Community Interactions Community Interactions Powerfully affect an ecosystem

Community Interactions

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

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

Rules, rules • Fundamental rule in ecology – Competitive Exclusion Principle • No two species can occupy the same niche in the same habitat at the same time • Prevents competition

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)

Symbiosis • 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? • Who is helping who?

Mutualism • 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 on here? • Who is helping who?

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

Ants and aphids

What type of interaction is going on here?

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 relationship; 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

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

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

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

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

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 form organic material that becomes soil…now plants can grow

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

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