Rhinos, Reproduction, and Receptors
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SAN D I E G O Z O O ’ S I N S T I T U T E F O R C O N SER VATION RESEARCH SPRING 2010
Rhinos, Reproduction, and Receptors:
Trying to Solve a Conservation Riddle in a Test Tube
Christopher Tubbs, Ph.D., Postdoctoral Associate, Reproductive Physiology Division
W
hy do fewer than one in ten female southern white rhinoceroses
born in captivity reproduce? This question has puzzled researchers
for decades. At the San Diego Zoo’s Institute for Conservation
Research, Dr. Matthew Milnes and I are trying to answer it in a way that might
surprise you. Unlike many researchers you may have read about, we don’t travel
to exotic locations to conduct our research. We don’t chase wild rhinos through
the bush and, thankfully, they don’t chase us! Instead, we are answering this
important question using a test tube.
CONTINUED ON PAGE 2
The southern white rhinoceros
is one of our greatest conserva-
tion successes. Hunted to near
extinction in the early 1900s,
protection of the final 100 indi-
viduals allowed their numbers to
reach 18,000 today. Breeding
colonies were also established at
zoos around the world as insur-
ance policies against future pop-
ulation collapses. The San Diego
Zoo’s Wild Animal Park is the
world’s leader with more than
88 white rhino calves born since
the early 1970s. But as years
passed, it became clear that
although wild-caught female
rhinos from Africa (called the F0
generation) reproduced well here
and in zoos around the world,
their captive-born daughters
(called F1) did not. Now captive
populations are declining, as
most of the original F0 females in zoos are deceased or past to a key opening a lock, estrogen unlocks its receptor to elic-
reproductive age. We are at risk of having our insurance it its effects. However, whereas estrogen production is
policy lapse. precisely controlled, estrogen receptors are somewhat pro-
Exactly what causes F1 infertility remains a mystery. We miscuous. They can mistakenly bind to either man-made or
know the problem is not behavioral. In fact, F1 females natural chemicals, tricking tissues into thinking estrogen is
engage in reproductive behavior just like F0 females, and present when it is not. This may prove detrimental. In other
males are equally eager to breed with any female, regardless species, the reproductive problems we see described in F1
of her birthplace. We also know infertility is not the only rhinos are caused by fetal exposure to high levels of estro-
problem more widespread in F1 females than in F0 females. gen. Therefore, we think F1 females were exposed to estro-
Reports abound in the zoo community of malformed repro- gen as fetuses, resulting in their infertility.
ductive tracts, hormonal imbalances, and higher incidences So where did the estrogen come from? It probably came
of reproductive tumors. Interestingly, these ailments have a from their mothers. F0 rhinos were not fed large quantities of
common thread: they can each be tied to exposure to the estrogen, but they did eat hay and commercial pellets. Read-
hormone estrogen. ing the ingredients in pellets reveals that they are made from
Estrogen controls many processes, including reproduction. soy and alfalfa plants. Both are rather nutritious, but they
Like all hormones, estrogen is made in one part of the body also contain high amounts of phytoestrogens. Contrary to
and travels through the blood to the tissues it regulates. When what their name implies (phyto = plant), phytoestrogens
estrogen reaches the tissue, it binds a receptor. Very similar aren’t actually estrogen but are plant compounds that mimic
How YOU Can Help Rhinos!
The Institute depends on the generous support of individuals, corporations, and foundations to carry out our ongoing work on
behalf of endangered species and habitats. Here are just two items that will immediately help our rhino reproduction research:
High Performance Liquid Chromatography Kit – $5,000 Travel for Multi-National Study – $2,000
This kit is used to identify compounds in the diets of captive These travel funds will be used to continue a multi-institutional
white rhinos that are likely to interfere with successful repro- and multi-national study of the effects of phytoestrogens on rhino
duction, such as those most likely to mimic estrogen. Once reproduction. The reproductive problems in captive-born white
these chemical compounds are identified, we can make rhinos are not unique to the San Diego Zoo, so we hope to
recommendations about optimal rhino diets. establish a collaborative program to improve rhino reproduction
in zoos around the world.
