Undergraduate Research: An Archive - 2022 Program

Katherine Irelan ’22
ECOLOGY AND EVOLUTIONARY BIOLOGY
Becky Colvin '95 Memorial Recipient; Senior
Thesis Research Funding Awardee
THESIS TITLE
How a Plant Survives:
The Effect of Soil
Resources on Fungal
Symbionts of a
Hawaiian Ericaceous
Shrub (L. tameiameiae)
ADVISER
Lars Hedin, George M.
Moffett Professor of
Biology, Professor of
Ecology and
Evolutionary Biology
and the High Meadows
Environmental Institute
Plant-fungal symbiotic relationships are integral
to the survival of plant species. Two fungal
symbiont types, ericoid mycorrhizae and dark
septate endophytes, are not very well understood.
Ericoid mycorrhizae are assumed to be a primary
reason for members of the ericaceous family
— their obligate plant partners — to be able to
survive in a variety of harsh environments that
other plant families are not able to withstand.
Dark septate endophytes commonly occur
in ericaceous roots, but have been shown to
have contradictory effects on plant growth. I
explored how one plant species, Leptecophylla
tameiameiae, adjusts its fungal relationships
in order to grow in a variety of environmental
conditions along a natural rainfall gradient in
Hawaii. I found that the colonization rate of both
ericoid mycorrhizal and dark septate endophyte
remains largely the same across changes in
rainfall, but that the composition of fungal taxa
in L. tameiameiae roots shifts dramatically.
From this, I could conclude that L. tameiameiae
has a consistent reliance on its fungal partners
regardless of environment, but that the function
of those partners likely adjusts based on specific
needs.
WATER AND THE
ENVIRONMENT
36