Ecology Obj. 3a & e

Ecosystems  An ecosystem is all the organisms that live in an area together with the nonliving factors of the environment  Ex. Pond or pine forest  Ecology is the study of how organisms interact with each other & the physical environment

Populations All the organisms in an ecosystem that belong to the same species – Ex. Mice living in a meadow or pine trees in a forest Species are a group of organisms that can mate to produce offspring that can produce more offspring – Ex. Brown pelican or human

Community All the populations of different species that live in an ecosystem & share resources – Ex. Pine tree forest forms a community with populations of deer, mice, raccoons, bacteria, mushrooms, & ferns – Ex. An arctic community might include populations of fish, seals that eat fish, and polar bears that hunt and eat seals

Limiting Factors that affect populations Food: plants make their own food, but other organisms obtain food by eating other organisms Water: required by all living things to move materials around cells & tissues in the body Light: required by plants & other organisms to make food through photosynthesis Living Space: organisms need room to obtain resources & reproduce

Ex. Polar Bear Habitat The polar bears main habitat is offshore pack ice, along coasts and islands of the Arctic region. Polar bears prefer the ice packs to other parts of their habitat because it allows them to remain in close contact with their main food source, the seal.

Niche The unique ways an organism survives, obtains food & shelter, reproduces, cares for its young, and avoids danger – Homeostasis: an organisms ability to keep the proper internal conditions no matter what is going on outside the organism’s body Example of niche: A male lion’s mane attracts a mate Why does each species have its own niche?

Ex. Polar Bear Niche Large feet and short, sharp, stocky claws are adaptations to this environment. Thick layer of fat under a thick fur to provide protection from extreme cold temperatures Polar bears depend on sea ice as a platform for hunting seals. Eat seals, walrus, & fish Care for young for 2 years

Interactions Within Communities All organisms need ENERGY to survive. The sun is the source of energy that fuels most life on Earth

Feeding Relationships 3 main groups – Producers – Consumers – Decomposers

Producers: Autotrophs Organisms that make their own food using energy from the sun & raw materials from the environment – Most producers are plants that contain chlorophyll required for photosynthesis

Photosynthesis Plants use carbon dioxide and hydrogen from light-energy in the presence of chlorophyll to make glucose and oxygen – Directly or indirectly produces food for almost all organisms – Removes carbon dioxide from and adds oxygen to the atmosphere – Phytoplankton & algae also play a huge role as producers in the environment CO 2 + H 2 O + sunlight oxygen + Glucose (energy) (sugar)

Respiration Respiration is a chemical reaction that occurs in the mitochondria of cells – combines oxygen & food to release energy for living organisms, carbon dioxide as a waste product, and water – Both plants and animals use aerobic respiration – Opposite of photosynthesis Oxygen + Glucose CO 2 + H 2 O + energy (sugar)

Consumers: Heterotrophs Organisms that cannot make their own food & Obtain energy by eating other organisms Three Types: – Herbivores: eat only plants/producers – Carnivores: eat only animals – Omnivores: eat both plant & animals

Decomposers: Heterotrophs Organisms that feed on the dead remains or waste products of other organisms to obtain energy Help recycle once-living matter by breaking it down into simpler substances to be used as food, nutrients absorbed by plant, or consumed by other organisms – Ex. Bacteria, earthworms, & fungi

Food Chains A model that shows the flow of energy through feeding relationships among organisms in a particular ecosystems

Food Webs A model that links the organisms within an ecosystem by how they depend on each other for food. The lines drawn represent the flow of energy through the ecosystem & show a variety of food chains

Food Web

Relationships b/t Populations 3 main categories of relationships – Competition – Predation – Symbiosis

Competition Occurs when more that one individual or population tries to make use of the same limited resources – Ex. Food, water, or space

Predation Type of feeding relationship in which one animal captures & eats another animal for food – Animal being eaten is the prey – Animal doing the eating is the predator – Predator/prey relationships help keep an ecosystem in balance by preventing any one population from growing too large

Symbiotic Relationships Symbiosis: any close relationships between organisms – Mutualism: both species benefit Ex. A hummingbird drinks the nectar from a petunia and carries the flower’s pollen to other flowers

Symbiotic Relationships Commensalisms: one organism benefits while the other organism is unharmed – Ex. A heron lives near a herd of cattle eating the insects the cattle stir up as they pass through the grass

Symbiotic Relationships Parasitism: one organism called a parasite feeds on the cells, tissue, or fluids of another organism called a host – Parasites benefits while the host is usually weakened but not killed – Ex. A flee lives on and drinks the blood of a dog