2 CONSERVATION UPDATE
estrogen. While some Meet a Conservation Researcher
species can consume
soy and alfalfa with- CHRISTOPHER TUBBS, Ph.D.
out any problems,
other species cannot.
We suspect that white
rhinos may belong to
T he great thing about going to college is meeting that life-
changing professor who is so enthusiastic about their field
that it just lights a fire in your belly, raises more questions than
the latter group. answers, and sends you on your life’s journey. So it was for post-
To test our idea, we doctoral associate Dr. Christopher Tubbs as an undergraduate at
start with small piec- the University of Florida studying the effects of chemicals on alli-
es of rhino tissue, gators and fish in Biology 101. “Being a student of Dr. Lou Guillette
compliments of the had a huge influence on my career,” said Chris. “He is such a
Wild Animal Park’s dynamic and accomplished professor that he really motivated
veterinary examina- me not only to pursue my own research questions but also to
tions, our pathology eventually become a professor myself. I just hope I can pass along
department, or even that passion for conservation to my students!”
Growing up in Englewood,
the Frozen Zoo. We
Florida, a stone’s throw from the
then isolate the
beach, it’s no wonder Chris en-
genetic material that
joys fishing, boating, surfing,
encodes rhino estro-
and just about anything to do
gen receptors and
with water. He left the Sunshine
use it as a template State to pursue his graduate de-
to produce large gree at the University of Texas–
quantities of actual receptors. We mix the receptors and Marine Science Institute and
phytoestrogens in a test tube and see how well they bind studied fish reproduction, which
each other. This tells us how well the phytoestrogens act led to his interest in hormone
as “keys,” fitting into the estrogen receptor “lock.” The better receptors (see article). Today,
they fit, the more likely they are to have harmful effects on his work at the Institute for Conservation Research combines his
developing rhinos. interest in the effects of environmental chemicals on an animal’s
We haven’t yet solved the F1 mystery, but we have made hormone receptors and a deep commitment to conservation.
important progress. Ours were the first researchers in the world “The great thing about working at the Institute is that we ad-
to isolate rhino estrogen receptors. Our test tube approach is dress important questions in a unique way, using the expertise
the first of its kind to be applied to conservation science. It is a from a variety of fields,” said Chris. “It’s a collaborative effort, and
powerful tool that allows us to assess risks that chemicals pose we are making progress in understanding the complexities of how
to reproduction in endangered species. Better yet, we never hormones, receptors, and phytoestrogens interact and influence
expose an animal to chemicals, and this approach is applicable an animal’s ability to reproduce. For instance, a tiny, noninvasive
to any chemical and any species. Since hormones and receptors sample from an endangered southern white rhino allows us to
work the same way in most species, all we need is a receptor make discoveries back in the lab using methods new to conserva-
and a clean set of test tubes to solve our next conservation tion research.”
problem. That is, of course, after we finish tackling—and That’s not to say Chris has always worked in the comfort of a
laboratory. Back in his Florida days, he took his now-wife on a date
solving—the rhino reproduction question!
to catch alligators in the swamp, a feat best tackled late at night.
As the airboat purred up the channel, spotlight scanning for the
red reflection of a gator’s eyes, Chris was lying over the bow of the
boat, poised to grab a juvenile alligator (approximately 3- to 4-feet
long) with his bare hands, wrestle it into the boat (without letting
go of its jaws), quickly measure it and take biological samples,
then release it. Perhaps he wanted to dazzle the damsel on the
Contact the Zoo Today
boat, or just beat the hand-grab record, but Chris found himself
If you are interested in supporting
this program, please contact landing a much larger alligator—6.175 feet long!—and breaking
Julie Denman in the San Diego the hand-grab record. Did that seal the deal with his girlfriend?
