1. K and r strategists

2. Understanding Population Growth 1.Exponential Growth Model Exponential growth: Exponential growth: The rate of expansion (growth) of a population under ideal conditions.

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

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

5. K: Carrying Capacity maximum environment supporttime (K)The maximum population size that a particular environment can sustainably support over a relatively long period of time (K).

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

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

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

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

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

12. Evolution Shapes Life Histories Life History:Life History: birth reproductiondeath Series of events from birth through reproduction to death. Two basic types of life history strategies: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. Survivorship Curves Late LossLate Loss High survival rates High survival rates until old age.Example: % of survivors % of maximum life span humans

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

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