• Population Dynamics:
• the pattern of any process or interrelationship that
affects growth or change in a population.
• Producers-consumer systems
• Predator/prey relationships
• Parasite/host relationships
• Organism Competition
An organism capable of producing organic compounds from
inorganic molecules through the process of photosynthesis or
chemosynthesis. It is also called an autotroph.
-The first level of a food chain
Examples:
An organism that obtains food by feeding on other organisms or
organic matter. It is also called a heterotroph
- All other levels of a food chain
Examples:
• Herbivores – organisms that eat plants and other organisms that
photosynthesize
• Carnivores – organisms that eat other animals
• Omnivore – an organism that eats both plant and animal matter
• Decomposers – organisms that eat and recycle dead animal and
plant matter and release chemical nutrients back into the environment
• Which picture is a herbivore? Carnivore? Decomposer?
A sequence of who eats whom in an ecosystem.
-food chains begin with an autotroph
-the second level of a food chain is called a primary
consumer
-the succeeding levels are called secondary consumer,
tertiary consumer, etc. until the end of the chain
• Animals often have more than one source of food – the food
chain is just one option of what they can eat.
• Food webs show how different organisms are interconnected by
different paths
• Food webs are made up of food chains
• Example of a food web:
• What are the producers?
• What are the primary
consumers?
• What are the secondary consumers?
• Are there any tertiary consumers?
• What are some different types of ecosystems?
• Terrestrial (prairies, forests, mountains, etc)
• Aquatic
• Freshwater (ponds, rivers, lakes)
• Marine (oceans, saltwater marshes)
• Let’s look at some food webs for these ecosystems in
Texas
• What are the producers?
• What are the consumers?
• Are there carnivores?
Herbivores? Omnivores?
• What kind of ecosystem
might this food chain be
from?
• What are the producers?
• Consumers?
• How many different
consumer levels are there?
• What are the
producers in this food
web?
• Who are the
predatory consumers?
• The herbivory
consumers?
• Some consumers are also called predators.
• Predators are animals who eat other animals, called prey. Another word
for predator is carnivore.
Which of the following are predators?
What about the sparrow?
• These animals are called omnivores
• The sparrow is an omnivore! They can eat seeds, grains, and bugs!
What are other omnivores?
Humans!
• Both predator and prey populations affect the
survival of the other.
• The bobcat is a predatory cat in the U.S. The bobcat’s favorite food
(prey) is a snowshoe hare. Let’s look at how populations of bobcats
and hares interact over time.
70
60
50
40
Snowshoe Hare
Bobcat
30
20
10
0
April
May
June
July
• What happened to the snowshoe hare population in April, May,
and June?
• What happened to the bobcat population in April, May, and
June?
• What happened to the snowshoe hare population in July?
• What happened to the bobcat population in July?
• What do you think will happen to the populations in August,
September, October, and November?
80
70
60
50
Snowshoe Hare
Bobcat
40
30
20
10
0
August
September
October
November
• What happened to the populations in the later months?
• Did the population numbers of the predators affect the numbers
of prey? Did the numbers of prey affect the numbers of
predators?
• Predator-prey systems generally work in constantly-changing
cycles much like the one we just saw with the bobcats and
hares.
• As the prey population increases, there is more food for the
predators, so predators increase.
• When the predators increase, there are more of them to eat the
prey, until the prey species begins to decline under the
predatory stress
• When the prey declines, there is not as much food for the
predators, so the predatory species declines until the prey
population recovers and the cycle begins again.
• In biology, the term parasite refers to an organism that grows,
feeds and is sheltered on or in a different organism while
contributing nothing to the survival of that organism.
• The organism where the parasite takes residence is called a
host.
• Serve as a physical location or microenvironment that provides
place for habitat, growth factors, nutrients supply to parasites
• Help in the multiplication of parasites
• Plants or animals can be hosts:
•
•
•
•
Metabolically dependent on the host for its survival
Smaller than host size
Sometimes harmful to the host
Parasites can be animals, plants, bacteria, fungi, protozoa, or
viruses:
• Ectoparasite – parasite found outside the host surface
• Endoparasite – parasite found inside the host or inside the host
cells
• Final host - host on which parasites sexually reproduce
• Intermediate host - Hosts that are not continuous and are
temporary
• Transfer host - Tool for reaching final host and it is not involved
in completion of life cycle
• Reservoir host – A host that is endangered or infected by
parasites
Ectoparasites
Endoparasites
• The natural environment of an organism
• Scientific name for an organism’s home
• A habitat must have all things that are essential for an
organism’s survival:
•
•
•
•
Food
Water
Shelter/cover
Space
Resources
• Food
• Nutrients consumed by an organism for energy
• Water
• All life on Earth requires water
• Shelter/cover
• Humans can consider shelter to be a house; or a structure they live in. An
animal’s shelter may be underground, in a bush, in the bark on a tree, or
in some rocks, etc.
• Space
• Organisms need enough space in which to live and find the
food/water/shelter
• Much of the time, there are not enough resources to go around.
• As a result in scarcity of resources, there is competition
between organisms in their environment.
• Competition between animals
• Competition between plants
• Resources that animals mainly compete for are:
•
•
•
•
•
Food
Water
Shelter
Space
Access to mates
What are these animals competing for?
• Resources that plants compete for are:
• Water
• Nutrients (food)
• Space (access to light, water or nutrients)
• What do you think these plants are competing for?
• When different species compete for resources, it is called interspecies competition
• When organisms of the same species compete for resources, it is
called intra-species competition
Inter-species competition
Intra-species competition
• Do predators (carnivores) compete for resources?
• Do herbivores compete for resources?
• Do producers compete for resources?