The survivorship of gobies, and the fecundity of sparrows, both decline at high population densities. This is an example which phenomenon?

a) density dependence

b) survival of the fittest

c) density independence

d) degenerate evolution

a) Density dependance

Explanation:

Density dependant factors are those factors that influence a population differently if the population is crowded than if it is not crowded.

For example:

A disease spreads more rapidly through a crowded population than through a sparse one. A loss of food source affects a crowded population severely since there is less food to go around.

These factors include:

Stress Predation Emigration Limiting sources Infectious diseases

Hence according to the given scenario, the survivorship of gobies and the fecundity of sparrows, both decline at high population densities, so this phenomena is density dependance.