Conservation Biology - Online Tutor, Practice Problems & Exam Prep

Conservation biology focuses on preserving Earth's biodiversity, which encompasses genetic, species, and ecosystem diversity. Key threats include habitat loss, pollution, and climate change, leading to endangered and threatened species. Biodiversity enhances ecosystem productivity and resilience, creating a positive feedback loop. Sustainable practices, such as protected areas and wildlife corridors, are essential for maintaining biodiversity. The ongoing Holocene extinction, driven by human activity, highlights the urgency of conservation efforts to prevent further loss of species and ecosystems.

Conservation Biology and Biodiversity

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, the 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.

Here you can see all the locations of the world's coral reefs. I've put this map here because coral reefs are some of the most diverse ecosystems on the planet. They're incredibly rich with different numbers of species. I've also included a map of the world's tropical rainforests, because those are 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 information contained in the individuals of a species. So, this is going to 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. 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.

Some very special species that add to species diversity are endemic species, and these are species that are unique to a specific geographic location. These are going to be 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.

One way of looking at these sorts of genetic markers is barcoding, and this is a taxonomic analysis that's going to use genetic markers to determine if an organism belongs to a particular species. Here, you can see an example of barcoding, 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.

We bring up genetic diversity as being very important for biodiversity. An example of where genetic diversity has hurt a species is with cheetahs, which have very low genetic diversity, and it has caused them to be a threatened species. Their populations are threatened due to their incredibly low genetic diversity.

I also want to mention some endemic species, these ringtail lemurs, which are only found in Madagascar. Actually, Madagascar is home to tons of endemic species. It's a massive island, and 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 only find in Madagascar. It's just an incredibly rich, biodiverse location.

Now with that, let's flip the page.

Biodiversity Hotspots and Endangered Species

Ecosystem diversity includes variation in ecosystems over the planet and variation between ecosystems in a region. Ecosystem function is the biological, geochemical, and physical processes that occur in an ecosystem. And ecosystem services are the ways in which humans benefit from ecosystems. Here, I've included 2 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 rainforest and river system. You can see the river system in this image here. And these are 2 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 resources and global climate change. And we'll be talking about each of these individually. Now biodiversity hotspots are these biogeographic regions that are rich in biodiversity and threatened with destruction.

It's worth noting that tropical rainforests are thought to contain about half the world's species, yet only, yet cover less than 10% of Earth's 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 is losing habitat at an alarming rate due to deforestation and other human interventions. 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 at an astounding rate right now, and it's pretty scary when you think about it because the tropical rainforest, and the Amazon particularly, plays such an important role in the carbon cycle, in fixing atmospheric carbon, which is very helpful for countering global warming.

Now endangered species are species that are labeled endangered because they're likely to become extinct. An example of that is the Siberian tiger, that you can see here, which is considered endangered. Some species are just considered threatened. That means they're at the risk of becoming endangered and extinct but are in a less compromised position than endangered species. And an example of a threatened species is the pangolin that you can see right here behind me. Now introduced species are species that are living outside of their natural range due to human activity. And this happens both intentionally and accidentally. I mean, humans accidentally carry freeloaders all the time when they travel around. So you can accidentally introduce species. Of course, sometimes, species are 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 the local flora and fauna, and can actually outcompete them. An example, kind of funny example, is the silver carp right here, which is an invasive species in the United States and is 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 resources 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.

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Habitat Destruction and Degradation

Overexploitation, 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 harvestable species in marine ecosystems are considered overexploited at this point. Here is a great example of the overexploitation of Atlantic cod, and why there was a collapse in Atlantic cod stocks. You can see the fishing, 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 overexploitation 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 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, due to the length of time, the difficulty in reestablishing, those very developed forests. And it's estimated that nearly half of the world's tropical rainforests could disappear in your lifetime.

Now, habitat degradation is just reducing the quality of a habitat. This can happen due to practices like habitat fragmentation, where a contiguous habitat is fragmented into smaller more isolated pockets. You can see that happening here, where these habitats in Africa are being fragmented into smaller and smaller habitats, and this can lead to forcing populations into meta-populations, which remember are 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, this image of deforestation in the Amazon rainforest. You can see huge swaths being removed, and not only fragmenting the 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 and Climate Change

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 the process where molecules accumulate in biomass and concentrate at higher levels of the food web. So, pollution can be particularly harmful to those higher trophic levels, including predators. And just to show you an example of the human causes of pollution, look at this cityscape. You can barely see the buildings there due to 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, as the Great Pacific Garbage Patch. There's a 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 a particulate form, meaning it's going to be incredibly difficult to remove because of how some particles are, and it's much easier for living organisms to 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 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, or red is above the average. So as you can see, 2015's, you know, an incredibly hot year compared to what we're used to. Now this is in part due to greenhouse gases like carbon dioxide, which are gases in the atmosphere that absorb and emit thermal radiation. The issue is we are increasing the amount of greenhouse gases 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 UVB 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.

Extinction

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 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 it was probably a lot bigger than that. Now, we are actually in the midst of a sixth mass extinction known as the Holocene extinction, and it's due to human activity. In part, you can see this trend in this chart here, which looks at the number of large mammals that remain in areas after humans have arrived. You can see 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, North America, and on Madagascar, there was a huge drop-off. It's theorized that this is due to the fact that when humans show up they're still hunter-gatherers, and they're going to hunt these large mammals to the brink of extinction. And once they've depleted that resource, that's when humans would finally settle down and form more agrarian societies. Of course, not everyone did. There were still tons of hunter-gatherers, but it's just part of the trend. Wipe out all the big animals, and when they're gone, we have to start farming.

