12 Difference Between R-selected And K-selected Species With Examples  

What Are R-selected Species?

R-selected species also referred to as r-strategists are species whose populations are governed by their biotic potential (maximum reproductive capacity, r). The production of numerous small offspring followed by exponential population growth is the defining characteristic of r-selected species. They require short gestation periods, mature quickly (and thus require little or no parental care), and possess short life spans. Unlike K-selected species, members of this group are capable of reproduction at a relatively young age; however, many offspring die before they reach reproductive age.

In addition, r-selected species thrive in disturbed habitats, such as freshly burned grasslands or forests characterized by canopies that open abruptly, such as when a forest’s tallest trees have been knocked down by a windstorm. Temporary environments, such as vernal ponds and carrion, also harbor r-selected species. Here the ability to reproduce rapidly (exponentially) is important. Such organisms have high fecundity (glossary) and relatively little investment in any one progeny individual; they are typically weak and subject to predation and the vicissitudes of their environment. The “strategic intent” is to flood the habitat with progeny so that, regardless of predation or mortality, at least some of the progeny will survive to reproduce. Organisms that are r-selected have short life spans, are generally small, quick to mature and waste a lot of energy.

Typical examples of r-strategists are:

• Salmon
• Corals
• Bacteria
• Oysters
• Weeds
• Mice
• Rabbits
• Jellyfish
• Dandelions
• Insects such as Mosquitoes, House flies, Daphnia and Goldenrod

Facts About R-selected species

• R-selected species live in variable, unstable habitats (environments with non-predictable conditions).
• R-selected species tend to be small in size and therefore requires a small habitat to live in.
• R-selected species reach sexual maturity early in life.
• They generally have a short life expectancy.
• Their population is not regulated by density.
• R-selected species undergo rapid reproduction to stabilize themselves.
• R-selected organisms reproduce only a single time during their lifespan and require less energy to procreate.
• R-selected species produce many offspring but only a few live out their full lifespan.
• Less prone to extinction because they mature early in life and have a large number of offspring.
• They are easily subject to predation.
• Have high mortality rate.
• R-selected species tend to have a J-shaped population growth curve.
• In R-selected species, there is little or no parental care of young ones.
• They have poor competitive ability.

Also Read: Different Types of Striped Caterpillars

What Are K-selected Species?

K-selected species, also called K-strategist, species whose populations fluctuate at or near the carrying capacity (K) of the environment in which they reside. K-selected species possess relatively stable populations and tend to produce relatively low numbers of offspring; however, individual offspring tend to be quite large with high probability of survival in comparison with r-selected species. K-selected species are characterized by long gestation periods lasting several months, slow maturation (and thus extended parental care), and long life spans. They are stronger or are better protected and generally are more energy efficient. In addition, they tend to inhabit relatively stable biological communities, such as late-successional or climax forests.

Examples of K-selected species include:

• Birds
• Tortoises
• Rhinoceros
• Sperm whales
• Blue whales
• Grizzlies Lemurs
• Larger mammals (such as elephants, horses, and primates)
• Larger

Facts About K-selected Species

• K-selected species live in stable environments (environments with predictable conditions).
• K-selected species tend to be larger in size and therefore requires a large habitat to live in.
• K-selected species reach sexual maturity later in life.
• They generally have long life expectancy.
• Their population stabilizes near carrying capacity.
• K-selected organisms are high in population and do not need to undergo rapid reproduction.
• K-selected organisms reproduce many times during their life span and require more energy to procreate.
• K-selected species have a few offspring that have a long life expectancy.
• K-selected organisms are more prone to extinction than r-selected species because they mature later in life and have fewer offspring with longer gestation periods.
• They are less easily subject to predation.
• Have low mortality rate.
• K-selected species tend to have an S-shaped population growth curve.
• In K-selected species, there is prolonged parental care of the young ones.
• They generally have a good competitive ability.

Difference Between R-selected And K-selected Species In Tabular Form

Further References

1. https://www.nps.gov/articles/bison-bellows-5-26-16.htm#:~:text=K%2Dselected%20species%20possess%20relatively,are%20all%20k%2Dselected%20species.
2. https://www.britannica.com/science/K-selected-species
3. https://www2.nau.edu/lrm22/lessons/r_and_k_selection/r_and_k.html
4. https://study.com/learn/lesson/r-selected-vs-k-selected-species-overview-population-growth.html
5. https://www.cs.montana.edu/webworks/projects/stevesbook/contents/chapters/chapter002/section004/blue/page003.html