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K and r strategists

K and r strategists. Understanding Population Growth. Exponential Growth Model Exponential growth: The rate of expansion ( growth) of a population under ideal conditions . Number of individuals (N). Time. Exponential Growth (J curve). Example: bacteria.

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K and r strategists

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  1. K and r strategists

  2. Understanding Population Growth • Exponential Growth Model Exponential growth: The rate of expansion (growth) of a population under ideal conditions.

  3. Number of individuals (N) Time Exponential Growth (J curve) • Example:bacteria produces a J-shaped curve

  4. Understanding Population Growth 2. Logistic Growth Model logistic growth:Environmental factors restrict the growth of a population (The factors are called: limiting factors.)

  5. K: Carrying Capacity • The maximumpopulation size that a particular environment can sustainably supportover a relatively long period of time (K).

  6. Number of individuals (N) Time Logistic Growth (S curve) • Example: turtles in a pond K produces a S-shaped curve

  7. Draw an s-curve and draw a j-curve • Label each with the lag phase the growth phase, the stationary phase

  8. Factors That Limit Population Growth 1. Density-Dependent Factors: a. Population-limiting factors whose effects depend on population density. b. The greater the pop, the greater the effects. Examples: 1. Limited food supply 2. Disease 3. Predation 4. Nesting sites

  9. Factors That Limit Population Growth 2. Density-Independent Factors: a. Population-limiting factors (abiotic) whose occurrence is not affected by pop density. b. the greater the population, the greater the effects Examples: 1. Earthquakes 2. Fires 3. Hurricanes 4. Freeze in the fall

  10. number of individuals in pop. Time Boom and Bust Species • A rapid increase (boom) in a population followed by a sharp decline (bust). • Examples: a. Daphnia in a pond boom bust

  11. number of individuals in pop. Years Boom and Bust Species • Sometimes species(carnivore) depend on other species (prey) for food. • Example: Snowshoehare and lynx

  12. Evolution Shapes Life Histories • Life History: Series of events from birth through reproduction to death. • Two basic types of life history strategies: 1. Opportunistic life history (r-selected species) 2. Equilibrial life history (K-selected species)

  13. 1. Opportunistic life history(r-selected species) Characteristics: 1. maturing time: short 2. life span: short 3. mortality rate: often high 4. times female is reproductive: usually once 5. age at first reproduction: early 6. size of offspring: small 7. parental care: none 8. Size of organism: small

  14. 2. Equilibrial life history(K-selected species) Characteristics: 1. maturing time: long 2. life span: long 3. mortality rate: often low 4. times female is reproductive: often many 5. age at first reproduction: late 6. size of offspring: large 7. parental care: often extensive 8. Size of organism: tend to be large

  15. Life History Examples r-selected species: 1. Garden weeds 2. Insects 3. Desert flowers K-selected species: 1. Humans 2. Apes 3. Elephants

  16. % of survivors % of maximum life span Survivorship Curves • Late Loss High survival rates until old age. Example: humans

  17. % of survivors % of maximum life span Survivorship Curves • Constant Loss Intermediate between the extremes. Example: squirrel

  18. % of survivors % of maximum life span Survivorship Curves • Early Loss High mortality rates as larvae but decreased mortality at later ages. Example: oysters frogs insects

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