Climate Change, Evolution and Conservation

Mike Conway: Good morning. Welcome to the broadcast studio of the Arizona Geological Survey in Tucson, Arizona. I am Mike Conway, Chief of the Geologic Extension, here with video grapher Jordan Matti running the operation for us. Today we are broadcasting John Wiens' "Climate Change, Evolution and Conservation." By way of introduction, John received his bachelor's degree at The University of Kansas in 1991, and he got his PhD at the University of Texas at Austin in 1995. He's held faculty positions at Carnegie Museum of Natural History in Pittsburgh and Stony Brook University in New York, before coming to the University of Arizona in the onset of 2013. Dr. Wiens is a professor in the Department of Ecology and Evolutionary Biology, specializing in the evolution and ecology of amphibians and reptiles, Dr. John Wiens. Dr. John Wiens: Thanks very much Mike. I would like to thank Amalka very much, for inviting me to have the chance to come and talk to all of you. I'd like to thank Mike and Jordan again, very much, for helping to set this up. The first thing I should tell you guys is that I am not primarily a conservation biologist. Let me take one second and tell you a little bit about what I do here. A big part of what I do involves making phylogenetic trees, or evolutionary trees for different groups of reptiles and amphibians. Then, I used those trees to answer questions like, "Why are there more species in some geographic regions than others? Why are there more species in the tropics and the temperate zones?" Questions like, "How does speciation work? How do new species evolve?" Question like, "How do species traits evolve over time, like climatic niches, life history, physiology, morphology, and behavior?" How I got into this topic of climate change, is that I found that a lot of the patterns that I were interested in seemed to be related to the inability of species to adapt to rapidly changing climates. That seems to play a big role in explaining geographic patterns of species richness, and also the origin of new species. I've become really interested in this topic of how species are going to respond to climate change, and I'm sure that's something that a lot of you are interested in, too. In my talk today, I'm going to be focusing on two main questions. First, will species adapt to climate change quickly enough to survive, to escape from extinction? Second, what will cause species and populations to go extinct when climate changes? In other words, what are the approximate causes of extinction from climate change? I'm going to be telling you about a couple of studies that I published with my collaborators last year. I think all of us recognize now, or I hope all of us, all of us at least watching this, we recognize that global climate is changing rapidly and it's changing due to human impacts. I'm showing you one of many possible slides there, but I think that a lot of reasonable forecasts are suggesting that there's going to be a four degree Celsius increase by about 2100. We're going to take that as a given. Many studies have predicted that there's going to be significant losses of global biodiversity by 2100 from climate change, especially when combined with other threats, especially with things like habitat destruction. I want to delve into this question of how exactly species respond. There are two important background concepts that you're going to need to have in your head to understand what I'm talking about. These are very simple. First, we need to recognize that every species has a geographic range. That simply is the place where it occurs. We have some species that are found only in the state of Arizona. That's where its geographic range is. Also, every species has what we call a climatic niche. The climatic niche is simply the set of large-scale temperature and precipitation conditions where that species occurs. That climatic niche may determine the geographic range, or it may not. The important question for climate change is this. What happens when the species climatic niche, the set of conditions that's it adapted to, what happens when that is no longer found in its geographic range? That's the scenario of that, a lot of us are worried about, and the scenario that leads to the idea that we're going to lose biodiversity. The important thing is that there are four possible things that can happen when the species climatic niche is no longer found in its geographic range. The first thing is that it can shift its geographic range to track suitable climatic conditions. In other words, it can track its climatic niche over space as climate changes. The most obvious thing and the easiest thing to get your mind around, is that a species that lives in the lowlands, when it gets hotter it can move up in elevation where it's cooler. Also, things that are in the lowlands can move north, so they can move to cooler climates further north. As I'm sure you all know, that depends somewhat on there being suitable habitats to move to. A second possibility is that they can acclimate. This can involve lots of different things, but maybe the easiest thing to thing about is a modification of the behavior, for example, simply spending more time in the shade. An important point about acclimation is that there is no evolutionary change involved there. It can get used to the new climate, for example, changing things in