14 Difference Between r-Selected And k-Selected Species With Examples

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What Are R-Selected Species?

R-selected species, also referred to as r-strategist, are species whose populations are determined by their maximum reproductive capacity (biotic potential). R-selected species thrive in unstable habitats such as freshly burned grasslands, vernal ponds, carrion or forests characterized by canopies that open abruptly such as when a forest’s tallest tree has been fallen by a windstorm.

The main characteristic of r-selected species is the production of numerous small offspring followed by exponential population growth. This species also require short gestation periods, reach sexual maturity early in life and thus requires little or no parental care. They also have short life spans and reproduce only a single time during their lifespan and require less energy to procreate. More importantly, R-selected species produce many offspring but only a few live out their full lifespan.

Examples of R-selected species are:

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

What You Need To Know About r Selected Species

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

What Are K-Selected Species?

K-selected species also referred to as K-strategist, species whose populations fluctuate at or near the carrying capacity of the environment in which they operate. K-selected species tend to inhabit relatively stable biological environments i.e environments with predictable conditions.

K-selected species also tend to be quite large in comparison to r-selected species, reach sexual maturity later in life and produce relatively low numbers of offspring that have a long life expectancy. More Importantly, 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.

Examples of K-selected species are:

  • Giant Sequoia
  • Red wood trees
  • Giraffes
  • Elephants
  • Bats
  • Tortoises
  • Rhinoceros
  • Sperm whales
  • Blue whales
  • Grizzlies Lemurs
  • Primates including humans etc.

What You Need To Know About K Selected Species

  1. K-selected species live in stable environments (environments with predictable conditions).
  2. K-selected species tend to be larger in size and therefore requires a large habitat to live in.
  3. K-selected species reach sexual maturity later in life.
  4. They generally have long life expectancy.
  5. Their population stabilizes near carrying capacity.
  6. K-selected organisms are high in population and do not need to undergo rapid reproduction.
  7. K-selected organisms reproduce many times during their life span and require more energy to procreate.
  8. K-selected species have a few offspring that have a long life expectancy.
  9. 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.
  10. They are less easily subject to predation.
  11. Have low mortality rate.
  12. K-selected species tend to have an S-shaped population growth curve.
  13. In K-selected species, there is prolonged parental care of the young ones. 
  14. They generally have a good competitive ability.

Also Read: Difference Between Biotic And Abiotic Factors

Difference Between r-Selected And k-Selected Species In Tabular Form

BASIS OF COMPARISON R-SELECTED SPECIES K-SELECTED SPECIES
Habitat They live in variable, unstable habitats (environments with non-predictable conditions).   They live in stable environments (environments with predictable conditions).  
Size The species tend to be small in size and therefore requires a small habitat to live in.   The species tend to be larger in size and therefore requires a large habitat to live in.  
Sexual Maturity Species reach sexual maturity early in life.   Species reach sexual maturity later in life.  
Life Expectancy They generally have a short life expectancy.   They generally have long life expectancy.  
Population Their population is not regulated by density.   Their population stabilizes near carrying capacity.  
Reproduction R-selected species undergo rapid reproduction to stabilize themselves.   The organisms are high in population and do not need to undergo rapid reproduction.  
Number Of Reproduction R-selected organisms reproduce only a single time during their lifespan and require less energy to procreate.   K-selected organisms reproduce many times during their life span and require more energy to procreate.  
Number Of Offspring Species produce many offspring but only a few live out their full lifespan.   Species have a few offspring that have a long life expectancy.  
Extinction Less prone to extinction because they mature early in life and have a large number of offspring.   The organisms are more prone to extinction than r-selected species because they mature later in life and have fewer offspring with longer gestation periods.  
Predation They are easily subject to predation.   They are less easily subject to predation.  
Mortality Have high mortality rate.   Have low mortality rate.  
Population Growth Curve R-selected species tend to have a J-shaped population growth curve.   K-selected species tend to have an S-shaped population growth curve.  
Competitive Ability They have poor competitive ability.   They generally have a good competitive ability.  

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