WHAT IS ECOLOGY
Studying Our Living Planet
• Biosphere: All life on Earth and the areas they exist
• Species: A group of similar organisms that produce fertile offspring
• Population: Group of individuals in the same species living in the
same area
• Community: Different populations living together in the same area
• Ecosystem: Organisms living in the same place + their physical
environment
• Biome: Group of ecosystems with similar climates and organisms
Science of Ecology
• Ecology: Study of interactions between and among organisms +
their environment
• Eco = House
• Ecology and Economics
• Humans: Interactions based on money and trade
• Animals: Interactions based on energy and nutrients
Biotic and Abiotic Factors
• Biotic factors: biological influences
• Example: Bullfrogs
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Algae eaten as a tadpole
Insects eaten as an adult
Herons that eat bullfrogs
Other species that compete for food and space
• Abiotic factors: physical influences
• Example: Bullfrogs
• Water availability
• Temperature
• Humidity
ENERGY,
PRODUCERS, AND
CONSUMERS
Primary Producers
• Without energy, there is no life!
• Organisms do not create energy, they only use it
• Sunlight is the ultimate source of energy for most living
things
• Some organisms use inorganic chemical instead
• Algae, some bacteria, and plants are the only
organisms that convert sunlight to consumable energy
Autotrophs
• Use the sun or chemical energy to produce food
• Primary producers: First producers of energy-rich compounds
that are used by other organisms
• Essential to the biosphere!
Energy from the Sun
• Most primary producers use photosynthesis
• Capture light energy which powers chemical reactions
• Converts carbon dioxide and water to oxygen and
carbohydrates
• Adds oxygen to the atmosphere
• Removes carbon dioxide from the atmosphere
• Life without light
• Deep sea ecosystems depend on chemosynthesis
• Convert inorganic materials to produce carbohydrates
Consumers
• Heterotrophs: Animals, fungi, many bacteria that get energy from
other organisms
• AKA: Consumers
Carnivores
Herbivores
Omnivores
Consumers
Scavengers
Decomposers
Detritivores
Eat carcasses of
animals that have
died naturally or
been killed by other
animals
Chemically break
down organic
matter and produce
detritus
Eat detritus and
detritivores
ENERGY FLOW IN
ECOSYSTEMS
Food Chains
• Energy flows in a one-way stream from producers to consumers
• Food Chains
• Steps in which energy transfers by eating and being eaten
Food Webs
• Transfer of energy is more
complicated when organisms eat
different things
• When transfer of energy can’t be
described by a simple chain, it is
described as a web
• Food chains are found within food
webs
• Decomposers and detritivores
help recycle energy in a food web
Trophic Levels
• Trophic level: Each
step in a food web
• Primary producers are
the first trophic level
Ecological Pyramid
• Shows the amount of energy or matter within a trophic
level
• Pyramid of energy: Amount of energy available at each
trophic level
• Pyramid of biomass: Total amount of living tissue in a trophic
level
• Pyramid of numbers: Number of individual organisms at each
trophic level