Energy and
chemicals flow
within ecosystems
12 Energy flows from producers to
consumers.
1
2
3
First Stop: Primary Producers
4
Primary Producers
5
Second Stop:
Primary Consumers – the
Herbivores
6
Herbivores
7
Third Stop:
Secondary Consumers – the
Carnivores
8
Carnivores
9
Fourth Stop:
Tertiary Consumers – the “Top”
Carnivores
10
Food Chain
11
Food Web
12
Food Web
13
Food Chains & Food Webs
14
GRASS

GRASSHOPPER

TOAD

SNAKE

HAWK

BACTERIA
IN GENERAL,
AUTOTROPHS
(PRODUCERS)

HERBIVORES
(PRIMARY
CONSUMERS)

CARNIVORES
(2, 3, ETC.)

DECOMPOSERS
Food Chains & Food Webs
15
Chain Reaction Game
16
17
Decomposers
18
Energy Flows through a Food Web

Losses at every “step” in a food chain

Inefficiency of energy transfers
19
Summary 12.1





Energy from the sun passes through an
ecosystem in several steps.
First, it is converted to chemical energy in
photosynthesis.
Herbivores then consume the primary
producers,
the herbivores are consumed by
carnivores, and
the carnivores, may be consumed by top
carnivores.
20
Summary 12.1


Detritivores and decomposers extract
energy from organic waste and the
remains of organisms that have died.
At each step in a food chain, some usable
energy is lost as heat.
21
Energy and
chemicals flow
within ecosystems
12.2 Energy pyramids reveal the
inefficiency of food chains.
22
Biomass

only about 10% of the plants in an
ecosystem is converted into biomass

Food Energy Pyramid
◦
trophic levels:
23
24
25
26
Summary 12.2




Energy from the sun passes through an
ecosystem in several steps known as
trophic levels.
Biomass of primary producers in an
ecosystem is far greater than the biomass
of herbivores.
Biomass transferred at each step along
the food chain is 10% of the biomass of
the organisms being consumed, due to
energy lost in cellular respiration.
Food chains rarely exceed four levels.
27
Energy and
chemicals flow
within ecosystems
12.3 Essential chemicals cycle through
ecosystems.
28
Chemical Reservoirs
29
The Most Important
Chemical Cycles
1)
Carbon
2)
Nitrogen
3)
Phosphorus
4)
Sulfur
30
31
Carbon Cycle Game
32
Fossil Fuels
33
Global CO2 levels
exhibit a sharp rise and
fall within each year
34
35
Fertilizers
36
37
Phosphorus
38
39
40
Sulfur Cycle
41
Sulfur Cycle
42
Summary 12.3




Chemicals essential to life, cycle through
ecosystems.
Captured from the atmosphere, soil, or water
by growing organisms; passed from one
trophic level to the next as organisms eat
other organisms;
Returned to the environment through
respiration, decomposition, and erosion.
human activities increase the amounts of the
chemicals utilized or released to the
environment.
43
Species interactions
influence the
structure of
communities.
12.4 Interacting species evolve together.
44
45
46
Coevolution
◦ predator/prey
◦ parasite/host
◦ competitive species
◦ mutualistic species
47
48
Penicillin was first isolated from a
fungus growing on a plate of bacteria.
49
Summary 12.4

In producing organisms better adapted to
their environment, natural selection does
not distinguish between living and nonliving (biotic and abiotic) things as
selective forces.
50
Species
interactions
influence the
structure of
communities.
12.5 Each species’ role in a community is
defined by its niche.
51
More than just a place for
living, a niche is a complete
way of living
52
A niche is a complete way of
living
53
Summary 12.5

A population of organisms in a community
fills a unique niche, defined by how they
use the resources in their environment.

Organisms do not always completely fill
their niche; competition with species that
have overlapping niches can reduce their
range.
54
Species interactions
influence the
structure of
communities.
12.6 Competition can be hard to see, but it
still influences community structure.
55
56
57
Competition
58

E.g. birds singing in the morning.
Why is competition hard to see?
59
Competitive exclusion principle
60
Summary 12.6

Populations with completely overlapping
niches cannot coexist forever.

