May 4, 2007 3:09 PM
Researchers in Paradise
Here's an article that peaked my interest from Berkeley's Spring 2007 edition of the Berkeley Science Review:
It's about the Gump Research Station on Moorea Island, French Polynesia. Since I'm going there this Fall, I figure it's a great time to learn about it!
Link to the article, which includes all posted images:
Researchers in Paradise
A tour of UC Polynesia
by Erica Spotswood
On the island of Moorea, a mere ten miles from Tahiti in the South Pacific, lies the Gump Research Station, UC Berkeley’s best kept secret. Known more for its attractiveness as a honeymoon destination than for its value to science, Moorea has nevertheless proved itself over the last twenty years to be a place where certain kinds of biological and anthropological research questions can be particularly well addressed.
If it works for Darwin...
The development of the Richard B. Gump South Pacific Research Station had much more to do with chance than with biology. In his later years, wealthy Californian Richard B. Gump donated his summer property on Moorea to the University of California. The land was turned into a research station in the late 1970s and since then, it has been administered by the College of Natural Resources at UC Berkeley.
When Dr. Neil Davies, Director of the Gump station, arrived there six years ago, he asked himself why scientists return to Moorea year after year. The answer was a lot simpler than he had anticipated. The station’s location on an oceanic island provides immediate access to the island’s ecological simplicity. Additionally, proximity to many similar islands provides a natural laboratory in which human and biological variation can be compared while controlling for many environmental factors.
For centuries, biologists have recognized the value of islands. Charles Darwin and Alfred Russell Wallace, founders of the theory of natural selection, both realized that the way that species varied from one island to the next could tell us something fundamental about how species colonized new places. Furthermore, one could study how species had changed once they arrived. Islands have been the basis for studies that tackle questions such as how species evolve, how individuals colonize new habitats, and how the environment shapes behavior and selection.
Islands, with fewer species and less complex interactions, are also simpler than mainland systems. Due to their isolation (at more than 3,000 kilometers from the nearest continent), Moorea and the other islands in French Polynesia are some of the least diverse places in the world. According to Davies, this is an asset if you are trying to sort out the complexity of a large system. “Islands are tractable; they are model systems where you can get at the underlying processes. Just like with the fruit fly, you can look at how simple systems compare to more complex ones, and you can make more progress with the simple ones.” This idea of a model system is so important that the Gump station’s primary mission is “to develop Moorea as a model ecological system to understand how physical, biological, and cultural processes interact to shape tropical ecosystems.”
Sex, butterflies, and bacteria
Snatching an insect net, postdoctoral researcher Sylvain Charlat leaps off a picnic table to chase after a butterfly. Charlat studies the butterfly Hypolimnas bolina using the Gump station as his base. Though fairly homely as butterflies go, H. bolina has more to offer than looks. The butterfly is the host of the bacteria Wolbachia, which is known for its ability to modify the sex ratios of host populations. Wolbachia lives in the cells of H. bolina and is transmitted via the mother’s egg to the next generation when H. bolina reproduces. Thus, the reasoning goes, since only the mother is able to transmit Wolbachia from one generation to the next, the bacteria does not benefit from the presence of males. One striking result is the killing of male embryos by Wolbachia before hatching.
What has made Polynesia an ideal place for Charlat’s work is the variance of male-killing across the islands of the Pacific. In some places only a small fraction of males survive, while in others the male-to-female ratio is 1:1. The island populations are also relatively isolated from each other (at least from the perspective of a butterfly). This provides Charlat with a natural laboratory that allows him to adopt a comparative approach by investigating islands with varying sex ratios.
Charlat is using H. bolina to understand some fundamental questions about reproductive biology, such as what happens when the sex ratios in a population shift. As sexual selection theory goes, the motivations for males and females in any species are different because the ways in which we maximize our fitness—or produce the most number of successful offspring—are different. This theory has made it into popular parlance through clichés such as “men spread their genes best by mating with many women, while women do better by being picky and by choosing the highest quality men.” Though one should maintain a healthy skepticism of clichés touting infallible evolutionary scenarios, it is nevertheless true that the ways in which males and females maximize the spread of their genes are not the same. Examining places in nature where sex ratios are naturally skewed provides a good framework for understanding reproductive biology.