the plastic way without an evolutionary change. The third thing that they can do is they can adapt to those new conditions evolutionarily. There can be niche evolution. That could involve a change to different abiotic conditions, like temperature, or to different biotic conditions, to a different set of species that it might be competing with or preying on. Those are the three options, one, two, and three. If none of those three are possible, then there's a good chance that the species may go extinct. As an evolutionary biologist, the main question that I've been interested in lately is, "Can climatic niches evolve fast enough?" We want to know how quickly do climatic niches evolve and how does that compare to projected rates of climate change by 2100. What I did is to use phylogenies and climate data from living species to try to estimate these rates of climatic niche evolution among species and then compare those rates of climatic niche evolution to rates of projected climate change in the next 100 years or so. Very important to point out this is not something I did by myself. This is a project that I did with a great postgraduate student named Ignacio Contero, who is coming from the Universidad de Los Andes in Bogotá, Colombia. He's now a PHD student at Yale University. The work I'll be telling you about and marked very important is done in collaboration with him. What exactly did we do? What we did is we focused on 17 families of vertebrates, focusing on all the major groups of tetrapods. We had frogs, salamanders, a few groups of lizards, snakes, lots of groups of birds, and a couple of groups of mammals, representing all the major groups of tetrapods. We focused on these families because they had time-calibrated phylogenies that were relatively complete. The important thing here is that we were able to identify sister species, closest relatives. From our 17 phylogenies, we identified a total of 270 species pairs. I should also say that these represented tropical species pairs, temperate species pairs, things that were found all over. What exactly did we do? I want you now to focus on that graph on the right. That is an evolutionary tree for three hypothetical species. For each one, I'm showing you a mean value for a temperature variable. What we did for each species pairs, like A and B, that's our two closest relatives, we reconstructed six climatic variables in the ancestor. For example, we have there species A, B, and C. We would reconstruct the ancestor of that species as having a value of 17.7. Then, we would take the difference between the ancestor and the extant species and divide it by the age of the species. That gives us our estimated rate of niche evolution for each species. To work through a very simple example here, we have species A. The ancestor species A and B has a value of 17.7. You take 17.7 minus 15.1, that would be the amount of change, and then divide that by the age of the split, which would be about two million years. We did than for a total of 540 living species. Those are our rates of climatic niche evolution. We did that for six climatic variables, three temperature variables, three precipitation variables. Then, within the geographic range of each species, we used projections of the future climate from the IPCC. I'm showing you some rough maps there on the right. Then, we compared these past rates of niche evolution within each species to the projected rate of climate change specifically within the geographic range of that species. That's going to be the change from about 2000 to about 2090 or so. That gives us a rate of climatic niche evolution and a rate of future climate change. There is a lot of results somewhat complicated, but I can make this very, very simple for you. What we found is that the rates of climatic niche evolution among species were typically 10,000 to 100,000 times slower than the projected rate of climate change by 2100. What I'm showing you here is specifically for the temperature variables. Looking at that graph below, you may not be able to see all the details. But you can see that on the bottom there's our 17 families of vertebrates. Each family, there's three bars associated with it. There's a row on top that are red and yellow. Those are the projected rates of climate change for the three temperature variables. The three variables are yearly minimum temperatures, like how cold it gets in the winter, the one in the middle is the annual mean temperature, and then the maximum is the one on the right. That's for each of our 17 families. You can see across the three variables the results are really similar. On the bottom is the rates of niche evolution in gray and black for each of those three variables. You can see across these 17 families the results are really similar. You might think this sounds crazy, right? 