Question

The population of an insect species shows an explosive increase in numbers during the rainy season followed by its disappearance at the end of the season. What does this show?
(A) S-shaped or sigmoid growth of this insect.
(B) The food plants mature and die at the end of the rainy season.
(C) Its population growth curve is of J-type.
(D) The population of its predators increases enormously.

Answer 1

Hint: The population growth curve is a graphical representation of how a particular quantity increases over time. Growth curves are used in statistics to determine the type of growth pattern of the quantity; be it linear or exponential.

Complete step by step answer: The population growth curve of houseflies is a ‘J-shaped curve’. In the rainy season, the production rate of crops is high, as a result of which the population of houseflies shows a drastic increase because of the abundance of the food available. Later, when the rainy season comes to an end, the production of crops decreases, which leads to a sudden decrease in the population of houseflies giving a graph that looks like the alphabet “J”. The J-shaped curve does not have the carrying capacity as it is present in the S-shaped curve. There are two types of a population growth pattern that may occur depending on specific environment conditions:
i. An ‘Exponential’ growth pattern (J-curve) occurs in an ideal, unlimited environment.
ii. ‘Logistic’ growth pattern (S-curve) occurs when environmental pressures slow the rate of growth.
Hence, the correct answer is option C.

Note: The J-shaped represents a trend that starts with a sharp drop and is followed by a dramatic rise. A typical insect for example, ‘housefly’ lives 6 weeks, and can produce 120 female offspring every 2 weeks. There are also male offspring, but since they don’t reproduce directly; it’s easier just to count the females.