1. Community Interactions

2. Community Interactions
• Powerfully affect an ecosystem
• Include:
– Competition
– Predation
– Symbiosis

4. Competition
• When organisms of the same or different
species attempt to use an ecological
resource at the same place and the same
time
– Resource any necessity to life
– Plants and animals compete
– Winner and losers

5. Rules, rules, rules
• Fundamental rule in ecology
– Competitive Exclusion Principle
• No two species can occupy the same niche in the
same habitat and the same time
• Prevents competition
Niche:the position or function of an
organism in a community of plants and
animals.

11. Predation
• Interaction where an organism captures
and feeds on another organism
• Predator
– Organism that does the killing and eating
• Prey
– Organism that is being killed and eaten
(victim)

17. Symbiosis
• Any relationship where
two species live closely
together
• Symbiosis literally
means “living together”
• 3 main types
– Parasitism
– Mutualism
– commensalism

18. What type of relationship is this?
• Who is helping who?

19. Mutualism
• Both species benefit
from the relationship
• A Happy couple
• Flowers and bees
– Flowers need bees for
pollination, bees need
flowers nectar

22. What type of relation ship is going
on here?
• Who is helping who?

23. Commensalism
• One member of the relationship benefits
while the other is neither harmed nor
helped
• One-sided
• Food or shelter
• Barnacles on whale

24. Ants and aphids

26. What type of interaction is going on
here?

27. Parasitism
• One organism lives on or inside another
organism and harms it
• Parasite obtains all or part of its nutrients from
the other organism
• Host
– Organism that is harmed in relation ship; the one that
provides the nutrients to the parasite
• Parasite
– Organism that gets its nutrients from the host
• Do they want to kill their host?
– No, because they need them…they will weaken or
hurt the host in some way

32. Recap
• What are the three types of interactions in
a community?
– Competition
– Predation
– Symbiosis
• What types do we have?
– Mutualism
– Commensalism
– Parasitism

33. Ecological Succession
• Do all ecosystems stay the same all the
time?
• What are some things that cause changes
to ecosystems?
– Natural and unnatural
– Quickly and slowly

34. • Ecosystems are constantly changing in
response to human and natural
disturbances.
• As an ecosystem changes, older habitants
die out and new organisms move in,
causing more change

35. Ecological Succession
• Series of predictable changes that occur
in a community over time
– Physical environment
– Natural disturbance
– Human disturbance

36. Primary Succession
• Succession on land
that occurs on
surfaces where no
soil exists
• Volcanic eruptions
• Glaciers melting

39. Stages of Primary Succession
• Start with no soil, just ash and rock
• First species to populate this area
– “pioneer species”
– For example, pioneer species on volcanic
rock are lichens (LY-kunz)
• Lichens made up of fungus and algae that can
grow on bare rock
• When lichens die, they for organic material that
becomes soil…now plants can grow

40. Secondary Succession
• Succession following a disturbance that
destroys a community without destroying
the soil
• Natural
– hurricane
– fires
• Human disturbances
– Farming
– Forest clearing

46. Succession in Marine Ecosystems
• Deep and dark
• Can succession happen?
• 1987 dead whale off of California
– Unique community of organisms living in
remains
– Represents stage in succession in an
otherwise stable, deep-sea ecosystem
– Whale-fall community

48. Whale-Fall Succession
• Begins when large whale dies
– Sinks to barren ocean floor
– Scavengers and decomposers flock to carcass , our first community
• Amphipods
• Hagfish
• sharks
• After a year, most tissues have been eaten
– Now, second small community of organisms live here
– Body is decomposing, releasing nutrients into the water
• Small fishes
• Crabs
• Snails
• worms
• Only skeleton remains…
– Third community moves in
• Heterotrophic bacteria
• Decompose oil in bones release of chemical compounds
• Who uses these chemical compounds?
– Chemoosynthetic autotrophs
• In come the crabs, clams, and worms that feed on this bacteria

49. Study
Chemical
reactions,
enzymes,
and
Chapters 3
and 4
Teacher,