Zoo’s Development Department at “Well, I don’t think so…I heard the word ‘stupid’ a lot that night,”
760-747-8702, ext. 5762, or send an Chris said. Yes, yet years later, they’re happily married and have a
E-mail to jdenman@sandiegozoo.org. daughter. That’s the great thing about following your dreams.
SPRING 2010 3
The Koalas of St. Bees Island:
Lending Conservation a Hand
William A. Ellis, Ph.D., Clark Endowed Conservation Research Postdoctoral Fellow
S
ix or seven times each year, I take a small team made up of volunteers, living on the mainland, especially motor
park rangers, researchers, and San Diego Zoo keepers to remote vehicles and dogs—the main causes of
St. Bees Island for a two-week visit. As the island is only accessible by mortality for koalas in Australia.
Thanks to the generosity of longtime
small boat and only during high tide, casual visitors are by necessity kept to a
San Diego Zoo friends and donors Dallas
minimum. Because of its remote nature, good preparation is essential and all and Mary Clark, I am currently working
the supplies needed for each trip must be carefully planned out in advance. on St. Bees, conducting postdoctoral
studies focusing on koala tree use, spatial
relationships, breeding behavior, and
Once on the island, our team either lives Despite their broad appeal, significant communication. Koalas on St. Bees Island
on the boat or rents one of the two houses gaps in our knowledge of this species eat leaves from blue gum trees (eucalyp-
on St. Bees. But with a wife and two small remain that pose big challenges for the tus), and it is from these trees that the
children over 660 miles away in Brisbane, conservation and management of the research team and I usually capture them.
just what am I doing here? koala and its habitat. Early in the last cen- Waving rags attached to long poles above
The iconic koala is one of Australia’s tury, koalas were introduced to a small the koalas, we manage to distract them,
most recognizable symbols, but its sur- island, St. Bees, approximately 12 miles encourage them to descend, and ulti-
vival hangs in the balance. Formerly off the coast of central Queensland, where mately catch them in cloth bags. Once
thought to be common and widespread, they still exist in harmony with their caught, we weigh them, assess their health
koalas are now vulnerable to extinction environment. Here they have remained status and body condition, and collect
across much of their northern range. free from the dangers associated with samples to investigate the presence of
4 CONSERVATION UPDATE
disease. Before releasing each koala How YOU Can
(pictured at right and below), we outfit Help Koalas!
him or her with a Global Positioning
System (GPS) collar that enables us The Institute depends on the
to track and monitor their movements generous support of individuals,
upon release. During the course of our corporations, and foundations
studies, we have developed groundbreak- to carry out our ongoing work
ing research tools, including using cell on behalf of endangered species
phone technology to continuously moni- and habitats. Here are just two
tor the sound environment on the island items that will immediately help
while we are away. our koala behavior research:
At the beginning of the study, I asked
very simple questions, such as how many Koala GPS Collar Refurbishment –
$440 per collar for 12 collars
trees does a koala need to survive on the
Koalas on St. Bees Island are remotely
island? It was strange to think that this monitored using GPS collars. These are
basic element of their biology could still placed on 12 koalas at a time and help
be unknown after many years of study. our researchers determine where and
Once these fundamental questions were how far they move during both breeding
and nonbreeding seasons.
resolved, I then wanted to know when
and why koalas share trees, and why they this goal. By investigating the seasonality EvaPower Solar Panels – $1,330
sometimes use trees that they do not eat of koala births on St. Bees and applying Wireless Internet Connection – $1,500
from. Over time, I have been able to ad- our knowledge to other sites, we have Mobile Wireless Modem – $480
dress more complex questions relating to discovered a significant relationship be- Currently, koalas on St. Bees are
remotely monitored at night using solar-
home range use and sociality. Putting all tween koala births and rainfall in central powered mobile phones that upload
the pieces together has resulted in a Queensland. This finding is likely to be sounds from the island for 2 minutes at
much deeper understanding of koala crucial to understanding the impacts of 30-minute intervals. The koalas’ bellows
breeding biology. climate change on many different Austra- and other noises are automatically
lian species. detected and monitored using software
custom built for this application.
