In an Era of Climate Change
DNA clues from the past may help preserve species for the future
by Suzanna Engman
photo by José V. Camacho
The Center for Applied Tropical Ecology and Conservation’s research strategy calls for collaboration among scientists from different fields and a shared vision of enhancing species’ future survival. To achieve their goal, these researchers must learn from the past to suggest management policy. That’s where plant evolutionary and population biologist Jason Rauscher’s expertise fits in. Rauscher earned a Ph.D. at Washington University in St. Louis. He held a postdoctoral position at Cornell for two years and was awarded a Fulbright to research and teach in Bogotá, Colombia, where he was also awarded a NSF fellowship. He came to the University of Puerto Rico, Río Piedras Campus in 2004 and is currently assistant professor of biology and a principal investigator of CATEC’s Molecular Ecology Evolution and Genetics Area.
Blue light reflects on the faces of Jason Rauscher and Yadira Ortiz Ruiz as they view DNA on an agarose gel.
Q: Describe your research.
Specifically, I study plants using genetic or molecular tools to try to understand evolution. My initial and continuing research concentrates on the evolution of a very specific group of plants, endemic to Colombia and Venezuela, which has undergone an explosive evolution. For a relatively young group in evolutionary terms, three million years—it sounds like a lot but in evolutionary time it is actually a blink—this group has undergone an explosion of speciation, more than 120 species, accompanied by an incredible diversity of morphology. One of the real mysteries in evolution is why there are some species with 50 million-year-old fossil records that look almost identical to what we see today. But in other cases we have groups that in just a very short period of time—for example in this case two to three million years—have diversified into forms as different as five centimeter tall matt-forming plants to 20 meter trees, which are actually completely interfertile. So things that look absolutely different can be very closely related. One of the fundamental questions in biology is, why does that occur? Why do some things go on these evolutionary explosions of diversity while other things are stable for long periods of time?
Q: How do you attempt to answer these questions?
We use DNA as a tool to reconstruct the evolution of these species. We’re basically biological historians. We look for clues that exist today that may tell us something about the past. Fossils are the most obvious way to do that, but for most organisms, they don’t exist or are difficult to find. Since the discovery that DNA is the genetic material of life, evolutionary biologists have also discovered that it contains a unique signal in the form of mutations that preserves some of this history. When a mutation in DNA occurs, it is passed from parents to their offspring. So, if a new mutation arises in the DNA of any organism, all of its descendants will also contain that mutation. If we can find a mutation that is unique and shared between different species, it tells us that the species are closely related. Species that share more mutations are more closely related than those that share fewer mutations. We can actually detect and quantify these mutations in the laboratory, work backwards in time to reconstruct what happened, and infer something about the processes that have occurred in the past.
Q: Can you relate your previous research to the CATEC project?
A lot of the genetic tools that we use to study evolution are also useful for conservation. The fundamental questions are quite similar. We want to understand how diversity is distributed, for example, in Puerto Rico. And we want to consider what that can tell us about how species adapt to their environment? How do they respond to changes in their environment, for example those that might result from climate change? We really don’t know how Puerto Rico’s flora and fauna will respond in the long term to climate change. Looking into the past gives us some clues about how that might occur. We’re looking at diverse environments in Puerto Rico to learn how species adapt to their environment and to understand something about the species itself. Often we know almost nothing about these species, how they reproduce, how their diversity is distributed, which is important information, especially when it comes to conservation. For example, if we have several populations of an endangered species on the island, are all of those populations genetically the same? If so, if we lose one, we might not lose much genetic diversity. Or, is each population completely distinct, in which case, if we lose a population we’re losing a unique piece of evolutionary history or a unique evolutionary group? Those are the kinds of things we don’t know until we actually look at the molecular level, the genetic level.
Q: Why study climate change in Puerto Rico?
Islands are very good places to study environmental changes. We have very well-defined populations and often, for evolution, isolation is an important driving force. It often creates a situation where diversification is quite rapid or at least has a different dynamic from a continental situation. Places such as the Hawaiian Islands, the Galapagos Islands, and the Caribbean tend to be biodiversity hotspots. That’s another reason why it is so important for us to conserve biodiversity in the Caribbean. It’s a legacy of millions and millions of years of evolution.
Q: Does more diversity result in a better chance of survival in a changing environment?
Most likely, yes. Genetic diversity is the raw material on which natural selection acts. This is the way species in the long term adapt to their environment. The genotypes or the individuals that have genes that allow them to survive in a particular environment and reproduce are going to be favored in the long run, and you can get evolutionary change that way. So yes, in that sense diversity is good. And as global climate change continues to modify the environment in the future, it may become even more important for these species to have the genetic diversity they need to adapt and survive.
Q: Why is the CATEC research so important?
We are at a point where we do have to manage our environment. Any time a species goes extinct, or a new species comes in, the ecosystem adjusts in some way to the absence or presence of these species, so any perturbation, even fixing something that we did wrong before, may have unintended consequences. We need to know what is truly unique. What is native to the habitat? If I were to go in and only study the genetics of these species, I would only understand a small fraction of their biology. A deeper understanding requires a collaborative effort between some researchers looking at the ecology and others looking at the molecular level. Together we get a more complete picture, and that information is something we can use to better manage and conserve the species.
Q: What is the prognosis for environmental recovery?
Humans have always altered their ecosystems. The difference now is the scale and the distance at which we find ourselves from the natural environment. We don’t depend on the natural environment for our daily survival as indigenous populations did. Today our survival equally depends on the natural environment, but it’s more difficult to see. Our family will probably still have food the next day if we ignore the problems facing our environment. We may not have food in 100 years, but it’s very difficult to think long term. We’re a product of our evolution and sometimes that is selfish in nature, but we’ve also evolved the consciousness to make decisions that are best for us as a species and as the caretakers of a beautiful, diverse world. Our hope is that the kind of research we do at CATEC has some impact on our understanding of the world and will help us make those decisions.
rauscher@evoandes.net |
