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Habitat and Lifestyle
Unit A: Topic 2
Interdependence
• Each species relies on many other species in its environment
• No species can survive by itself
• Example: Predator-Prey relationship
– Predators benefit because they get food
– Prey benefit because the old and weak are usually removed allowing
the healthy to reproduce
– Prey also benefit because the reduction of population allows the
resources to last longer.
Symbiosis
• Symbiosis
– “Sym” means together
– “Bios” means life
• A symbiotic relationship is when two organisms
live in direct contact with each other
• There are three main types of symbiosis:
commensalism, mutualism, and parasitism
• http://www.youtube.com/watch?v=zSmL2F1t81
Q&feature=fvwrel
Symbiotic Relationships
• Commensalism
– One organism benefits and one does not.
– No harm is done to the organisms.
• Example: A bird builds a nest in the tree
• Example: Barnacles attach to whales
• Identified by +/n
– One benefits (+) while the other
remains neutral (n)
Symbiotic Relationships
• Mutualism
– There is a benefit to both organisms
• Example: A certain tree gives food and shelter
to ants and the ants protect the tree from
other animals feeding on it by attacking them.
• Example: Lichens, formed by algae and fungi,
live off of each other’s resources.
• Identified by +/+
– Both benefit (+)
Symbiotic Relationships
• Parasitism
– One organism benefits and the other is harmed
– Parasites do not kill their hosts because
the host is the food source.
• Example: A tapeworm attached to the
intestine of a human.
• Example: Parasitic wasp larvae in caterpillar.
• Identified as +/– One benefits (+) while the other is harmed (-)
What type of relationships are shown
here?
Interspecies Competition
• Two or more species need the same resource
and neither benefit.
• Example: If there are two different species
competing for the same food source, there is
less for each species.
• Limits the sizes of the populations of the
competing species.
• Niche:
Niche
– The role that an organism plays in its ecosystem.
This includes:
•
•
•
•
•
What it eats
What eats it
Its habitat, nesting site or range.
Its effect on the populations around it
Its effect on the environments around it
• The niche of a population in one area may vary from a
population in a different area.
• Niches can also change throughout the lifetime of the
species. For example, the niche of a frog tadpole is
different than that of an adult frog.
Types of Niches
Type of niche Description
Examples of organisms
filling this niche

many are photosynthetic organisms, which
grow using energy from the Sun


plants
algae
Herbivores


eat producers
may be prey to other animals



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cows
deer
snowshoe hare
grasshoppers
Omnivores

eat consumers and producers


raccoons
bears
Carnivores

eat only other consumers


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dragonflies
hawks
lynx
Decomposers

break down dead organisms and organic
material
release nutrients, which are used by other
organisms


certain bacteria
fungi
Producers
Consumers

Broad Niches
• Broad niches
– Organisms that can survive in various conditions
and locations have broad niches
– Animals in Canada aren’t very diverse, but they
can span over large distances and can withstand
daily and seasonal changes in temperature.
– They must also be able to eat a variety of plants or
other animals.
– Animals with broad niches are known as
generalists
http://video.nationalgeographic.com/video/kids/animals-pets-kids/mammalskids/raccoon-kids/
• The raccoon is a generalist because it has a
natural range that includes most of north and
central America, and it is omnivorous, eating
berries, insects, eggs, and small animals.
Narrow Niches
• Narrow Niches
– Organisms that survive in a very small location
that require very consistent conditions.
– Organisms have adaptations directed towards
competing for one dependable food source, one
type of soil, or one level of light.
– These organisms are known as specialists.
– What could be the danger in narrow niches?
• Panda is a specialist species because over 95
percent of its diet consists of bamboo.
Resource Partitioning
• Division of a resource between species resulting
in each niche differing slightly.
• Example: 5 species of warblers feed on spruce
bud worms but they all feed
in slightly different areas
of the spruce tree.
• Planet Earth
Seasonal Forest
Review Assignment
1. Explain what is meant by the term biological
diversity.
2. In one or two sentences, explain why so many
different types of organisms exist on Earth
today.
3. Describe how scientists classify organisms.
4. Explain how the classification system helps us to
understand how living things are different from
or related to each other.
5. Compare and contrast the meanings of
population and community.