10,000 to 100,000 times slower. That has to be a mistake. Think about this for a second. What we typically found is that closest relatives, the sister species, species that are each others closest relatives, tend to differ for any given temperature variable by about 1 degree Celsius per million year. They tend to be different by about one or two degrees Celsius. They tend to be about one or two million years old. That gives an incredibly slow rate of climatic niche evolution. Then contrast that with, an overall shift in the annual mean temperature of about 4 degrees Celsius. Think about that. Four degrees Celsius over about 90 years versus one or two degrees Celsius or less than 1 degree Celsius in a million years or two million years. Now, you can see how it could be 10,000 or 100,000 times fold difference. That's for our three temperature variables. Now, let's look at our precipitation variables. It's a very similar story, a little bit more variability there. We're looking at three precipitation variables, precipitation during the driest quarter, total annual precipitation, and precipitation of the wettest quarter. We have three little bars for each of our 17 families. The lines represent the spread among the species. A very similar story. It's a 10,000 to 100,000 times fold difference for precipitation variables as well. There's lots of assumptions and uncertainties in these analyses. For example, when we talk about these rates, we're talking about, essentially, a constant rate of evolution. We're assuming that on average. Also, our spatial projections for the future climate change are really coarse, like at a hundred kilometer scale. The important thing that you can get out of this is that these forecast-ed rates of climate change are incredibly fast relative to the observed differences in climatic niches among species. The most important thing is that closely related species tend to have very similar climatic niches because they evolve slowly. This suggests that species may be unable to respond quickly enough by adaptation alone. We had data for over a thousand species in our data set. Some of that were not included as species pairs. We went through those. We looked at how many of those would have climatic niches, how many in their geographic ranges would be experiencing conditions that were entirely outside of their current climatic niche. The answer was about 50 percent. 50 percent of those species would either have to adapt or disperse to avoid extinction. Our results suggest they would never be able to evolve fast enough. That does raise the question of whether they can disperse quickly enough. That's not something I've addressed directly, but there's a lot of evidence that suggests that that might be really difficult for a lot of species. Particularly things on mountain tops, and things that live in restricted habitats, and things that have been surrounded by habitats that have been heavily impacted by man. Now, what I want to show you is that this idea that things don't adapt quickly enough and that they go locally extinct is, the most common signature of climate change that we're experiencing right now. The evidence that climate change is currently impacting populations comes from two things that show this. There's been some wonderful large-scale studies by Camille Parmesan, and by Chris Thomas and his collaborators that show this. The first signature is that spring is coming much earlier for lots of species. The other thing is shifts in geographic ranges. People have now documented rain shifts in, literally, hundreds of species. One of the best examples of this is a paper from Chris Thomas' group that came out in 2011 in "Science." These geographic rain shifts are consistent with the impact of recent climate change. The important thing is that these shifts include species ranges moving farther north in latitude and higher up in elevation. They include both expansions and contractions of the geographic range. They include expansions at the warm edge. I'll show you a cartoon of this in just a second. And contractions at the low edge. I would argue that these contractions at the low edge are caused by local extinctions. Let me show you a cartoon of this. Here we have, on the left, the species range before a climate change. We have a bunch of blue dots. Those are specific localities where the species occurs. Here, as you go up on the slide, that's north. Then we draw a circle around them. That's the species' current geographic range. The pattern that's being frequently observed in hundreds of cases is either a shift northward or a shift upwards in elevation. There's two processes that seem to drive that -- range expansion at the northern edge. Those are those light blue populations, and then a range contraction at that southern edge, at the bottom, those are the dots in red. I would argue that those contractions are indicating a local extinction of these species because they are not able to adapt quickly enough to climate change. That is the pattern that we're talking about. These patterns that we're seeing at this large scale of species not being able to adapt quickly enough. I would argue that we're already seeing a pattern like this in these rain shifts in hundreds of species, where you get a range contraction at the warm edge of the species range with the low elevations and the low latitudes. Now I'm going to shift to the second part of my talk. It will be a little bit shorter. I'm going to focus on the question of, "What actually causes species and populations to go extinct when the climate changes?" We've been looking at a very broad scale. Now I'm going to do a review of a much more finely-focused and mechanistic question. In the first part I asked, "Can species adapt to changing climate quickly enough?" Now what we want to know is, "What exactly is it that they're going to need to adapt to?" In other words, we want to know what are the proximate causes of extinction from climate change. We know that climate