Science 9 Unit A – Biological
Diversity
1.0 – Biological Diversity and the
Variety of Life on Earth
Goals of this Section:
1.
2.
3.
4.
5.
Describe the abundance of species on
Earth and in different environments.
Explain the role that variation plays in
survival.
Identify examples of niches and how
closely related living things can survive
in an ecosystem.
Explain how the survival of one species
depends on other species.
Identify examples of natural selection
1.1 – Examining Diversity
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Biological Diversity: All of the different
types of organisms on Earth
Scientists, of course, rarely study all of the
Earth’s creatures together
Rather, they focus on smaller groupings
Divisions in Ecosystems
Diversity
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Each ecosystem is different
This is because they contain different
biotic and abiotic components
These components dictate which
organisms can be found living in a
particular ecosystem
Genetic Variation
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This term refers to the variation between
individuals of the same species
These variations are typically due to small
differences at the cellular level
Some of these variations may not even be
visible
Distribution
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Species are not
evenly distributed
Regions near the
equator typically have
a far greater number
of species than those
regions near to the
poles
Classification
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Carolus Linnaeus developed a system for
naming and classifying organisms in the
18th century
The purpose of this system was to
establish common scientific names rather
than using names that varied from
language to language
Binomial Nomenclature
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Under the Linnean system, all organisms
have two names – their genus and their
species
For example, a wolf is known as Canis
lupus
Canis represents the genus and lupus
identifies the species
The Five-Kingdom Classification
System
Kingdom
Phylum
Plantae
coniferophyta
Animalia
Chordata
Class
pinopsida
Osteichthyes
pinales
Salmoniformes
pinaceae
Salmonidae
Order
Family
White
spruce
Genus
Picea
Species
glauca
Bull
Trout
Salvelinus
confluentus
Diversity Under the Sea
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Some regions, such as coral reefs have
very high levels of biodiversity
The coral itself is a living thing, and it also
houses thousands of different species of
life
1.2 - Interdependence
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No one species lives alone
All species are reliant on other species for
some aspect of their daily lives
Food chains and food webs show the
relationship between predator and prey
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Even prey benefit
from the
predator-prey
relationship
Symbiosis
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Sym-together
Bios-life
This is the association between two
different species that live close together
There are different types of symbiosis
depending on the benefit or harm to each
participant
Commensalism
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one benefits the other is neither harmed
nor helped
Mutualism
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both are benefited
Parasitism
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one benefits and the other is harmed
Niches
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The role of an organism within an
ecosystem
Interspecies competition occurs when two
different species are competing for the
same niche
Resource Partitioning
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For similar species to coexist in an area,
they must share resources
This can be accomplished by each species
changing their niche slightly, so there is no
direct competition
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This figure shows
resource
partitioning
between three
warbler species in
a single tree
1.3 – Variation Within Species
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Just as there is variation between species,
there is variation within species as well
Variation within a species is known as
variability
Variability and Survival
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Sometimes environments change
In these cases, variability in a species will
increase the chance of some of the
individuals surviving that change
Antibiotic Resistance
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Some bacteria are
naturally resistant to
antibiotics
When a bacterial
population comes into
contact with these
drugs, the naturally
resistant ones will
survive and reproduce
Natural Selection
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Natural selection occurs when the
environment “selects” which individuals
survive long enough to reproduce
The survivors usually have adaptations
that make them more suited to the
environment, and the adaptations are
passed on to their offspring