This presentation was originally rendered as an Apple Keynote presentation designed for use with IB Environmental Systems - For the new IB Environmental Systems and Societies course the topic numbers are incorrect but the content still applies. The presentation is also suitable for use with Ecology and Environmental science Courses. Copyright of sciencebitz.com more sciencebitz resources on iTunesU and iBooks https://itunesu.itunes.apple.com/enroll/DEZ-HWS-HNJ https://itun.es/gb/ymzI6.n

1. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Density dependent
factors tend to act as
direct regulators of
populations
• Negative Feedback

2. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
Population
Time

3. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
Population
Time

4. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
Resource limit reached
Population
Resources Plentiful
Time

5. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
Equilibrium Point
Resource limit reached
Population
Resources Plentiful
Time

6. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
Equilibrium Point
Steady State Equilibrium
Resource limit reached
Population
Resources Plentiful
Time

7. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
Falco pereginus

8. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Until the 1940’s the British population of
Peregrine falcons had remained fairly constant -
about 820 breeding pairs
Falco pereginus

9. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Until the 1940’s the British population of
Peregrine falcons had remained fairly constant -
about 820 breeding pairs
• Limited by available nest sites (same places each
year)
Falco pereginus

10. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Until the 1940’s the British population of
Peregrine falcons had remained fairly constant -
about 820 breeding pairs
• Limited by available nest sites (same places each
year)
• Average brood size was about 2.5 fledged young
each summer
Falco pereginus

11. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Until the 1940’s the British population of
Peregrine falcons had remained fairly constant -
about 820 breeding pairs
• Limited by available nest sites (same places each
year)
• Average brood size was about 2.5 fledged young
each summer
• Come the next breeding season the population
Falco pereginus
was back to about 820 pairs

12. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations

13. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Density independent factors also
regulate population size for many
organisms

14. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Density independent factors also
regulate population size for many
organisms
• Mosquitos are plentiful in the
summer months

15. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Density independent factors also
regulate population size for many
organisms
• Mosquitos are plentiful in the
summer months
• When autumn sets in the
populations crash

16. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Density independent factors also
regulate population size for many
organisms
• Mosquitos are plentiful in the
summer months
• When autumn sets in the
populations crash
• Boom or bust

17. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Density independent factors also
regulate population size for many
organisms
• Mosquitos are plentiful in the
summer months Summer
Population
• When autumn sets in the
populations crash
Winter
• Boom or bust
Time

18. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations

19. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Boom or bust may also be driven by
density dependent factors

20. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Boom or bust may also be driven by
density dependent factors
• Some species are very good at taking
full advantage of any opportunity

21. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Boom or bust may also be driven by
density dependent factors
• Some species are very good at taking
full advantage of any opportunity
• Locust populations can explode

22. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Boom or bust may also be driven by
density dependent factors
• Some species are very good at taking
full advantage of any opportunity
• Locust populations can explode
• They swarm in thousands eat
everything in their path and eventually
totally outstrip their food supply

23. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations

24. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Factors that regulate population size can be categorized as
INTERNAL or EXTERNAL

25. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Factors that regulate population size can be categorized as
INTERNAL or EXTERNAL
• INTERNAL - fertility rates, territory size

26. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Factors that regulate population size can be categorized as
INTERNAL or EXTERNAL
• INTERNAL - fertility rates, territory size
• EXTERNAL - predation pressure, parasitism, disease

27. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations

28. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Equilibrium or Boom and bust

29. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Equilibrium or Boom and bust
• Two types of life strategies can be identified

30. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Equilibrium or Boom and bust
• Two types of life strategies can be identified
• Equilibrium or K strategy species

31. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Equilibrium or Boom and bust
• Two types of life strategies can be identified
• Equilibrium or K strategy species
• Opportunist or r strategy species

32. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations

33. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Equilibrium or Boom and bust

34. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Equilibrium or Boom and bust
• Two types of life strategies can be identified

35. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Equilibrium or Boom and bust
• Two types of life strategies can be identified
• Equilibrium or K strategy species

36. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
• Equilibrium or Boom and bust
• Two types of life strategies can be identified
• Equilibrium or K strategy species
• Opportunist or r strategy species

37. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations

38. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
What are K and r

39. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
What are K and r
• The two variables that
define a population curve

40. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
What are K and r
• The two variables that
define a population curve
• K = carrying capacity

41. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
Population
What are K and r 120
• The two variables that
100
define a population curve 80
• K = carrying capacity
Growth
60
• r = growth rate
40
20
0
0 50 100 150 200 250 300
Time

42. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
K Population
What are K and r 120
• The two variables that
100
define a population curve 80
• K = carrying capacity
Growth
60
• r = growth rate
40
20
0
0 100 200 300 400 500 600
Time

43. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations

44. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
K strategists

45. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
K strategists
• Low reproductive rate

46. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
K strategists
• Low reproductive rate
• Large investment in parental
care

47. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
K strategists
• Low reproductive rate
• Large investment in parental
care
• Late maturity

48. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
K strategists
• Low reproductive rate
• Large investment in parental
care
• Late maturity
• Slow growth

49. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
K strategists
• Low reproductive rate
• Large investment in parental
care
• Late maturity
• Slow growth
• Large organisms

50. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
K strategists • Late successional species
• Low reproductive rate
• Large investment in parental
care
• Late maturity
• Slow growth
• Large organisms

51. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
K strategists • Late successional species
• Low reproductive rate • Niche specialist
• Large investment in parental
care
• Late maturity
• Slow growth
• Large organisms

52. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
K strategists • Late successional species
• Low reproductive rate • Niche specialist
• Large investment in parental • Require stable environment
care
• Late maturity
• Slow growth
• Large organisms

53. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
K strategists • Late successional species
• Low reproductive rate • Niche specialist
• Large investment in parental • Require stable environment
care
• Late maturity
• Slow growth
• Large organisms

54. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations

55. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
r strategists

56. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
r strategists
• High reproductive rate

57. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
r strategists
• High reproductive rate
• Low investment in parental care

58. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
r strategists
• High reproductive rate
• Low investment in parental care
• Early maturity

59. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
r strategists
• High reproductive rate
• Low investment in parental care
• Early maturity
• Rapid growth

60. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
r strategists
• High reproductive rate
• Low investment in parental care
• Early maturity
• Rapid growth
• Small organisms

61. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
r strategists • Pioneer species species
• High reproductive rate
• Low investment in parental care
• Early maturity
• Rapid growth
• Small organisms

62. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
r strategists • Pioneer species species
• High reproductive rate • Generalists
• Low investment in parental care
• Early maturity
• Rapid growth
• Small organisms

63. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
r strategists • Pioneer species species
• High reproductive rate • Generalists
• Low investment in parental care • Rapidly adapt to environmental
variation
• Early maturity
• Rapid growth
• Small organisms

64. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
The reality is more of a continuum

65. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
The reality is more of a continuum
Zebra
Rabbit
Bacteria
r K

66. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations

67. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations

68. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
If life Tables (Survivorship) is plotted for
different species three generalised types
of life curve form

69. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
If life Tables (Survivorship) is plotted for
different species three generalised types
of life curve form
Type 1 - Survivorship is high, most
mortality later in life span

70. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
If life Tables (Survivorship) is plotted for
different species three generalised types
of life curve form
Type 1 - Survivorship is high, most
mortality later in life span
Type II - Constant mortality throughout
life span

71. Topic 2: Ecosystems
2.6 Changes
2.6.3 What regulates populations
If life Tables (Survivorship) is plotted for
different species three generalised types
of life curve form
Type 1 - Survivorship is high, most
mortality later in life span
Type II - Constant mortality throughout
life span
Type III - High mortality early in life, low
survivorship into late life span