★All living organism exit in group of the same species k/a Population.
★The word population derived latin word populus—people.
Thus a population can be defined as the total accemblage of the same species occupying a perticular space at a given time.
★Some of the ecologist however recognised 20types of population but mostly population on the basis of groups and features can be study following —
★Population characterstics. ★Population dynamics. ★Regulation of Population.
★POPULATION CHARACTERISTICS:- The Population is a collective group of organism of the same species occupying perticular space —
- (1) Population size and density.
- (2) Pattern of population dispersion.
- (3)Age structure.
- (4) Natality (birth rate).
- (5) Motality (death rate).
“Population characteristics refer to the attributes or traits that describe a group of individuals, animals, or other entities within a defined geographic area or social context. These characteristics can be used to better understand the characteristics of the group as a whole and to identify patterns and trends within the population„
★Some common population characteristics include:
1-Age distribution:The distribution of individuals across different age groups within the population.distribution of individuals across different gender categories within the population.
2-Gender distribution:The distribution of individuals across different gender categories within the population.
3-Ethnicity/race distribution: The distribution of individuals across different racial and ethnic categories within the population.
4-Educational level:The educational attainment of individuals within the population, often measured by the highest degree earned.
5-Income level:The income distribution of individuals within the population, often measured by median income or poverty rate.
6-Employment status: The distribution of individuals who are employed, unemployed, or not in the labor force within the population.
7-Health status:The distribution of individuals across different health categories, such as chronic conditions or disabilities, within the population.
8-Familiy size: The average size and composition of families within the population.
9-Geographic location: The distribution of individuals across different geographic regions within the population.
By analyzing these and other population characteristics, researchers and policymakers can better understand the needs and characteristics of different groups within a population and develop policies and interventions to address them.
★Population size and density★
★Population size refers to the total number of individuals of a particular species that live in a specific geographic area at a given time. It can be measured in absolute numbers, such as the number of people in a city or the number of animals in a particular ecosystem.
★Population density, on the other hand, is the number of individuals of a particular species that live in a given area or volume. It is typically measured in individuals per unit area (e.g., people per square kilometer) or individuals per unit volume (e.g., fish per cubic meter of water).
★Population density can vary greatly depending on factors such as resource availability, environmental conditions, and social behavior. High population density can result in increased competition for resources, greater risk of disease transmission, and increased vulnerability to environmental disturbances.
Understanding population size and density is important for managing and conserving natural resources, predicting and mitigating human impacts on ecosystems, and developing strategies for sustainable development.
★Pattern of population dispersion★
Population dispersion refers to the way in which individuals of a particular species are distributed or spread out within a given area. There are three main patterns of population dispersion:—
★Clumped dispersion: This is the most common pattern, in which individuals are clustered together in groups or patches. This occurs when resources such as food, water, or shelter are concentrated in certain areas, leading to a higher density of individuals in those areas. Clumped dispersion can also result from social behaviors, such as herding or flocking.
★Uniform dispersion:In this pattern, individuals are evenly spaced throughout the area, with each individual occupying a defined territory or range. Uniform dispersion can occur when resources are limited and individuals need to maintain a certain distance from one another to avoid competition.
★Random dispersion:This pattern is the least common, in which individuals are distributed randomly throughout the area. Random dispersion can occur when environmental factors such as weather or soil conditions are unpredictable and do not influence the distribution of individuals in a predictable way. It can also occur when there is no strong social or ecological reason for individuals to aggregate or disperse in a particular way.
★In most types of population individuals are of different age. The perporstion of individuals in each age group is calledAge structure or Age distribution of the population. In human being the three ages are relatively equall in length about a third of his life falling in each class. Many plants and animals have very long pre-reproductive period for example – insect have extremely long pre-reproductive period,a very short reproductive period and no post reproductive period.
- Age pyramid
- Pyramid with broad base triangular structure
- Bell shape polygon
- Earn shape polygon
★AGE PYRAMID ★
•An age pyramid is a graphical representation of the age and gender distribution of a population. It is also known as an age structure diagram or population pyramid. The pyramid typically shows the percentage or number of individuals in each age group, with the youngest age group at the bottom and the oldest at the top. The shape of the pyramid can reveal important information about the population, such as whether it is growing, stable, or declining.
•In a growing population, the base of the pyramid is wider, indicating a higher proportion of younger individuals. In a stable population, the pyramid will have a more uniform shape, with similar percentages or numbers of individuals in each age group. In a declining population, the top of the pyramid is wider than the base, indicating a higher proportion of older individuals.
•Age pyramids are commonly used by demographers and social scientists to study population trends, such as changes in fertility rates, mortality rates, and migration patterns. They can also be useful for policymakers and planners in developing strategies for social and economic development, healthcare, and social welfare.
★PYRAMID WITH BROAD BASE TRIANGULAR STRUCTURE★ In indicate a rapidly expanding population with a high percentage of young individual and only few old individual.Thus in rapidly growing young population birth rate is high and population grow may be exponential as in yeast, housefly, paramecium.
★BELL SHAPE★ It indicates a stationary population having on equall no. of young and middle age individuals as the rate of growth become slow and stable i.e the pre-reproductive & reproductive age group become more or less equall in size, post reproductive remaining as the smallest size individuals.
★EARN SHAPE POLYGON★ It indicate yellow percentage of young individual it show a declying population such as earn shape when the birth rate is reduced. The pre-reproductive group in proportion to the other two age the groups of the population.
★NATALITY★ Population increase because of Motality, Natality is a broader term covering the production of new individuals by birth, germination, hatching or fission.
★MOTALITY★ Mortality means the rate of death of individual in the population.it is a negative factor for population growth. ★POPULATION DYNAMICS★
Population dynamics is the study of how populations of organisms change in size, density, and composition over time, as well as the underlying factors that contribute to these changes. This field of study includes analyzing birth rates, death rates, migration patterns, and other demographic factors that influence population growth or decline.
Population dynamics can be applied to a wide range of organisms, including plants, animals, and microorganisms. Understanding population dynamics is important for managing natural resources, predicting the effects of environmental changes, and developing strategies for controlling the spread of diseases and invasive species.
Population dynamics is also relevant to the study of human populations, including demographic trends such as changes in birth rates, life expectancy, and migration patterns. The study of population dynamics can help us to understand how and why human societies have changed over time and may provide insights into how they will continue to change in the future.
★REGULATION OF POPULATION SIZE ★
Regulation of population size refers to the mechanisms and processes that influence the number of individuals in a population over time. These mechanisms can be either biotic (related to living organisms) or abiotic (related to non-living factors).
★Some of the factors that can regulate population size include:
•Predation: Predators can limit the growth of prey populations by consuming individuals.
•Competition: Competition for resources such as food, water, and shelter can limit the growth of a population.
•Disease: Outbreaks of disease can reduce population size by killing individuals.
•Natural disasters: Natural disasters such as floods, hurricanes, and wildfires can kill individuals and destroy habitats, which can limit population growth.
•Migration: Migration can cause populations to increase or decrease in size, depending on the movement of individuals into or out of a population.
•Environmental factors: Environmental factors such as temperature, rainfall, and availability of resources can influence population size.
•Human activities: Human activities such as hunting, fishing, and habitat destruction can have a significant impact on population size.