changes may be the ultimate cause of extinction. But we want to know what is the specific proximate cause at the local scale. For example, is it limited tolerances to the highest temperatures during the peak of the summer? Or is it drought? Or maybe it's changes in species interactions? This is what we'd really like to know. I would argue that this is a somewhat neglected question in the climate change literature. What I'm going to be telling you about is the result of a graduate seminar that I led with 11 PHD students at Stony Brook University, in the fall of 2011. After a lot of discussion, a lot of work, what we ended up doing is conducting three searches on the Web of Science in late 2011 and early 2012, looking at all the studies that we could find that had documented local extinctions and declines due to climate change. And that had tried to look at their possible causes. We found a total of 687 unique studies. We went through all of them. We found 136 of these studies suggested that climate change was related to local extinctions or declines. We went very carefully through those 136 studies and what we found was out of those 136, almost none of them identified a proximate cause of extinction from anthropogenic climate change. We have only seven studies in that category. We also decided to broaden things out a little bit. We also decided to include studies with population declines associated with climate change. The idea here is that these declines are going to eventually lead to the extinction of populations. We think that those are also totally relevant. Finally, we also decided to include a few studies that had documented extinctions and declines that were associated with natural climatic oscillations, like El Niño. We think that those are relevant because, as you know, these climatic oscillations are thought to become more severe because of this overall anthropogenic impacts on climate. Something that we're obviously experiencing in the US, now with these overall really high temperatures, but also these incredible cold snaps that we're getting this year. The important thing from this slide is that we went through these hundreds and hundreds of studies and we ended up with a pool of 18 studies to potentially illuminate the approximate causes of extinction from climate change. Let me show you what we found. Here is a summary of the results here. On the right, you see three different graphs. Those are our three categories, the seven studies of Local Extinction, the seven studies of Population Declines, and then our four studies of the Impacts of Climatic Oscillation. I'm showing you a bar graph there. The ones on the right are the ones that are associated with biotic factors, and the ones on the left are associated with abiotic factors. The first thing that you can see from this is that there are many different proximate causes that are supported by empirical studies so far. Let me read them across the bottom for you if you can't see that. I'm looking at the lower right there. We have some studies that are associated with Pathogens. We know that amphibian declines are being caused by this chytrid fungus, so that's included there. We have reduced food. That turns out to be the most important factor. For example, bird species that are losing their prey, or bighorn sheep where the grasses are being reduced. Another one we have is Micro habitat Loss, for example, the loss of coral reefs due to coral bleaching and how that impacts butterfly fish that depend on them. In a similar vein, Symbiote Loss, that's when the coral lose their algae, their zooxanthellae, that's another important cause. Aquatic Habitat Loss, ponds drying up for aquatic amphibians, for example, or ponds drying up for fish. It's another important factor. Desiccation, there's one plant species in there suffering from desiccation. Finally, on the far left there, we have Extreme Temperatures. You can see there are only a couple studies in that category. The big impact, the big finding of this study was that in fact, if you look at the studies that have been published so far, it's changes in biotic interactions, especially reduced food resources that are the most important proximate cause of extinctions from climate change so far. Interestingly enough, there are relatively few studies that show limited tolerances to high temperatures as a direct proximate cause. Again, I'm going to come back to this point. That's not to say it won't be important in the future, but what's happening so far is those extreme high temperatures don't seem to be the most important thing. Some important cautions to make about this, the most important one is that these generalizations are based on few studies. We're only talking about two of the 18 studies here. Although one thing that does make us feel good is that we can divide these things up into different types of studies. You can see there is a broad congruence among them, showing the importance of biotic interactions, and showing the importance of reduced food. Second important caution to make is that our results our taxonomically biased. These results are dominated by vertebrates, and we only have one plant study in there. The important thing from that is that our conclusions may change as the pool of studies becomes more taxonomically representative. It may be that as we have more plants in there, for example, we get more data on plants in the