Explain the factors affecting the population?

There are multiple factors which affect the size and density of the population. It includes natality, mortality, emigration and immigration. The natality is defined as the rate at which new individuals are formed. This may occur due to reproduction, hatching or germination. The biotic potential is defined as the ability to achieve the maximum birth rate at ideal conditions. It is also known as potential natality. The realized natality means the actual number of births which take place under the existing conditions. Their numbers are less than the number which exists in ideal conditions. The mortality is defined as a rate at which the individuals in the population die. It mostly occurs in egg, larval and seed stages. The division of natality by mortality leads to the vital index. It is in the percentage and denotes the normal growth rate of population.
There are a lot of differences between the natality rate and mortality rate. The natality rate is the number of births per thousand individuals per year. It increases the population size and its density. It is the rate at which new people are added to the population. The mortality rate is the number of deaths per thousand individuals per year. It decreases the population size and its density. It is the rate at which people die.
The emigration is defined as the movement of individuals out of population. It is permanent. They settle somewhere else. It decreases the size of population but it leads to the diversity of population. The immigration is defined as the movement of individuals in the population. It is permanent. It increases the size of population and it does not lead to the diversity of population. The emigration and immigration leads to the dispersal of population. The movement of population occurs for food, space and protection. The dispersal is also brought by migration. It is a two way movement which occurs in the adverse circumstances. It occurs in the fishes and birds. The size of population is not affected by it.
The resources are linked to the carrying capacity. These are formed by food, water and space. The maximum number of the resources which can support the maximum number of individuals is known as a carrying capacity. So, more are the resources and more population it can support. The resources started declining and lead to the decreasing size of population. It occurs by the process of emigration. The natural calamities destabilize the ecosystem and population. The most common calamities include earthquake, land, flood and fire. The abiotic factors play a crucial role in the size of population. The sunlight variations, changes in the temperature and humidity, rainfall, mineral and substratum availability play an important role to determine the growth of population. The hibernation, aestivation are controlled by the changes in weather. The biotic factors are the population density and its relation with the food and pathogens. The growth of population is inversely related to the density of population. The more is the density of population less is the growth of population. In few cases the growth of population depends upon the growth of population. The size of population depends upon the carrying capacity of environment. The consumer food relationship keeps a constant check on the population growth. The increase in population is checked by the predators and decrease in the food population size occurs by the different pathogens. The resilience is defined as the ability of a population to bear the changes caused by the changes in temperature, biotic factors and the changes in humidity. There are many types of the population fluctuations which occur in the normal population. It includes irruptive and cyclic type. The irruptive type has no cyclic pattern of population density. There is a quick increase in population which occurs in a short time and increases the population density. It is also followed by the reduction in the size of population. The cyclic type has a cyclic pattern of population density. There is a slow increase in the population which occurs in a long time and increases the population density. It occurs due to the seasonal changes. The population of small mouse like rodents has a cyclic pattern of population. They eat all the available food. It is also followed by the reduction in the size of population which occurs due to the spread of diseases and mass scale suicides.
There are many factors which regulate the population of plants. It includes the plant factors, abiotic factors and animal factors. The population of plants increases by the vegetative propagation and seeds. The dispersal of seeds in the unit area and the mortality of plants are important plant factors. The animal factors are intraspecific competition, the degree of predation and attack by the pests and pathogens. The abiotic factors are the sunlight variations, changes in the temperature and humidity, rainfall, mineral and substratum availability.