Question

9. Be able to explain how disturbance influences community structure and species richness

10. Be able to describe ecological succession (both primary and secondary) and why succession occurs

11. Be able to explain the equilibrium theory of island biogeography

Answer 1

9.

Community structure refers to the composition of the community and total species of that community and their relative numbers. In a community interactions among the organisms play crucial role in maintaining the structure of the community.

Disturbance will disrupt these interactions and causes the loss in the structure of community.

Species richness refers to the total number of species of a community. Due to disturbance, the interactions between the species (which enable different species of organisms to flourish in the community) will be broken. This results in the extinction of several species. Thus species richness will be affected due to disturbance.

10.

Ecological succession is the process of formation of a biological community in an area.

Primary succession is the development of biological community in an area, where earlier there is no life at al (due to previous unsupportive conditions). Due to some strong physical forces if such soil gets changed so as to giving rise biological life. This is called primary succession.

Secondary succession is the evolving of biological life in an area, where earlier life was there, but was removed by some reasons. Those reasons could remove only life but not the life supporting factors. Succession occurs in the process of evolution of different species of organisms.

11.

The theory of Island biogeography is also called 'the theory of insular biogeography'.

As per this theory the total number of species in an isolated area is maintained constant or be at equilibrium due to the probable immigration of different species and extinction of some other species. Thus, the total number of species is maintained constant.