a postdoctoral fellow at the American Museum of Natural History
from 2000-2001, was born in Munich, Germany. As a girl, she
wanted to become a medical doctor, like her father, but he
counseled her against it. So when Claudia enrolled at the
University of Munich, she decided to study biology, with
a major in zoology and minors in biochemistry, human genetics,
and ecology. In her research for her Master's thesis, Claudia
used DNA sequencing to explore the evolution of small freshwater
The evolution of
species is normally represented as a tree of forked lines,
with new species branching out from older ones. Once separated,
these branches do not connect again, because different species
do not interbreed. But under a theory called reticulate evolution,
interbreeding can occur between closely related species,
which means the evolutionary tree can sometimes look like
a web (reticulate comes from the Latin word for net).
To find evidence
for reticulate evolution, one would have to look at a species'
DNA, because animals exchange genes when they interbreed.
Claudia focused on related species of the genus Daphnia ,
which were thought to have evolved by reticulation. She sequenced
DNA samples from several individuals in each species to look
for signs of past or present interbreeding. "Sequencing
then was not like it is today," she remembers. "It
was such a hassle, and it took so long." Though Claudia
was working less than a decade ago, DNA sequencing technology
was far less automated than it is today, and much more laborious.
Since her supervisor
was not trained in molecular biology, Claudia had to figure
out what she was doing as she went along. Ultimately she
got what she needed: enough lab experience to continue her
research after graduation.
Daphnia for another year, Claudia entered a Ph.D. program.
For her doctoral research, she continued to explore the process
of evolution, particularly speciation, or how one species
might evolve into two separate ones. The most common cause
of speciation is that animals from a single species become
separated geographically. Because they are no longer able
to interbreed, they evolve along different paths. This is
called allopatric evolution.
Claudia was interested
in a less popular theory, called sympatric evolution. According
to the sympatric theory, animals can go down different evolutionary
paths without being geographically separated. For example,
by developing different feeding habits, two distinct species
of the same fish can evolve in a single lake. But it is hard
to prove that this has happened after the fact. "The
problem with speciation," Claudia explains, "is
that you look at species when they are already present—the
end product. It's hard to see the process." Fortunately,
an animal's genetic history is recorded in its DNA.
to use DNA sequencing to search for signs of sympatric evolution
among Arctic char. "It's a good fish—it tastes
better than trout," she says with a grin. But more importantly—to
an evolutionary biologist at least—it is highly polymorphic,
meaning the species has many forms, or "morphs." In
some places, up to four different morphs of Arctic char live
together in a single lake.
is," Claudia wondered, "are these morphs different
species? And if so, did they evolve in one lake?" If
they had, it would be a clear example of sympatric evolution.
involved traveling to scenic lakes at the base of the Alps
to collect the fish she needed to study. "I really enjoyed
being outdoors," she recalls fondly. "Sometimes,
we would stay at the lake for days. I would walk up in the
mountains, and stay in a little cabin." Being outdoors
made her glad she had chosen to study biology. "It was
a good combination of lab work and leaving the lab to go
out into nature," she says.
Claudia could find only one lake in Germany that had two
morphs of char in it. And even there, she found just eight
samples of one morph—not enough to do a species analysis.
Worse yet, the lakes had been stocked with fish for decades,
so there was no way to know where the char actually came
from. This made them less useful for research, since the
essence of sympatric evolution is that the species must evolve
in the same place.
fish in the alpine lakes had never been stocked, including
the lowly bullhead, a small fish useless to the commercial
fishing industry. Claudia discovered that two groups of bullheads
were living in one very deep lake in Bavaria. One group lived
near the surface, the other 190 meters down, at the bottom
of the lake. If these different behavior patterns had caused
the groups to evolve apart, it would be an example of sympatric
The beautiful lake
was in a national park in Bavaria. "It was very special
just to be there," Claudia recalls. "It was out
of season, and we were the only ones there. It was sort of
like 'our' lake." To gather samples from both groups,
Claudia and her advisor hired a crew with a small, submersible
boat that allowed two people to venture to the bottom of
the lake. "That was fun," she says, though she
admits, "I was scared. It was a tiny little boat. "
When Claudia returned
to Munich and examined the fishes' DNA, however, she found
no genetic difference at all between the two populations.
