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The population of an insect species shows an explosive increase in numbers during rainy season followed by its disappearance at the end of the season. What does this show?
A
the food plants mature and die at the end of the rainy season
B
its population growth curve is of J-type
C
the population of its predators increases enormously
D
S-shaped or sigmoid growth of this insect
Detailed Solution
When resources are abundant, a population grows in an exponential or geometric fashion; the numbers increase slowly at first and then explosively.
The curve obtained by plotting the numbers against time is J-shaped.
In such growth the population overshoots the carrying capacity of the environment and then crashes suddenly, when an environmental factor (such as the end of the favourable season or a shortage of food) becomes limiting.
The explosive increase of the insect population in the rainy season, followed by its sudden disappearance at the end of the season, is exactly this pattern.
Similar J-shaped curves are seen in algal blooms and in a reindeer population allowed to grow in a predator-free environment.
In S-shaped (sigmoid) growth the population would level off at the carrying capacity and remain stable instead of crashing.
So this shows that its population growth curve is of J-type.
The curve obtained by plotting the numbers against time is J-shaped.
In such growth the population overshoots the carrying capacity of the environment and then crashes suddenly, when an environmental factor (such as the end of the favourable season or a shortage of food) becomes limiting.
The explosive increase of the insect population in the rainy season, followed by its sudden disappearance at the end of the season, is exactly this pattern.
Similar J-shaped curves are seen in algal blooms and in a reindeer population allowed to grow in a predator-free environment.
In S-shaped (sigmoid) growth the population would level off at the carrying capacity and remain stable instead of crashing.
So this shows that its population growth curve is of J-type.