How do survivorship curves show three types of reproductive strategies?

There are three slopes in a survivorship curve, which indicates the average life expectancy of a population.
Type I or convex curves in which few offsprings are produced, but they are cared well and get matured and survive.
Type II or diagonal curves where al almost constant rate of birth or mortality is observed.
Type III or convex curves where high mortality is observed in early life, but the aged population has a high survival rate.