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Ecology
 The scientific study of interactions among organisms and their environments
 Includes descriptive and quantitative data to learn about relationships
 Biosphere – portion of Earth that supports life
 From high in atmosphere to bottom of oceans
 Ecology includes non-living parts of environment = abiotic factors
 Temperature, moisture, air currents, light, soil
 Living organisms in an environment are the biotic factors
 Living things affect others
Levels of organization
 To understand relationships you have to look at more than one individual
 Population
 Community
 Ecosystem
 Population is a group of organisms of one species that interbreed and live in the
same place at the same time
 Individual frogs might compete for the same food source
 Community is a collection of interacting populations
 A change in one population may cause change in another population
more frogs = fewer flies
 While population and communities interact, they both interact with their
environment
 An ecosystem is made up of interactions among the populations in a community
and the physical surroundings, or abiotic factors
 Ecosystems
 Terrestrial = on land, forest, meadow, desert
 Aquatic = in water, 75% of Earth
 Freshwater = pond, lake, stream
 Saltwater = ocean
Organisms in Ecosystems
 Habitat is the place where an organism lives out its life.
 Prairie dog burrows in a grassland
 Birds in trees of a beech-maple forest
 Niche is the role a species has in its environment
 Several species may live in the same place, but use different
resources = their specialized niche
 Some species improve changes of survival by forming relationships with other
species
 Some relationships benefit one, harm other, like predator/prey relationship
 Symbiosis = living together, close relationship between species
 There are several kinds of symbiosis
 Commensalism
 Mutualism
 Parasitism
 Commensalism = a symbiotic relationship in which one species benefits and the
other is neither harmed not benefited
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 Clownfish lives amongst stinging anemone for protection
Mutualism = a symbiotic relationship in which both species benefit
 Ants get nectar from acacia trees and attack any animal that tries to eat
from tree. This protection allows trees to live longer.
Parasitism = a symbiotic relationship in which one organism benefits at expense
of other organism.
 Tick, flea, mosquito
Chapter 2.2 Nutrition and Energy Flow
How organisms get energy
 Autotrophs make their own nutrients
 Plants use the sun’s energy to produce nutrients
 Heterotrophs feed on other organisms
 Herbivores eat plants
 Carnivores eat other animals
 Scavangers eat dead animals
 Decomposers break down dead and decaying plants and animals
Energy flow in ecosystems
 Food chain = simple model used to show how energy flows through an ecosystem
algae
fish
heron
 Trophic level = step in the food chain
 Each higher trophic level has fewer individuals and less energy available
 Food chain is very simple, only one path
 Food web = a model that shows all the possible feeding relationships at each
trophic level in a community
Cycles in Nature
 Like energy, matter moves through trophic levels
 Matter gets recycled
 The water cycle
 Evaporation, condensation, precipitation
 The carbon cycle
 Photosyntheis converts CO2 to energy rich carbon molecules used by
organisms to grow
 The nitrogen cycle
 Bacteria convert nitrogen in the air into the soil where plants can use it to
make proteins
 The phosphorus cycle
 Plants get phosphorus from the soil, plants and animals need it to grow