K-strategist populations are more commonly regulated by density-dependent limiting factors. Their population sizes hover around a carrying capacity that is dependent on factors that increase in severity with the density of the population. On the other hand, r-strategist populations are regulated by density-independent limiting factors. They reproduce rapidly until a density-independent factor causes many of them to die.

Cultural carrying capacity suggests that humans have secondary needs, such as entertainment, palatable food, and mental/spiritual development. These non-vital resources can only be spread equally among a population of a limited size. Cultural carrying capacity describes the limitation on population size after taking into account these factors. 

A frequent questions asked by sustainability scientists is: Should the optimum sustainable population be based on cultural carrying capacity? Many would agree yes, for the reason that when cultural capacity is transgressed, living conditions spiral downwards and life is reduced to the struggle for mere survival. In such conditions, human inventiveness and creativity become obsolete.

Population growth can follow either a J curve trend or an S curve trend. A J curve represents exponential, or unrestricted growth. An S curve represents logistic, or restricted, growth and accounts for the carrying capacity of an environment.

In a J curve model, the population will continue to grow even when it has reached capacity. In an S curve model, the population will stagnate and stabilize at a maximum value when capacity is reached.

Clumped distribution patterns localize individuals around scarce resources in environments where they are not equally distributed throughout. The clumping of organisms around these resources attracts predators and makes for easy predation. Because of the scarcity of water in desert, plain and tundra biomes, it is seen in large quantities in nature.  

The carrying capacity of a certain habitat is the maximum number of individuals that it can support. Population numbers are limited by resources such as space, food, and water. Current estimates of Earth's carrying capacity are around 10 billion. 

The population's new size at the start of 2012 was = original population + (births + immigrations) - (deaths + emigrations) = 120 + (18 + 2) - (2 + 3) = 135. Then, the net population growth rate is equal to (net change in population / size of old population) = 15/120 = .125.

Species designated as K-strategists thrive through longevity and have a higher survival rate at birth, but produce far fewer offspring. Examples include elephants and whales. Consider an elephant; it may produce relatively few baby elephants, but these baby elephants each have the potential to live relatively long lives. On the other hand, contrast K-strategists like elephants with r-strategists like rats, locusts, and flies. These species are designated as r-strategists because in contrast, they produce numerous offspring, few of which may survive to adulthood, and each one of which reaches maturity quickly and lives a relatively short life. K-strategists in general spend more time than r-strategists caring for and raising their offspring; they have fewer offspring, so they put more care into ensuring the survival of each one. Contrast elephants with frogs to see this difference; elephants care for their young, while frogs lay their eggs and care for their offspring very little, if at all.

Species described as "r-strategist" have a survival strategy of producing large numbers of offspring, a short life expectancy, and typically smaller body sizes. Examples include mice, locusts, and frogs. These species survive by producing lots of offspring, since many individuals don't survive to adulthood.

R-selected individuals are characterized by the following: early age of sexual maturity, many lifetime reproductive events, large numbers of offspring per event, and minimal parenting. Many of the offspring of r-selected species will die before adulthood. On the other hand, K-selected individuals have only one or few offspring at once and invest larger amounts of time and energy into parenting to ensure survival. The rabbit is the only species listed whose life traits can be categorized as being r-selected.

Use the Rule of 72:

 is rate of growth

 is time (in years) it takes to double

By manipulating the equation to divide 72 by the given growth rate, you can find the number of years it takes for the population to double.