| The whorled sunflower grows in a rare environment called wet |
prairie. Jennifer Ellis investigates the sunflowers in an Alabama site
where a small population has been found.
(Click image to enlarge)
September 2007 —
For several months last spring, the Vanderbilt greenhouse held more
individual plants of a rare species of native sunflower than are known
to exist in the wild.
This unusual bounty was the result of research being conducted by
Jennifer Ellis, a doctoral student in the biological sciences
The species is called the giant whorled sunflower, Helianthus
verticillatus. It was discovered in 1892 but was thought to be extinct
until 1994 when it was rediscovered in Georgia. Today, it is known to
exist in only four locations in West Tennessee, Alabama and Georgia. It
has been a candidate for listing as a federal endangered species since
In the last four years Ellis has conducted a series of genetic
studies of the whorled sunflower that significantly improve the odds
that this gangly plant will make the endangered species list. Once a
species is listed, the federal government is empowered to take a number
of steps to protect it.
"Her study came at a perfect time and gave us answers that we really
needed," says Cary Norquist, assistant field supervisor and botanist in
the Ecological Services Field Office of the U.S. Fish and Wildlife
Service in Jackson, Miss. Norquist has recommended upgrading the
sunflower’s application for listing from a low to a high priority as a
result of the new information.
One of the questions that Ellis’ research answered was whether the
whorled sunflower was a distinct species or a hybrid of two common
varieties. If it was a hybrid, it would not qualify as an endangered
species. "Her work definitely confirmed that it is a distinct species,"
The other answer that Ellis has provided is a more accurate count of
the number of genetic individuals that exist in the wild. According to
previous estimates, there were several thousand whorled sunflowers
growing in Coosa Valley Prairie in Alabama and Georgia, about 7,000
acres of which is owned by Temple-Inland Inc.
The timber company donated a 929-acre conservation easement on the
most sensitive portion of that area to the Nature Conservancy in 1992
because of the sunflower population as well as the presence of two
other threatened or endangered species (Mohr’s Barbara Buttons and
Tennessee Yellow-eyed Grass). Even though whorled sunflower population
estimates at the other known locations were much smaller, the large
size of the Georgia population plus the conservation easement there
reduced the sense of urgency attached to its case for listing.
The genetic study proved that the field observations of the
sunflower had been misleading. The sunflower propagates clonally as
well as by sexual reproduction. As a result, many stalks that appear to
be individual plants are genetically identical to their neighbors. "I
went out and sampled a whole bunch of stalks and then genotyped them,"
Ellis says. "I found that the whole population in Coosa Valley Prairie
consists of about 20 to 40 genetic individuals. If they have the same
genotype, then they are the same genetic individual. There can be ten
stalks growing together that you would think are ten plants. But, when
you genotype them, you find they are all the same genetic individual."
The fact that there are so few individuals at the Georgia site
increases the importance of protecting the other sites, Norquist says.
One hundred of the plants that Ellis grew in the greenhouse are
adding to the population in a more direct fashion. She gave them to
researchers at Freed-Hardeman University in Henderson, Tenn., who are
restoring a wetland that is a suitable environment for the whorled
sunflower. They will be using the plants in an experiment designed to
identify the environmental variables that have the greatest effect on
the sunflower’s fitness.
The study had a somewhat haphazard beginning. After getting a
biology degree from Carson-Newman College in Jefferson City, Tenn.,
Ellis started her graduate work at Vanderbilt in 2003. "A lot of people
come to graduate school knowing what project they want to do and what
professor they want to study with. I didn’t. I knew I was interested in
conservation biology but didn’t have a project," Ellis says.
She spent time working with several different faculty members and
settled on Professor of Biological Sciences David E. McCauley. "He
works on plant genetics and studies an invasive species, so it was a
good match," she says. When she settled in, McCauley suggested that
they find a project of her own by contacting the state division of
natural areas and asking if they had any research that they needed one
on endangered plant species.
It just so happened that Ellis had a contact in the office: Rare
Plant Protection Program Manager David Lincicome. When she was still in
high school and thinking about pursuing a career in botany, a member of
her church put her in contact with the botanist. "She called me up and
I described the ins and outs of a career in botany," Lincicome recalls.
"I knew she had decided to attend Carson-Newman. Then, four or five
years later, she contacted me about possible projects and I talked to
her about the whorled sunflower. I had an opportunity to get out in the
field with her several times: It’s been a good project."
The study proved to be practical and relatively inexpensive because
Ellis found that she could apply biomarkers that John Burke — a plant
biologist at Vanderbilt who has since moved to the University of
Georgia — had developed for studying commercial sunflowers. It would
have taken Ellis several years and thousands of dollars to develop a
comparable library of genetic markers for the whorled sunflower. But
she tested Burke’s markers and found that they worked with the wild
relative. Her success in applying genetic markers developed for a
commercial plant to a related wild species was the subject of a paper
that she, McCauley and Burke published in the scientific journal
Molecular Ecology in August 2006.
"I’ve given her advice from time to time, but this has been entirely Jennifer’s project," says McCauley.
Source : Vanderbilt University.