Community InteractionsCommunity Interactions

QUICK REVIEWQUICK REVIEW

•What is community?•What is population?

Community InteractionsCommunity Interactions

• Powerfully affect an ecosystem

• Include:– Competition– Predation– Symbiosis

CompetitionCompetition

• 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

• Interspecific competition– Competition between same two species– When 2 or more species rely on same limited

resource in a community– Ex. African savannah

Rules, rules, rulesRules, rules, rules

• Fundamental rule in ecology– Competitive Exclusion Principle

• Russian biologist G.F. Gause– Paramecium caudatum vs. Paramecium aurelia

• 2 species so similar in requirements that the same resource limits both population’s growth, and one species may succeed over another

• No two species can occupy the same niche in the same habitat and the same time• Prevents competition

NicheNiche

• Each species unique living arrangement in a community

• “Role”

• Ex. Lizards in a rainforest

• Includes:– Habitat– Food sources– Time of day organism is most active

PredationPredation

• 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)

Predator AdaptationsPredator Adaptations

• Speed

• Agility

• Coloring/camouflage to ambush prey

• Packs/teams– Ex. Wolves

• Acute senses– Ex. Rattle snake heat sensor organs

• Claws, teeth, fangs, stingers, poison

Prey adaptationsPrey adaptations• Safe locations• Flee• Coloring/camouflage to hide• Defensive coloration

– “warning coloration”

• Mimicry– Organisms imitate dangerous organisms by appearance and

actions• Hawk moth larva

• Plants– Thorns, spines, poisonous chemicals

SymbiosisSymbiosis

• Any relationship where two species live closely together

• Symbiosis literally means “living together”

• 3 main types– Parasitism– Mutualism– commensalism

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

MutualismMutualism

• Both species benefit from the relationship

• A Happy couple• Flowers and bees

– Flowers need bees for pollination, bees need flowers nectar

What type of relation ship is going What type of relation ship is going on here?on here?

• Who is helping who?

CommensalismCommensalism

• One member of the relationship benefits while the other is neither harmed nor helped

• One-sided

• Food or shelter

• Barnacles on whale

Ants and aphidsAnts and aphids

What type of interaction is going on What type of interaction is going on here?here?

ParasitismParasitism• 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

RecapRecap

• What are the three types of interactions in a community?– Competition– Predation– Symbiosis

• What types do we have?– Mutualism– Commensalism– Parasitism

Ecological SuccessionEcological 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

• 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

Ecological SuccessionEcological Succession

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

Primary SuccessionPrimary Succession• Succession on land

that occurs on surfaces where no soil exists

• Volcanic eruptions• Glaciers melting

Stages of Primary SuccessionStages 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

Secondary SuccessionSecondary Succession

• Succession following a disturbance that destroys a community without destroying the soil

• Natural – hurricane– fires

• Human disturbances– Farming– Forest clearing

Succession in Marine EcosystemsSuccession 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

Whale-Fall SuccessionWhale-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

Human Activity and Species Human Activity and Species DiversityDiversity

• Land clearing– Farmland– Diverse forest replaced with single crop– Decreases species diversity

• Introduced species– Humans move a species from its native land

to a new location, intentionally or accidentally

Teacher,

Study Chapter 35, Population

Ecology and

Community Interactions