Ecology NOTES Part 1: Principles of Ecology
Ecology NOTES – Part 1: Principles of Ecology
The multiple levels of biological systems
ecology- the study of the interactions of living organisms with one another and with their physical environment
organism – an individual living thing
ex) a black bat
population – all of the individuals of a species that live in the same area
ex) the black bats
community-a group of different species that live together in one area
ex) the black bats, worms, moss, mushrooms, bacteria and beetles living in the cave
habitat- place where an organism usually lives
ex) a cave is a habitat for a black bat
ecosystem- the different species (community) plus the environment (soil, water, weather); biotic factors + abiotic factors
ex) soil in the bottom of the cave, light entering the cave, temperature in the cave, humidity in the cave, plus the community
biome – major regional or global community of organisms characterized by the climate conditions and the plant communities that thrive there
Biotic and Abiotic Factors
biotic factors- are organisms in a habitat
ex) animals, plants, fungi, protists, bacteria
abiotic factors- are the physical aspects of a habitat
ex) wind, water, rocks, sunlight, shade, etc.
Ecosystems are complex. Changes to the biotic OR abiotic factors in an ecosystem affect all species.
biodiversity – the assortment or variety of living things in an ecosystem
-biodiversity is threatened by human activity
- pollution
- global warming
- habitat destruction
keystone species – a species that has an unusually large effect on its ecosystem
ex) sea otter – has a tremendous effect on the ecosystem it is a part of
-sea otters eat sea urchins which keeps the sea urchin population under control
-when the sea otter population is over hunted there are not enough otters to eat the sea urchins
-the sea urchins, in turn, eat too much kelp (an aquatic plant, like seaweed) from kelp beds and the kelp population declines
-without kelp beds, fish have no place to lay their eggs and the fish population also declines
-when hunters stop hunting the sea otter population, the urchin populations decrease and the kelp beds and fish populations go back to normal.
Food Chains and Food Webs
Producers provide energy for other organisms in an ecosystem
producer – organism that obtains energy from nonliving resources; organism that makes its own food
-basis for ecosystem’s energy
-most rely on sunlight
Almost all producers obtain energy from sunlight
-most producers use sunlight as their energy source
-photosynthesis – 2-stage process that green plants and algae use to produce energy
6CO2 + 6H2O C6H12O6 + 6O2
autotroph – another word for producer; word parts: self feeder
consumer – organism that gets its energy by eating other living or once-living resources, such as plants and animals; connected to producers through energy, which ultimately comes from the sun
heterotroph – another word for consumer; word parts: different feeder
Label the organisms below as producer, autotroph, consumer, hetertroph (use all words that apply)
______
______
Types of Consumers
herbivores – organisms that eat only plants; ex) rabbit
carnivores – organisms that eat only animals; ex) snake
omnivores – organisms that eat both plants and animals; ex) chicken (eats seeds and insects)
detritivores – organisms that eat dead, organic matter; ex) millipede
decomposers – organisms that break down organic matter into simpler compounds; ex) fungi and bacteria
-responsible for the last step in every food chain, returning nutrients to the environment
-receive energy from every other level
A food chain is a model that shows a sequence of feeding relationships
***Energy FLOWS through ecosystems***
food chain – sequence that links species by their feeding relationships
-note that the arrows that link one organism to another show the direction that energy is flowing; energy flows from the organism being eaten to the organism doing the eating
Draw the arrows to complete the food chain below:
Trophic Levels
trophic levels – levels of nourishment in a food chain; ex) producerherbivorecarnivore represents a food chain with 3 trophic levels
-energy flows up the food chain from the lowest trophic level to the highest
- producer– autotrophs – level 1
- primary consumer – herbivores & omnivores– level 2
- secondary consumer – carnivores & omnivores- level 3
- tertiary consumer – carnivores that eat carnivores and some omnivores – level 4
A food web shows a complex network of feeding relationships
food web – model that shows the complex network of feeding relationships and the flow of energy within and sometimes beyond an ecosystem
-at each link, some energy is stored in the organism and some energy is dissipated (lost) to the environment
-stability depends on the base – the producers (plants, algae, phytoplankton, some bacteria)
marine food webs show multiple trophic levels and food chains
Pyramid Models
An energy pyramid shows the distribution of energy among trophic levels
-energy in ecosystems comes from sunlight
-energy flows UP the food chain from producer to consumer
-some energy is lost from the ecosystem, mostly as heat
-each level of a food chain contains less useful energy than the level below it
10% Rule- at each trophic level, the energy stored is about 10% of that stored by the organism below
Loss of Available Energy
biomass – measure of the total dry mass of organisms in a given area
-incorporated into the body of a consumer
-up to 90% of the energy stored in the eaten organism may be lost as heat (energy)
Energy Pyramids
-the longer a food chain, the more energy lost
energy pyramid – diagram that compares energy used by producers, primary consumers, and other trophic levels
-illustrates how available energy is distributed among trophic levels in an ecosystem
-energy is measured in kilocalories (kcal)
Label the correct amount of energy at each trophic level: