2.6.1 4,2.1.7


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2.6.1 4,2.1.7

  1. 1. 2.6.1-.4, 2.1.7 Population Dynamics 5/11/2013 Author -Guru IB/ESS 1
  2. 2. Population Dynamics A look at the factors that tend to increase or decrease the size of a population. 5/11/2013 Author -Guru IB/ESS 2
  3. 3. The population size of a species in a given space at a given time is determined by the interplay between BIOTIC POTENTIAL and ENVIRONMENTAL RESISTANCE. Biotic potential = growth rate with unlimited resources. Environmental resistance = all the factors acting jointly to limit population growth. 5/11/2013 Author -Guru IB/ESS 3
  4. 4. POPULATION SIZE Growth factors (biotic potential) Abiotic Favorable light Favorable temperature Favorable chemical environment (optimal level of critical nutrients) Biotic 5/11/2013 High reproductive rate Generalized niche Adequate food supply Suitable habitat Ability to compete for resources Ability to hide from or defend against predators Ability to resist diseases and parasites Ability to migrate and live in other habitats Author -Guru Ability to adapt to environmental change Decrease factors (environmental resistance) Abiotic Too much or too little light Temperature too high or too low Unfavorable chemical environment (too much or too little of critical nutrients) Biotic Low reproductive rate Specialized niche Inadequate food supply Unsuitable or destroyed habitat Too many competitors Insufficient ability to hide from or defend against predators Inability to resist diseases and parasites Inability to migrate and live in other habitats IB/ESS Inability to adapt to environmental change 4
  5. 5. Four variables change population size: 1. NATALITY = birth rate 2. MORTALITY = death rate 3. IMMIGRATION = rate of organisms moving in 4. EMIGRATION = rate of organisms moving out 5/11/2013 Author -Guru IB/ESS 5
  6. 6. REPRODUCTIVE STRATEGIES Carrying capacity K Number of individuals K species; experience K selection r species; experience r selection 5/11/2013 Author -Guru Time IB/ESS 6
  7. 7. Opportunistic or r-Selected Species cockroach dandelion Many small offspring Little or no parental care and protection of offspring Early reproductive age Most offspring die before reaching reproductive age Small adults Adapted to unstable climate and environmental conditions High population growth rate (r) Population size fluctuates wildly above and below carrying capacity (K) Generalist niche Low ability to compete Early successional species 5/11/2013 Author -Guru IB/ESS 7
  8. 8. Competitor or K-Selected Species elephant saguaro Fewer, larger offspring High parental care and protection of offspring Later reproductive age Most offspring survive to reproductive age Larger adults Adapted to stable climate and environmental conditions Lower population growth rate (r) Population size fairly stable and usually close to carrying capacity (K) Specialist niche High ability to compete Late successional species 5/11/2013 Author -Guru IB/ESS 8
  9. 9. SURVIVORSHIP CURVES 5/11/2013 Author -Guru IB/ESS 9
  10. 10. Population density affects population growth. 5/11/2013 Author -Guru IB/ESS 10
  11. 11. DENSITY INDEPENDENT FACTORS = affect a populations’ size regardless of its population density. 1. Weather 2. Earthquakes 3. Floods 4. Fires . . . Natural disasters R-strategists populations are most affected by these. 5/11/2013 Author -Guru IB/ESS 11
  12. 12. DENSITY DEPENDENT FACTORS = affect a populations’ size depending on its population density. 1. Predation 2. Disease 3. Availability of food and water 4. Space Negative Feedback!! 5/11/2013 Author -Guru IB/ESS 12
  13. 13. INTERNAL FACTORS = might include densitydependent fertility or size of breeding territory. EXTERNAL FACTORS = might include predation and disease. 5/11/2013 Author -Guru IB/ESS 13
  14. 14. Species interactions influence population growth and carrying capacity = SYMBIOSIS Competition for resources. High Relative population density Relative population density High Paramecium aurelia Paramecium caudatum Low 0 2 4 5/11/2013 6 8 10 Days 12 14 16 18 Author -Guru Each species grown alone Low 0 Paramecium aurelia Paramecium caudatum 2 4 6 8 10 Days 12 14 16 IB/ESS Both species grown together 14 18
  15. 15. Resource Portioning 5/11/2013 Author -Guru IB/ESS 15
  17. 17. Avoiding predators Span worm Wandering leaf insect Poison dart frog Viceroy butterfly mimics monarch butterfly 5/11/2013 Author -Guru Bombardier beetle Hind wings of io moth resemble eyes of a much larger animal IB/ESS Foul-tasting monarch butterfly When touched, the snake caterpillar changes shape to look like the head of a snake 17
  18. 18. Parasitism 5/11/2013 Author -Guru IB/ESS 18
  19. 19. Mutualism Oxpeckers and black rhinoceros 5/11/2013 Author -Guru Clown fish and sea anemone IB/ESS 19
  20. 20. Shark and ramora 5/11/2013 Author -Guru IB/ESS 20
  21. 21. Cleaning station Cleaner blenny Sabertooth blenny 5/11/2013 Author -Guru IB/ESS 21
  22. 22. Commensalism 5/11/2013 Author -Guru IB/ESS 22
  23. 23. Herbivory 5/11/2013 Author -Guru IB/ESS 23