Population Ecology

by Jason Amores Sumpter
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Hi. In this lesson, we'll be talking about population ecology. Ah, population is all the organisms of the same species that inhabit a certain area. Now population Ecologist. They're really gonna be interested in looking at the abundance and distribution of population and how that changes over time, some useful metrics. They'll look at our population size, which is abbreviated with capital letter end, which just represent our, which is just looking at the number of individuals in a population. So it's just a simple tally, and they'll also look at population density, which is the number of individuals per area or in some cases per volume, like, for example, looking at organisms in the ocean. Now you can see here a nice graphic that shows us the population by country. Now, this can actually give us an idea of population density. For example, you might notice India here is quite dark, meaning that it's going to have a pretty high population. Now Russia here is a lighter color. It's also a much bigger country, meaning that the population density in India is definitely going to be a lot higher than in Russia. Now, of course, population Ecologists are going Thio want uhh slightly more specific information than the density in the whole country of Russia. But you get the idea now they're also gonna wanna look at range. This is the geographic distribution of a species, and it's going to be due to biotic and a biotic. Factors in the biotic factors will be like the other organisms present in an area, and you know whether they can act as food, perhaps, or whether they'll compete with another species. Now, some of the a biotic factors or things like climate and, uh, physical barriers like mountain ranges or bodies of water like the ocean. And here you can see an example of range. We're looking at the distribution of the common juniper. Now, population dynamics look at the size and age composition of populations, and they're interested in the processes that drive them. So one of the things they're gonna be interested in is immigration and emigration. Immigration is the influx of new individuals from another population, so individuals from some other population will enter our population, as you can see here, and immigration is the movement of individuals away from a population, so that's going to be reducing our population size. Now, immigration and emigration, combined with births and deaths, will basically give you a good idea of the, um, sort of size and stability of a population now. Populations that are separated by space. You know, some type of space, but interact in some way are called meta populations. So, basically, if you have, let's say two populations that live on either side of a lake population one over here and population to over here. And occasionally they swim out into the middle and, you know, do a synchronized swimming routine or something, you know, just to entertain the local folks. Well, then you have a meta population because thes two populations are separate, uh, separated by space. But they do interact in some capacity. When they do, they're synchronized, dancer, swim or whatever it is Now, immigration, immigration can actually link populations into a meta population. So if you have those two populations again separated by space and maybe they don't really see each other, they don't do those synchronized swims anymore. But occasionally, Cem people from population one move over to population two or vice versa. Then you still have a meta population. Now the thing is populations in meta popular populations in a meta population that is will regularly go extinct. But individuals can colonize new territory. So in a meta population, you know, you might have, let's say, three populations in the meta population. Even if you know, let's say population to goes extinct. You might have some individuals, uh, start a new population and, you know, return to a state. We have three populations in your meta population, still or, for example, you know, if you think about it in much greater scale. You know, if you have 100 populations in your meta population, even if one of those goes extinct, the meta population, it's still going to survive. Right with that, let's go ahead and flip the page.