Everything is Connected
• All living things are connected in a web of life
• Ecology is the study of the interactions of organisms
with one another and with their environment
• The environment can be arranged into different
levels – organism – population – communities –
ecosystems - biosphere
• There are two parts of the environment:
– the biotic part is all the organisms that live together and
interact
– The abiotic part consists of the nonliving factors such as
water , soil, light and temperature
Levels of Environment
• Populations – each organism is part of a group
of individuals of the same species that live
together – individuals compete for food, living
space and mates Ex. Perch in Muzzy Meadow
• Community – all the populations of species
that live and interact in an area – populations
depend on each other for food, shelter, etc.
• Ecosystems – made up of a community of
organisms and the abiotic environment of that
community
• Biosphere – part of the Earth where life exists
Living Things Need Energy
• Organisms are divided into three groups based on
how they get energy
• Producers – organisms that use sunlight directly to
make food – process is called photosynthesis plants, algae and some bacterias
• Consumers – organisms that eat other organisms
– Herbivore – consumers that eat only plants – ex. cows
– Carnivore – consumers that eats animals – ex. coyotes
– Omnivore - consumers that eat both plants and animals
– ex. Grasshopper mouse
Decomposers – organisms that get their energy by
breaking down dead organisms – ex. bacteria
Food Chains and Webs
• A food chain is a diagram that shows how energy in
food flows from one organism to another - few
organisms eat just one kind of food so food chains
are rare
• A food web is a diagram that shows the feeding
relationships between organisms in an ecosystem
• An arrow goes from the organism that is the food to
the organism that will eat it
• Energy moves from one organism to the next in a
one – way direction
• Any energy stored in an organism’s tissues can be
used by the next consumer
Energy Pyramids
• An energy pyramid is a diagram that shows an
ecosystem’s loss of energy
• Less energy is available at higher levels because
only energy stored in tissues of an organism can be
transferred to the next level
• Gray wolves are consumers that control the
population of many other animals
• Because gray wolves are predators that prey on
large animals, they are at the top of the pyramid
• When gray wolves were almost wiped out, it
created an overpopulation of elk – this led to
overgrazing – almost all populations were affected
1. Name one biotic factor in an ecosystem.
Name one abiotic factor in an ecosystem.
2. What is the difference between a population
and a community?
3. What type of organism makes its own food?
4. What type of organism consumes other
animals?
5. What type of organism gets energy by
breaking down dead organisms?
6. What is the difference between a food chain
and a food web?
Interactions with the Environment
• Variations in sizes of populations within a
community happen because everything in the
environment affects every other thing
• Populations can’t grow without stopping because
the environment contains a limited amount of food,
water, living space and other resources
• A limiting factor is a resource that is so scarce that it
limits the size of the population
• Carrying capacity – the largest population that an
environment can support
• When a population grows larger that its carrying
capacity, limiting factors in the environment cause
individuals to die off or leave
Interactions Between Organisms
Competition
• Four main ways that species and individuals
affect each other: competition, predators and
prey, symbiotic relationships and coevolution
• Competition – when two or more individuals
or populations try to use the same resources,
such as food, living space, water or sunlight
• Competition happens between individuals
within one population and happens between
populations within a community
Interactions Between Organisms
Predator and Prey
• Predator and prey – one organism eating the other
– prey is the organism being eaten – predator is the
organism that eats the prey
• Predator adaptations – must be able to catch their
prey ex. cheetah’s speed
• Prey adaptations – methods and abilities that
organisms have to keep from being eaten ex.
buffalo herd
• Camouflage – one way animals avoid being eaten is
to blend in with the background
• Defensive chemicals – spraying predators with
irritating chemicals
• Warning coloration – predators avoid colors or
patterns they associate with pain
Symbiosis
• Symbiosis is a close, long-term association between
two or more species
• Individuals in a symbiotic relationship can benefit
from, be unaffected by, or be harmed by the
relationship
• Symbiotic relationships classified in three groups:
mutualism, commensalism and parasitism
• Mutualism – both organisms benefit from the
relationship ex. bacteria that lives in our intestine
• Commensalism – one organism benefits and the
other is unaffected ex. sharks and remoras
• Parasitism – one organism benefits while the other
is harmed – parasite is the organism benefitting and
host is the organism being harmed ex. tapeworm
Coevolution
• Coevolution is the evolution of two species that is
due to their mutual influence on each other, often
in a way that is helpful to both species
• The ant and acacia tree have a mutualistic
relationship – the ants protect the tree by attacking
other organisms that come near it – the tree has
special structures that make food for ants – may
have coevolved into this current situation
• Flowers have changed over millions of years to
attract pollinators (ex. bees)
• For example, flowers pollinated by hummingbirds
make nectar with just the right amount of sugar for
the bird
1. Give an example of a limiting factor in an
ecosystem.
2. What is carrying capacity?
3. Name one type of prey adaptation.
4. What is symbiosis?
5. What type of relationship benefits both
organisms?
6. What type of relationship benefits one organism
and doesn’t affect the other?
7. What type of relationship benefits one organism
and harms the other?
Habitat and Niche
• A habitat is the place where an
organism usually lives – it provides
all the resources that an organism
needs to grow and survive
• A niche is the role a population
plays in the ecosystem
Consumers
• There are three levels of consumers
• The first group of organisms are the
primary consumers - they are also
called herbivores
• Secondary consumers eat the primary
consumers – they are also
called carnivores
• There is a third level of consumer called
the tertiary consumer - they eat the
secondary and primary consumers