future, it may show that extreme temperatures and desiccations are much more important than we're showing here. Finally, a really important point to make from this is that the relative importance of these different proximate causes may change over time as temperatures increase further. There have been some wonderful studies done focusing specifically on physiology and physiological tolerances to extreme high temperatures. Those show that there are going to be lots of extinctions due to those limited physiological tolerances, by 2100. Every one of those studies may be absolutely true. We're not contradicting those studies at all. What we're talking about, though, is the changes that have already happened with relatively little warming. We know that the global annual mean temperatures have changed less than one degree Celsius, and we already we're having impacts in hundred of species. Physiology may very well be important in the future, but the problem is that we're seeing all sorts of declines and extinctions associated with the changes in species interactions happening right now. That may be much more important until we have lots of extinctions from physiology in the future. This was a class project that we did resulting from the seminar. We submitted it to this nice journal the Proceedings of the Royal Society of London, and they published it earlier last year. We were really excited about that, and the journal was quite excited about it too. They thought this was a really important result and so they promoted it in the popular press. I'd like to say that there can be some good points to that, and there can be some bad points to that. Some people say that there is no such thing as bad press, but this is a counter example here. Let me show you one example here. This is from MSN News in the UK. Warming is, quote, "Not a direct species threat," making it sound like climate change is not a problem for species survival." The funny thing is that's in quote, "Not a direct species threat." In our country, I think that usually when something is in quotes, it's something that somebody said, but that's not the case here. If you look in the article, we never said that, they never said that, they just made up some crazy stuff and put it in quotes. We were absolutely horrified by this. We couldn't believe this. This isn't like Fox News, or something. This is MSN News. We thought these were the good guys, but no, this is what they did. That aspect of it was a little horrifying, I should say. That about wraps it up. They told me to keep it down to about 30 minutes or so. A recap of what I've told you already, I'm going to be a couple minutes here. The first question I talked about is, "Will species adapt quickly enough to survive climate change?" What I showed is that rates of niche evolution are much slower than rates of projected climate change. The answer seems, to that first question, is no, but there are other ways that they might survive, such as dispersing, or things like that. Second, I asked the question, "What actually causes species in populations to go extinct when climate changes?" Our studies showed that species interactions appear to be very important so far, but of course, other things may become important in the future. To quickly tell you in the last couple minutes about what I'm doing now. One thing that I'm doing is analyzing rates of niche evolution in plants. We're replicating the vertebrates' study in the grasses. The grasses are particularly important because those are the plants that we depend on for food, so the grasses, as you probably know, includes wheat, rice, and corn, which is what people depend on for food. So far, we're coming up with very similar results. The rates of niche evolution in grasses are much faster than they are in vertebrates, but they are still orders of magnitude slower than rates of predicted climate change. That is disheartening, not just for the survival of various vertebrate species, various amphibians and reptiles, but also I think for lots of human populations that depend on those grasses, depend on those crops to survive. The second thing I'm doing is analyzing rates of niche evolution and conservatism and invasive reptile and amphibian species. I won't have much time to get into that, but I will say that there are some instances looking at that, where there are dramatic shifts in climatic niches, very rapid shifts in climatic niches, that have been going on there in invasive species. I think in some ways they may be cheating because they rely on people a lot for things, like water. Finally, the third thing that I've been working on that in this area is analyzing responses to past climate change in the montane sky islands of southeast Arizona. We have lots of really cool reptile species, like these two rattlesnake species I'm showing you in the lower right. They are found only on these very small mountain ranges that have really high peaks. They used to be widespread throughout the lowlands when the climate was much cooler. They have now been forced into these montane sky islands and they give us a chance to look at what happens on the low mountain ranges. What happens when populations either have to adapt or die? I've been looking at this question of whether we see signatures of rapid climatic niche evolution or whether we see these montane species simply going extinct on these low sky islands. So far, what