What characterizes a type two survivorship curve?

A type two survivorship curve is characterized by a relatively constant mortality rate throughout the individual's life, meaning the chance of dying remains fairly stable regardless of age. This pattern suggests that individuals in this category experience equal risks of mortality at all ages, leading to a consistent decline in population size as individuals die off.

This type of survivorship curve is often exhibited by organisms such as birds and some small mammals, where the likelihood of death does not dramatically increase as the individual ages. This contrasts with other types of survivorship curves that may show significantly increased mortality at specific life stages (such as type one, where mortality is high in older age, or type three, where high mortality occurs in the juvenile stage).

In this understanding of a type two survivorship curve, it is clear why the other options do not apply. For instance, a concave curve would suggest a different mortality pattern (typically type one), while stating that few individuals live to adulthood aligns more with type three curves. The idea of a high birth rate is not a defining characteristic of survivorship patterns but rather a demographic feature influenced by various ecological and evolutionary factors.