So here we have an example problem that asks, which of the following 5 species that you can see listed below exhibits a type 2 survivorship curve? And we've got these 4 potential answer options down below. Now, of course, recall from our last lesson video that a type 2 survivorship curve is when there is a similar mortality rate throughout the entire lifetime of the species. With that in mind, notice that option one says oak trees produce thousands of acorns, very few of which grow into mature oak trees. This suggests a really high mortality rate early in life, consistent with a type 3 survivorship curve.

Now, notice number 2 says rats do not have a significantly higher death rate at any specific age, which suggests very similar mortality rates throughout the entire lifetimes of this rat species. This is going to correspond with a type 2 survivorship curve. Now, number 3 says, humans living in the USA. We know that humans have a very low mortality rate early in life and higher mortality rates later in life, consistent with a type 1 survivorship curve. Next, we have number 4, which says frogs produce hundreds of tadpoles, most of whom cannot avoid predation or starvation.

This again suggests a really high mortality rate early in life, consistent with a type 3 survivorship curve. And then last but not least, number 5 says wrens, small songbirds that have approximately an equal chance of dying throughout their lifespan. This also suggests a similar mortality rate throughout their entire lifetime, so that's consistent with a type 2 survivorship curve. Notice that it's only 2 and 5 here that correspond with type 2 survivorship curves and that corresponds with answer option d which says 25. So what we can indicate is that d here is the correct answer to this example problem, and that concludes this example.

So I'll see you all in our next video.