Our research has highlighted the key
factors needed to protect koala habitats Contact the Zoo Today
and plan for the long-term future of wild If you are interested in supporting
populations. While this is something we our research to secure the future
can all celebrate, there is still plenty of for koalas on St. Bees and in other
parts of Australia, please contact
work to be done. Until the koala is secure Julie Denman in the San Diego
in the wild, effective conservation re- Zoo’s Development Department at
search will remain vital to their survival. 760-747-8702, ext. 5762, or send an
At the end of the day, the great thing E-mail to jdenman@sandiegozoo.org.
for me is to see a research project truly
mature. This is what the postdoctoral
support from the San Diego Zoo has fa-
cilitated for me on St. Bees Island. Long-
Taken together, our work has under- term studies require funding partners
scored the importance of the St. Bees with foresight who can see that it takes
Island koala population, resulting in the time to gather information on life histo-
Queensland Government recently declar- ries of long-lived animals. We have now
ing St. Bees a National Park. Yet a pri- been able to develop a comprehensive
mary objective of our research program understanding of how koalas use their
has been to contribute to the successful landscape over time. This is critical for
conservation and management of koalas the conservation of koalas and highlights
across their entire range, not just on St. the essential conservation work under-
Bees. As we have developed our knowl- taken by the San Diego Zoo’s Institute
edge base, we are proud to have achieved for Conservation Research.
SPRING 2010 5CONSERVATION EDUCATION
A Summer Camp Like No Other
Maggie Reinbold, Conservation Program Manager, Conservation Education Division
“Tell me and I’ ll forget; show me and I may remember; involve me and I’ ll understand.” — Chinese Proverb
how to frame content Feedback from our most valued critics,
standards in the context our teacher participants, has been over-
of wildlife conservation whelmingly positive with comments such
and to challenge stu- as, “This year I will be much better
dents to apply their prepared to implement genetics and bio-
textbook knowledge of diversity in hands-on, minds-on ways that
biology and chemistry will grab the students’ attention,” and “It
to issues relating to was an amazing experience for me and has
saving biodiversity. For added so much to my teaching and passion
example, as a model for for the subject of conservation.” Destined
teaching students vari- for further expansion and enhancement in
Zachary Sheffer
ous research methods, the future, this unique opportunity, just
our teachers are trained for teachers, is truly a summer camp like
to use differing strategies no other!
for these projects: This program is made possible through
I
t all began with a simple idea and 12 Explain the role of hormones in regulat- generous contributions from the Bank of
eager participants back in the summer ing conditions in the body by running America Foundation, the Arthur Vining
of 2006. The San Diego Zoo’s Institute hormone assays and urine samples from Davis Foundations, and the Life Technologies
for Conservation Research invited a dozen female African elephants at the Wild Foundation. Participating teachers receive a
high school life science teachers from all over Animal Park, which are assessed for stipend to cover transportation costs, and all
San Diego County to the Beckman Center reproductive status. workshop room and board is included. Inter-
to experience a day in the life of a conserva- Consider global amphibian decline and ested teachers are encouraged to visit our
tion biologist. The pilot program focused on the role of the chytrid fungus as a way to Web site at www.sandiegozoo.org/conservation
the conservation history and recovery of discuss how we diagnose and combat dis- for more information and to download
the California condor and was designed to ease and the role that infection plays in application materials.
bring topics of conservation science into the body.
local classrooms. Study the bushmeat crisis and DNA
Just four years later, we have built a na- barcoding technology to examine the
tionally recognized teacher training program ecological impacts of humans on endan-
with a stellar reputation for giving teachers gered ecosystems and populations as well
access to information and experiences that as how to construct and analyze a phylo-
no other conservation organization offers. genetic tree.
