Question

The Galapagos Islands were formed from underwater volcanic activity. The islands initially were barren, supporting no life, and then they went through a series of colonization stages. The equilibrium model of island biogeography states that the species composition on an island will constitute a balance between the immigration and extinction rates. Based on the equilibrium model of island biogeography, indicate if the following statements concerning succession on the islands are predicted to be true or false.
a. Species arriving later might outcompete earlier arriving species, driving them to extinction.
b. The number of species on an island decreases as a function of the distance from the source-pool (in this case, mainland South America).
c. The number of immigrants will increase the closer the island is to the source.
d. The rate of extinction will be lower on smaller islands due to small population sizes and less competition.

Answer 1

Answer:

a. Species arriving later might outcompete earlier arriving species, driving them to extinction. (True)

b. The number of species on an island decreases as a function of the distance from the source-pool (in this case, mainland South America). (True)

c. The number of immigrants will increase the closer the island is to the source. (True)

d. The rate of extinction will be lower on smaller islands due to small population sizes and less competition. (False)

Explanation:

The equilibrium model of island biogeography, from the question, states that the species composition on an island will constitute a balance between the immigration and extinction rates.

The succession on the island would be how the species composition on an island develops gradually with time.

So, species arriving later might outcompete earlier arriving species. As the Islands continue to develop, major players like the primary producers and other factors that aid ecological development would support the growth of species that would previously have struggled to live on the island.

The number of species on an island can also be determined by the distance from the source-pool (in this case, mainland South America).

The more the island gets food from a near source, the more the influx of those organisms to the island.

So many factors contribute to extinction, some include, natural disasters, evolutionary changes, loss of habitat. Small population sizes and less competition do not mean a lower rate of extinction.