Question

In any given ecosystem, number of individuals in a species remains more or less constant over a period of time. This constancy of number is maintained by

• A. Parasites
• B. Predators
• C. Man
• D. Available food
• E. All of the above

Answer 1

The correct option is E All of the above

The number of biotic component of an ecosystem is maintained constant in a closed ecosystem. The closed ecosystem remains in a static phase. In any closed ecosystem at equilibrium, all the energy of net production must be used up by consumers and decomposers in order for the system to have a balanced energy budget. Such an idealized system can be thought of as being saturated with individual organisms, because all available energy is used and no more organisms could be supported.

However, predators, by reducing densities of organisms at lower trophic levels, can prevent their prey populations from reaching otherwise maximal stable densities and thereby effectively preclude true saturation within that lower trophic level. If this is the case, only top predator populations reach complete saturation. Real ecological systems are almost never truly closed; rather, they usually both receive materials and energy from other systems and lose them to others.

So, the correct answer is option E.