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CHAPTER 4 – THE
ORGANIZATION OF LIFE
Section 1 – Ecosystems: Everything is Connected
Defining an Ecosystem

Ecosystem: Communities of organisms and
their surrounding environment

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- oak forest or a coral reef
Ecosystems are connected
a. Do not have clear boundaries
b. Things move from one ecosystem to
another
- Pollen can blow from a forest into a field
 - Soil can wash from a mountain into a lake

Ecology

Ecology: the branch of biology that deals with the
relations of organisms to one another and to their
physical surroundings.
The Components of an Ecosystem

- Ecosystems need five basic
components to survive:
 1.
energy (most comes from the sun)
 2. mineral nutrients
 3. water
 4. oxygen
 5. living organisms.

- If one part of the ecosystem is
destroyed or changes, the entire
system is affected
Biotic and Abiotic Factors

- Biotic factors
-
environmental factors that are living or
once living organisms OR materials that
come from organisms
-
plants, animals, dead organisms, and
their waste products

- Abiotic factors
-
environmental factors that never were
living organisms
-
air, water, rocks, and temperature, etc.
Levels of Ecological Organization
Ecologists organize life into categories
Organism: Living things that can
carry out life processes
independently.


-You are an organism, as is an ant, ivy plant,
and each of the bacteria living in your
intestines.
- Every organism is a member of a species.
 -Species
are groups of organisms
that are closely related and can
mate to produce fertile offspring.
(Mating pair)
Ecologists organize life into categories


- Members of a species may
not all live in the same place.
Field mice in Maine will not
interact with field mice in Texas
- Populations
-
groups of organisms of the
same species that live in a
specific geographical area
and interbreed.
 - All the field mice in a corn
field make up a population of
field mice.
Ecologists organize life into categories

- Members of a population
usually breed with one
another rather than with
members of other populations
-
Bison will usually mate with
another member of the same
herd not other a member from
another herd
Ecologists organize life into categories

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
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Communities: Groups of
various species that live in the
same habitat and interact with
each other
- Every population is part of a
community
- The most obvious difference
between communities is the types
of species they have.
- Land communities are often
dominated by plants species

- The plants determine what other
organisms can live in that
community
Ecologists organize life into categories


Habitat: Places where an
organism usually lives
- Habitats have specific
characteristics that the organisms
living there need to survive


- If any of these factors change, the
habitat changes
- Organisms tend to be very well
suited to their natural habitats

- animals and plants usually cannot
survive for long periods of time
away from their natural habitat
Ecologists organize life into categories



Ecosystem: Communities of
organisms and their surrounding
environment
Biome: a large region with a
similar climate and organisms
Biosphere: the regions of the
surface, atmosphere, and
hydrosphere of the earth
occupied by life.
Critical Factors
Organism Research Project

Pick an Organism and research the following
information about the organism:
Common Name, Scientific Name, Name of a group of your
organism (ex: Group of lion = Pride, sault, or troop)
 Other populations that interact with this species
 Detailed description of natural Habitat (include some
specific biotic and abiotic factors in description)
 Regional location (be specific as possible) and Biome
(include climate details) the organism is primarily located


Create a mini-poster with all of this information.
Include a colored drawing of your organism in an
example of it’s habitat.
-Turn in: Ecosystem Drawing and Organism Poster.
-Get a Evolution Note handout.
What do you think?
What are some adaptations organisms have to hunt
prey? What are some ways organisms defend for
themselves from hunters?
CHAPTER 4 – THE
ORGANIZATION OF LIFE
Section 2 - Evolution
Charles Darwin

- Charles Darwin observed that
organisms in a population differ slightly
from each other in form (structure),
function, and behavior
-
Some of these differences are hereditary
(get passed from parent to offspring)

- He proposed the environment exerts a
strong influence over which individuals
survive to produce offspring
-
Some are more likely to survive and
reproduce than other individuals because
of certain traits
Evolution by Natural Selection


- Natural selection: individuals that have favorable
traits and are better adapted to their environment.

