Ecology

Answer:

Populations are affected by the environmental factors such as abiotic factors and biotic factors.
The abiotic factors are also called density-independent factors as their action is usually not dependent on population density. These factors include temperature, rainfall, light intensity, gases, and natural phenomena such as floods and droughts.
The biotic factors are affected by population density. Hence, they are also called density-dependent factors. They include food, predation, competition, parasitism, and disease.
The action of density-independent factors can be explained through the following examples.
1. Temperature exerts similar effect on population irrespective of population density.
2. Rainfall varies with the geographical location and not with the population density.
3. Natural disasters are not predictable and can occur at any region of the world irrespective of the population density.
The action of density dependent biotic factors can be explained as follows:
1. An infectious disease can affect more individuals in a dense population compared to a sparse population.
2. Competition for food is more in dense population.
3. Depletion of resources is rapid in dense populations.
Abiotic factors can be sometimes influenced by population density in following ways:
1. The mortality caused due to natural calamities in an area is more if the population is dense.
2. Light intensity reaching the forest ground depends on the density and canopy structure of the trees in the forest.
3. Algal blooms affect the availability of light to the animals beneath them in the oceans.

Answer:

The human population shows a clumped distribution on a large scale. The density of human population is highly variable.
The human population shows the highest density in the coastal regions of all the continents and in valleys of major rivers. The highest density has been recorded in eastern and southern parts of Asia.
Human population shows the lowest density in the Arctic region and the Antarctica. Mongolia is a country that also shows a very low population density.
Human population exists on most of the regions of the earth. Some of the regions where humans do not inhabit are the oceans (except the islands), high mountain peaks, volcanic regions, regions of dense forests, and deserts. Most of the Polar Regions show absence of human population.
Human populations grow fast in the developing countries, especially in Africa. The birth rate greatly exceeds the death rate in these countries.
Human populations approximately stay stable and in some cases decline in the developed countries.

Answer:

The growth of a population can be assessed by studying the parameters of the population such as the net reproductive rate, the generation time, the geometric rate of increase, and per capita rate of increase.
Despite many efforts of protection, the population size of the right whale has remained small. This shows a slower growth rate when compared to the other species of the whale.
If the external factors such as the environmental factors are excluded from the study, the slow growth rate of the right whale population can be explained by estimation of the population parameters.
The right whale populations are found to reproduce once in a span of 4 to 7 years. This indicates a pulsed reproduction and geometric pattern of growth.
The other information needed for explaining the slow growth of the right whale population can be due to their birth rate and the death rate of the population.
The estimation of various population parameters needs information about the survivorship and number of individuals of each age class. This information can help to determine the net reproductive rate, the generation time, the geometric rate of increase, and the per capita rate of increase.
The values of population parameter such as per capita rate of increase can explain the population growth.
A positive value of per capita rate of increase indicates a growing population whereas a negative value indicates a declining population.