how species interact with eachother
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How Species Interact With Eachother
CommunityGroup of species living close enough
together for potential interaction
Figure 53.1
PredationA Predator eats the PreyPredator adaptations
Locate & subdue preyPrey adaptations
Elude & defend
Competition• Species
competing for the same limited resource.
• Competitive Exclusion Principle • One species
will outcompete the other, driving one to extinction in the ecosystem
ParasitismParasite lives on
or in its host organism
Parasites generally to do not immediately kill their host
SymbiosisMutualism (+/+)
Lichens (algae & fungus)
Ant and Acacia Tree
Commensalism (+/0)Barnacles
attached to a whale
Figure 53.9
Figure 53.5
Cryptic colorationCamouflage
Aposematic colorationBright warning to predators
Batesian mimicryPalatable or harmless species
mimics a harmful model
(a) Hawkmoth larva
(b) Green parrot snake
Figure 53.7a, b
Müllerian mimicryTwo or more unpalatable species
look like each other
(a) Cuckoo bee
(b) Yellow jacketFigure 53.8a, b
What kind of mimicry?Red next to yellow, killA fellow
Red next to black,Friend to Jack
Concept Check!According to the competitive
exclusion principle, what outcome is expected when two species with identical niches compete for a resource? Why?
Species diversityGreater diversity = greater
stability
Community 1A: 25% B: 25% C: 25% D: 25%
Community 2A: 80% B: 5% C: 5% D: 10%
D
C
BA
Figure 53.11
Trophic structureFood chains
Feeding relationships
Limited to 4 or 5 trophic levels
Length of food chain limited by inefficiency of energy transfer
Quaternary consumers
Tertiary consumers
Secondary consumers
Primary consumers
Primary producers
Carnivore
Carnivore
Carnivore
Herbivore
Plant
Carnivore
Carnivore
Carnivore
Zooplankton
PhytoplanktonA terrestrial food chain A marine food chainFigure 53.12
Food websFood chains are
hooked together into food webs
Who eats whom?A species may
weave into a food web at more than 1 trophic level
Humans
Baleen whales
Crab-eater seals
Birds Fishes Squids
Leopardseals
Elephant seals
Smaller toothed whales
Sperm whales
Carnivorous plankton
Euphausids (krill)
Copepods
Phyto-plankton
Figure 53.13
Food Webs
Limits on food chain length
Energetic hypothesisLimited by inefficiency of energy
transfer10%
Dynamic stability hypothesisLong chains less stablePop. fluctuations at lower levels
magnified at higher levels
Community structureRemoving a species
changes the communityDominant species
Most abundant species or highest biomass in community
Keystone speciesExert important regulating
effect on other species in a community
DisturbancesMost communities are in a state of
non-equilibrium due to disturbancesFire, weather, human activities, etc.Not all are negative
(a) Before a controlled burn.A prairie that has not burned forseveral years has a high propor-tion of detritus (dead grass).
(b) During the burn. The detritus serves as fuel for fires.
(c) After the burn. Approximately one month after the controlled burn, virtually all of the biomass in this prairie is living.
Figure 53.21a–c
Ecological SuccessionThe sequence of community &
ecosystem changes after a disturbance
Transition in species composition over ecological time
(a) Soon after fire. As this photo taken soon after the fire shows, the burn left a patchy landscape. Note the unburned trees in the distance.
(b) One year after fire. This photo of the same general area taken the following year indicates how rapidly the community began to recover. A variety of herbaceous plants, different from those in the former forest, cover the ground.
SuccessionPrimary
Begins in a virtually lifeless area without soil
SecondaryExisting community cleared, but soil
is intact
Succession
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