Fiveable
Fiveable

or

Log in

Find what you need to study


Light

Find what you need to study

3.2 K-Selected r-Selected Species

3 min readjanuary 7, 2023

Karla Jauregui Sandoval

Karla Jauregui Sandoval

Jillian Holbrook

Jillian Holbrook

Karla Jauregui Sandoval

Karla Jauregui Sandoval

Jillian Holbrook

Jillian Holbrook

Differential Reproductive Strategies

Population rates for species depend on the effectiveness of their reproductive strategies. Through comparing the reproductive strategies of species, we are prompted to ask:

  • What is the average size of the species?
  • How much time goes into parental care for offspring? 
  • How many offspring does the species produce?
  • How much competition is there for resources? 
  • What role does the species play in ?
  • Is the species invasive or affected by an ?
  • In ecology, the terms "r-selected" and "K-selected" refer to the two ends of a spectrum of reproductive strategies that species can adopt.

    R-selected species are those that have a high rate of reproduction and low investment in individual offspring. These species are adapted to environments where resources are scarce and unpredictable, and their strategy is to produce many offspring with the hope that a few will survive to reproduce. Examples of r-selected species include annual plants, insects, and some small mammals. 🐁

    K-selected species, on the other hand, have a low rate of reproduction and a high investment in individual offspring. These species are adapted to environments where resources are more stable, and their strategy is to produce a smaller number of offspring but to use more resources in their survival. Examples of K-selected species include large mammals. 🐘

    https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-ye22tYsYJbRM.jpg?alt=media&token=433b4ba0-74f7-4bad-8e0b-29373f1ba456

    Image Courtesy of BioNinja

    refers to the maximum reproductive rate of a population in ideal conditions. It is determined by the rate of reproduction and survival of the species, as well as the availability of resources.

    If a species has a high and is able to reproduce and survive at high rates, it will have the potential to grow and expand its range quickly. On the other hand, if a species has a low and is unable to reproduce and survive at high rates, it will have a slower rate of population growth and may be more vulnerable to extinction.

    Characteristics of K-Selected Species 

    https://cdn.pixabay.com/photo/2016/12/27/06/14/africa-1933329_960_720.jpg

    Image Courtesy of Pixabay

    A K-selected species can be described as larger species and tend to consist of terrestrial mammals. These species invest a lot of parental care into raising their offspring, which is why their family sizes, or numbers of offspring, are smaller.

    Because significant time, energy, and resources are invested into child rearing, K-selected species tend to have a Type I and . Offspring live longer lives and grow slowly through an extended period of youth until their habitat hits the . K-selected species reproduce more than once in their lifetime, but competition for resources tends to be relatively high.

    Characteristics of R-Selected Species 

    https://cdn.pixabay.com/photo/2014/07/17/20/56/mice-395831_960_720.jpg

    Image Courtesy of Pixabay

    R-selected species are generally small, and parents invest little time and energy into parental care. The family size of these species is large! R-selected species have many offspring per reproductive age. However, r-selected species have a , which means a shorter lifespan and that most offspring die off at an early age.

    Because r-selected species must adapt quickly to their unpredictable habitats, these species experience lower competition for resources. However, r-selected species tend to only reproduce once in their lifetime.

    Comparing K-Selected and R-Selected Species

    K-selected 

    r-selected 

    Size 

    Generally larger as species (terrestrial mammals)

    Generally small 

    Parenting

    LOTS of parental care ➪time, energy, and resources in child rearing 

    Parents invest a little amount of time. energy  and resources in children 

    Family Size 

    Small  ➪ few offspring per reproductive event 

     ➪ long lifespans 

     ➪ grow slowly until they hit  

    Large offspring per reproductive event 

     ➪ short lifespan 

     ➪ fast sexual maturity 

     ➪ grow quickly but are followed by overshoots and die-offs - predator-prey relationships 

    Competition

    Highly competitive for resources (crowded niches)

    Low competition for resources ➪  adapt quickly 

    Eco. Succession

    Late stage successors 

    Pioneer species

     

    Mostly affected by  

    Most are r selected because they reproduce quickly 

    Examples

    Humans, eagles, elephants, parrots, bison, and bears. 

    Insects, mice, bacteria, grasses, 

    🎥 Watch this video here at 34 minutes to discuss this key topic more!

    Key Terms to Review (8)

    Biotic Potential

    : Biotic potential refers to the maximum rate at which a population can grow under ideal conditions with unlimited resources.

    Carrying capacity

    : Carrying capacity is the maximum number of individuals of a species that an environment can sustainably support without degrading the ecosystem or depleting resources.

    Differential Reproductive Strategies

    : Differential reproductive strategies refer to the various ways in which different species reproduce and allocate their resources towards reproduction. Some species have a high reproductive rate with little parental care (r-selected species), while others have a low reproductive rate with significant parental investment (K-selected species).

    Ecological succession

    : Ecological succession refers to the gradual process of change in species composition and community structure in an ecosystem over time. It occurs as one community replaces another due to natural disturbances or human activities.

    Invasive Species

    : Invasive species are non-native organisms that cause harm to the environment, economy, or human health. They outcompete native species for resources and disrupt ecosystems.

    Type I survivorship curve

    : Type I survivorship curve refers to a pattern where most individuals survive to old age, with high mortality rates occurring later in life.

    Type II survivorship curve

    : Type II survivorship curve refers to a pattern where the probability of survival remains relatively constant throughout an organism's lifespan.

    Type III survivorship curve

    : Type III survivorship curve refers to a pattern characterized by high mortality rates early in life and higher chances of survival for those who reach adulthood.