Competition for resources occurs until one or
both species evolve in ways that reduce the
competition, through character
displacement, or until one becomes extinct
in that location.
61
Species interactions
influence the
structure of
communities.
12.6 Predation produces adaptation in both
predators and their prey.
62
Predation
63
Non-Native
Species
64
Prey Adaptations

physical
◦
Mechanical
◦
Chemical
◦
warning coloration
◦
camouflage mechanisms
65

behavioral

Hiding


Escaping

alarm calling

fighting back
Prey Adaptations
66
67
1) Mechanical Defenses
68
3) Warning Coloration
69
4) Camouflage
70
71
Predator adaptations
•toxic-avoidance methods
•sensory perception
•faster running ability
•mimicry
72
73
Why don’t predators drive the
prey to extinction?
•predator adaptations
•escape ability
•cost of losing is much higher for prey
74
The gazelle can change direction very
quickly while being chased by a cheetah
(fastest land animal). The gazelle uses
which method of defense listed below?
1.
2.
3.
4.
5.
Mechanical defense
Camouflage
Behavioral
Warning Coloration
Chemical defense
75
Symbiotic Relationships
Symbiosis: close relationship between
organisms of two different species
At least one participant gains some
sort of benefit (usually nutritional)
Types of symbiosis:



◦
◦
◦
Parasitism
Mutualism
Commensalism
76
Parasitism


Parasite derives nutrition from the host
This harms the host but a true parasite
does not usually kill its host (directly)
77
Ectoparasites
Remain outside the host
Ticks, fleas, leeches
78
Endoparasites
Live inside the host’s body
Tapeworms, malarial parasites
79
Parasite Transmission


◦
Many parasites live on or in a single
organism
Some will alternate between 2 or more
host species
Vertical transmission – from mother 
offspring
Horizontal transmission – between members
of a population
◦


Direct contact (head lice)
Vectors (mosquitos)
80
Mutualism



◦
◦
◦
◦
◦
◦
Both species benefit
Food or shelter
Examples:
Plants and microbes (rhizobium in root
nodules)
Plants and fungi (orchids and
mycorrhizae)
Protists and fungi (lichen)
Plants and insects (pollination)
Animals and bacteria (ruminants)
Animals and other animals (crocodiles and
plover birds)
81
Rhizobium
Rhizobium in root nodules of certain plants
convert nitrogen in soil to usable form.
82
Lichen
Most of the lichen is composed of fungal
filaments, but living among the filaments are
algal cells, usually from a green alga or a
cyanobacterium.
The lichen fungus provides its partner(s) a
benefit (protection) and gains nutrients in
return.
83
Ruminants
Ruminants are characterized by their four-chambered
stomach and "cud-chewing" behavior. Cud is a food
bolus that is regurgitated, rechewed, and
reswallowed. The rumen is a large fermentation vat
containing billions of microorganisms, including
bacteria and protozoa, which allow ruminants to digest
fibrous feeds such as grass and hay that other animals
cannot efficiently utilize.
84
Crocodiles &
Plover Birds
The bird gets into the crocodile's mouth
and picks out the tiny bits of food stuck in
his teeth, then eats it (the tiny bits).
This cleans the crocodile's teeth and keeps
his mouth fresh and free from infections.
85
Commensalism





Neither species is totally dependent on
the other
One benefits – no effect on the other
Feeding or protection
Cattle egrets
Porcelain anemone crabs and
anemones
86
Commensalism
87






http://www.blueplanetbiomes.org
http://www.marietta.edu/~biol/biomes/biome_main.
htm
http://www.ucmp.berkeley.edu/exhibits/biomes/
http://www.tburg.k12.ny.us/mcdonald/foodch1.htm
http://users.rcn.com/jkimball.ma.ultranet/BiologyPag
es/F/FoodChains.html
http://ic.galegroup.com/ic/scic/ReferenceDetailsPage/
ReferenceDetailsWindow?displayGroupName=Referen
ce&disableHighlighting=false&prodId=SCIC&action=e
&windowstate=normal&catId=&documentId=GALE%
7CCV2644030753&mode=view&userGroupName=cat
holiccenhs&jsid=71a9d03928f7c22aa5cc70824a0bbc9
9
THANK YOU TO…
88