we're finding, is they mostly go extinct, but there are a few cases of niche evolution. Finally, a lot of you may work on management, and doing wonderful on-the-ground work in conservation. I'd say that that's not my area of expertise. That may be the logical question to ask from this, is "What are the specific management implications?" Again, not my area of expertise, but I think in general, what is emerging from the literature on this is that it may be really important to provide species with access to higher elevation habitats that they can disperse to, like providing dispersal corridors. I'd have to say, it's not clear at all that this will do any good, because the species simply may not be able to disperse fast enough. Finally, the last thing I should say is doing all this work on this topic. I definitely don't know what is going to happen to all these species when climate changes, say two degrees or four degrees Celsius. In my opinion, this is the most colossally stupid experiment ever done. To not do anything we could save, lose half the species on the planet. There could be the deaths of millions or billions of people due to starvation if these crops all fail in countries where there is not a lot of water, and people are very close to starvation anyway. I think this is a crazy situation that we're in. Imagine if there was some country in the world for example, that was emitting gases that was going to lead to the deaths of thousands, or millions of people. There's no question we'd bomb that country and stop it, right? Of course, I'm talking about this country, is that we're creating gases that are going to potentially cause losses of species and maybe mass starvations in other countries. It seems like a crazy thing that we're doing. It seems like we need, instead of trying to figure out how to manage what to do when the temperature increases four degrees Celsius, I think we really need to make sure that that doesn't happen at this point right now, is to stop that from happening. That's my overall recommendation. With that, I really need to thank my collaborators who really did most of the work on this, particularly for that first part, Ignacio Quintero who did all that work on climatic niche evolution. And then this great group of students that I worked with for the work on how climate change causes extinctions, particularly Abigail Cahill and Matt Aiello-Lammens, who were the lead authors on that study that I told you about in "Proceedings of The Royal Society." With that, I'd like to thank you all very much for listening and for inviting me to talk to you. Mike: There's your text. Dr. Wiens: I guess what I'll do is I will go through these questions that are appearing on here from top to bottom. The first is from Brendan Carter, "Can people be the drivers to move species to more climatically-agreeable areas?" That is a fantastic question. An obvious thing, I've been thinking about this in terms of creating a corridor for species to disperse naturally. Certainly, another possibility is for people to just move the populations that are in danger to areas that might be more climatically suitable or become more climatically suitable. I think it's a great idea. That's definitely something I should incorporate when I talk about this. It's definitely something to think about. There's all sorts of issues there, though, in terms of what happens when they go there. Will the trans location be successful? In the long range, that might be one of the best options. This next question is from Sid. He says, "How do changes in day length on the movement of species northward?" That also is a good question. How do changes on those species northward? Look at the camera there. I don't know, but you could imagine that there is potential impacts there of species moving into more northerly climates with a very different day length and things like that. It's a problem. These are moving around a little bit. Eric Beaver, "Does the grade work on phycus?" I'll grab that. "Can you address what factors you think will mediate the ability of species to use acclimation. To cope with contemporary climate change, life, history, behavior, or otherwise?" That is a fantastic question. I'm going to stop reading and answer the question. I think that's going to vary from species to species, like you're implying here. I don't know. I have to admit I don't have a quick or pat answer to that question. It's a really good one. Let's see. Richard Inman is asking, "What sources of paleo or historic climate data did you use?" This is a very important point. We did not use any. We're looking at the data from extant species on the phylogeny and reconstructing their past ones. We didn't use paleoclimatic data because we would have to know not what the climate was in the past, but everywhere where the species was, where that past climate was. We have focused on the data from extant species and reconstruct it in the ancestors, and not incorporating, paleoclimate data because it's, not really clear how exactly we would do that. But it's a really great question. Pamela Benjamin, yes, we can send the cited publications. Pamela Benjamin asks, "Is it possible to get the cited publications sent to her email address?" I guess the answer is that you can go to my website and download them. Ryan O'Donnell asks, "Doesn't the first part of this presentation assume that adaptation has only been in one