Thus far we have supported 114 middle and Think about the role of chromosomes in
high school life science teachers from 19 determining an individual’s gender, then
counties and 9 states, with an additional 60 examine karyotypes and DNA from Cali-
teachers scheduled to participate in 2010. fornia condor blood samples to ascertain
Our teacher guests are treated to three days gender as an important basis for captive-
in the Conservation Education Lab and two breeding programs.
nights at the San Diego Zoo’s Wild Animal Learn about the California Floristic Prov-
Park, engaging with staff members and ac- ince (our local biodiversity hotspot) as a
quiring new skills that prove invaluable back backdrop for analyzing changes in eco-
Zachary Sheffer
at their home campuses. systems resulting from alterations in cli-
Teachers that participate in this unique mate, human activity, invasive species
professional development opportunity learn introductions and beyond.
6 CONSERVATION UPDATECONSERVATION RESEARCH
Gifts& Grants
The Institute for Conservation Research is grateful to the
following for their support of imperiled species:
The Allen Charitable Lead Annuity Trust gave to giant panda
research. A gift from Florence “Sis” Andrews purchased an
ultracold freezer for the Reproductive Physiology Division. The
Armstrong McDonald Foundation and an Anonymous Founda-
tion gave in support of the Reproductive Physiology Division. The
Beckman Coulter Foundation gave to the Conservation Educa-
tion Lab for visits by Orange County high school science students.
Support for the California Condor Recovery Program was made
possible by a gift from Eva and Per Borgstrom. The James &
Katherine Colachis Fund at the San Diego Foundation gave in
support of conservation research. A grant from the Virginia
Friedhofer Charitable Trust will support two Friedhofer Summer
Conservation Fellows for 2010. The Heller Foundation of San Diego gave a
grant for a Bud Heller Conservation Fellow at the Wildlife Disease
Achievements
Labs for one year. Grants from the Paula and Oliver Jones Foun-
dation, Northrup Grumman Foundation, and Carl E. Wynn
Foundation will bring science students from area schools to the
Conservation Education Lab. The Caesar Kleberg Foundation
for Wildlife Conservation provided funding for the purchase of
HONORS AND AWARDS equipment for a number of genetic characterization studies in the
San Diego Zoo was selected as one of the Director’s Recycling Award Genetics Division. A grant from the Life Technologies Founda-
winners for the City of San Diego’s 2009 Waste Reduction and Recycling tion will make possible a Summer Biology Workshop for middle
Awards Program. This is our 11th year winning this award! school teachers at the Conservation Education Lab. The Gilbert
J. Martin Foundation and the Donald and Marie Van Ness Fund
Director of the Wildlife Disease Laboratories Dr. Bruce Rideout was appointed
at the San Diego Foundation gave toward the summer college
to the board of the University of California Veterinary Medical Center here in
student fellows program for 2010. The Money/Arenz Foundation
San Diego. The UCVMC-SD is a cooperative program of the UC Davis
gave a grant to provide GPS collars for the Andean bear recovery
School of Veterinary Medicine, UC San Diego Health Sciences, and animal
program in Peru, and the C. Neil and Carolyn S. Norgren Foun-
institutes of the San Diego region, and is designed to promote interdisciplin-
dation gave for veterinary supplies for the program, both through
ary teaching, research, service, and outreach for the region.
