In logistic growth, a population’s per capita growth rate gets smaller and smaller as population size approaches a maximum imposed by limited resources in the environment, known as the carrying capacity ( K).

Logistic growth takes place when a population’s per capita growth rate decreases as population size approaches a maximum imposed by limited resources, the carrying capacity( K).

When resources are limited, populations exhibit logistic growth. In logistic growth, population expansion decreases as resources become scarce, leveling off when the carrying capacity of the environment is reached, resulting in an S-shaped curve.

Assumptions of the logistic equation:

• The carrying capacity is a constant;
• population growth is not affected by the age distribution;
• birth and death rates change linearly with population size (it is assumed that birth rates and survivorship rates both decrease with density, and that these changes follow a linear trajectory);

Assumptions of Exponential Model: All organisms are identical (e.g., no age structure) Environment is constant in space and time (e.g., resources are unlimited)

Examples of Logistic Growth Examples in wild populations include sheep and harbor seals ([Figure 2]b). In both examples, the population size exceeds the carrying capacity for short periods of time and then falls below the carrying capacity afterwards.

The carrying capacity depends on biotic and abiotic factors. If the factors become less plentiful, the carrying capacity drops. If resources are being used faster than they are being replenished, then the species has exceeded its carrying capacity. If this occurs, the population will then decrease in size.

Population size is the number of individuals in a population. For example, a population of insects might consist of 100 individual insects, or many more. Population size influences the chances of a species surviving or going extinct. Generally, very small populations are at greatest risk of extinction.

In population genetics and population ecology, population size is the number of individual organisms in a population. Overpopulation may indicate any case in which the population of any species of animal may exceed the carrying capacity of its ecological niche.

Larger populations may be more stable than smaller populations because they’re likely to have greater genetic variability and thus more potential to adapt to changes in the environment through natural selection.

In population genetics and population ecology, population size (usually denoted N) is the number of individual organisms in a population. Population size is directly associated with amount of genetic drift, and is the underlying cause of effects like population bottlenecks and the founder effect.

Population size is the actual number of individuals in a population. Population density is a measurement of population size per unit area, i.e., population size divided by total land area. Abundance refers to the relative representation of a species in a particular ecosystem.

Factors that decrease population growth can be defined as environmental stress including limitations in food, predation, and other density-dependant factors (Sibley & Hone 2002). However, many sources of environmental stress affect population growth, irrespective of the density of the population.

Population growth is based on four fundamental factors: birth rate, death rate, immigration, and emigration.

Populations and Environmental Issues More people require more resources, which means that as the population increases, the Earth’s resources deplete more rapidly. The result of this depletion is deforestation and loss of biodiversity as humans strip the Earth of resources to accommodate rising population numbers.

Population growth causes a disproportionate negative impact on the environment. Problems of population size and growth, resource utilization and depletion, and environmental deterioration must be considered jointly and on a global basis.

Factors Influencing Growth Pattern of Population in India are 1. Birthrate, 2. Death Rate, 3. Migration!

Intensity, duration of the causative agent determines the severity of disease.