Survivorship

by Jason Amores Sumpter
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survivorship is the average ratio of offspring that survived to a certain age compared to those that don't and a survivorship curve is a graphical representation of the number of individuals of a specific species species that survived thio each age and you'll see basically three stereotypical trends. What we refer to as a type one 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. So basically in humans, you know, thanks to modern medicine and all that, we have relatively low mortality rate early in life. But as we get older, you know it Z the mortality rate increases. Now. Type two is a constant mortality rate. This is gonna be a straight line, basically, and you'll see this in songbirds, For example, Type three 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 now a reproductive table. It's just a table of fertility and reproductive rates in the 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, thes air, all just ways of looking at population changes. Now here you can actually see the birth rates, so the fecundity of people in different countries on Earth. So we're looking at humans here, and you can see that the various colors correspond to a certain number of Children. And again, this is by country. So you know, you can see that, for example, the birth rate in Australia. I don't know why I'm picking on them. Just cause birth rate in Australia is lower, for example, than the birth rate in France now with 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 of mothers gonna have given what we know about the populations? Average age specific fecundity which, if you recall, it's the average number of female offspring produced by each age class. So basically, you know, according Thio, the averages on female offspring for this population and this populations mortality rate. What's the average number of female offspring of mothers gonna produce? So with that, let's go ahead and turn the page.