Chapter 5
APES
Things to remember this
week
 I will check Chapter 5 outlines today
 Turn in all sub-work from last week today
 Benchmark test on block day will cover Chapters 1-4 and part
of 5 (Evolution not on Benchmark!)
 Turn in hard copies of Biome project today and electronic
copies (Reminder you were specifically told NOT to e-mail
the e-copy!!)
 Vocab quiz tomorrow!!
 Biome presentation
APES Bell work 9/23/13

Farmers in Haiti are being encouraged to plant mango trees because the
provisions in the form of fruit are more valuable than the provisions in the form
of firewood. A group of Hatian farmers decide to plant mango trees. Magngo
saplings cost $10 each. Once the trees become mature, each tree will produce
$75 worth of fruit per year. A village of 225 people decides to pool its resources
and set up a community mango plantation. Their goal is to generate a per capita
income of $300 per year for the entire village.

1. How many mature trees will the village need to meet the goal?

2. Each tree requires 25 m2 of space. How many hectares must the village set
aside for the plantation? (1ha=10,000m2)

3. Each tree requires 20L of water per day during the 6 hot months of the year
(180 days). The water must be pumped to the plantation from a nearby stream.
How many liters of water are needed each year to water the plantation of 900
trees?
Group Work:
 In individual groups, look at each slide and determine what
it represents
 Write your answers down
 As a class we will go over each slide and discuss answers
Lower Level Org.
Generally Contain More
Energy, and Are in Greater
Numbers-
Trophic
Levels:
The Way
in Which
Energy
Moves
Thru
Systems
Food
Web
Resource
Partitioning:
Each Bird
Uses the
Tree for
Food,
However…
They Each
Divide up
Different
Portions of
the Trunk
Predator/Prey Paired Cycles: One
Increases, Causing the Other to
Decrease, and Vice Versa
KeyStone
Species Keep
Ecosystems
in CheckSea Otters
are the
Keystone
Species in
This
Environment
Species Interactions
 5 Major Types of Interactions Among Species
 Competition

When organisms are seeking same limited resource(s)
 Predation

When one organism (predator) eats another (prey)
 Parasitism

One organism benefits, the other is harmed
 Herbivory

An organism feeds on plant material
 Mutualism

Both organisms benefit from the relationship
 Interspecific:
Competition
 Among members of 2 or more DIFFERENT species (cardinals and blue
jays)

If one is more effective


Wipe-out competitor altogether
Through evolutionary time, co-existance is also possible

Timing events, slightly different food sources, etc.

RESOURCE PARTITIONING
 Intraspecific:
 Among member of the SAME species

Cardinals
 All competition events have a negative impact
Results of interspecific competition
 Competitive exclusion = one species completely excludes another
species from using the resource
 Zebra mussels displaced native mussels in the Great Lakes
 Species coexistence = neither species fully excludes the other
from resources, so both live side by side
 This produces a stable point of equilibrium, with stable population
sizes
 Species minimize competition by using only a part of the available
resource (niche)
Niche: an individual’s ecological
role
 Fundamental niche = the full niche of a species
 Realized niche = the portion of the fundamental niche that is
actually filled
 Due to competition or other species’ interactions
Resource partitioning
 Resource partitioning =
species use different
resources
 Or they use shared
resources in different ways
 Ex: one species is active at
night, another in the day
 Ex: one species eats small
seeds, another eats large
seeds
Character displacement
 Character displacement = competing species diverge in their
physical characteristics
 Due to the evolution of traits best suited to the resources they use
 Results from resource partitioning
 Birds that eat larger seeds evolve larger bills
 Birds that eat smaller seeds evolve smaller bills
Competition is reduced when two species become more
different
Predation:
 Predator/Prey relationships
 Predation can drive population dynamics
 Increase in predators will…..
 Increase in prey will ………
 These events can cycle throughout time
 Predation can also drive evolution
 Stronger adaptations become selected for
 Defense mechanisms become selected for
Case Study: black and white and
spread all over
 In 1988, Zebra mussels
were accidentally
introduced to Lake St. Clair
 In discharged ballast water
 By 2010, they had invaded
30 states
 No natural predators,
competitors, or parasites
 They cause millions of
dollars of damage to
property each year
Zebra mussel predation on
phytoplankton
 Zebra mussels eat phytoplankton and zooplankton
 Both populations decrease in lakes with zebra mussels
 Zebra mussels don’t eat cyanobacteria

Population increases in lakes with zebra mussels
 Zebra mussels are becoming prey for some North American
predators:
 Diving ducks, muskrats, crayfish, flounder, sturgeon, eels, carp, and
freshwater drum
Defenses against being
eaten

Parasites
Relationships in which 1 organism depends on another, while doing
harm
 USUALLY does not result in death. Why not?
 Most live inside their host
 Disease pathogens (ex; protist that causes malaria)
 Animals (tapeworms)
 Some live externally
 Lamprey
 Parasitoids
 Eggs are laid on the backs of others, when they hatch, use host as food
source
Co-evolution
 Parasites will adapt and evolve with changes in host
 Evolutionary Arms Race
 Host changes in order to adapt to parasite pressures
 Parasites will change in order to adapt to host pressures
Herbivore
 When animals feed on the tissues of plants
 Insects are most wide-spread
 Doesn’t usually kill plant, but can affect
growth and reproduction
 Plants have also evolved to defend themselves
 Chemically
 Arm themselves w/thorns, spines, or hairs
 Critter usually evolves as well, tho
 Evolutionary Arms Race
Mutualist
 Interacting species benefit from one another
 Each provides a service or resource the other needs
 Symbiosis: two organisms live in close physical contact

