Conservation Biology

Hi. In this lesson, we'll be talking about conservation biology, which is the ongoing effort to preserve the Earth's species habitats and ecosystems in order to maintain Earth's biodiversity. Now, biodiversity, which is a contraction of biological diversity, includes variation within species, number of species and ecosystem variety. We're going to take a look at some different metrics of biodiversity, including the genetic diversity in a population, species, diversity in an ecosystem and community and ecosystem diversity. Now here you can see all the locations of the world's coral reefs have. Look, I've put this map here because coral reefs are some of the most diverse, uh, ecosystems on the planet. They're incredibly rich with different numbers of species. Now I've also included a map of the world's tropical rainforests because those air also hotbeds of biodiversity, it's estimated that about 50% of the species on earth are going to be living in those tropical rainforests. Now, genetic diversity is really just looking at the total genetic, uh, information contained in the individuals of a species. So this is gonna be things like variation between individuals within a population and between populations. Now species diversity is a measure of both species richness and the relative abundance. So species richness is the number of species present in a community, and the relative abundance is the relative numbers of the different species compared to each other in that community. Now, some very special species that add to species diversity are endemic species and these air species that are unique to a specific geographic location. These are going to be, uh, species that you know really only exist in one place. And so it's very important to protect and preserve them because you won't find them anywhere else in the world. You'll see a lot of endemic species on islands, for example. Now, one way of looking at these sort of genetic markers is barcoding, and this is a taxonomic analysis that's going to use genetic markers to determine if a new organism belongs to a particular species. Now you can see an example of bar coding here where we have two varieties of wheat, and I'm going to use some genetic markers to see whether or not they belong to the same species. Now we bring up genetic diversity as being very important for biodiversity and an example off where genetic diversity has hurt. A species is with cheetahs, which are actually, uh, they have very, very low genetic diversity, and it has caused them thio be a threatened species there, you know, their populations are threatened due to their incredibly low genetic diversity. Now, I also want to mention, uh, some endemic species thes ringtail lemurs, which are on Lee found in Madagascar. And actually Madagascar is home to tons of endemic species. It's a massive island, and it's some of the Onley place. It's one of the only places in the world. You'll find forests like this, for example, and there are tons of species that you'll Onley find in Madagascar. It's just an incredibly, uh rich, biodiverse location. Now with that, let's flip the page.

ecosystem. Diversity includes variation and ecosystems over the planet and variation between ecosystems in a region ecosystem function is the biological, geo, chemical and physical processes that occur in an ecosystem. An ecosystem services are the ways in which humans benefit from ecosystems. Here I've included two incredibly diverse ecosystems. The Great Barrier Reef, which is a major coral reef off the coast of Australia, and the Amazon, which is a massive rain forest and river system. You could see the river system in this image here, and these are two of the world's most precious and diverse ecosystems. Now, threats to biodiversity can be found at the local, regional and global levels, and they're going to involve habitat loss and introduced species as well as the overharvesting of natural resource is and global climate change. And we'll be talking about each of these individually. Now. Biodiversity hotspots are these bio geographic regions that are rich in biodiversity and threatened with destruction. Now it's worth noting that uh, tropical rainforests are thought to contain about half the world's species yet yet cover less than 10% of Earth land surface, and they're also a good critique of this label of the biodiversity hotspot notice here that we don't see the Amazon. That's because the Amazon is not considered a biodiversity hotspot. It is actually still relatively intact. However, it's losing habitat at an alarming rate due to deforestation and other human intervention. So this label is sometimes criticized because it doesn't account for things like that, like the Amazon, which is very much so threatened due to human activity. It's losing ground, and you know, a nostalgic rate right now. And it's pretty scary when you think about it, because the tropical rainforests in the Amazon particularly play such an important role in, um, the carbon cycle in fixing atmospheric carbon, which is very helpful to for countering global warming now endangered species our species that are labeled endangered because they're likely to become extinct. Example of that is a Siberian tiger that you can see here, which is considered endangered. Some species were just considered threatened. That means there at the risk of becoming endangered and extinct, but they're less sort of. They're in a less compromised position than endangered species, and an example of a threatened species is the penguin that you can see right here behind me. now introduced species or species that are living outside of their natural range due to act human activity. And this happens both intentionally and accidentally. I mean, humans accidentally Cary freeloaders all the time when they go around with, you know, when they travel around so you can accidentally introduced species. Of course, sometimes species air introduced intentionally, and that can often have some unintended consequences. And one of those unintended consequences is when an introduced species becomes invasive, meaning that it's an exotic species. It's a foreign species that spreads in a new environment and competes with local flora and fauna and can actually out compete them. Um, example. Kind of funny example is the Silver Carp right here, which is an invasive species in the United States and is, uh, currently a huge threat to the Great Lakes, which are probably, I mean, if you ask me, America's greatest natural resource, one of the world's greatest natural resource is. In fact, the irony is that silver carp are actually threatened species in their natural environments in Asia. So, you know, kind of hilarious that a species could be threatened in its natural habitat, yet invasive in another. So with that, let's flip the page

