Transcript 20CommunityEcology

Community Ecology
Species Interactions
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Predators vs. Parasites
How is mimicry used?
Plant defenses
Competition
Mutalism vs. Commensalism
Predation
• Predators capture,
kills and consumes
prey
– Regulates pop. Size
• Think: what examples
of adaptations that
improve a predators
abilities can you think
of?
– Poison, webs, teeth,
comouflage
Prey
defenses
Mimicry
• A harmless species resembles a poisonous or distasteful
species
• King Snakes vs. Coral Snakes (found in S. US)
• Bees and wasps
"If red touches
black, it's OK,
Jack. If red
touches yellow,
you're a dead
fellow.“
"Red on yellow, kill
a fellow. Red on
black, okay jack."
• Left Monarchs eat poison Milkweed
• Right Viceroys are harmless
Plant-Herbivore interactions
• Plant defense?
– Thorns, spikes, tough
leaves,
– Chemical defenses:
Secondary
Compounds that are
poisonous, irritating or
bad tasting
• Strychnine
• Nicotine
• Poison Ivy/ Oak
Devil’s Club
Devil’s walking stick
• One organisms is
harmed, and the other
benefits
• Usually does not
immeadiately kill host
• Ectoparasites:
external
– Ticks, fleas, lice
• Endoparasites:
internal
– Bacteria, malaria,
tapeworms
• Tapeworms don’t even
need a digestive
system, since they get
food from hosts
Parasites and
Hosts
Competition
• Niches overlap
• Resources are limited
• Happens between plants
– What do plants compete
for?
• Light, water, nutrients
– How do plants compete?
• Herbicides, creosote, out
growing
Competitive Exclusion
• One species
uses resources
more efficiently
and has a
reproductive
advantage that
eventually
drives out
another species
from a habitat.
• tidal zonation of Chthamalus and Balanus
(barnacles) is the result of competition and what
environment each can tolerate. Competition for
space, however, was responsible for the sharp
boundary between the two species.
A scientist grew 2 species of Galium
(Bedstraw)
The presence/absence of a species
determined by competition with other
species;
(2) that conditions of the environment (in
this case, soil type) affected the outcome
of competition;
(3) that competition might be felt very
broadly at first (i.e., from other vegetation
throughout the community); and
(4) that the present ecological segregation
of species might have resulted from
competition in the past
Avoiding competition
• Niche Differences or anatomical
differences evolve that lessen competition
• Character displacement
• A bunch of finches live in the same area
but have dif. beaks and eat slightly dif
foods.
• Resource Partitioning
– I’ll use this part of the resource, you use that
part.
• Mutualism: A cooperative
relationship in which both species
benefit
– Ants live in the bull horn acacia
plant 
• Ants get food from plant and protect it
– Pollination: Bees and flowers
– Us and the gardens in our guts
• Commensalism: one species
benefits and the other is not
affected
– Little birds follow around buffalo and
eat insects they scare up
– Remora fish
Side note
• The African (cape)
Buffalo
• Takes several lions to
bring one down
• Very Aggressive, Known
as the “black death”
• Once wounded, have
doubled back and
ambushed hunters