R and K selection

As the name implies, r-selected species are those that place an emphasis on a high growth rate, and, typically exploit less-crowded ecological niches, and produce many offspring, each of which has a relatively low probability of surviving to adulthood.

HIGH (Reproductive Rate) = R
LOW (Reproductive Rate) = K

K species live in populations that are near or at the equilibrium conditions for long periods of time. Competitive for limited resources is very important in these environments.
I.e. Lemmas, Giraffe, elephants and bats.

R species live in populations that are highly variable. the fittest individuals in these environment have many offspring and reproduce early.  
I.e. Mosquitos and Toads.


Figure 1. A table showing r-K scale of reproductive of balancing egg outputs

Dis/Advantages of being a K species;

• reproductive rate last long time along with parental care making them a weakness to a competitive environment. (Dis)
• More care to young makes them more ability to survive in the wild as they will have learned behaviours from parents (Ad)
• The young will have be dependant on the mother which in order makes the mother a target for predators as she has herself to protect as well as her young (Dis)
• Fewer, Larger offspring. (Dis)
• Later reproductive age (Dis/Ad)
• High parental Care and protection for offspring (Dis)
• Larger Adults (Ad)
• Adapted to stable conditions of the environment (Ad)
• Population size fairly stable and usually close to carrying the capacity (Ad)

Dis/ Advantages of being a R species;

• where there is a short reproductive period there is less weakness for the a competitive environment (Ad)
• Likely that more young is produced known that at least one young will survive however they do have to learn on there own due to lack of parental care. (Dis)
• No young dependent on mother however this means lack of survival (Dis)
• Lower population growth rate (Dis)

Figure 2; Comparison chart for the R and K