl, Helena; Cornwallis, Charlie K.

doi:10.1098/rspb.2019.2675

Cited by 19 publications

(21 citation statements)

References 67 publications

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“…In the sections below, we highlight where evidence supports the suggestions that human fungal pathogens will have competitive fitness advantages as their local niches expand bringing them into contact with more people. We will also highlight evidence showing that the number of individuals predisposed to fungal infection will increase, due to increases in primary infections, and how climate change may impact the interactions between pathogens and the host immune system [ 36 ].…”

Section: The Ability To Infect Requires Pathogens To Adapt To a Hostile Host Environmentmentioning

confidence: 99%

The Consequences of Our Changing Environment on Life Threatening and Debilitating Fungal Diseases in Humans

Rhijn

Bromley

2021

JoF

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Human activities have significantly impacted the environment and are changing our climate in ways that will have major consequences for ourselves, and endanger animal, plant and microbial life on Earth. Rising global temperatures and pollution have been highlighted as potential drivers for increases in infectious diseases. Although infrequently highlighted, fungi are amongst the leading causes of infectious disease mortality, resulting in more than 1.5 million deaths every year. In this review we evaluate the evidence linking anthropomorphic impacts with changing epidemiology of fungal disease. We highlight how the geographic footprint of endemic mycosis has expanded, how populations susceptible to fungal infection and fungal allergy may increase and how climate change may select for pathogenic traits and indirectly contribute to the emergence of drug resistance.

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Section: The Ability To Infect Requires Pathogens To Adapt To a Hostile Host Environmentmentioning

confidence: 99%

The Consequences of Our Changing Environment on Life Threatening and Debilitating Fungal Diseases in Humans

Rhijn

Bromley

2021

JoF

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“…One body of evidence for pathogen-driven immunogenetic selection in wild animals comes from the major histocompatibility complex (MHC; Dionne et al 2007 ; Sallaberry-Pincheira et al 2016 ; O’Connor et al 2020 ), which is important for presenting antigens to the adaptive immune system. However, investigating functional genetic diversity in the MHC is challenging in non-model organisms because of the complexity associated with extensive gene duplication and gene loss events ( Cummings et al 2010 ).…”

Section: Introductionmentioning

confidence: 99%

Adaptation and Cryptic Pseudogenization in Penguin Toll-Like Receptors

Fiddaman

Vinkler

Spiro

et al. 2021

Molecular Biology and Evolution

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Penguins (Sphenisciformes) are an iconic order of flightless, diving seabirds distributed across a large latitudinal range in the Southern Hemisphere. The extensive area over which penguins are endemic is likely to have fostered variation in pathogen pressure, which in turn will have imposed differential selective pressures on the penguin immune system. At the front line of pathogen detection and response, the Toll-like receptors (TLRs) provide insight into host evolution in the face of microbial challenge. TLRs respond to conserved pathogen-associated molecular patterns and are frequently found to be under positive selection, despite retaining specificity for defined agonist classes. We undertook a comparative immunogenetics analysis of TLRs for all penguin species, and found evidence of adaptive evolution that was largely restricted to the cell surface expressed TLRs, with evidence of positive selection at, or near, key agonist-binding sites in TLR1B, TLR4 and TLR5. Intriguingly, TLR15, which is activated by fungal products, appeared to have been pseudogenized multiple times in the Eudyptes spp., but a full-length form was present as a rare haplotype at the population level. However, in vitro analysis revealed that even the full-length form of Eudyptes TLR15 was non-functional, indicating an ancestral cryptic pseudogenization prior to its eventual disruption multiple times in the Eudyptes lineage. This unusual pseudogenization event could provide an insight into immune adaptation to fungal pathogens such as Aspergillus, which is responsible for significant mortality in wild and captive bird populations.

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“…But we cannot say whether the absence of a pattern in immune indices suggests the absence of local adaptation to infection risk or similar infection risk or similar response to different infectious agents. Recent multi-species studies on MHC-I diversity suggest that the acquired immune www.nature.com/scientificreports www.nature.com/scientificreports/ system of birds has evolved greater pathogen recognition in wetter tropical environments 82 . So, perhaps, the aspects of innate immune function we considered require greater environmental variability to show significant local variation.…”

Section: Discussionmentioning

confidence: 99%

Geographic variation in baseline innate immune function does not follow variation in aridity along a tropical environmental gradient

Nwaogu

Cresswell

Tieleman

2020

Sci Rep

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Geographic variation in baseline innate immune function does not follow variation in aridity along a tropical environmental gradient chima J. nwaogu 1,2,3,4* , Will cresswell 2,3 & B. irene tieleman 1 Geographic variation in aridity determines environmental productivity patterns, including large-scale variability in pathogens, vectors and associated diseases. If disease risk decreases with increasing aridity and is matched by immune defense, we predict a decrease in innate immune function along a gradient of increasing aridity from the cool-wet forest to the hot-dry Sahel, from south to north in Nigeria. We sampled blood and measured five innate immune indices from 286 Common Bulbuls Pycnonotus barbatus between 6 and 13°N. We sampled in the dry season; we resampled the first location (Jos) also as the last sample location to test temporal change in immune function. immune indices did not decrease with aridity. One immune index, nitric oxide concentration showed a weak quadratic pattern. In Jos, ovotransferrin concentration, haemagglutination and haemolysis titres increased 12 weeks into the dry season, contrary to expectations that immune indices should decrease with increased dryness. In this tropical system, innate immune function does not decrease with increasing aridity but temporal factors within a location may influence immune function more strongly than spatial variation in aridity, suggesting that immune variation does not follow a simple environmental productivity pattern. Consequently, caution should probably be exercised in predicting effects of climate variability on immune function or disease risk. Geographic variation in aridity determines environmental productivity patterns 1,2 , including large-scale differences in infectious diseases 3,4 and/or important vectors for disease transmission 5-7. Consequently, animal distributions are hypothesized to be adapted to variation in disease risk 8-10. These patterns are largely driven by spatio-temporal variability in temperature and precipitation, and they underpin the mechanisms that together or independently shape interactions among infectious agents, vectors and hosts, including host contact rate, susceptibility, infectiousness and immunity 11-13. Assuming that innate immunity-the first line of defense against infection 14 , varies with the risk of infection 15 , we might expect immune investment to decrease with decreasing environmental productivity (or increasing aridity) due to reduced immune challenge 15 or limited resource availability for immune function 16 under similar life history circumstances. Both free living and parasitic species decrease with environmental productivity, and are more diverse in the tropics 7,17-19. This high biological diversity in tropical environments is not only associated with high environmental productivity, but also with the diversity of environmental conditions within the tropics. But despite the understanding that tropical environments are relatively disease prone and capable of imposing higher immune costs compared...

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Wetter climates select for higher immune gene diversity in resident, but not migratory, songbirds

Cited by 19 publications

References 67 publications

The Consequences of Our Changing Environment on Life Threatening and Debilitating Fungal Diseases in Humans

The Consequences of Our Changing Environment on Life Threatening and Debilitating Fungal Diseases in Humans

Adaptation and Cryptic Pseudogenization in Penguin Toll-Like Receptors

Geographic variation in baseline innate immune function does not follow variation in aridity along a tropical environmental gradient

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