Life Strategies

In order to survive, organism of different species choose different methods that ensure their species' survival. This methods are called life strategies.

In nature, there are two  types of life strategies: r-selected and k-selected.

R-selected

Ants are found in millions in the environment. They are
characterized as r-selected organism, specially, due to their
number of offspring and the lack of parental carrying.

R-selected organism are very likely to survive in unstable and unpredicted environment, since they can reproduce quickly and, usually, in large number. This organism usually share common traits, like small bodies, high fecundity, short life spam, produce large number of offspring and there is a few, or none, parent caring. Some examples of this organism are insects and bacteria. 

This species reproduce as close as the their biotic potential as they can get, representing the extreme size along a continuum.

K-selected

Organism organism are usually found in stable and predicted environment. They produce number of offspring that is close to their carrying capacity, since they

have to deal with several factors, for example competition for limited resources like food. This organism are usually big sized and have a long life spam. 

Whale are known to nurse their offspring for several years.

The k-selected organism produce very few offspring, however they take care of them until they reach a mature age, increasing their chance to survive. Some examples of k-selected organism are: humans, bears, whale, crocodiles, birds and etc.

It is very important to remember that the use of k-selected and r-selected descriptions for an organism will depend on who are they be compared to. Rats are usually say to k-selected organisms, however, they r-selected when compared to human beings.