Abiotic factors and an organism's range | High school biology | Khan Academy

So, let's talk a little bit about abiotic factors for an organism's range. Before we even get into it, let's just think about what these words mean. In other videos, we've talked about how abiotic means non-living, while biotic would refer to living. So, this is non-living factors for an organism's range.

What do we mean by range? In everyday language, you could say, “Where do you range? Where do you go?” It’s a similar meaning. An organism's range is the geographic area where the organism can live.

Let’s just think about some of those factors. One of the more obvious ones might be whether an organism can live on land or live in water. For example, let’s say there is an island. Let me draw it in a better color here. Let’s say there's an island surrounded by water. If you have some animal here that needs to live on land, then its range is definitely going to be limited by the water around it. So, it’s only going to be able to stay on that island.

Likewise, there might be some other creature inside the water that can’t go on land. Its range is going to be limited to that water; it won’t be able to go on land. You could even imagine it could be some type of an inland pond or maybe it’s a lake of some kind.

This is all land on the outside, and this is water right over here. If this thing needs to live in the water, well, it’s definitely going to be limited. Its range is going to be limited to that water. But it's not just about whether there's land or water, or whether you can cross from one to the other.

There are also a lot of other things that could be physical barriers that keep an animal from going one place or another, like land or water, mountain ranges, or rivers. But it could also be factors that determine where an organism can survive or is more likely to survive.

For example, this picture right over here is a world map where it shows us where we have reef-building coral. All these little brown spots are where you have actual reef-building coral. You might notice something: they are all relatively close to the equator or in the tropics, at relatively low latitudes between 30° north latitude and 30° south latitude.

In other videos, we have talked about those being the parts of the earth that are warmer. If we’re talking about the seas, the parts of the seas that are warmer is exactly where reef-building coral needs reasonably warm waters—not too warm, but reasonably warm waters. That’s why you don’t see it in these colder latitudes further to the north or further to the south.

So, temperature—whether you’re on the water or you’re on land—matters. For example, most of us, if we go to Antarctica, would have trouble living there without significant use of technology. That’s why, if you go really into the interior of Antarctica, away from the coast, you see almost nothing that is living there.

Temperature matters. Access to moisture or water matters. Are we in a swamp, or are we in a desert? One of those might be better for one type of species than another. If we’re talking about a water-dwelling creature, it can matter what’s in the water. What is the acidity of that water? What is the salt content? Are we talking about saltwater, freshwater, or something in between?

Then, there are other factors like floods, wildfires, and volcanic eruptions that can also affect all of that. Now, we aren’t done talking about all the factors for an organism’s range. We just touched on the abiotic factors in this video, but you could imagine there are also biotic ones, like access to food or other organisms that might view you as food.