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Analyzing interspecific competition

A hypothetical bat species (species 1) lives in a city. Another hypothetical bat species (species 2) established a population in the same city after a number of individuals escaped from a zoo. In isolation, each species prefers to roost in buildings that are three or more stories tall.

After species 2 became established in the city, species 1 began roosting only in buildings less than three stories tall, whereas species 2 roosted in buildings three or more stories tall. Observers determined that the bright streetlights at ground level had previously deterred most bats from roosting in shorter buildings. Over many generations of existing in the same city with species 2, species 1 showed changes in eye size and retina structure.

Complete the following statements about the two bat species.

Drag the terms on the left to the appropriate blanks on the right to complete the sentences. Not all terms will be used.

intraspecific competition

interspecific competition

resource partitioning

character displacement

realized niche

competitive exclusion

-/-

fundamental niche

1. Roosting areas in buildings of any height are the (????) of species 1.

2. (????) between the two bat species occurs because both species prefer the same roosting areas.

3. In parts of the city with only tall buildings (over two stories), (????) of species 1 may occur.

4. Roosting areas in buildings that are one to two stories tall are the (????) of species 1 when species 2 is present.

5. The change in the roosting habits of species 1 after species 2 became established in the city is an example of (????) .

6. The competition between the species for roosting areas is an example of a (????) interaction.

7. The changes in the eyes of species 1 are examples of (????) .

1 Answer

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Answer: The appropriate terms are in bold in each sentence.

Step-by-step explanation:

The interspecific competition occurs when individuals of different species compete for some resource that is scarce. These interactions will affect in a negative way their survival, growing or reproduction, and it will reduce the niche width.

1. Roosting areas in buildings of any height are the fundamental niche of species 1.

The fundamental niche of one species is the niche that it can occupy in the absence of competitors of any other species. It includes all the conditions and resources that the species can use to maintain its populations. Before that individuals of species 2 could escape from the zoo, the species 1 could use any building to roost. Its fundamental niche was all the buildings.

2. Interspecific competition between the two bat species occurs because both species prefer the same roosting areas.

As both bats species choose the same resources (buildings with 3 or more stories tall), they compete for them. In this case, the species 2 excludes the species 1, leading the species 1 to use suboptimal resources that aren't its preferred resources.

3. In parts of the city with only tall buildings (over two stories), competitive exclusion of species 1 may occur.

The species 2 occupy the tallest buildings, so they won't be available to the species 1. When competitive exclusion happens, species cannot coexist in the same niche, and one of them is excluded and is led to use other resources.

4. Roosting areas in buildings that are one to two stories tall are the realized niche of species 1 when species 2 is present.

The realized niche is the niche that remains available for one species when there are competitors from other species. The fundamental niche (all the resources that the species could use) of one species is then reduced to the realized niche (the resources that can be effectively used, because the others are being used by the competitors)

5. The change in the roosting habits of species 1 after species 2 became established in the city is an example of resource partitioning.

Available resources have to be partitioned to allow that both species coexist. The species 2 will rest in the tallest buildings and the species 1 in buildings with less than 3 stories. Then, the effects of competition can be minimized.

6. The competition between the species for roosting areas is an example of a (-/-) interaction.

Interactions between species are symbolized with “+”, “-” or “0” depending on whether the effects are positive, negative or neutral over each species.

The interspecific competition is represented by “-/-” because both species have negative consequences when they interact. Although in this case the species 2 wins over the species 1 in the competition, is considered that both species will have a smaller survival than living alone

7. The changes in the eyes of species 1 are examples of character displacement.

As the interspecific competition leads species to use suboptimal resources, across time the species will adapt to these conditions, and, after many generations, these conditions would be optimal for them.

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