3.5 Population Growth and Resource Availability

Population Growth refers to the rate a population can grow at with given limitations by surrounding environments. More specifically, population growth rate documents how competition (other species), biome (environment), and self-sufficiency leads to growth in a certain population. Almost always, a species with a higher population growth rate will outlive a species with a lower rate.

Exponential Growth 

An exponential growth is when populations grow at their intrinsic rate of increase (r) and are limited by resource increase by a fixed rate each year.  This type of exponential growth is described using a J Curve because of the shape of the accelerated growth rate. An example of a species with an exponential growth is bacteria. The population size of bacteria grows exponentially because there are no limiting factors on their growth.

Diagram Courtesy of Encyclopedia Britannica, Inc. 

Logistic Growth

A logistic population growth model shows a population exponentially growing until environmental resistance such as limited factors make it reach its carrying capacity. The line at the top of the graph demonstrates this limit, and any population that exceeds it will go into overshoot. The population growth makes an S shaped curve.

Diagram Courtesy of Encyclopedia Britannica, Inc. 

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