<Li> Type I or convex curves are characterized by high age - specific survival probability in early and middle life, followed by a rapid decline in survival in later life . They are typical of species that produce few offspring but care for them well, including humans and many other large mammals . </Li> <Li> Type II or diagonal curves are an intermediate between Types I and III, where roughly constant mortality rate / survival probability is experienced regardless of age . Some birds and some lizards follow this pattern . </Li> <Li> Type III or concave curves have the greatest mortality (lowest age - specific survival) early in life, with relatively low rates of death (high probability of survival) for those surviving this bottleneck . This type of curve is characteristic of species that produce a large number of offspring (see r / K selection theory). This includes most marine invertebrates . For example, oysters produce millions of eggs, but most larvae die from predation or other causes; those that survive long enough to produce a hard shell live relatively long . </Li> <P> The number or proportion of organisms surviving to any age is plotted on the y - axis (generally with a logarithmic scale starting with 1000 individuals), while their age (often as a proportion of maximum life span) is plotted on the x-axis . </P>

Which type of survivorship curve describes populations whose mortality is highest at young ages