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Chris Schneider: Rethinking Conservation

Q: Tell us about your research.

A: What we're doing in our large research project is actually testing different ideas about how new species arise. We're asking whether new species arise because of geographic isolation, or whether perhaps they arise across habitat transitions. For instance, in transitions from rain forest to savannah, from lowland rain forest to cloud forest and grasslands high on the east slope of the Andes. [We're asking] whether these ecological gradients are important in generating new species.

In South America, one of the most striking habitat transitions is from the lowland forest to the uplands on the east slope of the Andes, and it's been known for a long time that this is one of the most diverse areas of the world. Traveling over a few hundred kilometers, you go from steamy tropical lowland forest to high Andean alpine meadows. It's a stark and dramatic transition that involves changes between habitats over relatively short distances of a few tens of kilometers.

Q: Why are you studying these transitional areas?

A: We think that areas that are very complex geographically -- like the east slope of the Andes, where you have complex habitats and differences in habitats in very close proximity -- really are the pumps that generate new species. They're really the areas of active diversification. We're testing that idea by analyzing populations of birds, bats, rats, frogs, lizards across that habitat transition, across that gradient from lowland tropical forests all the way up to the high Andes.

What we're really interested in is the role of adaptation to novel environments in generating new species. And what we're trying to investigate is how populations become adapted to new environments, and whether or not that actually translates into speciation, into the formation of new species.

So we're really testing a very old idea: that new species come about through adaptation to local environments. We're also asking whether geographic isolation is necessary for this, and in fact what we've found to date suggests geographic isolation isn't particularly important, but that the overriding process is really one of adaptation to novel environments.

This is part of the reason that the east slope of the Andes seems to be such an important area for generating new species. As the Andes were uplifted, the lowland species would have had the opportunity to invade new sorts of habitats, novel habitats. And as they did so they would have adapted to these new conditions.

They may or may not have been geographically isolated. But the real question is whether adaptation to these new environments can lead to the formation of new species, and then whether those new species then can come back -- for instance, into the lowlands to increase the diversity of lowland rain forests. And what we've found to date suggests that adaptation across ecological gradients is really a fundamentally important process in creating new species.

If we're right about the importance of habitat transitions in generating diversity, then those edges, those transitions between habitats, become incredibly important, because it's across those transitional zones that new species can form. [They] provide the opportunity for species to adapt to a novel environment, for populations to diverge and become adapted to new environments, and ultimately, that may be the engine that drives speciation.

Q: Where do habitat transitions occur?

A: You know, these habitat transitions are everywhere. They occur over different sorts of geographical scales. They can occur over a few hundred meters, or a few kilometers, or hundreds or thousands of kilometers. But the important point is that there's the opportunity for species that exist in one of those habitats to adapt across that transition to a novel habitat. And that may be what may be fundamentally important in generating new species.

Q: What about the role of geographic isolation?

A: For the last 40 years or so, 50 years, really, biologists have thought that geographic isolation was fundamentally important for the formation of new species. And the reason that idea was so widely accepted is because it's intuitively obvious: If things are isolated on an island or on separate islands, then it's easy for them to evolve reproductive isolation where they become different. But recently I think we've found that geographic isolation may not be as important as we thought. We're finding that populations can adapt to different selective pressures over very short geographic distances and without geographic isolation, and that this local adaptation could be critically important in generating new species.

Q: Will your research help us make better decisions about conservation?

A: I think it's important to understand how new species arise and what the evolutionary and ecological processes are that generate and maintain diversity for long-term conservation. Currently, we tend to be a little bit shortsighted, and we tend to try and preserve areas that have high numbers of species without much concern for the process that generated those species or the processes that maintain that diversity.

Without understanding the processes that generate diversity and that maintain diversity, we have very little hope of preserving it. We're in for some enormous changes in the next few decades, changes in the climate that exceed anything that's happened in the last million years.

We have no idea whether or not evolutionary processes are going to be able to keep pace with this rate of change in the environment. And a fundamental part of species' persistence is their ability to adjust to new environments. And a fundamental part of new species coming into existence is their ability to adapt to new situations.

If our goal in conservation is to try and preserve the evolutionary and the ecological processes that generate diversity and that sustain diversity over the long term, then our finding that habitat gradients are important in generating new species really changes the way we do conservation biology. It changes the way we plan reserves.

Q: How should conservation efforts change?

A: Traditionally, conservation biology aims to preserve species diversity, and that's an approach that preserves the patterns produced by evolutionary history. Reserves are most often placed in areas of contiguous habitats. So you get a reserve in a big block of lowland rain forest and you get a reserve in the grasslands in the mountains. But you rarely get reserves that capture the transition between those habitats. What we're finding suggests that those transitions are incredibly important in generating new species and generating novelty, and that it's selection across those habitat differences that's critically important in generating diversity. So if we take that into consideration, then it changes the way we design reserves.

We think that conservation biology needs to change the focus slightly and emphasize more the processes that generate and sustain diversity. How do new species come into existence? What ecological conditions favor new species? What we're finding is that geographic complexity, changes in elevation and vegetation type and soils and things, are probably very, very important. That is, these things result in changes in habitats, and it's the differences in selection across those habitats that seems to be critically important for generating new species and for generating diversity.

So if we take the view that it's important to preserve evolutionary and ecological processes, then the focus of conservation shifts from trying to preserve areas of high species diversity to trying to preserve those areas that are important for generating diversity. And that is areas that have high geographic complexity, high habitat complexity, and transitions between habitats.

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