Next Generation Science Standards:
- HS-LS4-1. Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence.
- HS-LS4-6. Create or revise a simulation to test a solution to mitigate adverse impacts of human activity on biodiversity.*
Key Vocabulary: evolution, genetic isolation, common ancestor, herpetologist, DNA, speciation, specimen, developing nation, infrastructure, reptiles, amphibians, biodiversity
How far would you go in the name of science? Would you travel through malaria-infested jungles to gather data? Would you risk the ire of villagers armed with machine guns to collect samples for a study? For Dr. Eli Greenbaum, these are simply job hazards he encounters when studying the reptiles and amphibians in jungles of the Central Africa.
Dr. Greenbaum, a professor of evolutionary genetics at the University of Texas at El Paso, has been using DNA to understand the evolutionary relationships of frogs in the Democratic Republic of the Congo for over a decade. His new book, Emerald Labyrinth: A Scientist’s Adventures in the Jungles of the Congo, recounts his tales of expeditions into the developing nation and reads more like the diary of Indiana Jones than the memoir of a biologist, including adventures such as rediscovering a species of frog thought to be lost to extinction and saving a colleague after he received an eye full of venom from an misidentified cobra.
Though the stories are exciting, reality paints a less glamorous picture. Years of colonial rule by the Belgians and several decades of internal struggles for power has left the Congo with poor roads and infrastructure, unregulated mining and deforestation, and little access to clean water or health care for its citizens. However, despite the logistical challenges of research and the personal dangers to himself, Dr. Greenbaum remains dedicated to cataloging and protecting the species in the region. His work has helped name several new species of amphibians and has been instrumental in conservation efforts. I sat down with Dr. Greenbaum to discuss his research and what makes the jungles of the Congo so special.
Chris Anderson: Of all the things to research in the natural world, why did you choose reptiles and amphibians? What about them did you find so fascinating?
Eli Greenbaum: I think like many other biologists, my fascination with reptiles began as a kid. During visits to the reptile house at the Buffalo Zoo, I was especially fascinated by venomous snakes. The keepers were great and allowed me to watch them eat when the facilities were closed to the public. It was like being transported to another tropical world and I never imagined I would visit where the exotic animals were from.
When I moved to Louisiana to work on my Master’s degree, I was amazed by the huge numbers of frogs that emerged to breed in the spring. The roads in the wildlife refuge I visited were literally crawling with legions of different species of frogs. While working on my Ph.D., my colleagues’ enthusiasm for frogs was infectious. Although snakes remain close to my heart, I now consider myself to be a herpetologist with very broad interests in all species of amphibians and reptiles.
CA: Your work is based on using molecular genetics to understand how these species are related. How do you and your team collect data, especially given the challenges of where you work?
EG: Because of the enormous logistical challenges that are involved when working in Congo, including lack paved roads, bridges, electricity, running water, and medical facilities, we can collect only a limited amount of data in the field. Working with armed escorts in the middle of the jungle makes things difficult, but it’s also essential. Very few biologists are working in Congo nowadays, and I am confident that we are sampling many sites that have never been visited by herpetologists.
When we are in the field, we take photographs, record frog calls, collect DNA samples, and even natural history specimens. We then bring our data back to the laboratory to further understand how the species are related to one another. A big part of our work is sequencing DNA data to try and identify new species to science, which is an exciting discovery every time it happens.
CA: Changes in DNA can result in different traits and adaptations. Can you see how specific changes to the genetic code translates into physical traits?
EG: We don’t link genetic changes directly to physical traits. Instead, we try to look for changes in the DNA to see how closely different species of frogs are related and how long ago their common ancestor lived.
CA: So how has your research changed our understanding of the evolutionary story of these reptiles and amphibians?
EG: The biggest impact of my research has been on our understanding of amphibian and reptile diversity in Central Africa. Because Congo has been so understudied, my research helps to define what are called cryptic species. These species look very similar, even identical to each other, but sometimes DNA sequence data suggest they are unique.
Before we can implement sound conservation policies, there must be a solid understanding of the species that are involved and where they live. If our current pattern of finding new species of amphibians and reptiles through this method holds, it is likely that we have underestimated the number of species in Central Africa by at least a factor of three. This means that there are many new species that await discovery that we are in a race against time to discover, describe, and recognize before they go extinct. This is especially important for many species of amphibians and reptiles that occur only at one site. It is crucial to protect these areas to ensure that species that live there do not lose their only habitat and slip into extinction.
CA: Has your research given you any insight on how and how quickly speciation occurs?
EG: Several of my studies have pointed to the Miocene (5–23 million years ago) as an important time for speciation of several different groups of amphibians and reptiles in Central Africa. Around this time, the Earth began to cool, causing the forests in Central Africa to shrink into tiny fragments called refugia. Many species that were confined to these refugia could not leave them; the heat, lack of shade, and low humidity outside of forests would have killed them. Isolated in these refugia, different populations of amphibians and reptiles would have experienced genetic changes over time, eventually diverging into different species.
While most of our studies suggest that speciation takes hundreds of thousands or even millions of years, one study of forest treefrogs found that speciation can happen relatively quickly. My former graduate student Dr. Frank Portillo described a new species from the Itombwe Plateau called Leptopelis anebos. Even though its DNA is very similar to its closest relative, Leptopelis karissimbensis, Leptopelis anebos has different body proportions, mating call, color patterns, and it lives only in the forest, suggesting a different ecological niche.
CA: As the climate warms, how are these species being affected?
EG: A recent study by scientists from the Wildlife Conservation Society predicted that climate change will destroy large portions of the remaining natural habitat in eastern Congo by 2080. These mountains contain huge numbers of amphibian and reptile species that live nowhere else in the world, in areas often threatened with deforestation, pollution from agriculture, mining, and cattle grazing. Some species that were described in the mid-20th century haven’t been seen for nearly 70 years, so it’s possible they are extinct already and climate change might be playing a role. Much more work is needed to fully understand how climate change is affecting Congo’s reptiles and amphibians, but more likely than not, it is already having a negative effect.
CA: Your work has taken you to some of the most remote places in the world, undoubtedly changing your perspective. What is one thing you want your students to understand?
EG: My students are always surprised to learn of the many connections between the United States and Congo, from the slave trade to the present pillaging of Congo’s resources for electronic devices like smartphones. Congo needs to be better understood by the developed world, and the country needs a lot of help, including with the recent Ebola outbreak. As climate change worsens in the coming years, the world is going to need the immense rainforests of Congo to filter greenhouse gases out of the atmosphere. The enormous untapped potential for medical treatments and even cures for horrible diseases could be hiding in the toxic proteins secreted by toads and other frogs, and in the venom of many species of snakes. The entire world needs to recognize the enormous importance of Congo’s beautiful natural areas, and the poorly known biodiversity they contain.