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Reproduction Pattern and Environments Carrying Capacity

Grade 10
Jun 15, 2023



Population dynamics refers to the study of how and why a population changes in size and structure over time. Population dynamics are influenced by rates of reproduction, death, and migration. The term population dynamics refers to the variation in population of a species over time.

Population on Earth
Population on Earth

Carrying Capacity

The carrying capacity of a biological species in a certain habitat refers to the maximum number of individuals (of that species) that the ecosystem can carry and support, taking geographical or physical factors into account. The maximum load of an environment is used to calculate carrying capacity. The physical characteristics of the surroundings operate as limiting factors (e.g., food, water, competition). As a result, these factors are likely to have an impact on the population limit.

Carrying Capacity
Carrying Capacity

Environment’s Carrying Capacity

The carrying capacity of an ecosystem is the number of creatures that it can sustainably maintain. Many variables can impact an ecosystem’s carrying capacity for a certain species, such as the ability to regenerate food, water, environment, or other essentials that populations require to exist. Ecosystems cannot sustainably surpass their carrying capacity for an extended period. When a species’ population density surpasses the carrying capacity of the habitat, the species will run out of food, water, or other needs.


Carrying capacity is also the population size at which the population growth rate equals zero. In short, food availability is an essential element since it influences the size of the species’ population.

It does so in such a way that if food demand is not supplied over a specific time period, population size will gradually fall until resources become enough.

In contrast, when food availability exceeds demand, population growth accelerates and eventually stops when the source becomes depleted.

The carrying capacity of an ecosystem is determined by the maximum population during a specific time period.

Carrying Capacity Graph

Population vs Time Graph
Population vs Time Graph

The carrying capacity (symbol: K) of a biological species is shown by the red dotted horizontal line, which describes the number of organisms that the environment can sustainably maintain for a particular time. It is worth noting that it corresponds with the stable equilibrium, which refers to a population size that has attained a steady state as it approaches the carrying capacity. This position denotes “zero growth.” The development is depicted as an S-shaped curve (a characteristic of logistic growth). The S-shape logistic growth pattern occurs when the growth rate is slow initially (lag phase) and then accelerates (exponential phase). The rate then decreases again when the population achieves carrying capacity.


Calculating Carrying Capacity

The equation for the change in population size may be used to derive a formula for K in order to compute the carrying capacity (K). 

formula for K


Examples of Carrying Capacity

A pond populated initially by ten turtles will be sufficient to support the species’ population. Because there is plenty of water, food, and room, turtles may live and breed at an exponential rate. However, as the population expands, so does the level of competition. Turtles battle for resources such as food, water, and space. Male turtles struggle for mates with other males. These conditions will limit the turtles’ biotic potential. When the population appears steady, for example, at a population of 100 turtles, the carrying capacity for that region is 100 turtles.

Fishes in Tanks
Fishes in Tanks

Reproductive Pattern

Opportunities produce a huge number of tiny offspring, whereas rivals produce fewer, more developed offspring.

Number of Individuals vs Time
Number of Individuals vs Time

K-Selected Species

K selected species:

Population increase in K-selected species follows the logistic growth equation.

In this equation, N denotes the number of people in the population, t is the passage of time, and r denotes the biotic potential.

Population Size vs Time
Population Size vs Time

R-Selected Species

Reproduction pattern for R selected species:

  • R selected species expand rapidly into new, colonized places.
  • They reproduce and spread swiftly, but they are less competitive and must invade new places to survive.
  • When conditions are favorable, they generate a large number of offspring, typically more than the ecosystem can support (carrying capacity), and this is frequently followed by a sudden decrease in population.
  • These animals spend the majority of their time in the reproductive ‘r’ phase.

R selected species:

Population expansion in r-selected species follows the exponential growth equation.

In this equation, N denotes the population size, and t denotes the passage of time. To account for environmental resistance, the factor (1–[N/K]) is frequently included to the equation to provide an upper limit on population expansion.

Carrying Capacity


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