1. Chapter 4 Ecosystems & Communities
Section 4-2
What Shapes an Ecosystem?

2. What Shapes an Ecosystem?
The PHYSICAL factors of a habitat are known as ABIOTIC.
(a=not bio=life)
aka: anything not living
-soil, water, temperature, light, wind, minerals, organic compounds
The biological influences of a habitat are known as BIOTIC.
-Anything living—both macroscopic and microscopic!

3. Biotic & Abiotic Factors
Key Concept:
Together, biotic and abiotic factors determine the survival and growth of an organism and the productivity of the ecosystem.

4. Diverse Communities in Ecosystems
There are many measures of biodiversity
Considering species diversity, more diverse communities tend to be more productive.
The role of diversity in community stability is less clear.

5. HABITAT
HABITAT: The place where a particular population of a species lives
Niche is an organism’s total way of life

6. Niche
You might think that competition for resources would make it impossible for so many species to live in the same habitat.
However, each species has different requirements for its survival.
As a result, each species has its own niche.
An organism’s niche is its role in its environment – how it obtains food and shelter, finds a mate, cares for its young, and avoids danger.

7. Habitat
One habitat might contain hundreds or even thousands of species.
A rotting log in a forest can be home to many species of insects, including termites that eat decaying wood and ants that feed on the termites.
Other species that live on and under rotting log include millipedes, centipedes, spiders, and worms.

8. Niche
The full range of physical and biological conditions in which an organism lives AND the way in which the organism uses those conditions.
Determined by the biotic & abiotic factors of the ecosystem

9. Niche
Essentially it is the sum of all activities and relationships a species has while obtaining and using the resources needed to survive and reproduce.
A species' niche includes:
a. Habitat - where it lives in the ecosystem
b. Relationships - all interactions with other species in the ecosystem
c. Nutrition - its method of obtaining food.

10. Community Interactions
Key Concept:
Community Interactions, Such As Competition, Predation, and Various Forms of Symbiosis, Can Powerfully Affect An Ecosystem

11. Competition FOOD (LIGHT) WATER SHELTER SPACE REPRODUCTION
Resource: FWSSR
Any Necessity of Life:
FOOD (LIGHT)
WATER
SHELTER
SPACE
REPRODUCTION

12. Competition
Occurs When Different species attempt to use the same resource at the same place & time.

13. Competition
2 Species have the same niche: both compete head to head in the niche for resources, nesting sites, or territory. One of the species will be superior to the other in utilizing the niche. The 2nd species disappears from the ecosystem.
2 Species partially share a niche: both compete in the overlapping parts of the niche for resources, nesting sites, or territory. If the overlap is minimal, both species can coexist.

14. Competitive Exclusion Principle
No Two Species Can Occupy The Same Niche In the Same Habitat At The Same Time.

15. A fourth species, D, which has the same environmental requirements as species B, enters the tree at point X. Members of species B will most likely:
live in equilibrium with species
move to a different level and live with species A or C
stay at that level but change their diet
compete with species D for resource

16. The competitive exclusion principle

17. Predation

18. Predation

19. Predator and Prey
An organism’s niche includes how it avoids being eaten and how it finds or captures its food.

20. One organism captures and feeds on another organism.
Predation
One organism captures and feeds on another organism.
Predator = Killer/Eater
Prey = The Eaten One

21. Predator and Prey The deer is being eaten by the python. It is prey.
The python has captured and is eating the deer.

22. Predator and Prey
The alligator did get some revenge. The meal was too big for the python and caused it bust.
This python swallowed the alligator. It is the predator.
This alligator was swallowed by the python. It was the prey.

23. Predator and Prey
Predator
Prey

24. Predator and Prey This alligator is the predator. It eats the python.
This python is the prey. It is eaten by the alligator.

25. Predator and Prey
Predator
Prey

26. Predator and Prey
Predator
Prey

28. Symbiosis
Not all relationships among organisms involve food.
Many organisms live together and share resources in other ways.
Any close relationship between species is called symbiosis.

