Download HEREDITY - EVOLUTION

HEREDITY - EVOLUTION
Lesson Objective:
By the end of the lesson (s), I can:
1. DEFINE the biological process of evolution.
2. SUMMARIZE the history of scientific ideas about evolution.
3. DESCRIBE Darwin’s contributions to scientific thinking about evolution.
4. ANALYZE the reasoning in Darwin’s theory of evolution by natural selection.
5. RELATE the concepts of adaptation and fitness to the theory of natural
selection.
Vocabulary:
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Evolution
Strata
Natural selection
Adaptation
Fitness
Fossil
Superposition
Relative age
Absolute age
Biogeography
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Homologous structure
Analogous structure
Vestigial structure
Phylogeny
Convergent evolution
Divergent evolution
Adaptive radiation
Artificial selection
Coevolution
Lesson Questions:
1. What is Medelian inheritance?
2. What is the difference between dominant and recessive alleles?
3. What are the definitions of homozygous, heterozygous, , genotype, and
phenotype?
4. What are Mendel’s laws of inheritance?
5. How are the results of monohybrid and dihybrid crosses diagrammed?
6. What are the effects of multiple alleles, codominance, and incomplete dominance
on phenotype?
Focus Question:
1. How do the structures of organisms enable life’s functions?
2. Why do individuals of the same species vary in how they look, function, and
behave?
Overarching questions:
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How do organisms live, grow, respond to their environment, and reproduce?
How are the characteristics of one generation passed on to the next?
How can individuals of the same species and even siblings have different
characteristics?
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HEREDITY - EVOLUTION
HISTORY OF EVOLUTIONARY THEORY
Charles Darwin took a trip around the world on the HMS Beagle. He was fascinated by diverse
and unique organisms. Went onto form one of the most important theories in biology
1. History of Evolutionary Theory
 The Idea of Evolution
 On Darwin’s travels to the Galapagos Islands he noted groups of animals.
 Noted that tortoises on the same island resembled each other
closely, while those from neighboring islands were different
 Noticing similarities and differences among many animals as he
traveled, he became convinced that organisms had changed over
time and he wanted to know why.
 The development of new types of organisms from preexisting ones over
time is called EVOLUTION.
 Modern scientists define evolution as a heritable change in the
characteristics within a population from one generation to the next.
2. Ideas of Charles Darwin
 In the 18th century most scientists thought that all species were permanent and
unchanging.
 Also they thought that the Earth was only 1000s, not billions, of years old.
 Scientist began presenting evidence that the species on the Earth have
changed over time and more evidence that the Earth is much older than
people thought.
3. Ideas About geology
 In the 1800s European scientists began studying the rock layers called strata.
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They found that strata were formed as ne layers of rock are deposited over time.
 They inferred that in general lower strata were formed first and therefore
are older.
 Also found that different lock layers hold fossils of different kinds of
organisms.
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HEREDITY - EVOLUTION
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Georges Curvier spent years reconstructing the appearance of unique organisms
from fossil records.
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 He gave evidence that some organisms in the past differed greatly from
any living species and that some had become extinct.
 Meaning that the species is not living anymore after a certain point
in time.
 He continued to find many sudden changes in the kinds of organisms he
found in the strata.
 He explained his observations as the idea of catastrophism.
 The idea that sudden geologic catastrophes caused the extinction of
large groups of organisms at a certain point in time.
 This is no longer accepted by scientist but Cuvier contributed to
scientific acceptance that geologic change and extinction had
occurred.
 Charles Lyell shared Cuvier’s ideas but he thought that the geologic processes
that have changed the Earth’s surface in the past continued to work the same
ways.
 Lyell’s idea is uniformitarianism
 Darwin read some of Lyell’s work during travels and was excited to find
how well Lyell’s ideas worked with his own observations and ideas.
4. Lamarck’s Ideas on Evolution
 Jean Baptiste Lamarck also supported the idea that populations of organisms
changed over time.
 His idea of inheritance of acquired characteristics, while not supported
states that individuals could acquire traits during their lifetime as a result
of experience or behavior; then pass on those traits to their offspring.
5. Darwin’s Ideas
 Descent with modification
 Describes the process of evolution. He carefully reviewed evidence that
points to the notion that every species, living or extinct, must have
descended by reproduction from preexisting species and that species must
be able to change over time.
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HEREDITY - EVOLUTION
 Darwin was not the first person to present this idea but rather was the first
to argue that al species had descended from only one or a few original
kinds of life
 Darwin saw the animals of the Galapagos Islands as evidence of
descent with modification.
 He noted that the islands are home to 13 similar species of finches.
Each bird has a beak that has adapted for a certain kind of food.
6. Natural Selection
 Darwin proposed the theory of natural selection as the mechanism for descent
with modification.
 Darwin carefully thought about the forces that could cause changes in
organisms over time.
 Has for major components:
 Overproduction
 The production of more offspring than can survive to
maturity.
i. Each female deer has one or more offspring per
year for many years in a lifetime.
ii. This increases the population in a short time. But
each new deer needs food and is also vulnerable to
predators and disease. Therefore not all deer live
for very long.
 This thinking was drawn from Thomas Malthus’ work. He
pointed out that human populations can increase more
quickly and that populations are often limited by conditions
such as war, disease, or lack of food.
 Darwin realized that environment limits the population of
all organisms by causing death or by limiting births.
 Genetic Variation
 Within a population individuals have different traits.
i. Some deer have thicker fur or longer legs than
others.
ii. Variations can be inherited and occasionally new
traits appear in a population.
 Struggle to survive
 Individuals must compete with each other in what Darwin
Calls struggle for existence.
i. Deer that have thick fur may survive I the cold
better than those without thick fur.
ii. A trait that makes individuals successful in its
environment is called an adaptation.
 Differential Reproduction
 Darwin concluded that organisms with the best adaptations
are most likely to survive and reproduce.
 Through inheritance those adaptations will become more
frequent in populations.
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HEREDITY - EVOLUTION
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 Darwin used the phrase SURVIVAL OF THE FITTEST to describe
natural selection.
 Fitness in evolutionary terms is the measure of an individual’s
hereditary contribution to the next generation.
 A FIT individual is one that has offspring that also survive
long enough to reproduce in a given environment.
 The term adaptation in evolutionary terms is used to
describe changes in traits in populations over time.
 Acclimatization is a short-term process in which
physiological changes take place in a single being in its
own lifetime.
i. An animal adjusting to a new climate by growing
thicker fur.
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