Transcript Evolution of Living Things

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Species- a group of organisms that can mate
and produce fertile offspring
Population- all the members of a particular
species living in a given area
Adaptation- a characteristic that helps an
organism survive and reproduce in its
environment; it can be a behavior that helps
the organism find food, protect itself, or
survive, or it can be physical trait like striped
fur, or long claws
Penguin Adaptations
Their wings, shaped like flippers, help them “fly” under water at speeds of
15mph
Heavy, solid bones act like a divers belt, allowing them to stay under water
Blubber for warmth
Tightly packed feathers for waterproofing
They coat their tails with oil to increase impermeability
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In a single square mile of rain forest there may
be dozens of species of frogs
Across Earth, there are millions of different
species of organisms
The species that live on Earth range from single
celled bacteria to multi-cellular plants, fungi and
animals
99.9% of all species that have lived on Earth are
extinct today!!
Prokaryotes (bacteria) are the oldest living things
on Earth..they have been around about 3.5 billion
years!
How old is Earth again? Raise your hand to tell
me…
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Scientists observe that, yes, species can
change over time, but it takes lots of time for
change to occur
They also observe that the inherited
characteristics in population change over
time
Scientists think that when populations change
over time, new species may form
So newer species descend from older species
The process in which populations change
over time is called evolution
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Comparing DNA, scientists can determine
which organisms are closely related
The greater the number of similarities
between the DNA of any two species, the
more recently the two species shared a
common ancestor
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By examining the fossil record, scientists can
learn about the history of life on earth
The fossils in Earth’s newer layers of rock
tend to be similar to present-day organisms
This indicates that they were close relatives to
modern organisms
The fossils in older rocks are less similar to
present day organisms
Comparing organisms in the fossil record
provides evidence for how organisms have
changed over time
FOSSILS FORM WHEN A DEAD ORGANISM IS COVERED BY A LAYER OF SEDIMENT.
OVER TIME, MORE SEDIMENT FORMS ON TOP OF THE ORGANISM’S REMAINS.
MINERALS IN THE SEDIMENT SEEP INTO THE ORGANISM AND GRADUALLY
REPLACE IT WITH STONE. IF THE ORGANISM ROTS AWAY COMPLETELY AFTER
BEING COVERED, IT MAY LEAVE AN IMPRINT
In 1835, Charles Darwin, a naturalist, set out on a ship called the
Beagle, to study the animals and plants on the Galapagos Islands
Darwin was interested in the laws of life.
He left medical school because of his disgust with blood, to follow his
true passion- studying plants and animals
Darwin wrote a book called The Origin of Species to
describe his theory of evolution. It was based largely
on observations he made on his 5 year voyage around
the world on the HMS Beagle.
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“Science was obviously not a profession to
Darwin…it was a necessity to sustain his
mind, just as the food he ate and the air he
breathed…”
Theodosius Dobzhansky
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P. 315 figure 4
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The finches previously occupied the South
American mainland, but somehow managed to
occupy the Galapagos Islands some 600 miles
away
They occupied an ecological niche with little
competition
As the population began to flourish in these
advantageous conditions, intraspecific
competition became a factor, and the resources
on the island became squeezed and could not
sustain the population very long
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As competition increased, the finches found
new ecological niches that would present
them with less competition and allow them,
and their genome to be continued
The finches adapted to the different food
sources on the island and over time became
very different from their original ancestors
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Darwin, after years of studying animals in
their natural habitat, theorized that the
organisms with the more adaptable traits are
likely to survive and reproduce than those
with less adaptable traits, especially in a
competitive environment, this over time led
to evolution of species.
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Natural selection acts on the phenotypes of
individuals
The individuals with the more desirable or
adaptable traits will be more likely to survive
and reproduce
The less desirable traits, or phenotypes, are
more likely to disappear and leave the gene
pool
Once the phenotype is no longer in the gene
pool, it is lost
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Overproduction-Typically, in nature more young
are produced than will survive
Inherited variations- every individual has its own
combination of traits, similar but different to
their parents and to other members of their
species
Struggle to survive-competition among
resources and the threat of predators, lead to
the “survival of the fittest” among organisms
Successful Reproduction-the individuals that are
better adapted to their environment are more
likely to survive and reproduce
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A species of bright colored guppies live on a
coast of South America. The female guppies
prefer to mate with the bright colored male
guppies. You see many bright colored male
guppies in the shallow waters there, but few
in the deeper waters. Why do you think that
might be?
What trait is natural selection acting on in this
situation?
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A species is a group of organisms that are
closely related and can mate to produce
fertile offspring
A group of species living in a particular area
is called a population
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Sometimes drastic changes can form a new
species
A new species may form after a group
becomes separated from the original
population
Over time both populations evolve different
adaptations
The two populations differ so greatly that
they no longer mate successfully
The new population may be considered a new
species
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A species of brown and white moths blend in
to the trees in the area they populate.
The brown moths blend in to the trees which
are the same shade of brown as the moths,
making them harder for predators to see. The
white moths are easier for predators to spot,
since they stick out more on the brown trees.
Which moths is this situation has an
adaptation that will make them more likely to
survive and reproduce?
In time, which color moths might you see less
of? Why?
Why is natural selection called survival of the
fittest?
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Non- random mating
Mutations (rare, but do occur)
Environments that are rapidly changing
Environments in which individuals among the
species have genetic differences
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Humans did not evolve from monkeys. Humans
are more closely related to apes, but we didn’t
evolve from them either
Humans share a common ancestor with modern
African apes, like gorillas and chimpanzees
Scientists believe this common ancestor existed
between 5-8 million years ago
The species diverged into two separate lineages,
one evolved to become gorilla and apes, the
other to become early humans, hominids
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Taxonomy is the science that involves
classifying living things; developed by
Carolus Linnaeus in 1750
The general idea is to give two names to for
an animal, a genus and a species, a general
and a specific name, plus other levels of
classification
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Classifying living things allows biologists to
answer questions, such as:
What are defining characteristics of each
species?
When did characteristics of an organism
evolve?
What are relationships between various
species?
Branching Diagrams
Branching diagrams show which characteristics
organisms share and when these organisms
evolved
Kingdom
 Phylum
 Class
 Order
 Family
 Genus
 Species
Tip to remember the order: King Phillip Came
Over For Good Supper.
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Kingdom Animalia
Phylum Chordata
Class Mammalia
Order Primates
Family Hominidae
Genus Homo
Species sapiens
Homo sapiens (the genus name is always capital
and the species name is always lower case)
Homo meaning “man”, and sapiens meaning
“wise”.
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Kingdom Animalia
Phylum Chordata (animals with a backbone)
Class Mammalia (breast-feeding animals)
Order Lagamorpha (rabbits, hares, pikas)
Family Leporidae (rabbits and hares)
Genus Orytcolagus
Species Cuniculus
Lago is Greek for rabbit; lepus is Latin for
hare;cuniculus is Latin for rabbit
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Vertebratesanimals with a
backbone
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Invertebratesanimals which lack
a backbone