over exploitation or overharvesting is the harvesting of a renewable resource to the point where there are diminishing returns. It should be noted that the majority of harvest a ble species and marine ecosystems are considered overexploited. This point here is a great example of the over exploitation of Atlantic cod and why there was a collapse in Atlantic Cod stocks. You can see the fishing, uh, the amount of fishing that was done per year, and it steadily has, you can see is increasing. And then it spikes right here, and then it crashes because the population crashes. And so there's just nothing left to be fished due to this over exploitation of the resource. Now, another threat to biodiversity is habitat destruction, which is when habitats are rendered unable to support the species that are currently present. It's unfortunate, but humans cause a vast amount of habitat destruction all over the world. One of the major major destroyers of habitats is deforestation. Because this removes primary forests, which reduces biodiversity and globally, this is just one of the most destructive practices. Now, tropical rainforests are particularly vulnerable to deforestation. Uh, due to the length of time, the difficulty in reestablishing uh, those very developed forests, and it's estimated that nearly half half of the world's tropical rainforests could disappear in your lifetime. Now, habitat degradation is just reducing the quality of a habitat. And this can happen due to practices like habitat fragmentation, where a contiguous habitat is fragmented into smaller, more isolated pockets. And you can see that happening here, where these habitats in Africa are being fragmented into smaller and smaller habitats. And this can, uh, lead thio, forcing populations into meta populations, which remember our populations that are somehow connected. But that means that we'll actually have smaller populations making up that meta population, and smaller populations are at greater risk of extinction. Now, edge effects are changes in a population or community that occur at the boundary between two habitats and habitat. Fragmentation pronounces edge effects, and you can see the increase in these edge territories in areas where there is deforestation. And behind me, I just want to point out, uh, this image of deforestation in the Amazon rainforest. You can see huge swaths being removed and not only fragmenting habitats, but increasing the amount of what you'd consider an edge area. These deforested areas. With that, let's go ahead and flip the page

pollution is the introduction of contaminants into the natural environment. This can surpass the critical load of nutrients, which is the amount that can be absorbed without damage to the ecosystem. And this can also intensify biological magnification, which is that process where molecules accumulated biomass and concentrate at higher levels of the food web. So pollution could be particularly harmful to those higher trophic levels, including those predators. And just to show you an example of the human causes of pollution, look at the cityscape you convey arely. See the buildings there do toe all of this air pollution. Though I live in Los Angeles, so I can't really talk about air pollution, I guess now here in the North Pacific gyre, which is this area of the Pacific Ocean is located. What is fondly known, shall we say, is the Great Pacific garbage patch. There's a massive, massive amount of trash, mainly plastic, in the Pacific Ocean here, and what's particularly harmful about it is that most of this plastic is in particulate form, meaning it's going to be incredibly difficult to remove because of house um, particles are, and it's much easier for living organisms. Thio accidentally absorb it now. Climate change is obviously a major threat to global biodiversity, and climate change is the long term change in the statistical distribution of weather patterns. You can see the increase in carbon dioxide measurements in these charts here. This is, uh, just one thing that's contributing to global warming, which is the long term rise in global temperatures that you can see nicely charted in this graphic from NASA, which is from 2015. Everywhere that's in color on this map is off the average, and everywhere that's in a shade of yellow, orange red is above the average. So as you can see, 2015, uh, you know, incredibly hot year compared to what we're used thio Now this is in part due to greenhouse gasses like carbon dioxide, which are gasses in the atmosphere that absorb and emit thermal radiation. The issue is we are increasing the amount of greenhouse gasses in our atmosphere due to, for example, fossil fuel use, which increases the amount of carbon dioxide. Now, depletion of the ozone in the atmosphere is also an issue, but this is actually unrelated to climate change and global warming. It has some loose connections to it. But it is a separate thing, and the reason I'm pointing this out is because the media often confuses these two ideas and equates them, which is just wrong. But when does the media ever get science ideas, right? So what does ozone depletion actually do? Well, it allows more UV B light to pass through the atmosphere, and this is very harmful light. It's very damaging. It can do things like damage your DNA, so it's bad for life. So just to emphasize that point again, this is separate from climate change and global warming. With that, let's go ahead and flip the page.

