Question

A male stickleback fish attacks other males that invade its nesting territory (see Figure 51.2a). Predict the likely pattern of dispersion for male sticklebacks, and explain your reasoning.

Short answer

Male stickleback fish exhibit a uniform pattern of distribution. They show antagonistic behavior towards the other males to protect their nesting territory. Therefore, male stickleback fish always manages to have relatively constant spacing with others.

Step-by-step solution

Population dispersion and its pattern

Population density is the occupation of any population per unit area or volume.It shows the pattern of spacing, or individuals of the population set boundaries within the population and this is called dispersion.

There are three types of population dispersion – clumped, uniform, and random.

Stickleback fish

Stickleback fish belong to the family of fishes called Gasterosteidae. The male stickleback constructs the nest from water weeds, and a kidney secretion binds the nest properly in its place. Female stickleback fish lay the eggs inside the nest, and males fertilize them.

Dispersion pattern in stickleback fish

The males of the stickleback fish are very protective of their territory. They prefer a shallow bottom area to mate. After fertilization of the egg, males guard the nest for 7-14 days until they hatch. They attack other males that invade their territory by showing antagonistic behavior.

Therefore, uniform distribution is found in stickleback fish. The aggressive nature of the males makes them keep the spacing constant with other nests.