direction for millions of years? By comparison, if I compare the stock market today to six years ago.. ..I might conclude that the market can only change a few points per day. But all the change is up and down interim." We include both changes. We're also including changes in both directions. It's a really good point, but we're not only looking at responses to warming. But if they have changed into a cooler climate, for example, we're including that also in our overall measures of rates of climatic niche evolution. Those estimates of rates include both ups and downs, for example in terms of temperature or precipitation, so both directions. Excellent question. Let me scroll down here. Dr. Wiens: We had Eric Beaver, Kathy, lost video. Is that it? Mike, can I turn down the volume on this? Mike: Yeah. We trying. It keeps bumping up, but we'll get it. Dr. Wiens: ..."To continue on this path toward determining the proximate causes of local extinctions, population declines, and climate oscillations." A fantastic question. I don't know. I'd give more money. I think that would be one way. It would be, for example, for NSF or for some other funding agency to open up a call for proposals for research, specifically in that area. If you offer the money, they will come. I guarantee it. Let's see. Let me go down here. Day length. We have, "What is the role of adaptive capacities, such as phenology?" from Jake Welson. I think that's a great question. One thing I didn't really emphasize that much is that species can have a relatively wide geographic range. They can potentially be adapted to a wide range of conditions because of that. It may be that phenology plays some role in that. It's really irritating to be hearing myself from several minutes go, but let's see. All right. Sorry. Adaptive capacity in phenology could be a little bit different. Overall, I think that if species were capable of these really rapid niche shifts, we'd be seeing a lot more of it when we look in the past. But it's a great question. Dr. Wiens: Let me scroll down here. Does this work? Mike: No. Dr. Wiens: It does not work. That's fine. Let's see here. From Sid Hamilton, "Day length is likely to impact plants significantly?" This is shifting around here. Let me get back down to that. Sorry. This is probably not entertaining to watch. Sid Hamilton. OK. Sid about changes in daylight, the movements species. "Day length is likely to impact plants significantly, possibly other organisms, in terms of reproduction?" Yes. You're absolutely right. I think we're seeing these shifts. Phenology is seeing shifts in the advancement of spring for lots of different species. I don't know how. There hasn't been that much work. There's two major impacts that we have been seeing in terms of reposes to climate change. One are shifts in the phenology, shifts in the seasonal activity patterns. The second one is shifts in geographic ranges. I don't know that there's been that many studies that have looked at how they interact with each other. That's a great question. I think we need a lot more work on that. Next one we have is Tim Fry. He's asking, "How did you get 17.7 again?" That's a really good question. That was a hypothetical example. But, for example, we could have used the mean value for one of our temperature variables. The mean species value, for annual mean temperature across the locations in the species range. That's an overall estimate of the climate where that species occurs. Then, we do that for multiple species across the phylogeny. We estimate a model of trait evolution. We reconstruct the values across the trait. We do that for specific nodes. From that, we have the value at a node. Then, we reconstruct the change between the reconstructed node and the extant species. That gives us the change that we're going to use to estimate the rate. That's how do you get 17.70. Mike: One or two more questions. Dr. Wiens: One or two more questions. Let me go up to the top here. Nancy Skinner, "How might we expect differences in montane and desert ecosystems due to the complexity of existent habitat and differences in resiliency?" That's a really great question. To state the obvious, in montane systems, they potentially don't have anywhere to go. They can't go any higher up. We might expect to see a lot of extinctions there. Also, in desert ecosystems, similarly, it seems like they may not be able to adapt to conditions that are much hotter. We might very well expect to see the biggest impacts in those systems. One more? Let's see here. Skyland research is not published yet. Then, Ryan O'Donnell asks, "Do you know of anyone modeling or predicting future rates of adaption to climate change by using quantitative genetics?" Great question. What I would look at is the paper in nature by Ary Hoffmann in 2011, a very nice review of adaptation to climate change, a very nice summary of what's been done so far. I guess our problem there is, in terms of using quantitative genetics, I would argue we still don't know what traits to be looking at. I think a lot of times people would say, "Let's look at physiological tolerances." The stuff that we've been finding is that species interactions seem to be much more important. It's much less clear what traits one should be looking at. It's a great question. I should chop it off there. Thank you all very much for these great questions, some really insightful questions. Thank you.