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Visiting Assistant
Professor
Oberlin College Science Center, #K102
Office Phone: 440/775-8319
Email: Angie.Roles@oberlin.edu
Specialties: Population and quantitative
genetics; spontaneous mutation; molecular ecology.
My current research includes several projects:
1) Molecular ecology of local species of crayfish in the genus
Orconectes. (with Mr. Laushman)
We are studying three species in the genus
Orconectes: O. rusticus (rusty crayfish), O. sanbornii
(Sanborn's crayfish), and O. obscurus (Allegheny crayfish).
These species inhabit adjacent, non-overlapping ranges that
span Ohio, Pennsylvania and West Virginia. During the Wisconsinian
glaciation, about 20 thousand years ago, the distributions
of these species were forced south into glacial refugia. Upon
the recession of the glacier, each species migrated north
as the climate warmed and the modern watershed was established,
eventually filling their current distributions. More recently,
the rusty crayfish has become an invasive species in many
parts of the northeastern and midwestern United States (and
also north into Canada), perhaps spread by its use as bait.
In Wisconsin the rusty crayfish has eliminated native crayfish
species from some habitats. We are studying the mechanisms
of invasion of the rusty crayfish in Ohio, which may include
out-competing the native species for shelter and other resources
and genetic swamping through hybridization with the native
species. We use laboratory designed competition studies to
examine the behavioral invasion mechanisms of the rusty crayfish
(with undergraduate Liz Baird '09). We employ genetic markers,
microsatellites, to study possible hybridization between rusty
crayfish and the native Sanborn's or Allegheny crayfish. These
microsatellite genetic markers are useful also in elucidating
the general population genetics of each species as well as
in studies of paternity analysis (with Ariel Kahrl '09) and
the correlation of genetic diversity with water quality for
each species (honors project: Erica Borg '08).
2) Comparison of genetic variation in the
native swamp rose (Rosa palustris) and the invasive
multiflora rose (R. multiflora). (with Mr. Laushman)
This project also studies invasion biology,
in this case in plant species. Multiflora rose was introduced
into North America for use as a hedgerow/windbreak but has
proven highly successful at spreading from planted locations
to new habitat. In these new habitats multiflora rose forms
dense thickets that may exclude native species and alter the
forest understory species composition. In the Oberlin area,
we have noted multiflora rose growing alongside the native
rose species, swamp rose. These two rose species differ slightly
in morphology: swamp rose fruits (rose hips) are much larger
than those of multiflora rose but multiflora rose has larger
seeds than swamp rose. Given our observation of these two
species in close proximity, we are concerned that they might
be hybridizing. We are using two genetic methods to detect
hybridization. Variation in proteins can be assayed by allozyme
gels and if each species is fixed for different protein variants
we may be able to detect hybridization (with Adrian Oei '09).
Microsatellite genetic markers have recently been developed
for multiflora rose and we are working on amplifying these
markers using PCR in both multiflora rose and swamp rose (with
Nick Bunce-Herring '08). Similar to the allozymes, we hope
to identify alleles that are fixed for each species, thus
we would expect hybrids to show a mix of genotypes.
3) The effect of spontaneous mutation on
gene expression in A. thaliana.
This project is a continuation of my doctoral
work on spontaneous mutation in plants. As the ultimate source
of genetic variation, spontaneous mutation is an essential
part of evolution. However, many aspects of mutation, such
as the rate and average size of phenotypic effect, are not
well understood. Individual mutations usually have very small
phenotypic effects, decrease fitness, and may occur anywhere
in the genome making it difficult to study spontaneous mutation.
In order to increase the visibility of mutational effects,
researchers perform mutation accumulation (MA) experiments
in which they allow mutations that would normally be removed
by natural selection (because most are harmful to an organism's
fitness) to remain in the genome and be passed on to offspring
who may have new mutations of their own. After several generations
(10 or more), each MA genotype (or line) has multiple mutations
and the combined effects on the phenotype (number of seeds,
fruits or flowers produced) may be detectable. Recall that
phenotype is derived from genotype and that to achieve that
final phenotype the organism must translate the genotype into
phenotype through gene expression. Thus, mutations which affect
a phenotype like number of fruits must also affect gene expression
during plant development. I have chosen several MA lines displaying
divergent fitness relative to the un-mutated Ancestor, kindly
provided by Ruth Shaw at the University of Minnesota, and
measured gene expression for all 29,000+ genes of Arabidopsis
thaliana (a small annual plant of the Mustard family,
Brassicaceae). From that data, I have identified a smaller
list of several hundred genes that may display differential
expression in a MA line relative to the expression of that
same gene in the Ancestor. I am now in the process of confirming
causation of the phenotype of interest through specific gene
knockouts and confirming differential gene expression through
quantitative PCR. I do not currently have a student working
on this project. If you are interested please contact me.
I teach courses in the above areas. In fall
of 2008 I will be teaching a first-year seminar, Cats, cattle
and corn: On the origin of domesticated species (FYSP 197)
and an upper-level lab course in Molecular Ecology (Biol 316).
When I'm not teaching or doing research I
enjoy running with my puppies, playing soccer, hiking, and
cooking.
B.S., Wake Forest University, 2000
PhD, Michigan State University, 2007
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