Answer :
The question involves determining the type of survivorship curve for the plant species Doctorus dumsii, based on observed data. Survivorship curves are important in ecology as they illustrate how the number of surviving individuals in a population decreases over time. There are three main types of survivorship curves:
Type I: Characterized by high survival rates during early and middle life, followed by a decline in survival in later life. This type is typical of species that produce few offspring but invest a lot of care and resources in each.
Type II: Represents a constant rate of mortality at all ages. In other words, the chance of dying is independent of age.
Type III: Indicates low early survivorship, with few individuals surviving to adulthood. This is common in species that produce many offspring, but do not provide much care for them.
In this case, Doctorus dumsii plants start with 200 individuals, and only a handful die over a span of 10 years, with the population decreasing from 200 to 196. This suggests that the mortality rate is relatively low and somewhat constant throughout the observed time period.
The best match for this pattern is Type II survivorship. The data suggests that Doctorus dumsii exhibits a consistent reduction in numbers rather than a rapid decrease in early life or an eventual sharp decline later. The marginal change each year hints at a roughly constant probability of death, characterizing a Type II curve. Thus, the most likely type of survivorship for Doctorus dumsii based on the given data is Type II.