Now, an extinction vortex is a downward spiral of smaller and smaller population sizes. It has been said before that small populations are very vulnerable to extinction, and they can get trapped in these cycles where, basically, because of their small population size, the population has trouble surviving, and so it gets smaller and smaller. Small populations are particularly vulnerable to inbreeding and genetic drift, which can actually lead to these extinction vortexes.

Minimum viable population is the smallest population size that can exist without facing extinction. So, basically, it's the smallest population that's not going to get trapped in any of these situations. You can see an example of it charted out here, where this is a small and unstable population with a high chance of extinction, and these larger population sizes are going to be more stable.

Effective population size is the number of members of a population that will contribute to offspring of the next generation. This is essentially a way to determine the health and survival ability of a population. You can also look at species-area relationships to help determine biodiversity loss and extinction rates of populations based on what is called a species-area curve. This is a relationship that shows that the larger the area the species have available to them, the more species you will tend to see there.

Biodiversity and Sustainability

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 more biodiversity, you are going to more 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 feed back and cause more biodiversity.

Now biodiversity can also help with facilitation, which is when the presence of certain species allows 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 a community recovers from a disturbance. And you can see here, one of those recoveries in this community after a fire, and now here, or sorry, this community, right after a 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 form their whole community based on eating hippo poop. So there's so many resources and niches available, and there are things that you're not even thinking of probably. Like for example, a large mammal's 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 would require that humans only use resources at the rate which they can be replaced, so not over-exploiting things like we have a habit of doing.

Now, other ways in which humans are protecting biodiversity are 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 ex situ conservation is the preservation of endangered species outside their natural habitat. This is happening in zoos, and, you know, other types of preservation efforts all over the world.

Now, it's probably, in some senses, more 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, protected-based nature reserves. And some nature reserves can be called zone reserves, which are large regions that are mostly undisturbed by humans. Now, another way we can help with, you know, this sort of protection of our environment is with wildlife movement corridors, which will connect habitats that are 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 a wildlife movement corridor here that crosses a highway, which would normally be very dangerous for any animal. However, this nice grass bridge provides a wonderful access point. Now in a more 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. Now 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 goodnight and good luck.

Here’s what students ask on this topic:

What is conservation biology and why is it important?

Conservation biology is the scientific study focused on preserving Earth's biodiversity, which includes genetic, species, and ecosystem diversity. It aims to understand and mitigate the impacts of human activities on natural habitats and species. The importance of conservation biology lies in its role in maintaining ecosystem services, such as clean air and water, pollination of crops, and climate regulation. Biodiversity also enhances ecosystem productivity and resilience, making ecosystems more robust against disturbances. By preserving biodiversity, conservation biology helps ensure the sustainability of natural resources for future generations and maintains the intricate balance of ecosystems that support all life forms on Earth.

What are the main threats to biodiversity?

The main threats to biodiversity include habitat loss, pollution, climate change, overexploitation, and the introduction of invasive species. Habitat loss, often due to deforestation and urbanization, reduces the available living space for species. Pollution, such as plastic waste and chemical contaminants, can harm ecosystems and accumulate in food webs. Climate change alters weather patterns and temperatures, affecting species' survival. Overexploitation, like overfishing, depletes populations faster than they can recover. Invasive species outcompete native species for resources, leading to declines in native biodiversity. Addressing these threats is crucial for conserving biodiversity and maintaining ecosystem health.

How does genetic diversity contribute to the overall biodiversity of an ecosystem?

Genetic diversity refers to the total genetic variation within a species. It is a crucial component of overall biodiversity because it enables populations to adapt to changing environmental conditions and resist diseases. High genetic diversity increases the likelihood that some individuals in a population will possess traits that allow them to survive and reproduce under new or stressful conditions. This adaptability is essential for the long-term survival of species and the stability of ecosystems. Genetic diversity also contributes to ecosystem resilience, making ecosystems more robust against disturbances and enhancing their ability to recover from adverse events.

What are biodiversity hotspots and why are they significant?

Biodiversity hotspots are biogeographic regions that are both rich in biodiversity and threatened with destruction. These areas are significant because they contain a high number of endemic species—species found nowhere else on Earth. Protecting biodiversity hotspots is crucial for conserving global biodiversity, as these regions often harbor a large proportion of the world's species in a relatively small area. Conservation efforts in hotspots can yield significant benefits by preserving unique species and ecosystems. However, hotspots are under severe threat from human activities such as deforestation, habitat fragmentation, and climate change, making their protection a high priority in conservation biology.

What is the role of seed banks in conservation biology?

Seed banks play a vital role in conservation biology by preserving the genetic diversity of plant species. They store seeds from various plants, including those that are rare, endangered, or have agricultural importance. By maintaining a repository of seeds, seed banks ensure that plant species can be reintroduced into the wild or used in breeding programs to enhance crop resilience. This genetic reservoir is crucial for restoring ecosystems, supporting food security, and adapting to environmental changes. Seed banks act as a safeguard against the loss of plant diversity due to habitat destruction, climate change, and other threats, thereby contributing to the overall goal of biodiversity conservation.