Biology Chapter 2 Principles of Ecology

2.1 Organisms & Their Environment Ecology-the study of interactions that take place between organisms and their environment Biosphere- the portion of earth that supports living things It starts at the bottom of the oceans and extends high into the atmosphere It includes all parts of the environment, both living and non-living

2.1 Organisms & Their Environment The environment has 2 types of factors: Biotic- living parts of the environment Includes plants and animals Abiotic- non-living parts of the environment Includes rocks, soil, rainfall, temperature, etc. You cannot study an organism without studying both the abiotic and biotic factors that affect that organism

2.1 Organisms & Their Environment The living world has been organized into 4 levels in order to better understand the interactions Organism-this is the actual plant or animal by itself For example: a rabbit Populations- a group of organisms, all the same species, which interbreed and live in the same area at the same time For example: the rabbits in Holden Communities- composed of multiple populations in an area at the same time For example: the rabbits and squirrels and birds and people in Holden Ecosystems- includes the interacting of communities and their abiotic factors For example: the rabbits, squirrels, birds, people and soil, houses, climate, roads, etc. in Holden

2.1 Organisms & Their Environment Habitat- the place where an organism lives out its life For example: your dog’s habitat includes the backyard, and maybe the front yard and house, possibly a dog house Niche- the role or position a species has in its environment For example: your dog’s niche may be to eat dog food, sleep on the couch, play in the backyard and provide you with unconditional love Species can occupy the same habitat, but they cannot occupy the same niche

2.1 Organisms & Their Environment Symbiosis- a close, permanent relationship between 2 species Commensalism- one species benefits and the other species is not hurt or helped Mosses or ferns grow on larger plants, which provide a habitat, but are not damaged Parasitism- one species benefits and the other is harmed For example: ticks benefit by gaining food and dogs can be harmed by diseases carried by ticks Mutualism- both species benefit For example: ants and acacia trees-the ants receive shelter and food, the trees receive protection from being eaten

2.2 Nutrition & Energy Flow Autotrophs- use the sun’s energy to make their own food Also called producers Includes plants and algae Plants make food through photosynthesis Heterotrophs- consume other organisms for food Can eat only autotrophs, only other heterotrophs, or both autotrophs & heterotrophs Examples include deer, owls, humans

2.2 Nutrition & Energy Flow Heterotrophs are further classified: Herbivores- eat only plants Examples: deer, cows, caterpillars Carnivores- eat only animals Examples: lions, sea otters Carnivores include scavengers, who eat only dead animals for food, such as vultures Omnivores- eat both plants and animals Examples: humans, bears, raccoons, bass Decomposers- break down dead organisms and release their nutrients back to the environment Examples: bacteria and fungi

2.2 Nutrition & Energy Flow Matter and energy is transferred among organisms based on who eats what This is called a food chain Food chains show feeding relationships in a single chain of trophic levels as follows: Producer- plants 1 st order consumer- animal that eats the plant 2 nd order consumer- animal that eats the 1 st order consumer 3 rd order consumer- animal that eats the 2 nd order consumer Decomposers-break down all of the above after they die

2.2 Nutrition & Energy Flow Food Webs- food webs show multiple feeding connections among organisms in an ecosystem

2.2 Nutrition & Energy Flow Ecological Pyramids- show graphically the quantities of matter and energy transferred between trophic levels The standard rule is that 10% of the biomass or energy from one trophic level is transferred to the next trophic level The lost energy or biomass is “burned” off as heat or growth

2.2 Cycles in Nature There is a constant amount of matter in the universe at all times This matter is constantly being recycled and reused Four examples of nutrient cycling: Water Cycle Carbon Cycle Nitrogen Cycle Phosphorus Cycle

2.2 Cycles in Nature Water Cycle surface water (oceans, lakes, streams) evaporates into the atmosphere It then condenses in the clouds When enough water is in the clouds, it falls as precipitation, such as rain, snow, or ice It then runs back into the surface water, or gets absorbed into the ground water

2.2 Cycles in Nature Carbon Cycle: carbon cycles, but can also be stored in the atmosphere and oceans for extended periods of time Producers absorb carbon dioxide from the atmosphere through photosynthesis Consumers eat the producers and absorb the carbon Producers and consumers release carbon dioxide into the atmosphere through respiration Dead and decaying organisms form fossil fuels over time

2.2 Cycles in Nature Nitrogen Cycle: 78% of atmosphere is nitrogen Bacteria in the soil “fix” nitrogen from the air into the soil Plants use the nitrogen in the soil to make proteins Herbivores eat the plants and convert the nitrogen to animal proteins Urine from organisms or decay from dead organisms return nitrogen to the soil or the atmosphere Certain bacteria release nitrogen from the soil back to the atmosphere

2.2 Cycles in Nature Phosphorus Cycle SHORT TERM LONG TERM Soil decomposers act on plant and animal waste to release phosphorus Plants use phosphorus from the soil Plants die Phosphates leach from soil into streams Rain washes phosphates from soil Phosphate weathers from rocks into streams Phosphates settle and get trapped in rocks at the bottom of streams Geologic processes raise phosphate rocks to surface