the Applied Animal Ecology Division. The Moore Family Founda-
Dr. Allan Pessier, scientist in the Wildlife Disease Laboratories, has been tion completed its commitment to aviary construction for the
invited by the leading journal Science to provide expert commentary on Hawaii Endangered Bird Conservation Program. Jean Pierre
major publications in the field of amphibian disease and conservation. Nagy made a gift in memory of John Kearin, in support of the
cheetah research station. Dr. Geoff Pye made a gift in support of
collection health research. The J. V. Schiro Zavela Foundation
THE SCIENCE OF SAVING SPECIES™
gave to the California Condor Recovery Program. The Schlum
Lamere, S. A., J. A. St. Leger, M. D. Schrenzel, S. J. Anthony, B. A. Rideout, Charitable Trust gave a grant for a seed banking fellowship
and D. R. Salomon. 2009. Molecular characterization of a novel gammaretro- through the Applied Plant Ecology Division. Grants from the
virus in killer whales (Orcinus orca). Journal of Virology 83: 12956-12967. Sonny Foundation and the John and Beverly Stauffer Founda-
This article is the first report of a retrovirus in a cetacean. It provides tion will advance conservation of endangered species through the
important insights into the evolution of the host-virus relationship, and Genetics Division. Dr. Meg Sutherland-Smith made a gift in
will ultimately help marine mammal veterinarians provide better care for support of equipment needs for the Andean bear project in Peru.
these animals.
Melzer, A., and W. A. Ellis. 2009. Integrating research and conservation land
management: A case study from koala research in St. Bees Island National
Park. Australasian Journal of Environmental Management 16: 236-241.
This paper details how research and management can be integrated using
koalas on St. Bees Island as a case study. We show how science and policy
can be coordinated through a multilevel partnership to achieve effective
conservation outcomes.
Swaisgood, R. R., F. Wei, D. E. Wildt, A. J. Kouba, and Z. Zhang. 2009.
Giant panda conservation science: how far we have come. Biology
Letters. Published online October 28, 2009, doi 10.1098/rsbl.2009.0786.
This publication is the outcome of a special symposium at the 2009
International Congress for Conservation Biology in Beijing. Here we discuss
recent advancements in panda conservation science and suggest that the
way forward is more direct application of emerging science to management
and policy.
SPRING 2010 7Zoological Society of San Diego Non-Profit Organization
Development Department U.S. Postage
Post Office Box 120551 PAID
San Diego, California 92112 San Diego, California
Permit Number 410
What’s New
IN CONSERVATION RESEARCH
Central Africa Program to EDITOR
develop a molecular diagnostics Mary Sekulovich
laboratory at the Limbe Wildlife
EDITORIAL ASSISTANT
Centre in Cameroon to treat Betsy Sanders
and manage primates for future
SPECIAL THANKS TO
reintroduction to the wild. CONSERVATION UPDATE
l CONTRIBUTORS
Allison Alberts, Ph.D.
Collaborative studies have Karyl Carmignani
demonstrated for the first time Julie Denman
that female giant pandas use William A. Ellis, Ph.D.
acoustic signals to advertise Georgeanne Irvine
their breeding status to males Judy Kinsell
and that males perceive these Matthew Milnes, Ph.D.
differences, allowing them to Maggie Reinbold
time the female’s fertile phase. Jennifer Tobey
Christopher Tubbs, Ph.D.
l
With partner Nature and Culture GRAPHIC DESIGN
CPG Design
International, plans unfolded
to construct a new palm propa-
K ey data from our behav- sequencing, amphibian biology, PHOTOGRAPHS/
gation center in the Sierra de ILLUSTRATIONS
ioral ecology field studies and invasive species.
Ken Bohn
were presented at an Australian Alamos Reserve in Mexico,
l William A. Ellis, Ph.D.
government workshop focused where we are currently working Zachary Sheffer
Reproductive Physiology re- with local communities to
on the potential listing of the searchers successfully recovered develop sustainable harvesting
koala as an endangered species preimplantation embryos from strategies.
at the national level. black bears in South Dakota to
l identify paternity and test the For more information about
A National Science Founda-
hypothesis that each recurring the San Diego Zoo’s global
estrus during a single breeding conservation efforts and
tion workshop on Extinction,
season can produce offspring. how you can join us in our
Genomics, and Conservation fight against extinction,
was hosted at the Beckman l
please visit our Web site,
Center that brought together Scientists in the Wildlife Disease www.sandiegozoo.org/ Zoological Society of San Diego, 2010.
All rights reserved.
diverse experts in genome Laboratories teamed with our conservation.You can also read