    3.2 K-Selected r-Selected Species

    3 min readjanuary 7, 2023

    Karla Jauregui Sandoval

    Karla Jauregui Sandoval

    Jillian Holbrook

    Jillian Holbrook

    Karla Jauregui Sandoval

    Karla Jauregui Sandoval

    Jillian Holbrook

    Jillian Holbrook

    Differential Reproductive Strategies

    Population rates for species depend on the effectiveness of their reproductive strategies. Through comparing the reproductive strategies of species, we are prompted to ask:

  • What is the average size of the species?
  • How much time goes into parental care for offspring? 
  • How many offspring does the species produce?
  • How much competition is there for resources? 
  • What role does the species play in ?
  • Is the species invasive or affected by an ?
  • In ecology, the terms "r-selected" and "K-selected" refer to the two ends of a spectrum of reproductive strategies that species can adopt.

    R-selected species are those that have a high rate of reproduction and low investment in individual offspring. These species are adapted to environments where resources are scarce and unpredictable, and their strategy is to produce many offspring with the hope that a few will survive to reproduce. Examples of r-selected species include annual plants, insects, and some small mammals. 🐁

    K-selected species, on the other hand, have a low rate of reproduction and a high investment in individual offspring. These species are adapted to environments where resources are more stable, and their strategy is to produce a smaller number of offspring but to use more resources in their survival. Examples of K-selected species include large mammals. 🐘

    https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-ye22tYsYJbRM.jpg?alt=media&token=433b4ba0-74f7-4bad-8e0b-29373f1ba456

    Image Courtesy of BioNinja

    refers to the maximum reproductive rate of a population in ideal conditions. It is determined by the rate of reproduction and survival of the species, as well as the availability of resources.

    If a species has a high and is able to reproduce and survive at high rates, it will have the potential to grow and expand its range quickly. On the other hand, if a species has a low and is unable to reproduce and survive at high rates, it will have a slower rate of population growth and may be more vulnerable to extinction.

    Characteristics of K-Selected Species 

    https://cdn.pixabay.com/photo/2016/12/27/06/14/africa-1933329_960_720.jpg

    Image Courtesy of Pixabay

    A K-selected species can be described as larger species and tend to consist of terrestrial mammals. These species invest a lot of parental care into raising their offspring, which is why their family sizes, or numbers of offspring, are smaller.

    Because significant time, energy, and resources are invested into child rearing, K-selected species tend to have a Type I and . Offspring live longer lives and grow slowly through an extended period of youth until their habitat hits the . K-selected species reproduce more than once in their lifetime, but competition for resources tends to be relatively high.

    Characteristics of R-Selected Species 

    https://cdn.pixabay.com/photo/2014/07/17/20/56/mice-395831_960_720.jpg

    Image Courtesy of Pixabay

    R-selected species are generally small, and parents invest little time and energy into parental care. The family size of these species is large! R-selected species have many offspring per reproductive age. However, r-selected species have a , which means a shorter lifespan and that most offspring die off at an early age.

    Because r-selected species must adapt quickly to their unpredictable habitats, these species experience lower competition for resources. However, r-selected species tend to only reproduce once in their lifetime.

    Comparing K-Selected and R-Selected Species

    K-selected 

    r-selected 

    Size 

    Generally larger as species (terrestrial mammals)

    Generally small 

    Parenting

    LOTS of parental care ➪time, energy, and resources in child rearing 

    Parents invest a little amount of time. energy  and resources in children 

    Family Size 

    Small  ➪ few offspring per reproductive event 

     ➪ long lifespans 

     ➪ grow slowly until they hit  

    Large offspring per reproductive event 

     ➪ short lifespan 

     ➪ fast sexual maturity 

     ➪ grow quickly but are followed by overshoots and die-offs - predator-prey relationships 

    Competition

    Highly competitive for resources (crowded niches)

    Low competition for resources ➪  adapt quickly 

    Eco. Succession

    Late stage successors 

    Pioneer species

     

    Mostly affected by  

    Most are r selected because they reproduce quickly 

    Examples

    Humans, eagles, elephants, parrots, bison, and bears. 

    Insects, mice, bacteria, grasses, 

    🎥 Watch this video here at 34 minutes to discuss this key topic more!

    Key Terms to Review (8)

    Biotic Potential

    : Biotic potential refers to the maximum rate at which a population can grow under ideal conditions with unlimited resources.

    Carrying capacity

    : Carrying capacity is the maximum number of individuals of a species that an environment can sustainably support without degrading the ecosystem or depleting resources.

    Differential Reproductive Strategies

    : Differential reproductive strategies refer to the various ways in which different species reproduce and allocate their resources towards reproduction. Some species have a high reproductive rate with little parental care (r-selected species), while others have a low reproductive rate with significant parental investment (K-selected species).

    Ecological succession

    : Ecological succession refers to the gradual process of change in species composition and community structure in an ecosystem over time. It occurs as one community replaces another due to natural disturbances or human activities.

    Invasive Species

    : Invasive species are non-native organisms that cause harm to the environment, economy, or human health. They outcompete native species for resources and disrupt ecosystems.

    Type I survivorship curve

    : Type I survivorship curve refers to a pattern where most individuals survive to old age, with high mortality rates occurring later in life.

    Type II survivorship curve

    : Type II survivorship curve refers to a pattern where the probability of survival remains relatively constant throughout an organism's lifespan.

    Type III survivorship curve

    : Type III survivorship curve refers to a pattern characterized by high mortality rates early in life and higher chances of survival for those who reach adulthood.


    © 2024 Fiveable Inc. All rights reserved.

    AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.


    © 2024 Fiveable Inc. All rights reserved.

    AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.