Transcript ENVIRONMENTAL SCIENCE

ENVIRONMENTAL
SCIENCE
Chapter 8 Understanding
Populations
8.2 How Species Interact With
Each Other
8.2 How Species Interact With
Each Other Objectives
Explain the difference between niche
and habitat.
 Give examples of parts of a niche.
 Describe the five major types of
interactions between species.
 Explain the difference between
parasitism and predation.
 Explain how symbiotic relationships
may evolve.
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Introduction
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In order to
understand a
species, it is best
to study it in its
natural
environment.
The interactions
between species
in the natural
environment are
often complex and
cannot be
replicated exactly
in an artificial
habitat.
An Organism’s Niche
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A niche is the specific role of a species in
an ecosystem.
A niche can include the environmental
factors necessary for survival of that
species, the species’ home, and all of the
species’ interactions with other organisms.
A habitat is simply a location and type of
factors in that location.
A niche involves the habitat plus
interactions and behaviors characteristic of
the species.
An Organism’s Niche
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A niche can also be
described as the
functional role, or
“job” of a species in
an ecosystem.
For example, the
bison is the large
grazer on the plains of
North America and the
kangaroo is the large
grazer in the
grasslands of
Australia.
Ways in Which Species Interact
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There are five major types of species
interactions.
• Competition – each species negatively affects
the other
• Predation – one species consumes the other
species
• Parasitism – a smaller species feeds off of the
tissues or fluids of another species
• Mutualism – each species is helpful to the
other
• Commensalism – one species benefits from the
relationship, but the other is unaffected
Ways in Which Species Interact
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The categories of species interaction are
based on whether harm or benefit is
caused by the interaction.
Other types of interactions between
species are possible.
Some types of interactions between
individuals are atypical and do not
represent the general trend as related to
the species involved.
Many interactions in nature are still not
well studied.
Competition
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Competition is part of daily life for most
species from male lions competing for who
will dominate the pride to kudzu
competing for sunlight as it overgrows a
stand of trees in an interstate median.
Competition is a relationship in which
individuals or populations attempt to use
the same limited resource.
Each individual, as a result of the
competition, has less access to the
resource and is therefore harmed by the
competition.
Competition
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Competition can occur between individuals of a
species or between species themselves.
Members of the same species tend to occupy the
same niche, therefore, they will compete among
themselves.
If the niches of two different species overlap,
then they will compete for the resources.
Indirect competition is when species compete
with one another for resources, yet they never
come in direct contact while using the resources.
For example, humans compete with insects for
the crops that we grow for food.
Competition
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When two species with overlapping or similar
niches are placed in the same ecosystem, the
compete directly against one anther.
Sometimes one species out-competes the other
and pushes it out of the habitat through
competitive exclusion.
If the change is slow enough, one species may be
able to adapt and change enough so that both
species remain extant.
Niche restriction occurs when each species uses
less of the niche than they are capable of using.
Niche restriction often occurs between two closely
related species using the same resources in a
habitat.
Predation
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An organism that kills and consumes
another organism is called a predator.
The organism that is fed upon is called the
prey.
Predation is the relationship where a
predator kills and consumes the prey.
A snake eating a mouse is an example of
predation.
In complex food webs – typical of most
ecosystems – predators can be the prey in
some cases.
Predation
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Most organisms have evolved some sort of
defense against predation like the toxic taste of
some toads or the shell of a tortoise.
Predator populations tend to mirror prey
populations in an ecosystem with a short lag
time.
For example, if a prey population spikes, the
predator population will spike shortly thereafter
due to the abundant food sorce.
When the predator population has increased, a
decrease will be noticed in the prey population
due to increased predation.
Parasitism
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An organism that lives in or on another
organism and feeds off of its tissues or
fluids is called a parasite.
Parasitism is rarely fatal.
The parasite takes nourishment from the
host organism.
Parasites are normally much smaller than
their host.
Examples of parasites include ticks, fleas,
hookworms, tapeworms, leeches, and
mistletoe.
Mutualism
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A close relationship between two species
in which both species benefit is called
mutualism.
Humans and intestinal bacteria are an
example of mutualism because the
bacteria help us with the breakdown of
food and the synthesis of certain vitamins
and our intestine provides habitat and
food for these bacteria.
Termites and the intestinal protozoa are
another example because termites alone
cannot digest wood!
Commensalism
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Commensalism occurs when a relationship
exists in which one species benefits and
the other species is neither harmed nor
helped.
Remoras, which hitch a ride with a shark
to get scraps of food, and sharks are an
example of comensalism.
Birds used trees for habitat and neither
harm, nor help the tree.
Symbiosis and Coevolution
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Symbiosis is any relationship in which two
organisms live in close association.
Many interactions are considered
symbiotic in some way.
Over time, species involved in close
relationships may coevolve.
Coevolution occurs when the evolutionary
pathway of a species is affected by
another species.
Symbiosis and Coevolution
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Flowering plants and
their insect pollinators
often exhibit extreme
cases of coevolution.
The development of
articulation in
brachiopods to starfish
predation is another
example of
coevolution.
References
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Arctic Food Web http://bioinquiry.biol.vt.edu/bioinquiry/Cheetah/c
heetahpaid/cheetahhtmls/ecosysfdweb1.html
Bison http://www.americaslibrary.gov/es/sd/es_sd_biso
n_1_e.html
Kangaroo http://faculty.uca.edu/~johnc/comparative_anato
my_vertebrat1441.htm
Hippo and Tortoise http://bigpicture.typepad.com/writing/2005/02/h
ippo_adopts_10.html
References
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Mammal That Ate a Dinosaur http://www.msnbc.msn.com/id/6817636?
GT1=6065
Barnacles and Niche http://io.uwinnipeg.ca/~simmons/ysesp/c
omeco8.htm
Predator and Prey Populations http://www.tvdsb.on.ca/saunders/courses
/online/SBI3C/Environmental_Science/pop
ulation_curves.htm
Flea (parasite) http://www.naturespet.com/flea.html
References
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Flea (musician) http://www.guitarcenter.com/interview/fle
a/index.cfm
Mistletoe http://www.hsu.edu/content.aspx?id=187
8
Tapeworm http://www.riverside.sd43.bc.ca/art/long_
bi_11/cestoda/pages/Tapeworm_jpeg.htm
Trichonympha http://biology.unm.edu/ccouncil/Biology_2
03/Summaries/Protists.htm
References
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Termite Intestines Spilled http://www.stcsc.edu/ecology/TermSymb.
htm
Termites http://www.thesahara.net/termites.htm
Remoras With Whale Shark http://flmnh.ufl.edu/fish/Gallery/Descript/
Whaleshark/whaleshark.html
Remora - http://foros.pesca.org.mx/cgibin/Blah.pl?b=IGFA,m=1111122886
References
Barnacles on a Whale http://www.coreresearch.org/what.h
tm
 Insect Pollination http://faculty.uca.edu/~johnc/repres
entative_plant_groups.htm
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