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

Ecological Relationships 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

Ecological Relationships Herbivore – an animal that eats only plants Carnivore – an animal that only eats other animals Omnivore – an animal that eats plants and animals

Ecological Relationships Competition – the conflict between organisms when they try to use the same resources at the same time Some resources Food Mating Habitat

Ecological Relationships Symbiosis – living together Symbiotic Relationships (involves two species) Mutualism – both species benefit Ex. – Insect and flower

Ecological Relationships Symbiotic Relationships Commensalism – only one species benefits but the other is neither helped nor harmed Ex. – Whale and barnacle

Ecological Relationships 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

Energy Flow in Ecosystems 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

Energy Flow in Ecosystems Food chain – a simple representation of how energy is passed from a producer to consumers

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

Energy Flow in Ecosystems 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

Energy Flow in Ecosystems 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.

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

Climax community

Secondary Succession 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.