ECOLOGY
ECOLOGY
•	General Info
•	Ecology is the study of the interactions of living (biotic) organisms with their non-living (abiotic) environment.
•	Levels of Organization (smallest to largest)
•	Species - any organism that is able to interbreed and have fertile offspring
•	Populations - groups of the same species living in the same area
•	Communities - groups of populations that live together in a defined area
•	General Info
•	Different levels (cont)
•	Ecosystem - the relationship of the community with its nonliving environment
•	Biomes - ecosystems in different locations with similar climate and communities (e.g. desert, temperate forest, arctic, etc)
•	Biosphere - area on the planet where life exists (e.g. all biomes put together)
•	General Info
•	Abiotic Factors (Non-Living)
•	Light
•	Ecosystems are driven by solar energy
•	Why?    
•	Photosynthesis and heat
•	Temperature
•	Temperature affects an organism’s metabolism
•	Ordinary range 0° C – 50°C (32° - 122° F)
•	Abiotic Factors (Non-Living)
•	Water
•	Water is necessary for life. Why?
•	Cells are mostly made of water
•	Water is good for dissolving chemicals within cells
•	Most of the chemistry in living things involves adding or removing water
•	Many organisms live in water
•	Abiotic Factors (Non-Living)
•	Oxygen
•	Depth of life in soil affected by oxygen
•	Aquatic organisms are limited by oxygen supply in water
•	Soil Conditions
•	Soils physical makeup (clay, sand, rocks etc.) affects organisms
•	Animals feed on plants, which are affected by soil conditions
•	Biotic Factors (Living)
•	Food
•	Predation
•	Disease
•	Competition
•	All communities have producers, consumers and decomposers
•	Producer - anything that produces its own food (plants and/or algae)
•	Biotic Factors (Living)
•	Consumer - anything that eats other organisms (e.g. humans, wolves etc.)
•	Decomposer - anything that breaks down dead matter and returns its chemicals to the earth (e.g. bacteria and fungi)

Biotic + Abiotic factors =
 Habitat

•	Habitat - species surroundings
•	Niche - a way of life or the role a species plays
•	How would you describe a coyote’s niche?
•	Ecological Succession
•	Succession
•	The process by which an existing community is gradually replaced by another one
(May take hundreds or thousands of years )

•	Can you think of an example of succession?
•	Ecological Succession
•	Types of Succession
•	Primary Succession - begins where there were no living organisms 
(e.g. lava flows, above the timberline or edge of a lake)
•	Pioneer Organisms - first to settle 
(e.g. lichens, grasses and mosses help build-up the soil)
•	Ecological Succession
•	Ecological Succession
•	Ecological Succession
•	Types of Succession (cont)
•	Climax Community - is a somewhat stable, permanent community
•	Secondary Succession
•	Occurs in an established ecosystem after it is destroyed or damaged by a disaster
(e.g. Fires, floods, agriculture, etc.)
•	The Flow of Elements
•	The 4 most common elements found in organisms are:

•	These elements are continuously recycled throughout the biosphere. 

•	The Flow of Elements
•	The Water Cycle
•	Eutrophication
•	Fertilizers (N and P) run off into freshwater ecosystems 
•	Explosive algal growth
•	Ecosystem is drained of nutrients and dissolved oxygen (DO)

•	What effect does this have on a lake?
Eutrophication
•	The Flow of Elements

Composition of Earth's Atmosphere
Nitrogen 78.1%
Oxygen 20.9%
Argon 0.9%
Carbon dioxide, Methane, inert gases 0.1%
•	The Flow of Elements
•	The Water Cycle
•	Acid Rain
•	Burning fossil fuels produces SO2 and NOx.
•	They mix with water forming H2SO4 (sulfuric) and HNO3 (nitric) acids.
Acid Rain
•	Acid Rain
•	This lowers the pH of the soil and aquatic ecosystems.
•	What are the effects of acid rain?
Acid Rain
•	The Flow of Elements
•	The Carbon Cycle (sketch this)

•	The Carbon Cycle
•	Global Warming “Greenhouse Effect”
•	Caused by the accumulation of excess CO2 in the atmosphere
•	What are some sources of the CO2?

•	Global Warming “Greenhouse Effect” (cont)
•	CO2 and other gases warm the surface of the planet naturally by trapping solar heat in the atmosphere (draw)

•	The Carbon Cycle (cont)
•	Ozone Depletion
•	Ozone is a layer of O3
•	Absorbs biologically harmful UV radiation emitted by the sun
•	Chloroflurocarbons (CFCs) used in refrigerants (freon) and in propellants break down the ozone
•	What is the problem with this? 
•	Ozone Depletion
•	The Nitrogen Cycle
•	Nitrogen makes up 78% of the Earth’s atmosphere and we need N to live. 
•	Why can’t we breathe in the N we need?

•	Why is N such an important element?
Nitrogen Cycle (draw)
Nitrogen Cycle (draw this)
•	Energy Flow in a Community
•	Producers (autotrophs)
•	Photosynthesis is the main source of energy for life on earth
 6CO2 + 6H2O → C6H12O6 + 6O2

•	Consumers (heterotrophs)
•	Herbivores, carnivores, omnivores, scavengers, and detritivores (feed on plant and animal remains, e.g. mites, earthworms, crabs)
•	Decomposers

•	Energy Transfer
•	As organisms eat and in turn are eaten, they transfer energy.
•	This flow of energy travels in one direction and is illustrated by a food chain or web.
•	Food Chain
•	Always begins with a plant or algae
•	Why?

•	Food Chain (cont)
sun → producers → consumers

•	Food Web
•	Complex feeding relationship among various organisms

•	Food Pyramid
•	Each organism in the food chain/web is placed in a different level called trophic levels.

•	Food Pyramid (cont)
•	Only 10% of energy is transferred to organisms at next trophic level.  Why?
•	Total amount of living tissue in a given trophic level is called the biomass.

•	Biological Magnification
•	Some chemicals (DDT) and elements (lead and mercury) cannot be burned or removed with the organism’s wastes.
•	They accumulate as you move up the food chain.
•	Population Ecology
•	Population Growth Curve (draw this)
•	When a new organism is introduced into a new environment it takes a while to establish itself – the “lag phase”.
•	Once established there is a population explosion and growth accelerates.
•	When the population approaches the carrying capacity, various biotic and abiotic factors keep the population in balance.
•	Population Ecology
•	Carrying capacity is the maximum number of individuals an ecosystem can support.

•	Why does this area of the graph * fluctuate?
•	Where is the human population on this curve?
•	Population Ecology
•	Limits to Growth
•	A limiting factor is an ecological factor that causes population growth to decrease (e.g. habitat space, food, water)
•	Density Dependent Factors
•	Competition for limited resources
•	Predation
•	Parasitism
•	Crowding
•	Population Ecology
•	Density Independent Factors
•	The population size doesn’t matter.
•	Natural disasters like severe storms, drought, or other climate conditions.
•	Population Ecology
•	Community Interactions
•	Symbiosis-close relationship between two species
•	Parasitism - two organisms living together in which one is harmed 
•	Mutualism - both species benefits 
•	Commensalism - one benefits, while the other neither benefits nor is harmed 
•	Name some examples of each