Unit 3.2 ~ K-selected & r-selected species

Quality vs. Quantity

K-selected - “quality”

• Few offspring, heavy parental care to protect them
• Usually reproduce many times
  • Ex: most mammals, birds
• Long lifespan, long time to sexual maturity = low biotic potential = slow pop. growth rate
  • More likely to be disrupted by environmental change or invasive

R-selected - “quantity”

• Many offspring, little to no care 
• May reproduce only once
  • Ex: insects, fish, plants
• Shorter lifespan, quick to sexual maturity = high biotic potential = high pop. growth rate
  • More likely to be invasive
  • Better suited for rapidly changing environmental conditions 

K-selected

• Low biotic potential (rep. rate) = hard for pop. to recover after a disturbance (env. change)
• High parental care means death of parent = death of offspring
• Invasives (usually r) outcompete for resources with high biotic potential & rapid pop. growth
• Less likely to adapt & more likely to go extinct

R-selected 

• High biotic potential (rep. rate) = more rapid pop. recovery after disturbance
• Low parental care means death of parent doesn’t impact offspring
• Not as impacted by invasive species since their pop. grow quickly
  • More likely to be the invasive
• Larger pop. & faster generation time = higher chance of adaptation & lower chance of extinction

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