Charlat’s findings have been startling. In some cases, the male butterflies represent less than one percent of the population. Most females are virgins, indicating that there are not enough males to fertilize the relatively abundant females. In other cases, such as in Southeast Asia where the sex ratio is even, Charlat and his team are finding evidence that females have evolved the ability to suppress male killing by Wolbachia. This change has likely taken place on the order of decades, which is very fast on an evolutionary timescale. When females from male-killing suppressor populations are mated with those on Moorea, their offspring are also suppressors. Hence, this mechanism has the ability to spread rapidly across populations. Such rapid changes in populations are big news in evolutionary biology, where evolutionary change is typically assumed to occur on the order of millennia.
Models for human history
Comparisons of populations across islands are also central to Dr. Patrick Kirch’s use of Moorea as a model system in anthropology. Kirch, an anthropology professor at UC Berkeley, has pioneered an approach in the Polynesian islands that resembles the comparative systems that ecologists routinely use to design experiments. Kirch points out that in anthropology, “we can’t run experiments where we stick people on an island and wait a few thousand years to see what happens, but we can make inferences by looking at places where this has happened naturally.” With multiple islands to study, Kirch is using Polynesia to interpret how culture has influenced the environment, and vice versa.
The Polynesian islands provide a laboratory for anthropology for many of the same reasons that they are ideal for biologists. Geologically, Polynesia is fairly young (between one and two million years old, hundreds of millions of years younger than any continent), and the islands were created in similar ways as the oceanic crust floated over hot spots in the earth’s core. Islands of different sizes and ages can be compared while maintaining the sample sizes necessary to test hypotheses. Polynesia was also one of the last places to be colonized by humans, with arrivals on most islands dating between one and two thousand years ago. The Polynesians share a common ancestry, which is still visible in the similarity of their languages. Using these factors, Kirch is able to look at which cultural variables have remained constant across islands and which have changed.
Kirch and his team have been particularly interested in the human-induced changes to the environment that began when the Polynesians arrived. Polynesian sailing canoes were large enough to hold families, domesticated animals, plants, and no small number of stowaways. When these proverbial arks arrived on new islands, exotic species hopped off (no doubt in twos) and in these new environments, they were fruitful and they multiplied. These introductions were followed by the extinction of native endemic species, most notably of birds. In some cases, such as on Easter Island in the isolated far east of the South Pacific, the story of environmental degradation is well known. However, Kirch has shown that these same processes of invasion, extinction, and repopulation by introduced species were taking place throughout the Polynesian islands.
Like Jared Diamond in his recent book Collapse, Kirch has asked what led some societies to collapse while others flourished and what environmental and cultural factors are related to success. Looking broadly across the islands of Polynesia, Kirch noticed a pattern so striking that Diamond included it in his book. The very smallest islands, with populations of 2,000 people or less, tended to flourish, with administrative systems based on consensus and the idea of a common good. Much larger islands of more than 5,000 people also succeeded and followed trajectories towards increasing complexity, top-down administration, and hierarchy. Those in the mid-range, however, tended to be characterized by the development of factions, continuing conflict, and cannibalism. The patterns, he argues, “are telling us something about a fundamental variable in society which is population and social group size. If you are small enough, you know everyone, and you can have an idea of the commons. A bit bigger, and you have factions. Bigger yet, and you have the possibility of top-down administration.”
Kirch adds that the comparative model system approach has not been the only benefit to working on Moorea. “What is really great about the station,” he says, “is that it fosters interdisciplinary work. I couldn’t have done the research I have done without interacting with biologists, and without the insight of anthropology, they don’t see the whole picture either.” It is these kinds of interactions that inspired Davies to think about developing a species database for Moorea.
