Ecology Population Growth and Regulation Questions and Answers 1 — Questions and Answers
Question 1: A population of deer is introduced to a new island with abundant food and no predators. Initially, the population grows rapidly. However, after several years, the growth rate slows and the population size stabilizes around 1,000 individuals. This pattern is best described by which model of population growth?
- Exponential growth
- Linear growth
- Logistic growth (Correct answer)
- Chaotic growth
Correct answer: Logistic growth
The scenario describes an initial phase of rapid, near-exponential growth followed by a slowing growth rate as the population approaches the environment's carrying capacity (K), which is characteristic of the S-shaped curve of logistic growth. [1, 15, 17] Exponential growth assumes unlimited resources and would not show a stabilization phase. [3, 7]
Question 2: Which of the following is an example of a density-dependent factor that can regulate population size?
- A sudden, severe frost
- A volcanic eruption
- A prolonged drought
- Increased predation (Correct answer)
Correct answer: Increased predation
Density-dependent factors have a greater effect as population density increases. [14] Increased predation is a classic example, as a larger, denser prey population can support a larger predator population, which in turn limits the prey's growth. [10, 11] The other options (frost, eruption, drought) are density-independent factors; they affect individuals in a population regardless of its density. [5, 6]
Question 3: An organism that produces a very large number of offspring, provides no parental care, and has a high mortality rate early in life exhibits which type of survivorship curve?
- Type I
- Type II
- Type III (Correct answer)
- Type IV
Correct answer: Type III
A Type III survivorship curve is characterized by high mortality among the young, followed by a much lower mortality rate for those individuals that survive to older ages. [8] This pattern is typical for species, like most insects and marine invertebrates, that produce many offspring but invest little to no parental care. [2, 24]
Question 4: In the logistic growth equation, dN/dt = rN((K-N)/K), what does the term (K-N)/K represent?
- The intrinsic rate of increase
- The carrying capacity of the environment
- The current population size
- The proportion of available resources (Correct answer)
Correct answer: The proportion of available resources
In the logistic growth model, K represents the carrying capacity. The term (K-N)/K represents the fraction of the carrying capacity that is still available for population growth. [20] As the population size (N) approaches the carrying capacity (K), this term approaches zero, causing the population growth rate (dN/dt) to slow down and eventually stop. [12, 13]
Question 5: A species characterized by a long lifespan, late reproductive maturity, and extensive parental care for a small number of offspring is referred to as a(n):
- r-selected species
- Pioneer species
- K-selected species (Correct answer)
- Indicator species
Correct answer: K-selected species
K-selected species are adapted to stable environments and tend to have populations that exist at or near the carrying capacity (K). [27] Their life history traits include large body size, long life expectancy, producing fewer offspring, and providing significant parental care, which increases offspring survival. [9, 21, 25]
Question 6: A population of birds on a remote island has a constant mortality rate regardless of age; an individual's chance of dying is the same at age one as it is at age five. Which type of survivorship curve would this population exhibit?
- A concave curve (Type III)
- A convex curve (Type I)
- A diagonal straight line (Type II) (Correct answer)
- An S-shaped curve
Correct answer: A diagonal straight line (Type II)
A Type II survivorship curve is characterized by a constant mortality rate throughout the life of the organism. [18] When plotted on a graph of survivorship versus age, this results in a relatively straight diagonal line. [2, 23] This pattern is common in some bird and reptile species. [24]
Ecology Population Growth and Regulation Questions and Answers 1
A population of deer is introduced to a new island with abundant food and no predators.
Initially, the population grows rapidly.
However, after several years, the growth rate slows and the population size stabilizes around 1,000 individuals.
This pattern is best described by which model of population growth?