Hi. In this video, we'll be taking a look at ecology, which is the study of organisms' interactions with one another and their environment. Now, just as the living world can be broken down into various layers of a hierarchy, the field of ecology can also be subdivided based on these different hierarchies. So, for example, the organism is, sort of, the fundamental unit of the living world. Atoms are to a chemist as organisms are to an ecologist, in a sense. Now, the organism is just an individual living system, and so an organismal ecologist is going to be interested in studying that individual living system, and so they're gonna want to look at things like physical adaptations of an organism. For example, you know, traits that increase an organism's ability to gather or obtain food, something like that.

Now, populations are groups of organisms of the same species that live in the same area, and it's worth noting that it's possible to have multiple populations of one species in the same area, and that's actually a concept we'll visit later. Now, population ecologists are going to want to look at things like the abundance and distribution of organisms in a population. So for example, you know, how many members of the population are there? Something as seemingly simple as that is an interesting question. And especially the population ecologists are going to want to look at changes in this stuff over time. So, are the populations increasing? Are they decreasing? Are populations merging together? Are populations splitting into different populations? That sort of stuff.

Now, a community is a group of populations that cohabit the same area. Now these are populations of different species, but basically, it's the sum of all the different populations of species in a particular area. And community ecologists are going to want to look at the interactions between species. And don't let the seemingly positive term 'community' fool you. Oftentimes this is gonna be one organism eating another organism. Now, the ecosystem is basically the community plus the physical environment, so the community is just the populations, just the organisms. The ecosystem adds the physical terrain that those organisms live in. And ecosystem ecologists are gonna want to look at things like the flow of nutrients and energy through ecosystems and through organisms.

So, looking at our images here you can see, here we have a single organism, it's just a frog. Right? And here this is actually a graph of the human population. And hopefully, you can see that we are looking at 1,000,000,000 on the side here, and we are very close to that 8,000,000,000 mark at present. And hopefully, this chart astounds you, as the rate of human population growth has been just, you know, unbelievable in the past century. I mean, we went from having less than 2,000,000,000 humans on Earth ever to now almost 8,000,000,000 in under a 100 years. Pretty mind-boggling stuff.

Now here we can see both a community and an ecosystem. Let me actually jump out of the way. Now, in terms of the community you have these fish, you have a nice little starfish there, coral all around. Those are gonna all make up the community. Now, the ecosystem here is also going to include things like the rock and the water that's all around these organisms. So, you know, community, I just, you know, always think of it as basically ecosystem minus all the terrain and stuff.

Now, landscapes are an idea; it's essentially interconnected ecosystems, sort of like a hierarchical layer above ecosystems. And it's helpful because, you know, ecosystems aren't just discrete units. You know, there's not a border on, you know, like a national border, I mean, on an ecosystem, you know, they touch each other, there's sort of transitional zones between them. And so landscapes sort of take a look at the greater picture of how ecosystems interact, and also, you know, how energy and materials are going to be exchanged across ecosystems.

Now when you get all the ecosystems that exist together, what you have is the biosphere, Earth. And global ecology is going to be, again, just, you know, the study of the biosphere. It's everything, really. Often though, they're going to be looking at the human impact on the biosphere. So they're gonna be interested in things like, for example, climate change, which we'll be talking about at length.

Now, conservation biology is essentially the effort to counteract a lot of this stuff. It's the effort to preserve and manage Earth's biodiversity, and we'll be talking more about that later. Now, related to ecology is the study of biogeography, which is essentially, the study of the distribution of species and ecosystems over geologic history. So this is going to be, for example, studying things like, you know, why there are certain organisms on some continents and not others, you know. For example, here, you know, we're looking at the, sort of supercontinent that used to exist on Earth, But, you know, of course due to tectonic activity, you know, the continents broke apart, they went their own directions, and some types of organisms got isolated to particular continents. So, you know, these are all just ideas that biogeography is going to explore. That's that's sort of the interest that those scientists would have.

So with that, let's turn the page.