Notes Ecosystem Structure Objectives Explain how biotic and

Notes: Ecosystem Structure

Objectives • Explain how biotic and abiotic factors influence an ecosystem • Identify the interactions that occur within communities • Describe how ecosystems recover from a disturbance

biotic • Living factors of an environment

abiotic • The non-living factors of an environment Ex. ) water, soil, air

Biotic and Abiotic • Together, biotic and abiotic factors determine the survival and growth of an organism and the productivity of the ecosystem in which the organism lives

Habitat • Where an organism lives

Squirrel in tree

Fish in stream

Niche • The role an organisms plays in its environment • A niche is what the organism eats, what organisms eat it, what interactions in has with other organisms and its environment. • No two species can share the same niche in the same habitat

Community Interactions • Community interactions, such as competition, predation, and various forms of symbiosis, can powerfully affect an ecosystem.

Competition • Competition occurs when organisms of the same or different species attempt to use an ecological resource in the same place at the same time • Direct competition in nature often results in a winner and a loser— with the losing organism failing to survive

Competitive exclusion principle • States that no two species can occupy the same niche in the same habitat at the same time

Predation • When one organism captures and feeds on another organism • The organism that does the killing and eating is called the Predator, and the food organism is the Prey.

Symbiosis • Any relationship in which two species live closely together • Biologists recognize three main classes of symbiotic relationships in nature

Mutualism • When both members benefit – Examples: Cats and Humans or Dogs and Humans

Lichens: close association between algae and fungi

Ant – Acacia Tree

Commensalism • When one member benefits and the other is neither helped nor harmed – Example: birds nesting in trees

Clownfish – Sea Anemone

Parasitism • When one member benefits and the other is harmed

Humans - Tapeworms

Ecological Succession • Ecosystems are constantly changing in response to natural and human disturbances. As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community. • The series of predictable changes that occurs in a community over time

Primary Succession • Succession that occurs on new land where no soil exists Ex. ) volcanic islands, bare exposed rock when glaciers melt

Pioneer species • The first species to populate an area Ex. ) lichen, algae, mosses

Secondary Succession • When a disturbed area grows back to normal. For example natural disaster areas (Fire on Mt. Lemmon)

Closure • In your own words, summarize what you learned about each of the following: – Biotic and abiotic factors in ecosystems – Habitat and Niche – Competitive Exclusion Principle – Types of community interactions – Primary and secondary succession Share with your partner !!!