mass extinctions are widespread, rapid decreases in the earth's biodiversity. And there are five that are thought to have occurred in the past, including the ever famous one that wiped out the dinosaurs due to a meteor, though actually, the asteroid that hit the Earth was thought to be about the size of Manhattan. So probably be a heck of a lot bigger looking than that. Now, we are actually in the midst of 1/6 mass extinction known as the Holocene extinction. And not gonna not gonna split hairs here. It's due to human activity. In part. You can see this trend in this chart here, which looks at the amount of large mammals that remain in areas after humans have gotten there. So you can see, uh, where humans have entered the scene with these arrows. And in Africa, there wasn't as much of a diminishment of the number of large mammals. But you can see that in Australia, in North America and on Madagascar, there was a huge drop off. And it's theorized that this is due to the fact that you know, when humans show up, they're still hunter gatherers, and they're going to hunt these large mammals, which we're gonna provide lots of food to the brink of extinction. And once they really exhausted that resource, that's when humans would finally, um, you know, settle down and form more agrarian societies. Of course, not everyone did their. You know, we're still tons of hunter gatherers, but it's just part of the trend. You know, wipe, eat all the big animals and when they're gone well and we've got to start farming now extinction of or a next Inc shin vortexes a downward spiral of smaller and smaller population size. I mean, we've said before that small populations are very vulnerable to extinction, and they could get trapped in these cycles where basically because of their small population size, the population is having trouble surviving. And so it gets smaller and smaller and smaller and smaller populations are particularly vulnerable thio in breeding and genetic drift, which can actually lead to these extinctions. Vortexes. Now minimum viable population is the smallest population that can exist without facing extinction. So basically the smallest population that's not gonna get trapped in any of these situations, and you can see an example of it charted out here where, uh, This is a small and unstable population with a high chance of extinction, and these larger population sizes are going to be more stable now. Effective population size is the number of members of a population that will contribute two offspring of the next generation. And, uh, this is going to essentially be a way to determine the health and the survival ability of a population. You can also look at species area relationships. Do help determine biodiversity loss and extinction rates of populations based on what is called a species area perv. And basically, uh, this is a relationship that shows that, uh, the larger the area the species have available to them, the more species you will tend to see their with that. Let's go ahead and flip the page.

biodiversity is so important because it increases productivity in so many ways and it helps prevent extinction. It almost is like a positive feedback loop now. The reason for that is biodiversity increases the efficiency of resource use with more species to take advantage of every possible resource and niche. So with mawr biodiversity, you're going to If mawr efficiently take advantage of all the opportunities available in the environment and this greater net resource use will actually lead to greater net production of biomass, hence the positive feedback loop. The greater biodiversity leads to greater resource use, which leads to more biomass, which is going to feedback and cause more biodiversity. Now biodiversity can also help with facilitation, which is when the presence of certain species allow other species to grow and thrive in an area resistance, which is the degree to which a community is affected by a disturbance and resilience, which is the rate at which community recovers from a disturbance. And you can see here one of those recoveries in this community after a fire. And now here are sorry, this community right after fire and now on this side after the recovery and just to point out how there are really tons of niches to be filled. I want to just point to the fact that there are species of fish that literally formed their whole community based off eating hippo poop. So there's so many resource is and niches available, and they're things that you're not even thinking of probably like, for example, a large mammals feces that supports, like this whole community of fish. So what's the key to protecting biodiversity? Well, sustainability. Sustainability is really the key to our continued existence on this planet. I mean, remember, the Earth has a carrying capacity for humans, and sustainability is basically this property we see in biological systems that allows them to remain productive and diverse almost indefinitely. Basically, sustainable practices, um, would require that humans Onley use resource is at the rate which they could be replaced. So not over exploiting things like we have a habit of doing now. Other ways in which humans air protecting biodiversity is in seed banks. Seed banks are long term seed storage that will help preserve the genetic diversity of plants as some big agribusinesses go and destroy that genetic diversity for capitalist gains. Now XY to conservation is the preservation of endangered species outside their natural habitat. This is happening in zoos and, uh, you know, other types of preservation efforts all over the world. Now, it's probably, in some senses, mawr ideal, though sometimes more difficult to have a protected area of biological importance where you can conserve species in their natural habitat. We call these, uh protected is nature reserves and some nature reserves could be called zone reserves, which are large res regions that air mostly undisturbed by humans. Now, another way we can help with, uh, you know, thes sort of protection of our environment is with wildlife movement corridors, which will connect habitats that air separated by human activity and therefore, break down some of those barriers, break down some of that fragmentation, undo that fragmentation and connect populations to increase diversity. And you can see a beautiful example of wildlife movement corridor here that crosses highway, which would normally be very dangerous for any animal. However, this nice grass bridge provides a wonderful access point now, in um, or extreme form. You can also have assisted migration where you deliberately move plants or animals to a different habitat. So here we are at the end, and I just want to say what a lovely journey it's been and that I hope you guys now see the importance of protecting our natural earth. And now that you understand how incredibly rich, complex and amazing it is, you know don't let places like this disappear. It's up to us to protect them. No one else is going to do it. So with that, say good night and good luck.