What processes occurring in a population affect its number and density?

The population size is affected by:
Fertility – the number of individuals born over a given period of time (month, year, decade). Its effect on the population size depends on the presence of individuals capable of reproduction, their fertility, the survival rate of young individuals, the ratio of the breeding period to the total life expectancy of the species.
Mortality – the number of individuals in a population that died during a certain period of time (month, year, decade). Fertility and mortality are often expressed as a percentage of the total.
Fertility is the average number of offspring produced by individuals at a certain age. High fertility is characterized by individuals with high mortality. In populations where the care of the offspring is well developed, fertility is low.
The ratio of fertility, fertility, mortality of individuals affects the number of populations.
What is meant by population dynamics?
Population dynamics is the process of changing its population over time, depending on environmental factors. Any population is theoretically capable of unlimited population growth, if it is not limited by environmental factors. These changes can be associated with processes that occur spontaneously within the population itself, are caused by exposure to abiotic environmental factors, or by interactions between populations of different species within a biocenosis.
The range of fluctuations can vary over a wide range (in a thousand or more times). Abrupt non-periodic drops in numbers occur as a result of a fire or flood. In this case, favorable conditions are inevitably created for the development of some populations and unfavorable for others.

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