Ensuring the Survival of Offspring:
Okay, so you’ve managed to locate an individual of the proper species and sex. Even better, this individual proved to be healthy, so you’ve mated. That isn’t going to do you much good if your offspring don’t survive.
Parental investment refers to the amount of resources (of whatever sort) that parent(s) invest in offspring. Of course, it’s frequently (but by no means
always) the case that females invest more in their offspring than do males. In any event, even after fertilization has occurred, parents must continue to devote resources to their offspring for some time if those offspring are to have any chance of survival. Broadly speaking, there are two general parental-investment strategies.