Intro to Ecology Chapter 18

Cellular Organization

Levels of Ecological Organization

Levels Smallest to largest  Cells  Tissues  Organs  Organ Systems  Organism  Population  Community  Ecosystem  Biosphere

Interdependence  Species interact with both other species and their nonliving environment

Levels of organization  Population- Includes members of a single species that live in one place at one time.  Community- All the interacting organisms living in an area. Example: Fish, Turtles, plants, algae living in a pond together.

Ecosystem  Ecosystem- includes all of the organisms and the nonliving aspects found in a particular place.  Example: Fish, Turtle, plants, water, sunlight.

The Biosphere  The broadest, most inclusive level of organization is the biosphere, the volume of Earth and its atmosphere that supports life.

Biotic vs. Abiotic Factors  Biotic - All living things that affect an organism. (living components of the environment)  Abiotic - Nonliving factors.(physical and chemical characteristics of environment)  Examples are climate, water, sunlight, and pH.

BIOTIC OR ABIOTIC?? QUIZ:  Tree? Oxygen?  Cotton Shirt? Rain?  Rabbit? Grass?  Dead squirrel? Clouds?  Owl Pellets? Bones?  Steak? Leather?

Organisms in a changing environment  Acclimation  Some organisms can adjust their tolerance to abiotic factors through the process of acclimation

Organisms in a changing environment cont…  Conformers are organisms that do not regulate their internal conditions; they change as their external environment changes.  Regulators use energy to control some of their internal conditions. (homeostasis)

Organisms in a changing environment cont…  Escape from Unsuitable Conditions  Some species survive unfavorable environmental conditions by becoming dormant or by migrating.

Dormant Grass Birds migrating

Niche  An organism’s niche is its way of life or its role in its ecosystem.  Generalist- broad niches (oppossum)  Specialist - narrow niches. (koala)

Niche

Producers  Most producers are photosynthetic and make carbohydrates by using energy from the sun.  Autotrophs  Example: trees, plants, algae

Producers Cont…  Gross primary productivity the rate producers in an ecosystem capture the energy of sunlight by producing organic compounds.  The rate biomass accumulates is called net primary productivity.

Consumers  Consumers obtain energy by eating other organisms and include herbivores, omnivores, carnivores, detritivores, and decomposers.  Consumers are heterotrophs

Types of Consumers  Herbivore- eats only producers (eats plants)  Carnivore- eats only consumers (eats animals)  Omnivore- eats both producers and consumers (eats animals and plants)  Detritivores- eats dead or decomposing material

Energy Flow  Food Chains and Food Webs  A single pathway of energy transfer is a food chain.  A network showing all paths of energy transfer is a food web

Food Chain

Food Web

 Energy Transfer  Ecosystems contain only a few trophic levels because there is a low rate of energy transfer between each level

Energy Transfer  On average 10% of energy is transferred from one trophic level to the next.  The lower the tropic level the higher percent of energy available.

Energy Transfer  Organisms at the lower levels are usually much more abundant than higher levels.  (1000 Zebras/ 1 Lion)

Water Cycle  Key processes in the water cycle are evaporation, condensation, and precipitation.  Transpiration- the process of water evaporating from leaves of plants.

Water Cycle

Carbon Cycle  Photosynthesis and cellular respiration are the two main steps in the carbon cycle.  Burning fossil fuels releases carbon dioxide into the atmosphere.

Carbon Cycle

Nitrogen Cycle  Nitrogen-fixing bacteria live in soil and plant roots.  This bacteria is important in the nitrogen cycle because they change nitrogen gas into a usable form of nitrogen for plants.  The process of converting nitrogen gas to nitrate is called nitrogen fixation.

Recycling Nitrogen  Decomposers break down bodies of dead organisms and urine to release the nitrogen they contain as ammonia, this process is known as ammonification.  The soil bacteria take the ammonia and then oxidize it into nitrates, this process is known as Nitrification.  Denitrifying bacteria then break down the nitrates and release the nitrogen to the atmosphere, this process in known at denitrification.

Nitrogen Cycle

Phosphorous Cycle  In the phosphorus cycle, phosphorus moves from phosphate deposited in rock, to the soil, plants absorb it through their roots, then passes to other living organisms, and finally to the ocean.