Exam 44: Ecological Communities

The number of trophic levels in communities is limited by

What is one hypothesis biologists have proposed to explain latitudinal gradients in species richness?

Edith's checkerspot butterfly,found on rock outcrops near San Francisco,depends on plants that only grow on soils containing high concentrations of certain heavy metals,called _______ soils.

Refer to the table below.Fauna groups A-D are populating an island.They have the dispersal abilities shown,and they are either strongly affected or little affected by similar species already present on the island.If strongly affected,their extinction rate rises;if not strongly affected,extinction rate does not change.Which group of fauna would most likely maintain the largest number of species on the island,assuming all other factors are equal?

Why is it important to place a value on ecosystem services?

Between 1950 and 1985,half of Central America's tropical forests were cut,and the remainder was scattered in small isolated fragments.Another 19 percent of the forest had disappeared by 2005.A survey of the remaining tropical forest areas would most likely show

A study of arthropod species on a series of mangrove islands shows that two years after all arthropods were removed,the number of species on each island has returned to approximately its original number.However,the numbers are not constant-they vary from month to month as new censuses are taken.Explain why this might occur.

According to the island biogeography model,which two factors primarily determine the number of species on an island?

Cows,which eat grass and other plant materials,belong to the _______ trophic level.

Ecosystem services provided by a natural community are likely to be of higher quality if the natural community has _______ species diversity.

Which of the following would not be considered an example of an ecosystem good or service?

What is the most likely reason that the curve in the top graph mostly levels off between five and ten species?

Introduction of new dung beetle species into Australia eventually resulted in a species composition that enabled decomposition of built-up dung,improved soil quality and net primary productivity,and made cattle healthier.This series of events illustrates the value of

A scientist measuring the amount of energy per unit time that moves between a community and its abiotic environment is measuring the community's energy _______.

In determining sizes of habitat patches,corridors,and other conservation techniques,ecologists should develop their plans around key species (such as wolves in Yellowstone National Park),whose removal from ecosystems may cause a(n)_______.

A forensic entomologist can date an organism's time of death according to the species of insects found on or near the body.This scientist is applying knowledge about the process of

An island begins to recolonize after a volcanic eruption.In the first year of recolonization,20 new species become established.In the second year,10 new species become established,and in the third year,5 species become established.The decrease in number of colonizing species over time most likely occurs because by years 2 and 3

A common way to measure community function is to measure

Refer to the diagram below.Briefly explain the similarities and differences in species diversity among communities A,B,and C,taking into account both species richness and species evenness.

Species composition,species number,and species abundance together constitute the major components of _______.