Transcript Interspecies Interactions

COMMUNITY ECOLOGY: Interspecific Interactions
• There are different interactions between the species
of a community.
• Populations may be linked by 4 interactions:
competition, predation, mutualism, and
commensalism
• Interspecies Interaction: Competition
• Interspecific competition is:
• The competitive exclusion principle is:
• The ecological niche is the sum total of an
organism’s use of abiotic/biotic resources in the
environment.
• An organism’s niche is its role in the
environment. Video
• The competitive exclusion principle:
two species cannot coexist in a community if
their niches are identical.
• Classic experiments confirm this (Video).
• Resource partitioning is
Video
Fig. 53.2
• Interspecies Interaction: Predation
• Predation is:
• Herbivory is:
• parasitism is:
• Pathogens are disease-causing organisms that
can be considered predators/predation.
• Plant defenses against herbivores include chemical
compounds that are toxic.
• Animal defenses against predators.
• Behavioral defenses include fleeing, hiding, selfdefense, noises, and mobbing.
• Camouflage includes cryptic coloration,
deceptive markings.
• More Animal defenses against predators.
• Mechanical defenses include spines.
• Chemical defenses include odors and toxins
• Warning colors, sometimes associated with
other defenses (toxins).
• More Animal defenses against predators.
• Mimicry –
Batesian mimicry –
Müllerian mimicry -
Interspecies Interactions: Mutualism/Commensalism
• Mutualism –
• Commensalism –
Example barnacles attached to
a whale.
Coevolution and interspecific interactions.
• Coevolution refers to reciprocal evolutionary
adaptations of two interacting species.
• When one species evolves, it exerts selective
pressure on the other to evolve to continue the
interaction.
• When a prey evolves better defenses against
its predator, this selects for predators that are
able to overcome this. As the predator
evolves to better catch prey, exerts pressure
on the prey to evolve even better defenses.
Summary: 4 Interactions Between Species:
Interspecific interactions of Table 53.1, note the positive, negative
or no affect of the interaction on the individual populations.
What’s the interaction?
1. Cow and Grass?
2. Tiger and ape?
3. Moss on trees?
4. Lion and cheetah?
5. Man & sheep-dog?
6. Human & this animal?
•
•
live in our home, eat our food,
wake us when we are sleeping!
Dominant and keystone species exert strong
controls on community structure
• Dominant species are:
abundance and biomass
• If we remove a dominant species from a
community, it can change the entire community
structure.
• Keystone species
exert an important
regulating effect
on other species
in a community.
• If they are removed, community structure is greatly
affected.
Video on
keystone
species ©
Next Class: Topics on Man’s Interaction w/ Biosphere
•
Working in groups to learn a topic, present your findings
to the class. Split into groups (2/topic, each group must
quickly decide how to split the work). Turn in
worksheet for points.
• Five topics:
1. Birth defects
2. Frog populations
3. Increasing testicular cancer
4. Autism (ask older students if they knew of any when they were in grade
school)
5. Bees
Extra Credit
• Find New Articles (w/I a year) discussing these
topics and if possible, a theory on its cause.
• Must be good (reliable) articles, but can be
newspaper or internet or some other source.
• I will keep the articles, so make a second copy if
you want the article.