(a) During short period of time, some population produce many offsprings which require little care. Therefore, these populations usually have a survivorship curve similar to type $III$.

These tend to have $J$-shaped growth curves until some environmental change causes them to decline usually with in a short time. From an evolutionary point of view, such species have undergone selection to maximize their rate of natural increase and for this reason they are termed as $r$-trategies.