Transcript Ch 12 - 1 Ideas about Evolution

12
Chapter 12
Adaptations over Time
Table of Contents
12
Chapter: Adaptations over Time
Section 1: Ideas About Evolution
Section 2: Clues About Evolution
Section 3: The Evolution of Primates
12.1 Ideas About Evolution
12.1
A. Early Models of Evolution
1. A species is a group of
organisms that share
similar characteristics
and can reproduce
among themselves to
produce fertile
offspring.
Ideas About Evolution
12.1
A. Early Models of Evolution
2. The characteristics of a
species that are passed
from parent to offspring
are called inherited
characteristics.
3. Change in these
inherited
characteristics over
time is evolution.
Ideas About Evolution
12.1
B. Hypothesis of Acquired
Characteristics
1. In 1809, Jean Baptiste de Lamarck suggested
that characteristics, or traits, developed
during a parent organism’s lifetime are
inherited by its offspring.
2. His hypothesis is called the inheritance of
acquired characteristics.
Ideas About Evolution
12.1
B. Hypothesis of Acquired
Characteristics
3. Scientists collected data on traits that are
passed from parents to offspring.
4. The data showed that traits developed during
a parent’s lifetime, such as large muscles built
by hard work or exercise, are not passed on to
offspring.
5. The evidence did not support Lamarck’s
hypothesis.
Ideas About Evolution
12.1
C. Darwin’s Model of Evolution
1. In December 1831, Charles Darwin set out
on a journey from England that took him to
the Galapagos Islands.
Ideas About Evolution
12.1
C. Darwin’s Model of Evolution
2. He was amazed by the variety of life on the
Galápagos Islands, which are about 1,000 km
from the coast of Ecuador.
Ideas About Evolution
12.1
C. Darwin’s Model of Evolution
3. Darwin noted that the species on the islands
were similar in many ways to the species he
had seen on the mainland. However, he
observed different traits in many species on
the islands as well.
Ideas About Evolution
12.1
C. Darwin’s Model of Evolution
4. Darwin studied several species and develop
hypotheses to explain the differences in traits
he observed.
Ideas About Evolution
12.1
D. Darwin’s Observations
1. Darwin observed 13 species of finches on the
Galápagos Islands.
2. He noticed that all 13 species were similar,
except for differences in body size, beak
shape, and eating habits.
Ideas About Evolution
12.1
D. Darwin’s Observations
3. He also noticed that all the Galápagos finch
species were similar to one finch he had seen
on the South American coast.
Ideas About Evolution
12.1
D. Darwin’s Observations
4. Darwin reasoned that the Galápagos finches
must have had to compete for food.
5. Finches with beak shapes that allowed them
to eat available food survived longer and
produced more offspring than finches without
those beak shapes.
6. After many generations, these groups of
finches became separate species.
Ideas About Evolution
12.1
E. Natural Selection
1. In the mid 1800s,
Darwin developed a
theory of evolution
that is accepted by
most scientists today.
2. He described his ideas
in a book called “On
the Origin of Species.”
Ideas About Evolution
12.1
F. Darwin’s Theory
1. Darwin’s ideas became
known as the theory of
evolution by natural
selection.
2. Natural selection means
that organisms with traits
best suited to their
environment are more
likely to survive and
reproduce.
Ideas About Evolution
12.1
F. Darwin’s Theory
3. A population is all of the individuals of a
species living in the same area.
4. Members of a large population compete for
living space, food, and other resources.
5. Those that are best able to survive are more
likely to reproduce and pass on their traits to
the next generation.
Ideas About Evolution
12.1
G. Variation and Adaptation
1. A variation is an inherited trait that makes
an individual organism different from other
members of its species.
2. Variations result from permanent changes,
or mutations, in an organism’s genes.
3. Some gene changes produce small
variations, such as differences in the shape
of human hairlines.
Ideas About Evolution
12.1
G. Variation and Adaptation
4. Other gene changes produce large variations,
such as an albino animal in a population of
normal colored animals.
5. If individuals with
these variations
continue to survive
and reproduce over
many generations,
a new species can
evolve.
Ideas About Evolution
12.1
G. Variation and Adaptation
6. An adaptation is any variation that makes an
organism better suited to its environment.
7. Camouflage (KA muh flahj) is an adaptation.
A camouflaged
organism blends
into its environment
and makes it easier
for the organism to
hide, increasing the
chance to survive
and reproduce.
Ideas About Evolution
12.1
H. Changes in the Sources of Genes
1. Over time, the genetic makeup of a species
might change it appearance.
2. Many kinds of environmental factors help
bring about these changes.
3. When individuals of the same species move
into or out of an area, they might bring in or
remove genes and variations.
Ideas About Evolution
12.1
I. Geographic Isolation
1. Sometimes mountains, lakes, or other
geological features isolate a small number
of individuals from the rest of a population.
2. Over several generations, variations that
do not exist in the larger population might
begin to be more common in the isolated
population.
Ideas About Evolution
12.1
I. Geographic Isolation
3. Also, gene mutations can occur that add
variations to populations. Over time, the two
populations can become so different that they
no longer can breed with each other.
Ideas About Evolution
12.1
J. The Speed of Evolution
1. Many scientists hypothesize that evolution
occurs slowly, perhaps over tens or hundreds
of millions of years.
2. Other scientists hypothesize that evolution
can occur quickly.
3. Most scientists agree that evidence supports
both of these models.
Ideas About Evolution
12.1
K. Gradualism
1. The model that describes evolution as a
slow, ongoing process by which one species
changes to a new species is known as
gradualism.
2. According to the gradualism model, a
continuing series of mutations and variations
over time will result in a new species.
3. A series of intermediate forms can indicate a
gradual change from the earliest species to
today’s species.
Ideas About Evolution
12.1
L. Punctuated Equilibrium
1. According to the punctuated equilibrium
model, rapid evolution comes about when the
mutation of a few genes results in the
appearance of a new species over a relatively
short period of time.
Ideas About Evolution
12.1
L. Punctuated Equilibrium Today
2. Evolution by the punctuated equilibrium
model can occur over a few thousand or
million years, and sometimes even faster.
3. For example, many bacteria have changed
in a few decades.
4. The antibiotic penicillin originally came
from the fungus Penicillium.
5. But many bacteria species that were once
easily killed by penicillin no longer are
harmed by it.
Ideas About Evolution
12.1
L. Punctuated Equilibrium Today
6. Penicillin has been in use since 1943.
7. Just four years later, in
1947, a species of bacteria
that causes pneumonia and
other infections already
had developed resistance
to the drug.
8. By the 1990s, several disease-producing
bacteria had become resistant to penicillin
and many other antibiotics.
Ideas About Evolution
12.1
L. Punctuated Equilibrium Today
9. When penicillin was used to kill bacteria,
those with the penicillin-resistant variation
survived, reproduced, and passed this trait
to their offspring.
10. Over a period of time, this bacteria
population became penicillin-resistant.
Section Check
1
Question 1
_______ is the change in inherited
characteristics over time.
A. adaptation
B. evolution
C. gradualism
D. variation
Section Check
1
Question 2
Who developed the theory of natural selection?
A.
B.
C.
D.
Alfred Russell Wallace
Charles Darwin
Gregor Mendel
Jean Baptiste de Lamarck
Section Check
1
Question 3
The changes observed
in camels over time
have been traced by
studying _______.
End of Chapter Summary File