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BITC / Biodiversity Diagnoses - Richness and Endemism 2

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We're down in Australia because my student was Australian, we contrasted this Dove that's found across the arid land of Australia with a Parrot and the Doves are these two which are in northern Australia. And so the point is (obviously we need the clarity) but this aerial definition sets a single criterion. And what that does is it means that biomes or biogeographic units in some sense that are big, get left out. If you look at Psophia leucoptera, it is tightly confined to a single biome and in fact to a single biome between two rivers. And it is found nowhere else on earth. But it's more than 50,000 square kilometers. The Andes are a narrow mountain chain just the Eastern Arc Mountains here. And so almost any species in the Andes, especially at higher elevations, will be closer to that 50,000 square kilometers criterion than any species in the Amazon, even though each fills a single biome or a single set of conditions or a single biogeographic unit. So essentially, we certainly need a multiscalar approach. Why 50,000 square kilometers? Why not 40,000 square kilometers? Why not a 100,000 square kilometers? Is it just convenient because 50,000 square kilometer gives about 2,500 species and if we use a 100,000 square kilometers maybe we'll 6,000 species and it'll be too many to work with. Is it just convenience? But we're losing a lot of biology. So really what we end up seeing is that an aerial based definition of endemism or an aerial definition of importance, an aerial based criterion of importance of species, is going to discriminate among biomes or among regions based on their grain. Small grain regions maybe archipelagoes like parts of Indonesia and the Philipines or mountain chains like the Andes. They're going to be the big winners, and the big losers are the big footprint areas, even though they're diverse. They're diverse, but ops they're big and so they get left out. So this is just a commentary on the need to be explicit, the need to ask questions about the products that people throw at you, especially people who want money, or who want effort, or who want you to join their cause, and that's not just getting money out of rich people, it's getting scientists to join causes. You need to demand that clarity, and endemism is a perfect example. I don't who had the word first ( the biologist or the public health people), but that's an initial confusion. I work in both field and so I get in all sorts of trouble because I use the word endemic to refer to restricted to a particular area, and the public health people are surprised and vice versa. But even within biology we've blown the definition of endemism. There are areas based definitions and they're regions based definitions and we're never careful of defining what endemism is. So we really need that clarity. This is a deeper point than what I've said so far, but if we use primary point based biodiversity data in our biodiversity analysis, it has a world of advantages. Points, in theory, have no area, and so we can use a point or a data set of points at very fine levels, at medium levels, and at the global levels. That is a lower limit set by the spatial resolution of those points (the uncertainty associated with them). If a point is accurate to within a few kilometers, then can go down to a local landscape level. But those point data are relevant at every scale and resolution coarser than their uncertainty. Patterns in biodiversity will frequently or maybe even universally be multiscalar. Remember those maps I showed of Mexico, where one spatial resolution (the inventory of the plants of Mexico) is completely finished). And then at other spatial resolutions, the inventory of the plants of Mexico hasn't even started. And the answer is both are right because they're at different scales. So if you distil multiple scales and multiple answers and multiple outputs down to a single map or a single answer, it's usually a bad idea. Now maybe it's a very good idea if the reason you're making that map is to raise money, or is to convince people or teach people who are thinking very deeply about your map. But generally, a single answer or a single output or a single picture is going to be a pretty bad idea. So, any questions? [Question] If a plant species is restricted to a given geographical area, and then after sometimes it spreads widely, do we consider it endemic? Well, that's a good question. So if you have a plant that for example becomes invasive and spreads in other regions, does it stop to be endemic? That's another little detail of our definition. A lot of people will make differences between natural spread verses human assistant spread or human subsidy in range. But I think if you saw a species spreading naturally, you will essentially revise your idea about its geographic range. And so then it will lose that endemic status. [Question] Is endemism dependent on the presence of the species or on the sampling effort? For example, I may sample a particular area and I found a new species and I conclude that species is endemic to that place. And after about three years, another person sample in Benin and found the same species. Will the person counter my publication? But I think when we speak about endemism, we're speaking about the state of knowledge at the moment. So when you published your description of that new species, maybe it was known only from the type locality. Then the question is what is its full geographic range? But if you get your new species and it's one of your extremely cryptic micro plants, that maybe in a biome that's very extensive, then probably in your species description you say at this moment this species is known only from the type locality. But our guess is that it probably occurs across this biome which is all over central Cameroon or wherever. But if the species restricted to a single mountain top or the type locality is in a biome or an ecosystem that has a very small extent, and you feel it's isolated from others like your XXX, then maybe you say in the description or some subsequent paper that my best guess is this species is here and nowhere else. But I've certainly had a lot of fun over the years taking very simple niche modeling techniques and taking species known only from the type locality, and doing kind of very local distribution models or maps of environmental similarity. And many times what you can do is if this is that exact site where the type was collected (the only individual that was known when the species was described), many times when you look for similar conditions a kilometer a away, or 10 kilometers away, many times you find more populations. I mean very rarely or perhaps never is a species consisting of a single individual. So there is probably a local population and you don't know whether it extends tens of meters out or tens of kilometers out or what. [Questions] For instance if a species is found in the Amazon and nowhere else but also Benin, can it be considered to be endemic to Benin when we considered Africa? If your universe were Africa, that would be a bit of a strange definition, I would rather say that the species is endemic to the Amazon and Benin or Earth. Which is to say the usual way that we manage the term endemism is to say a species is endemic to a single area. You could say endemic to the tropics, endemic to earth, but endemic to the Amazon and Benin or within Africa endemic to Benin, we are getting into some murky territory because, okay what about Africa, is it everywhere in Europe but in Africa only in Benin. So I rather just say simply the species is just found only in the Amazon and Benin. Any questions? [Qouestions] Do barriers cause a certain species to be endemic in a particular place? I think that's the usual reasoning. We usually see species distribution that's constraints by the conjunction of their requirements in terms of the environment (it may be a particular interval of temperature or humidity value), by interaction with another species and by barriers. And usually, species are constraint by those three in different quantities or different levels but a conjunction of those three. So for example, let's Mountain Gorilla in one sense is probably limited by not tolerating warmer temperatures that are associated with lowland habitats. That's one scale where I am here and I'm not going to go a kilometer that way because the elevation goes down and a kilometer that way is warmer or is drier or is wetter. Now some local tolerance, so those are environmental requirements. But at a different scale, you where are Mountain Gorillas only these mountains in east Africa? Why are they not in the Himalayas or in the Cameroon mountains? That's more of a barrier thing. There is a vast lowland area and probably the Gorillas could survive on those other mountain habitats, but they've not gotten there. They've not been able to disperse there so that's a barrier. So again it's multiscalar.

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Posted by: townpeterson on Jul 26, 2016

This talk was presented in the course on National Biodiversity Diagnoses, an advanced course focused on developing summaries of state of knowledge of particular taxa for countries and regions. The workshop was held in Entebbe, Uganda, during 12-17 January 2015. Workshop organized by the Biodiversity Informatics Training Curriculum, with funding from the JRS Biodiversity Foundation.

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