ECOLOGY & the ENVIRONMENT

ECOLOGY The study of interactions among organisms & their environment Ecologists divide environmental factors that influence organisms into 2 groups: ABIOTIC and BIOTIC.

ABIOTIC NONLIVING PARTS OF THE ENVIRONMENT Ex: Water, light, temperature, air, soil Air is a mixture of 3 main gases: oxygen, carbon dioxide, & nitrogen (used by plants & animals

Soil type is determined by the amounts of sand, humus, & clay that it contains Humus: decaying matter found in soil

BIOTIC Living or once-living organisms in the environment Can be arranged into levels of organization:

1. organism 1 individual from a population Example: catfish

2. Population All the individuals of one species that live in the same area at the same time. Example: All the catfish living in a lake at the same time

3. community Populations of different species that interact in some way Example: Population of bass and all the species they interact with it

4. ecosystem All the communities in an area & the abiotic factors that affect them Example: lake, pond, coral reef, forest, etc.

5. Biome Large region with plants & animals well adapted to soil & climate of the region Example: Mountain, rainforests, tundra, desert, grasslands, temperate forests (where we live)

6. biosphere All the ecosystems on earth; the part of the earth that supports life Example: Top part of the earth’s crust, all the waters that cover the Earth’s surface, the surrounding atmosphere, & all the biomes.

Interactions among living organisms

1. Population size The number of individuals in a population

2. Population Density The number of individuals in a population that occupy a definite area

Classroom population density Length of room (m) X width (m) # of students =A (in m2) = how much space each person has

3. Population spacing How organisms are arranged in a given area Can be evenly, random, or clumped clumped EVEN random

4. Limiting factors Any biotic or abiotic factor that limits the number of individuals in a population Ex: drought, fewer plants, fewer nesting sites, predators

Food, water, & space are all factors in the growth populations in an ecosystem If an environment had no limiting factors, the population would INCREASE.

5. Carrying capacity Largest number of individuals of a species that an environment can support & maintain for a long period of time.

Energy flow through ecosystems Most of the interactions among members of different species occur when one organism feeds on another

When one organism is food for another organism, some of the energy in the first organism (the food) is transferred to the second organism (the eater).

producers Organisms that take in & use energy from the sun or some other source to produce food. Another name for producer is autotroph. Examples: algae & plants

Consumers Organisms that take in energy when they feed on producers or other consumers. Another name for consumer is heterotroph.

decomposers Organisms that take in energy from organisms that have died by breaking down the remains of organisms.

Scavenger Organisms that feed on dead animals or plant material present in its habitat.

Characteristics of Autotrophs vs. Heterotrophs Are producers Are consumers and decomposers Plants, bacteria, and algae Need food Animals, humans, monkeys Both are living things Get food from autotrophs Make food from water, sunlight, and CO² Autotrophs Heterotrophs Need water, sunlight, and air Means “self nutrition” Means “other nutrition” Characteristics of Autotrophs vs. Heterotrophs

Movement of energy through a community can be diagrammed as a food chain or food web.

Food chain Simple way of showing how energy passes from one organism to another. Usually 3 or 4 links

Example of food chain: Water plant insects bluegill bass Grass grasshopper frog snake owl

Energy pyramid Compares energy available at each level of the food chain in an ecosystem As you move from level to level, energy decreases.

2. Food web Series of overlapping food chains that exist in an ecosystem More complete model of feeding relationships.

Primary Consumer-an animal that feeds on plants; a herbivores Secondary Consumer-an animal that eats primary consumers and plants. They are omnivores. Tertiary Consumer-an animal that eats secondary consumers. They are carnivores.

Other Ecological Terms to Know: Symbiosis is a close relationship that may occur when two organisms of different species live together. There are several different kinds of symbiotic relationships: 1) Mutualism: Both species benefit. The two organisms help each other. An example would be a honey bee and a dandelion. The honey bee gets to eat the pollen from the flower. The dandelion uses the bee to spread its pollen to another flower.

More Ecological Terms cont. 2) Commensalism: One species benefits. The other species is unaffected. A common example is an animal using a plant for shelter. An American Robin benefits by building its nest in a Red Maple tree. The tree is unaffected. 3) Parasitism: Ones species benefits. The other species is harmed. An example would be a deer tick and a White-tailed Deer. The tick gets food from the deer without killing it. The deer is harmed by losing blood to the tick, and possibly by getting an infected wound or disease. 4) Predation: A predator/ prey relationship. An example is an owl hunting a mouse. 5) Cooperation: Organisms work together for a common or mutual benefit. An example would be a group of lionesses hunting prey.