Survivorship is the average ratio of offspring that survive to a certain age compared to those that don't. A survivorship curve is a graphical representation of the number of individuals of a specific species that survive to each age. You'll see basically three stereotypical trends, what we refer to as a type 1 curve, which you see in humans, where there's a really low mortality rate early in life, and then later in life it becomes much higher. Essentially, in humans, thanks to modern medicine and all that, we have a relatively low mortality rate early in life. But as we get older, the mortality rate increases. Now, type 2 is a constant mortality rate. This is going to be a straight line, basically. And you'll see this in songbirds, for example. Type 3 has a really high mortality rate early in life that then peters out and becomes much more mild, and you'll see this in frogs.

A reproductive table is just a table of fertility and reproductive rates in a population. Fecundity is the reproductive rate of an organism in a population, and age-specific fecundity is the average number of female offspring produced by each age class. These are all just ways of looking at population changes.

Here you can actually see the birth rates, so the fecundity of people in different countries on earth. We're looking at humans here, and you can see that the various colors correspond to a certain number of children. Again, this is by country. You can see that, for example, the birth rate in Australia is lower than the birth rate in France.

The net reproductive rate is a kind of a weird measure. It's the average number of female offspring that a mother will have as she passes through life, conforming to age-specific fecundity and average mortality rates. Basically, it's just saying, what's the average number of female offspring a mother is going to have, given what we know about the population's average or age-specific fecundity, which, if you recall, is the average number of female offspring produced by each age class. Essentially, according to the averages on female offspring for this population and this population's mortality rate, what's the average number of female offspring a mother is going to produce?

So with that, let's go ahead and turn the page.