The r/K Selection Theory
There are a few scientific theories that involve evolution and genetic inheritance. One such theory is the r/K selection theory which theorizes that living organisms are divided into the types r or K (both derived from algebra) in terms of the characteristics of their reproduction. In the theory, the inheritance and combination of selected traits trade off either the quality of the organism or the quantity in which the organism is produced. However, both aim for the organism's success in their given environment.
To illustrate, an organism that follows the laws of r‐selection is usually found in uncrowded environments. Often, these environments are also unstable and/ or unpredictable. They produce multiple offspring which often need little care and also have a low chance of surviving or reaching adulthood. These r‐selected organisms are known as opportunistic organisms. Perhaps because it seems that they are trying to give themselves as many opportunities as possible for the survival of the species.
Apart from providing multiple offspring, they also reproduce faster than other living species. Their species is given little time to adapt to an environment because the environment is likely to change quickly and adaptation is a characteristic of competition with other organisms, something they do not worry about. They usually have small bodies, mature quickly, and have short time periods between generations. Common r‐selected organisms are insects, weeds, bacteria, semelparous cephalopods and semelparous mammals like rodents.
K‐selected organisms, on the other hand are usually found in relatively crowded environments. Often, these environments are stable. They produce few offspring which often need a lot of care and are verylikely to reach adulthood or maturity. These K‐selected organisms are known as organisms in equilibrium. This name is likely due to the fact that they are able to keep their species in balance despite producing such few offspring and with long gaps between generations.
A characteristic of K‐selection is that the organisms are able to compete successfully for resources needed for survival. Their traits include having large bodies, long lives, extensive care of the young, and their population is almost at the maximum that can be handled by the environment. Many mammals, like humans, whales, elephants, and some plants like the giant redwoods are of this type of organism.
Understanding the differences between r/K selection can help us better understand how the environment works. For example, in extreme environmental disasters wherein large groups of animals and plant life are wiped out, the first plants that usually begin growing are r‐selection plants. Over time, and many generations, as the environment becomes healthy and stable and reaches equilibrium again, these plants begin to compete with each other, changing their characteristics and become K‐selection plants. The same can be said for small animals in the same situation.
The r/K selection theory is quite popular among scientists, though it has been contested by certain scientists who have provided proof of animals with K‐selection traits, but with r‐selection forms of producing offspring. Nevertheless knowing the difference between r and K selection is an important part of advancing our knowledge on the living organisms on the planet.
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