A Type 1 survivorship curve is associated with which of the following? Select one:
a. has relatively the same mortality risk for all ages
b. has the highest mortality for the youngest individuals
c. has the highest mortality for the oldest individuals
The Correct Answer and Explanation is :
The correct answer is:
c. has the highest mortality for the oldest individuals
Explanation:
A Type 1 survivorship curve is a graphical representation of how the probability of surviving changes with age in a population. In this type of curve, individuals typically have a high probability of surviving through their early and middle years, and the mortality rate increases as they age. This curve is most commonly associated with species that invest significant resources into the survival of their offspring, leading to low mortality rates early in life but a marked increase in death rates in later stages of life.
Examples of organisms that display a Type 1 survivorship curve include humans in developed countries (especially in societies with advanced healthcare systems), large mammals like elephants, and some species of birds. These organisms tend to have few offspring but invest heavily in ensuring those offspring survive to maturity, typically through parental care and protection.
In such populations, infant mortality is relatively low, and most individuals live to old age. However, once individuals reach older age, the likelihood of death increases significantly, resulting in the characteristic steep slope at the end of the curve. Diseases, aging, and other age-related factors become more prevalent as individuals grow older, leading to higher mortality rates among the oldest members of the population.
This curve contrasts with a Type 2 survivorship curve, where the mortality rate is relatively constant throughout the organism’s lifespan, and a Type 3 survivorship curve, which is characterized by high mortality early in life and lower mortality once individuals reach maturity.
Thus, the hallmark of a Type 1 survivorship curve is the highest mortality occurring among the oldest individuals, as they are more susceptible to factors like aging, disease, and other risks associated with advanced age.