The following graph shows the relationship between extinction and habitat area. Which statements help explain the trend shown on the graph? Check all that apply.

Question

_____  Larger patches are more likely to be encountered by new immigrants.

_____  Larger patches are likely to have a more uniform habitat.

_____  Larger patch size reduces genetic drift.

_____  Larger patches are more geographically isolated than smaller patches.

_____  Species richness is higher on larger patches.



Additional:

Clarify Question

· What is the key concept addressed by the question?

     

Gather Content

· What do you already know about habitat area and extinction?

        

Choose Answer

· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

       

Reflect on Process

· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

__X__  Larger patches are more likely to be encountered by new immigrants.
_____  Larger patches are likely to have a more uniform habitat.
__X__  Larger patch size reduces genetic drift.
_____  Larger patches are more geographically isolated than smaller patches.
__X__  Species richness is higher on larger patches.


Additional:
Clarify Question
· What is the key concept addressed by the question?
        o This question addresses habitat area and extinction.
· What type of thinking is required?
        o This question is asking you to analyze the information given, using logic, to dissect the problem and determine the answer.
 
Gather Content
· What do you already know about habitat area and extinction?
        o Too often, part of the habitat for a particular species may simply be destroyed. This destruction is a common occurrence in the “clear-cut” harvesting of timber, in the burning of tropical forest to produce grazing land, and in urban and industrial development. Deforestation has been, and continues to be, by far the most pervasive form of habitat disruption -- many tropical forests are being cut or burned at a rate of 1% or more per year.
        o Biologists have a well-established observation that larger areas support more species. Although this relationship varies according to geographic area, type of organism, and type of area, in general a 10-fold increase in area leads to approximately a doubling in the number of species. This relationship suggests, conversely, that if the area of a habitat is reduced by 90%, so that only 10% remains, then half of all species will be lost. Evidence for this hypothesis comes from a study in Finland of extinction rates of birds on habitat islands (that is, islands of a particular type of habitat surrounded by unsuitable habitat) where the population extinction rate was found to be inversely proportional to island size.
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o The theory of island biogeography predicts that larger islands have greater habitat heterogeneity (more diverse habitats) and therefore have greater species richness than smaller islands. Larger islands have larger habitats and therefore can support larger populations. The larger the population the less likely the populations would experience severe declines due to chance events. A larger population is less subject to genetic drift. Finally, larger islands may also be easier to find and colonize. This is called the target area effect.
 
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o The question required you to analyze the information given, using logic, to dissect the problem and determine the answer.
        o Did you recognize that larger habitats can support many more species, and help protect species from extinction?
        o What implication does this have for conservation efforts?