Undergraduate Research: An Archive - 2022 Program
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Emily Yu ’22<br />
ECOLOGY AND EVOLUTIONARY BIOLOGY<br />
Senior Thesis <strong>Research</strong> Funding Awardee<br />
THESIS TITLE<br />
The Relationship<br />
Between the Gut<br />
Microbiome and<br />
Immunity Phenotypes in<br />
Northern Elephant<br />
Seals (Mirounga<br />
angustirostris)<br />
ADVISER<br />
Bridgett vonHoldt,<br />
Associate Professor of<br />
Ecology and<br />
Evolutionary Biology<br />
Pups of the northern elephant seal (Mirounga<br />
anguistirostris) offer a unique opportunity to<br />
explore host-pathogen-microbiome interactions.<br />
My research assessed gut microbiome<br />
differences between pups infected with<br />
lungworm (Otostrongylus circumlitus) and<br />
uninfected pups. Alpha- and beta-diversity<br />
metrics were conducted to identify the factors<br />
driving differences in microorganism diversity.<br />
Taxonomic composition and differential<br />
abundance analyses also were conducted to<br />
investigate microbiome composition. There was<br />
conflicting evidence to support the hypothesis<br />
that infected pups would exhibit dysbiosis,<br />
which is decreased microbial diversity with an<br />
increased abundance of pathogenic bacteria.<br />
While infected pups had a higher abundance of<br />
the pathogenic bacterium Edwardsiella tarda,<br />
they also exhibited greater median richness<br />
and evenness, had the same core microbiome<br />
as uninfected pups, and possessed a significant<br />
increase of a commensal bacterium Odoribacter.<br />
My findings also showed that both extrinsic and<br />
intrinsic factors drove beta-diversity differences<br />
and that, surprisingly, an environmental factor<br />
(county of stranding) explained the greatest<br />
proportion of variance.<br />
HEALTH AND DISEASE<br />
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