-They survive and reproduce more successfully than lessadapted individuals

- Darwin proposed that over many generations, natural
selection causes the characteristics of populations to change
- Evolution: change in the characteristics of a
population from one generation to the next. AKA
“decent with modification”
Nature Selects
Nature Selects

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- Nature ‘selects’ for certain traits,
such as sharper claws, because
organisms with these traits are more
likely to survive
- Over time, the population includes a
greater and greater proportion of
organisms with the beneficial trait
- As the populations of a given
species change, so does the species.
Sickle Cell Anemia


In the heterozygous condition, both alleles are
expressed equally
Example: Sickle Cell Anemia in Humans
NN = normal cells
SS = sickle cells
NS = some of each
http://www.youtube.com/watch?v=1fN7rOwDyMQ
Nature Selects

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Adaptation: an inherited trait that increases an
organism's chance of survival and reproduction
in a certain environment
-Can be an Physical, Behavioral, or Physiological
change that improves a population’s ability to
survive
Three Types of Adaptations

Physical Adaptations: some type of structural
modification made to a part of the body.
 Ex:

Behavioral Adaptations: something an animal does
(how it acts) usually in response to some type of
external stimulus.
 Ex:

webbed feet, sharp claws, fur.
hibernation, mating dances, flying south for winter
Physiological Adaptations: the ability of the
organism to perform special functions
 Ex:
venom production, temperature regulation, growth
and development.
Darwin’s Four Premises
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Overproduction – each species produces more
offspring than will survive to maturity
Variation – individuals in a population have slightly
different traits
Selection – individuals compete and the
environment selects those with traits that help
survival and reproduction
Adaptation of a Population/Successful
Reproduction – beneficial traits become more
common in the next generation
Coevolution

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Coevolution: When two species
evolve in response to long-term
interactions with each other
- The Hawaiian honeycreeper has
a long, curved beak to reach
nectar at the base of a flower
- The flower has structures that
ensure the bird gets some pollen
on its head
- When the bird moves the next
flower, some of the pollen will be
transferred, helping the flower
reproduce
Coevolution

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- The honeycreeper’s adaptation is a long, curved
beak.
- The plant has two adaptations:
-
1. the sweet nectar to attract the birds
 - 2. the flower structure that forces pollen onto the bird’s
head when it sips nectar

Newt vs. Snake
Man Selects

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Artificial selection :selective breeding
of organisms, by humans, for specific
desirable characteristics.
- Dogs have been bred for certain
characteristics

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- Sporting, Hunting, Herding, Terriers,
Working, etc.
- Fruits, grains, and vegetables are also
produced by artificial selection.

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- Humans save seeds from the largest, and
sweetest fruits
- Farmers direct the evolution of crop plants
to produce larger, sweeter fruit
Evolution of Resistance


Resistance: the ability of an
organism to tolerate a chemical
or disease-causing agent
- An organism may be resistant to a
chemical when it contains a gene
that allows it to break down a
chemical into harmless substances

- Humans promote (encourage) the
evolution of resistant populations by
trying to control pests and bacteria
with chemicals.
Evolution and Resistance

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Pesticide and Corn:
-A pesticide is sprayed on corn to kill grasshoppers,
may kill most of the grasshoppers, but some
develop resistance
- The hoppers that survive could have a gene that protects
them from the pesticide
 - These surviving insects pass on this resistant gene to their
offspring
 - Each time the corn is sprayed, more resistant grasshoppers
enter the population
 - Eventually the entire population will be resistant, making
the pesticide useless

Pesticide Resistance
Antibiotic Resistance Video
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http://sixtyminutes.ninemsn.com.au/article.aspx?id=
8615278
http://abcnews.go.com/GMA/video/aimeecopeland-gma-interview-battle-flesh-eatingdisease-17216238
Evidence for Evolution
1. Homologous Structures
2. Vestigial Structures
3. Biochemical Evidence
Homologous structures:
Similar Structures in Different species suggest
a common ancestor
Homologous Structures
-Show descent with modification
-Traits that are similar between different species have
been inherited from a common ancestor
Vestigial Structures
 traces
of structures from ancestral species that serve no
current useful function ex. Pelvic Bones in whales, appendix in Humans
Whale pelvic bones are vestigial
Example: Hand bones in a manatee
Comparing DNA

Biochemical Evidence: Shows DNA similarities and
relatedness
 The
more DNA species have in common, the more
closely related they are
 Ex.
Human and Chimp are about 98% same DNA
Convergent vs. Divergent
 Convergent
evolution
Different species produce similar adaptations
 Divergent evolution
Similar species produce different adaptations
Darwin’s Finches