Island supermarkets: scanning the barcodes of life
In 2003, Davies set about organizing a project to DNA barcode every organism on Moorea. He envisioned a database that could be used by researchers around the world. Categorizing every species, no matter how tiny and species-poor the island, is no small undertaking. But Davies enjoys the challenge of big ideas, and he has managed to stir up both the scientific expertise and the support (through a pilot grant from the Gordon and Betty Moore foundation) to take on the project.
Barcoding is a technique that identifies a species based on the sequence of a short gene in mitochondrial DNA. Mitochondrial DNA has a relatively fast mutation rate, resulting in a large degree of variation between species and a smaller variance within species. The technique is cheap, quick, and easily replicable, making it possible to obtain sequence data for large numbers of organisms without needing information from the entire genome. Once the database exists, researchers are able to use it either to identify organisms or to discover new species. Dr. Chris Meyer, project manager for the Moorea Biocode project, is enthusiastic about the possibilities. “If you are an ecologist, maybe you can’t visually identify all the polychaete worms on a reef or all the caterpillars on a plant, or the gut contents of a bird.”
Barcoding provides a powerful approach for identifying such fragments of living tissue, but it is not the only method. Indeed, there is nothing inherently new about barcoding, except the emphasis on standardization and the use of a single gene for all animals. Though the technique is not new or complex, it has nevertheless spurred considerable controversy. Whereas ecologists have tended to see the intrinsic benefits of adopting a systematized approach to genetic data collection offered by barcoding, taxonomists (those who study the classification of organisms) have been more critical. The use of a single gene, they argue, is prone to error because the variability of the gene between species is different across groups of organisms. This means that a single species may erroneously be split into several, while species that are distinct may be falsely lumped together. Meyer is aware of the controversy: “I have always been honest about the pitfalls, but it will still work really well. So, why not do it and use it and then leave that little window of error as fruit for evolutionary biologists?”
The real advantage, Meyer maintains, is the systematization of tissue collection and the public access. “It has galvanized the museum communities who have traditionally not had to think about how to collect tissue samples, and has helped standardize data collection.” The big challenge has been figuring out how to handle the quickly growing database. Though the team has members that are IT specialists trained in informatics, data collection is going much faster than it can be properly managed. “We want to make it as easy for a user as possible,” says Meyer. “That is the frustrating part.”
In the first three weeks of data collection in March 2006, the team identified, tagged, sequenced, and sent off to museums almost 500 species of fish. Since then, they have been working on the marine invertebrates, terrestrial insects, and are in the planning stages for the plants. They plan to complete the project in three years. Though they may not find every species on the island, they are likely to come close.
Spreading island fever
As the information database at the Gump station grows, it becomes an ever more powerful environment both for research and as a center for teaching. Since 1991, interdisciplinary research lessons have been shared with students through a field course for Berkeley undergraduates. Every fall, students from the departments of Environmental Science, Policy, and Management (ESPM) and Integrative Biology spend two months on Moorea participating in a field course. Each student chooses his or her own biological or geological field project with the mentorship of the five participating faculty and three Graduate Student Instructors.
The class offers a unique opportunity for students young in their careers to experience what scientists do. The successes have been visible; many class alumni have gone on to graduate school in the sciences and are still working in biology and geology today. But Professor Vince Resh from ESPM thinks that there are also longer-term effects that are harder to measure. “The students come away with an understanding of isolation and biological evolution, and ultimately gain an appreciation for why so many scientists are nesomaniacs [crazy about islands].”
Davies is enthusiastic about the future of the Gump station. “The more we know about a place, the more there is to teach. We want to try to kick off these positive feedback loops where the more we learn, the more interesting the questions become.” The dynamic research environment at the Gump offers compelling evidence that this feedback is already happening. If the trend continues, the Gump may well become an ecological equivalent of the fruit fly.
Erica Spotswood is a graduate student in environmental science, policy, and management.
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