Furthermore, the fish at the bottom carried a parasite that
could only be picked up near the surface, which meant they
must have been in the shallow part of the lake at some point
in their lives. This was clearly not a case of sympatric
evolution—there were no signs the two groups had begun
to evolve apart at all.
But Claudia was
not finished with her studies of bullheads. Since they live
throughout Europe, Claudia decided to examine the DNA of
bullheads from as many different locations as she could,
to see if the history recorded in their genes showed the
path they took as they first spread across the continent.
Recreating their evolutionary tree could also help reveal
the history of the river systems of Europe.
DNA from bullheads all over Europe and found that they fell
into six groups, each of which had branched off the bullhead
family tree at a different time. Using this genetic evidence,
she concluded that bullheads entered Central Europe from
the Black Sea, and then spread west and north. The fishes'
DNA also revealed the effects of the huge glaciers that covered
northern Europe during the Pleistocene Epoch. Bullheads from
areas that had once been covered by ice showed far less genetic
diversity than bullheads from other climates. Claudia concluded
that the bullheads now living in these places had all descended
from a small group of "pioneers" that resettled
there after the glaciers receded.
While deep into
her research, Claudia learned that other researchers were
studying the same fish, including teams from Belgium, France,
and England. "I won the race," she recalls with
a rueful smile. "I couldn't back down—I already
had 400 animals." But she was weary of the frustrations
and competitive nature of academia, and when she completed
her Ph.D., she turned her sights toward private industry.
Though her friends
were landing good jobs with biotech companies in Munich,
Claudia's thoughts were on America. Claudia had stayed in
Munich to finish her Ph.D., but she now wanted to live in
the U.S. She set herself a time limit of three months—the
length of a tourist visa—to find a job; if she didn't,
she would go home. Fortunately, while visiting New York she
was offered a year-long postdoctoral position at the American
Museum of Natural History, so she moved to Manhattan.
while at AMNH, Museum Curator Rob DeSalle, not only does
research in molecular evolution and co-directs the Museum's
molecular labs, but also serves as a scientific consultant
for the Museum's children's magazines, teachers' guides,
books, online professional development courses like this
one, and the children's website, OLogy . Claudia's responsibilities
included sharing Rob's duties as an advisor for these projects.
The shift from
research to education brought new challenges as well as new
satisfactions. Though Claudia was familiar with the elaborate
review process required for scientific publications, she
was surprised to find the process of creating publications
for children just as rigorous. Every word has to be revised,
tested, and rewritten for young readers by an editorial team
with experience in children's publications. She can express
herself more freely writing for the online genetics course,
because she can write essays at an adult level on subjects
that especially interest her. "The purpose of the course
is to give people a solid, informed basis to talk about issues
like cloning, selecting genes, and assessing risk," she
says. Although the course focuses on ethical questions, Claudia
also draws on her research experience to write about topics
such as the tools and techniques used in molecular labs.
It has been a wonderful
experience sharing her knowledge with others. "In research,
you're always struggling and worrying whether you've read
all the latest publications," she says. She marvels
at her new role as a teacher, saying "For the first
time, you have the feeling that you really know something." Though
she considers herself a shy person, Claudia enjoys discussing
genetics with nonscientists.
After working at
the AMNH, Claudia moved back to Germany in June of 2001 to
work in a bioinformatics research institute. She admits that
the Museum had a strong impact on her career—the Museum's
focus on genomics sparked her interest in working to analyze
genome sequences. She points out that "the bulk of sequences
generated everyday is only raw data and needs interpretation
in order to understand it." Currently she works on the
computational interpretation of bacterial DNA, using computer
programs to find genes in the raw DNA sequence and to infer