Section: Science

23) An island in the Pacific Ocean was overpopulated with Anguidae lizards. Sailors came to the island and carried weasels, an animal that fed on the lizards. The population of the weasels grew immensely as there was plenty of food. No predators existed on the island that kept the weasel population in check. People began populating the island and at the same time a shortage of lizards occurred. The weasels, facing a shortage of lizards, began eating chickens that the people raised. The people realized what was happening and began protecting their chickens from getting eaten. The weasel population began to decrease. Some weasels still remain on the island, but their number is now at equilibrium, kept in check by the availability of food.

The passage illustrates:

1. the fragility of an ecosystem.
2. the relationship between the population of predator and prey.
3. the ability of humans to change an ecosystem.
4. the interdependence of organisms.
5. all of the above.

All the choices are correct.

• The balance in the ecosystem was disturbed when a new predator was introduced, choice a.
• When the population of mongooses increased, the population of snakes decreased, causing a drop in the population of mongooses, choice b
• Humans entirely changed the ecosystem when they brought the mongooses, choice c.
• Weasels depend on snakes for food, choice d.