30. Nutritional Relationships
Symbiosis: close association of 2 organisms of different species

31. Symbiosis
Three Different Types:
Commensalism
Parasitism
Mutualism

32. Mutualism
both species benefit from the relationship

33. Lichens: Pioneer Species
Mutualistic Relationship Between Fungus & Algae or Cyanobacterium

34. The Perfect Relationship!
~90% of legumes become nodulated
Rhizobium gets a nice place to live (plant provides nutrients & energy to the bacteria)
Rhizobia fix nitrogen gas for the “breadwinner” (plant)
N is most limiting element in terrestrial ecosystems

35. Cowbirds and Large Animals
The cowbird benefits by eating the ticks and mites off the large animal. The large animal benefits from have the parasites removed from them. The birds can also warn them of danger.

37. Termites and Trichonympha
You probably think termites eat wood; they do – in a way.
Termites can’t digest cellulose, which is the main component of wood.
Therefore, they get help from a protozoan called trichonympha.
This protozoan lives in the gut of the termite. It breaks down the cellulose for the termite.
The trichonympha gets a free meal and shelter; the termite is able to eat and receive nutrients from the wood.

38. Termite and Trichonympha

39. Trichonympha

40. Bees and Pollen
Bees receive nectar from the flowers in order to make honey. As the bees collect nectar, they collect pollen on their body. As they fly to another flower, they pollinate it by dusting the pollen on the flowers stamen.

42. Commensalism
One species (visitor) lives on another species (host) without doing harm to it.

43. Clown Fish and Sea Anemones
The clown fish is immune to the stings of the sea anemones tentacles. The clown fish makes its home in the tentacles for protection. The clown fish gets shelter, but the sea anemone gets nothing.

45. Shark and Remora
The remora hangs around the shark picking up any scraps it may leave. The remora gets food while the shark gets nothing.

52. Loggerhead Sponge & Pistol Shrimp

53. Epiphytes on trees

55. Parasitism
The host is always harmed by the visitor (parasite)

56. Isopod

60. Lamprey

61. Lamprey Mouth

62. Tapeworm and Humans

63. Tapeworms

64. Tapeworms

65. Tapeworms and Humans

66. Hookworms

67. Roundworms

68. Cuckoo and Warbler

69. Cuckoo birds and warblers
Soon after hatching the cuckoo chick, still naked and blind,
Ejects the warbler’s eggs out of the nest, one by one.
The warbler never interferes, even as its reproductive
Success is destroyed in front of its own eyes.

70. Cuckoo and Warbler

71. Cuckoo and Warbler

72. Even Athletes foot is a parasite

73. Flea

74. Tick

75. Ticks

76. Mite

77. Mistletoe

79. Ecological Succession
Key Concept:
Ecosystems are constantly changing in response to natural & human disturbances.
As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community.

80. Change of Ecosystem over Time
When a volcano forms a new island, a glacier recedes and exposes bare rock, or a fire burns all of the vegetation in an area, a NEW HABITAT is created.

81. Ecological Succession
This is a series of predictable changes that occur in a community over time.
PRIMARY SUCCESSION
occurs when organisms colonize a barren environment where no soil exists.
-volcanic eruptions
-bare rock exposed when glaciers melt

82. Pioneer Species PIONEER SPECIES
-the first organisms to live in a new habitat
-small, fast-growing lichens
They build soil

85. New island= Primary Succession

86. Succession at Mt. St. Helens

87. Retreating Glaciers at Glacier Bay Alaska Make It a Natural Laboratory for Studying Primary Succession
Primary succession occurs when organisms colonize a barren environment.

88. Primary Succession at Glacier Bay, Alaska
A climax community is the stable community at the final stage of succession.

89. Succession after the Yellowstone fires.
SECONDARY SUCCESSION occurs where there has been a disturbance of some kind to the existing community without removing the soil.
-Wildfires that burn forests
Succession after the Yellowstone fires.

93. NO TWO SUCCESSIONS ARE ALIKE
Trends in Succession
Succession shows some general trends that include:
1) Biomass increase over time.
2) An increase in the number and proportion of longer-lived species.
3) Increased species diversity.
NO TWO SUCCESSIONS ARE ALIKE

94. 3. Climax
community
2. Intermediate
species
Pioneer
species

95. Ecological Succession
Climax Community
Mature, Stable Communities That Change Very Slowly.

96. Ecological Succession
In Marine Communities
Whale Carcass
Stage 1 Attracts scavengers & decomposers
Stage 2 Attracts Fewer, Smaller species. Area is fertilized
Stage 3 Heterotrophic bacteria & chemosynthetic autotrophs