Not always the case however;

Pollination; physical contact may only happen once
Commensalism
 One species benefits from relationship while the other is
neither harmed nor benefits
 Cattle Egret: benefits from cattle stirring up insects, cow is
neither harmed nor really benefits
 Amensalistic: hard to prove- One organism harms or inhibits
another while remaining unaffected itself;
 Fungus Penicillium notatum which produces penicillin- the
penicillin inhibits growth of bacteria, but it appears that the
Penicillium is unaffected
Otter video clip
Sea otter impact on urchins
 Otters substantially
reduce populations of
large urchins. Estes and
Palmisano (Science
1974)
Roles are NOT the same
 Keystone Species: species with strong or wide-reaching
impact far out of proportion to its abundance
 Removal of this species will have substantial ripple effects
 Can alter large portions of food webs
 Usually large-bodied 2nd ary or tertiary consumers near the
top of food chain
 Controls herbivores, who if left unchecked can devastate
ecosystems
Kelp density and otters
100
100
60
60
20
20
0 3 7 11 15 19
0 3 7 11 15 19
0 3 7 11 15 19
0 3 7 11 15 19
Some organisms play big roles

Initial Keystone Species
Concept
The idea was developed in 1969
by Dr. Robert Paine during his
time at the University of
Washington as a zoology
professor. The idea also
originated from his work with
the Makah Indian Tribe and
lands along Washington’s
Pacific coastline.
Initial Keystone Species
Concept
 A keystone species is a species whose whose impact on its
community or ecosystem are larger and greater than would
be expected from its relative abundance or total biomass in
the environment.
 Originally, keystone species were characterized as a predator
species that feed preferentially on the dominant competitor
among its prey species, preventing the dominant prey from
excluding other species.
 The presence of keystone species maintain higher species
diversity in ecosystems than if keystone species were absent.
Predator-prey interactions
 Example: Pisaster ochraceus and the mussel Mytilus
californianus
 Bob Paine’s Caging experiments
 Follow-up (14-17 yrs)
 Comparisons to Chile and New Zealand studies
Bob Paine’s experiments:
Effects of Pisaster removal
Castro and Huber, Fig. 11.22
Bob Paine’s experiments:
Effects of Pisaster removal
 What happened when he returned to his study site 14-17
years after cages were removed?
 How do Bob Paine’s results compare to similar studies
in New Zealand and Chili?
Fig. 6.18: Pisaster ochraceus as a
Keystone species
Fig. 6.19: Natural experiments on New
England coast (Menge and Lubchenco)
Role of grazers
 Limitation of algae by
grazers
 Overview
 Case study: Katharina tunicata
Role of grazers
 Maintenance of diversity by grazers
 Example: Effects of snails on algal diversity in a tidepool.
Keystone Species Concept
 Since 1969, non-predator
keystone species have been
identified and studied, such as
beavers (Castor canadensis),
bison (Bison bison), kangaroo
rats (Dipodymys spp.), and
plant species such as the
quaking aspen (Populus
tremuloides).
Salmon as a Keystone Species
-Salmon play a vital role in their ecosystems
-They help support approximately 137
different species
-41 mammals
-89 birds
-5 reptiles
-2 different amphibians
Without salmon as a keystone species, we
could see a tremendous decrease in
dependent creatures.
Example of Salmons importance
-In 1981, at McDonald Creek, more than 600 bald
eagles gathered to feed on Kokanee salmon carcasses.
When a non-native shrimp was introduced in an
adjacent lake, the shrimp competed with the salmon for
zooplankton - the salmon run lost.
-In 1989, only 25 eagles were found at McDonald Creek.
-The loss of salmon caused what is called an
"ecosystem collapse."
Northwest species now struggling because of depleted
salmon runs include the following:
Black Bear
Grizzly Bear
Bald Eagle
Osprey
Caspian tern
Harlequin duck
…Dependent species continued
Sea lion
Orca
River Otters
Canis lupus
 Traditionally had the
largest range of any
terrestrial mammal
 Extirpated from U.S. by
farmers, settlers and
hunters in the early 20th
century
After 60 years
 Wolves are necessary
components of their
ecosystems
 Why?




Controls elk populations
Increased elk browse
negatively effects growth of
seedlings along riparian areas
Decreased growth of riparian
vegetation causes river bank
erosion and widening
This has negative effects on
salmon and other aquatic life,
and increases flooding and
nutrient loss from the soil
The controversy concluding predatory
keystone species
 Wolves are beautiful
creatures until they start
killing your livestock or
pets
 Do you want really want
to meet him when you are
out on a hike?
•
Also too many wolves
would put stress on prey
species such as elk and
deer.
Species can change
communities
 Trophic Cascade = predators at high trophic levels indirectly
affect populations at low trophic levels
 By keeping species at intermediate trophic levels in check
 Extermination of wolves led to increased deer populations, which
overgrazed vegetation and changed forest structure
 Ecosystem engineers = physically modify the environment
 Beaver dams, prairie dogs, ants, zebra mussels