Ecology Chapter 2

Ecology

Chapter 2

Ecology - The study of interactions that take place between organisms and their environment

Levels of Ecological Organization Organism – an individual living thing Species – a group of very similar organisms

that can interbreed and produce fertile offspring

Hybrids are not species Examples

Ligers Mules

Levels of Ecological Organization Population – organisms of the same species

that live in the same place and at the same time Community – different populations of different

species that live in the same place at the same time

Ecosystem – a community of living organisms plus their non-living environment

Biosphere – all the combined ecosystems of the world where organisms can live

Biotic vs. Abiotic

Biotic factors – living organisms in an ecosystem

Examples: Bee Dandelion Oak tree Deer

Abiotic factors – non-living parts of an ecosystem

Examples Water Air Soil Rocks

Ecological Relationships

Niche – an organism’s role in its ecosystem Habitat – the place where an organism lives Example

Lion’s niche and habitat


Predator-Prey Predator – an animal that captures and eats a

member of another species Prey – an animal that is subject to being caught

and eaten


Herbivore – an animal that eats only plants

Carnivore – an animal that only eats other animals

Omnivore – an animal that eats plants and animals


Competition – the conflict between organisms when they try to use the same resources at the same time

Some resources Food Mating Habitat


Symbiosis – living together Symbiotic Relationships (involves two

species) Mutualism – both species benefit

Ex. – Insect and flower


Symbiotic Relationships Commensalism – only one species benefits but

the other is neither helped nor harmed Ex. – Whale and barnacle


Symbiotic Relationships Parasitism – one organism benefits at the

expense of another organism Ex. Tick and dog Cuckoo

Brood parasite

Energy Flow in Ecosystems

Producers (or autotrophs) – organisms that make their own food usually by using energy directly from the sun Ex. - plants

Consumers (or heterotrophs) – organisms that cannot make their own food and must get energy by eating producers or other consumers Ex. - animals


Decomposers (or saprotrophs) – organisms that obtain nutrients by breaking down dead and decaying plants and animals

Scavenger – organisms that eat dead or decaying organisms

Primary consumer – eats producers Secondary consumer – eats a primary consumer Tertiary consumer – eats a secondary consumer Quaternary consumer – eats a tertiary consumer


Food chain – a simple representation of how energy is passed from a producer to consumers


Food web – a more complex representation of how energy is passed from producers to consumers in an ecosystem


Trophic level – organism that represents a feeding step

Energy pyramid – a representation in the shape of a pyramid that shows how energy is passed from one trophic level to the next


Most energy is located at the producer level

As the trophic level increases, 10% of energy is lost

Ecological Succession

Ecosystems are constantly changing. Ecological succession – a gradual process of

change and replacement of the types of species in a community.

Primary Succession

Primary succession – a type of succession that occurs on a surface where no ecosystem existed before Example: Hawaii islands

Primary Succession

Pioneer species – a species that colonizes an uninhabited area and that starts an ecological cycle in which many other species become established.

Primary Succession

Lichen and bacteria are the pioneer species Mosses are usually the second organisms to

form

Secondary Succession

Secondary succession occurs on a surface where an ecosystem has previously existed.

Secondary succession can occur in ecosystems that have been disturbed or disrupted by humans, animals, or by natural process such as storms, floods, earthquakes, or volcanic eruptions.


Climax community – the final, stable community in equilibrium with the environment

Climax community


Old-field succession is a type of secondary succession that occurs when farmland is abandoned.

When a farmer stops cultivating a field, grasses and weeds quickly grow and cover the abandoned land.

Over time, taller plants, such as perennial grasses, shrubs, and trees take over the area.

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Ecology Chapter 2