http://www.youtube.com/watch?v=
GUY_-LK_lOc&feature=related
4.2 – Niches and Community
Interactions
Notes – be sure to understand
definitions and have a few examples
to describe each concept
I. Niche
A. A niche is the role that an organism plays in an
ecosystem
B. Includes physical factors (abiotic)
*Ex:
C. And biological factors (biotic)
*Ex:
D. Includes how the species uses these factors to
survive and reproduce
Analogy of a niche: the role of your favorite sports
player on their team – needs “resources”,
“habitat”
II. Resources and Tolerance
A. Resource is any necessity of life (Ex:
water, food, shelter, place to feed, place to
build nests or raise young)
B. Tolerance is the range of environmental
conditions a species needs to survive and
reproduce (Ex: temp., sunlight)
C. Tolerance determines how WELL we deal
with the LACK of resources
III. Tolerance Example
A.
B.
C.
D.
Humans can tolerate a wide range of temp
Body temps as low as 75 degrees F
As high as 105 degrees F
Optimal range is a few degrees cooler or
warmer than 98.6 degrees F
E. The further from optimal range, the more
stress it causes the individual, and lowers
ability to survive and reproduce
IV. Tolerance determines Habitat
A. Habitat is the general place where an
organism lives
B. Determined by how much tolerance the
organism has to live in that habitat and
still be able to survive and reproduce
C. Ex: temp, access to food and water,
shelter, competition
V. Competition
A. Competition is when organisms attempt to use
the same limited ecological resource in the
same place, at the same time
B. Ex: Plant competition – invasive species
http://www.youtube.com/watch?v=00o4bZB4c
sA
C. Ex: Animal competition –
http://www.youtube.com/watch?v=hK8TQQp1
qAA; http://www.youtube.com/watch?v=pd7yTRnYzg&feature=relmfu
V. Competition
D. Competition between the same species is known
as intraspecific competition
E. Competition between differing species is known
as interspecific competition
F. There is ALMOST always a winner and a loser
(likely the loser will die)
G. Ex: 2 species of bacteria growing in different
dishes – both live. Grown in the same dish – will
compete and one will die off
VI. Competitive Exclusion
Principle
A. The Competitive Exclusion Principle
- No 2 species can occupy exactly the same
niche in exactly the same habitat at exactly
the same time
VI. Competitive Exclusion
Principle (Example)
B. Some species divide resources instead of
competing (Yes! Animals share, sometimes)
C. Ex: Warbler birds – live in SAME tree
with other warbler birds, and all eat insects
D. One species feeds on higher branches,
another in the middle, another on lower
branches
E. Each occupies its OWN, separate niche
F. Each species has its own niche and doesn’t
compete for food as long as it doesn’t leave its
niche
G. What would happen if 2 species occupied the
same niche in the same tree at the same time?
VII. Relationships in Communities
1. There are MANY types of relationships
between members in a community
2. Need to know def. and examples of each:
D. Mutualism
A. Predation
E. Parasitism
B. Herbivory
C. Keystone species F. Commensalism
VII – A. Predation
1. Predation – interaction when one animal
captures and feeds on another animal
2. Predator – prey relationship
3. Predators can affect the size of prey
populations in a community and
determine the places prey can live in and
feed
4. Ex: Think of the predators from Planet
Earth videos – is this true?
VII. – B. Herbivory
1. Herbivory – interaction when an animal
(herbivore) feeds on a producer (plant)
2. Herbivores can affect both the size and
distribution of plant populations in a
community
3. Can determine the places that certain
plants can survive and grow
VII. – C. Keystone Species
1. Keystone species – single species that is
not usually abundant in a community, yet
exerts strong control on the community’s
structure
2. Ex p.103: Sea otters of Pacific coast feed
on lots of sea urchins; urchins are
herbivores that eat kelp (giant algae)
3. What happens if otters are wiped out?
VII. *Symbiotic relationships
* Symbiosis – any relationship in which two
species live closely together
* Mutualism, parasitism, and
commensalism are symbiotic relationships,
meaning the organisms involved have a
LITERALLY close relationship (live in
each other’s space)
VII. – D. Mutualism
1. Mutualism – relationship in which both
species benefit
2. Ex: Finding Nemo: sea anemone and
clownfish – clownfish hide from predators
in deadly tentacles (have a special coating
so they don’t get stung); anemone get
cleaned and protected by territorial
clownfish – some will even bring food to it
3.
http://www.youtube.com/watch?v=0a3RuQQ0fYg
VII. – D. Mutualism
3. Ex: Stomach bacteria – breaks down
carbohydrates for the human, but also feeds
on some
4. Ex: Flowers and pollinators –
pollinators (bees, butterflies) get food;
flowers get their pollen
transferred
VII. – E. Parasitism
1. Parasitism – relationship in which one species
benefits and one species is harmed
2. Parasites typically live in or on a host
3. Ex: Tapeworms live in intestines, feed on host’s
blood, taking nutrients from host
4. Ex: Ticks, fleas, lice, leeches – live on host and
feed on blood – often transmit disease
http://www.youtube.com/watch?v=bb32g02IIs8&feature=relm
fu
VII. – F. Commensalism
1. Commensalism – relationship in which
one organism benefits, and the other is
neither helped or harmed (is unaffected)
2. Ex: Barnacles attached to whale’s skin –
don’t harm the whale or provide any
service, yet barnacles benefit
by constant movement thru water allows
them to filter feed much more easily
Battle at Kruger
• Overall theme – Competition
• See if you can find other concepts being played
out
– Niche, physical or biological factors, resources, habitat,
tolerance, types of competition
• You will write a paragraph (5 – 7 sent) reflecting
on what you learned
• http://www.youtube.com/watch?v=LU8DDYz68k
M