Undergraduate Research: An Archive - 2022 Program

Aria Buchanan ’22
ECOLOGY AND EVOLUTIONARY BIOLOGY
Senior Thesis Research Funding Awardee
THESIS TITLE
Mapping Variation in
Duffy Blood Group by
Local Environmental
Factors in Northwestern
and Central Kenya
ADVISER
Julien Ayroles,
Assistant Professor of
Ecology and
Evolutionary Biology
and the Lewis-Sigler
Institute for Integrative
Genomics
The Duffy negative genotype confers protection
from Plasmodium vivax malaria by inhibiting
the receptor through which P. vivax invades
red blood cells. Positive selection for the Duffy
negative phenotype has caused high frequencies
of the Duffy negative allele in sub-Saharan
Africa, but differences between local populations
have not been sufficiently studied. My study
mapped allelic variation in 220 individuals from
32 locations in northwestern and central Kenya
by temperature, precipitation and altitude to
understand if differences in local environments
drive selection at the Duffy locus. I hypothesized
that selection for the Duffy negative phenotype
would be greatest in areas most suitable for
malaria transmission on a regional scale.
Polymerase chain reaction (PCR) and gel analysis
showed significantly higher malaria infections in
northern Kenya, but not a higher frequency of the
Duffy negative allele in this region. I found little
variation in allele frequencies between locations,
suggesting that regional environmental
factors do not drive selection at this locus. The
increasing urbanization of central Kenya and
migration of individuals to urban centers likely
explain this genetic similarity. Further studies
should test this hypothesis to better understand
how changing environmental conditions —
including migration and urbanization — shape
Duffy allele selection.
HEALTH AND DISEASE
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