Question

Marine ecologists have generally thought that organisms in different oceans are more similar than organisms on different continents. Which one of these options seems valid from theory as support for this idea?

A.

The different oceans are all connected, so there must be few dispersal barriers.

B. Marine species are often poorly characterized taxonomically.

C. The species extinction rate in the ocean is slower than on land so different oceans have retained similar species sets.

D. Since most species live within the upper 100m of the ocean, the environmental factors differ very little from ocean to ocean.

Which one of the following correctly relates area, isolation, and richness?

(In each option: the word “island” may refer to any patch of a given habitat-type isolated from similar patches by intervening different habitats; the word “source” refers to a large area of habitat like that on the “island”, which would serve as a source of colonists for the “island”.)

A.	Large islands far away from the mainland usually have a high extinction rate and low immigration rate, therefore low biodiversity.

Small islands far away from the mainland usually have a high extinction rate and low immigration rate, therefore low biodiversity.

B. Small islands close to the mainland usually have a low extinction rate and high immigration rate, therefore high biodiversity.

C. Small islands usually have high extinction and low immigration rates independent of the distance to the mainland, therefore low biodiversity.

D.	Islands close to the mainland usually have high immigration and low extinction rates independent of the size, therefore high biodiversity.

Answer 1

1.Since most species live within the upper 100m of the ocean, the environmental factors differ very little from ocean to ocean.

Since the habitat of most species in oceans is nearly same, this could be correct answer.

As different oceans are connected, geographical regions of land are also connected by some manner. Therefore, first option is incorrect. Second option is vague.

2. Correct statement:

Small islands far away from the mainland usually have a high extinction rate and low immigration rate, therefore low biodiversity.