Question

Question 1. Is species endemicity and richness increase or decrease with increasing of altitude? Justify your answer briefly. 2. According to theory of Island Biogeography, the rate of immigration of new species to an Island decreases as the number of species on the Island increases and the rate of species extinction on the Island increases as the number of species on the Island increases. Explain the reason behind these theories briefly. 3. Discuss the role of ecosystem rehabilitation and restoration in economic, ecological and social aspects. 4. Write the known ecosystems of Ethiopia and categorize them as forest and non-forest ecosystems. them as Forest and Mon-Forest​

Answer 1

Answer: Note in Figure 2 that as species richness increases, immigration rate decreases, and extinction

rate increases. At some value of species richness, the two lines cross, indicating that

immigration and extinction rates are equal. At that point, species richness is at equilibrium. In

this figure, equilibrium species richness is a little less than 400 species.

2. It is stable, as you can see from examination of Figure 2. When species richness is less than

the equilibrium value, the immigration rate is higher than the extinction rate, and so species

richness will increase. If species richness exceeds the equilibrium value, the extinction rate is

greater than the immigration rate, and species richness will decrease. Thus, even if species

richness deviates from the equilibrium value, it tends to return to it.

Explanation:It is a dynamic equilibrium. Figure 2 shows that when species richness is at equilibrium,

immigration and extinction are both still greater than zero: thus even though overall species

richness has reached equilibrium, individual species are still going extinct and new species are

still arriving. In this example, the rates of immigration and extinction are equal at about 20

(e.g., in units of species per year). This is the turnover rate.

4. Examine Figure 4, the graph of immigration rates for islands at three distances from the

mainland.

You should see that the immigration line for the near island is the steepest and the line for the

far island is the shallowest. Consequently, the immigration line for the near island crosses the

extinction line farthest to the right, and that for the far island, farthest to the left.

If you drop a vertical line from each of the three crossing points to the horizontal axis, you

will see that the near island has the highest equilibrium species richness (about 550), and the

far island has the lowest Hope this helps :(