Exam 34: Communities in Ecology

The zebra mussel, Dreissena polymorpha, was introduced to the United States in the late 1980s from its native habitat in eastern Europe, brought accidentally by ships entering the canals of the Great Lakes. The dense populations are threatening many native species of mollusc with extinction. This is an example of:

In 1975 in Sweden, mange mites were found to infest the carnivorous red fox, causing hair loss, skin deterioration, and finally death. At its peak, this mange, specific to this fox, reduced the population of the fox by over 70 percent in Sweden. Biologists noted that hare and grouse populations increased in number by a factor of 2 to 4. Most likely, the hare population increased because:

Zebras are identified as top predators on the African savanna.

An ornithologist has observed two species of nuthatch that appear to live in similar environments: both species forage for insects on the same trees, but one species forages in the upper canopy, and the other species forages in the lower canopy. This is probably an example of:

Which level of organization is often dominated by only a few species?

An insectivorous gray lizard was once very abundant in disturbed habitats of a small island off the coast of the eastern United States. When the black lizard, a close relative, was introduced from South America, the range of the gray lizard was reduced in size, and over the course of a few decades, the average jaw size of the gray lizard increased. Explain these phenomena, giving the names for the phenomena.

What is the role keystone predators play in an ecosystem?

The relationship between a tree and a bird that both nests in its branches and eats its seeds is both ________ and ________.

A community with high biodiversity is characterized by geographic diversity.

Oak leaves contain high concentrations of tannins, which make them unpalatable to humans and many herbivores. However, several insects feed on oak leaves. These phenomena provide a good example of :

Sea stars consume barnacles and clams. This identifies them as:

A top predator may increase the diversity of species lower on the food chain by:

A very tasty butterfly evolved to have the same coloration of a butterfly that it is not closely related to it but has high concentrations of extremely toxic compounds in its wings. This is an example of: