In this video, we're going to talk about 2 critically important metrics that are used to describe and understand populations, which are population size and population density. Now population size is commonly abbreviated with the variable n and it is simply the total number of individual organisms in the population. So really it's just a simple count. Now as a simple count, it disregards the area that the population occupies and gives no sense of how crowded the population is. And therefore, population size does not provide a standardized measure for comparing different populations in different regions that have different areas.
Now, on the other hand, population density is the population size or n, but within a defined unit of area or volume. And because it does consider the area, population density gives a sense of how crowded the population is. And therefore, it also provides a standardized measure for comparing populations in different regions regardless of whether those different regions vary in their area. And so let's take a look at this image down below where we're looking at populations of these black-tailed deer on these 3 different islands that have different sizes. And so notice that the population size of all three of these islands is identical, and if that was the only thing that we were given, we might assume that these three populations are living under the same conditions.
However, notice that their population densities differ drastically. Where the small island has a high population density indicating that the population is quite crowded and the large island has quite a low population density indicating that the population is not very crowded. And of course, this middle-sized island falls right in between. And so this here concludes our lesson, and we'll be able to get some practice moving forward. So I'll see you all in our next video.
