The San Diego Frozen Zoo is the largest collection of animal gene samples in the world, and might be the answer to saving endangered animals from extinction.
A collection of vials containing gene samples from different species of animals. San Diego Zoo. CC BY-NC-ND 2.0.
Although the San Diego Zoo regularly receives a few million visitors every year, very few, if any at all, are aware of a collection much larger than the one on public display. Diligently maintained by a team of dedicated scientists and researchers, the San Diego Frozen Zoo houses gene samples from over 10,000 individual animals, all being preserved in the hopes that they will be able to help resurrect the rapidly dwindling populations of many at-risk species. It is the largest and most diverse collection of its kind in the world, and even includes a sample from the extinct po’ouli bird that vanished in 1988.
This ingenious strategy of species conservation can be traced back to the work of the German-American pathologist and geneticist Kurt Benirschke. He began his collection of skin samples from rare and endangered animals back in 1972 while working as a researcher with the University of California San Diego, and he quickly grew it into the very first cryobank of its kind at the San Diego Zoo. While Benirschke unfortunately passed away in 2018, his legacy is still very much alive in the continuing efforts of the growing team of scientists at the Frozen Zoo, who contribute their expertise on everything from recovery ecology and biodiversity banking to population sustainability and disease investigations.
Kurt Benirschke, the late scientist and founder of the San Diego Frozen Zoo. San Diego Zoo. CC BY-NC-ND 2.0.
Using cutting edge in vitro fertilization technologies, the Frozen Zoo has made huge strides towards developing a sustainable procedure, using artificially inseminating sperm that has been frozen for extended periods of time to produce viable offspring. Early attempts saw the successful development of cheetah and white rhino embryos in the lab, as well as the birth of chicks from a number of pheasant species, all from cryopreserved sperm. Perfecting this method would allow scientists to increase populations of rare and endangered species by introducing animals delivered in vitro back into the wild.
Another strategy the Frozen Zoo is looking into involves the genetic cloning of endangered species using the frozen genetic material in their collection. Since 2001, the zoo has cloned the Black-Footed Ferret, the Indian Gaur (an Asian humpbacked ox), the Banteng (a Southeast Asian species of cattle) and Przewalski’s Horse (a species from Mongolia that was extinct in the wild until not long ago). While their cloning process is still very much in the works, any advances in this type of cloning and genome sequencing can also be used to better understand the biology of endangered species in the wild and help with current conservation efforts.
Scientists from the Frozen Zoo successfully cloned a wild horse (center) believed to be extinct in the wild using cryopreserved sperm. Tanya Durrant. CC BY-ND 2.0.
One of the zoo’s most recent projects has a slightly different focus: they are putting together a database of unique barcodes to help identify species of primates and deer being transported as part of the illegal bushmeat trade. Another recent collaboration with The Scripps Research Institute involves members of the zoo’s Reproductive Sciences and Conservation Genetics teams looking for new state of the art stem cell technologies that could help to revive the critically endangered Northern White Rhino. This collaboration is also just the first step in the zoo’s goal to create a worldwide network of similar cryobanks, which will share knowledge and resources to continue developing an even more diverse bank of genetic material in support of species conservation.
The Frozen Zoo stores thousands of samples of genetic materials in their cryobank. US Department of Agriculture. CC0.
For those interested in getting involved, the zoo runs a number of educational opportunities for high school and college students in the form of fellowships, internships and externships, as well as a master’s degree program in conjunction with Miami University, Ohio. They also have a regular schedule of seminars run by various experts in the field which are open to the public.
Tanaya Vohra
Tanaya is an undergraduate student pursuing a major in Public Health at the University of Chicago. She's lived in Asia, Europe and North America and wants to share her love of travel and exploring new cultures through her writing.