So here we have an example problem that asks, according to the figures below, which of the following options likely has the highest extinction rate? Notice that we've got these three figures or graphs and four potential answer options below. In all three graphs, we have the species richness on the x-axis, which, recall, is the total number of species in the community, just a simple count. On the y-axis, we have both the immigration rate and the extinction rate, where immigration rates are color-coded in blue and extinction rates are color-coded in red.

This first graph tells us that the equilibrium number of species in a community is indicated by the intersecting point of these immigration and extinction curves.

The next graph has curves that correspond with a large island, which I'm highlighting here, and it has curves that correspond with a small island, which I'm highlighting here. Notice that the number of species at equilibrium for the small island is lower than the number of species at equilibrium at the large island. This is consistent with our previous lesson videos, as we know larger islands offer more resources, habitats, and micro-habitats to support more species at equilibrium. Also, larger islands are simply more likely to be found by species migrating off the mainland, giving them a higher number of species at equilibrium.

The final graph focuses on distance from the mainland. We have curves that correspond with near shore islands that are close to the mainland, and curves that correspond with remote islands that are far from the mainland. Notice that the equilibrium number of species for remote islands is smaller than the equilibrium number of species for near shore islands, close to the mainland. Again, this is consistent with our previous lesson videos. Islands that are near shore and close to the mainland are more likely to be found by species migrating off of the mainland, giving them a higher number of species at equilibrium.

Given this context, the problem asks us which of these options likely has the highest extinction rates. Islands that are small have higher extinction rates than islands that are large because the extinction rates are colored red. Islands that are remote and far from the mainland have higher extinction rates than islands that are near shore and close to the mainland. If we aim for the highest extinction rates, then a small island that is remote or far from the mainland is the target. This corresponds with answer option b, which states that the island is small and far from the mainland. Thus, answer option b is the correct response to this example problem.

Option a is incorrect because it says an island that is small and near the mainland; being near shore results in slightly lower extinction rates, explaining why it does not have the highest extinction rates. Option c, which states an island that is large and near the mainland, would actually have the lowest extinction rates, not the highest, so we eliminate option c. Finally, option d also fails because, although being far from the mainland raises extinction rates, being large does not maximize them. Consequently, option b is the correct answer to this example, and I will see you all in our next video.