Dual Enrollment Environmental Science Practice Exam

Type II survivorship means a constant mortality rate across the life span. In these populations, the chance of dying in a given time period is about the same no matter how old the individual is, so the number of survivors declines steadily with age. This is different from patterns where many die early in life (Type III) or where mortality increases sharply with age (Type I). Some birds, small mammals, and certain reptiles are examples that can show this constant-risk pattern. The statement that the death rate is constant over the organism’s life span best captures what Type II represents.