Sunday, 10 January 2016

Common Ecology Interview Questions and Answers pdf

91. What is predatism?
Predatism is the ecological interaction in which one individual mutilates or kills other to get food. Predatism is an inharmonious (negative) ecological interaction since one participant is harmed.
Symbiosis and Other Interactions - Image Diversity: predatism

92. Is herbivorism a form of predatism?
Herbivorism is the form of predatism in which first order consumers feed from producers (plants or algae). For example, birds and fruits, humans and eatable vegetable, etc. (There are proposals to consider the herbivorism of leaves a form of parasitism and the herbivorism of entire plants and seeds a form of predatism).

93. What is ammensalim?
Ammensalism is the ecological interaction in which an individual harms other without obtaining benefit. Ammensalism is an inharmonious (negative) ecological interaction since one participant is harmed.
(Sometimes it is wrongly said that ammensalism is a form of ecological interaction in which an organism releases in the environment substances that harm another species; this situation is indeed an example of ammensalims but the concept is not restricted to it.)
One of the best examples of ammensalism is the one established between humans and other species under extinction due to human actions like habitat devastation by fires, ecological accidents, leisure hunting, etc. Other example is the red tide, proliferation of algae that by intoxication can lead to death of fishes and other animals.

94. What is ecological succession?
Ecological succession is the changing sequence of communities that live in a ecosystem during a given time period.
Image Diversity: ecological succession

95. What are pioneer species? What is the role of the pioneer species?
Pioneer species are those first species that colonize places where previously there were no living beings, like, for example, algae that colonize bare rocks. In general, pioneers species are autotrophs or maintain harmonious ecological interaction with autotrophic beings (like autotrophic bacteria, herbaceous plants, lichens).
The pioneer community is formed of species able to survive under hostile environments. The presence of these species modifies the microenvironment generating changes in abiotic and biotic factors of the ecosystem undergoing formation. Therefore, they open way to other species to establish in the place by the creation of new potential ecological niches.

96. What is the difference between primary ecological succession and secondary ecological succession?
Primary ecological succession is the changing sequence of communities from the first biological occupation of a place where previously there were no living beings. For example, the colonization and the following succession of communities are in a bare rock.
Secondary ecological succession is the changing sequence of communities from the substitution of a community by a new one in a given place. For example, the ecological succession from the invasion of plants and animals are in an abandoned crop or land.

97. What is the climax stage of an ecological succession?
The climax stage is the stage of the ecological succession in which the community of an ecosystem becomes stable and does not undergo significant changes. In the climax community practically all ecological niches are explored and the biodiversity is the greater possible. In this stage the biomass, the photosynthesis rate and the cellular respiration reach their maximum levels and thus the net primary production (NPP = organic material made by the producers - organic material consumed in the cellular respiration of the producers) tends to zero. At the climax, the amount of oxygen released by photosynthesis is practically equal to the oxygen consumed by respiration. (This is one more reason why it is wrong to say that the Amazon Rainforest, an ecosystem at climax stage, is "the lung" of the earth. Other reasons are lungs are not producers of oxygen; the algae and cyanobacteria of the phytoplankton are the main producers of the molecular oxygen of the planet.)

98. How do biodiversity, the total number of living beings, and the biomass respectively vary during the ecological succession?
Biodiversity, the number of living beings, and the biomass of an ecosystem tend to increase as the succession progresses and they stabilize when the climax stage is reached.
At the initial stage of the succession the use of carbon dioxide and the fixation of carbon into the biomass are high, since the total number of living beings in the ecosystem is increasing. At the climax stage, the use of carbon dioxide by photosynthesis equals the production by cellular respiration and the fixation of carbon into the biomass tends to zero.

99. What is a population?
In Biology population is a set of individuals of the same species living in a given place and in a given time.
Population Ecology - Image Diversity: world human population

100. What is population density?
Population density is the relation between the number of individuals of a population and the area or volume they occupy. For example, in 2001 the human population density of the United States (according to the World Bank) was 29,71 inhabitants per square kilometer and China had a population density of 135,41 humans per square kilometer.

101. What is population growth rate?
Population growth rate (PGR) is the percent variation between the numbers of individuals in a population in two different times. Therefore, the population growth rate can be positive or negative.

102. How different are the concepts of migration, emigration, and immigration
Migration is the moving of individuals of a species from one place to other. Emigration is the migration seen as exit of individuals from one region (to other where they will settle permanently or temporarily). Immigration is the migration seen as the settling in one region (permanently or temporarily) of individuals coming from other region. Therefore, individuals emigrate "from" and immigrate "to".

103. What are the main factors that affect the growth of a population?
The main factors that make populations grow are births and immigration. The main factors that make populations decrease are deaths and emigration.

104. What are some examples of migratory animals?
Examples of migratory animals are: southern right whales from Antarctica, that procreate in the Brazilian coast; migratory salmons that are born in the river, go to the sea and return to the river to reproduce and die; migratory birds from cold regions that spend the winter in tropical regions; etc.
Population Ecology - Image Diversity: migratory animals

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