Download Darwin`s Theory of Evolution notesheet

Name ______________________________________
Date _________________________
Block __________
Darwin’s Theory of Evolution
The Puzzle of Life’s Diversity
 Define the following:

Evolution –

Theory –

Fossil –
 The total variety of all the organisms in the biosphere is _________________________.

The person who contributed to most to our understanding of evolution was
________________________ ________________________.

In 1831, at age 22, he joined the crew of the ________________________ as a
naturalist for a ________________________ voyage around the world.

During his travels, Darwin wrote thousands of pages in his journals, drew
pictures of things he saw, and collect a vast amount of ________________________ that led
him to propose a ________________________ ________________________ about the way ________________________
________________________.
 Darwin observed many ________________________. He saw that many plants and animals were very
well suited to their ________________________.
 Darwin collected ________________________, or the preserves of ancient organisms.
 Some of the fossils were unlike any creatures he had ever seen.
 Darwin wondered why the species in the fossils had disappeared.
 Darwin wondered?
 Why do Argentina and Australia have ________________________ ________________________even though they
have ________________________ ________________________ ________________________?
 Why are there no ________________________ in Australia and no ________________________ in England?
 Why have so many species disappeared?
 How are these ________________________ species ________________________ to living species?
 Who was Charles Darwin?
 While on his voyage around the world aboard the ________________________, Charles Darwin spent
about one month observing life on the
________________________ ________________________.
 There, he encountered some unique animals, such as ________________________ and
________________________.
 The Galapagos Island are close together but have very different
________________________.
 Some were hot and dry, with little vegetation.
 Others had more rainfall and were rich in vegetation.
 Each island had its own ________________________ ________________________ of plant and animal species.
 Darwin’s observation on the Galapagos Islands (group of
small islands west of South America) influenced him the
most.
 Darwin saw that the ________________________ of many animals and
plants ________________________ noticeably among the different
islands.
 He wondered whether animals on different islands had once belonged to the ________________________
________________________.
 According to this hypothesis, these ________________________ ________________________ would have
________________________ from an original ancestor species after becoming ________________________ from
one another.
 After his voyage, Darwin spent a great deal of time thinking about his findings.
 He began to wonder if animals living on different islands had once been members of the
________________________ ________________________ that had developed ________________________
characteristics after becoming ________________________ from one another in different habitats.
 Ideas that Shaped Darwin’s Thinking

________________________ and ________________________ helped scientists
recognize that Earth is many million years old, and that it changed over
time.

These ideas helped Darwin realize that ________________________
might ________________________ as well.

Knowing that Earth was very old convinced Darwin that there
had been ________________________________________________.
 ________________________ ________________________ observed that babies were being
born faster than people were dying. He reasoned that if the human
population continued to grow, sooner or later there would be
 Darwin thought this was true for all ________________________.
 ________________________________________________was one of the first scientists to recognize
living things ________________________________________________and that all species were
________________________ from other species.
 Lamark published his hypothesis of ________________________________________________ the year
Darwin was born.
 What’s wrong with Lamark’s hypothesis?
 Lamark didn’t know about genes and how traits are ________________________.



Lamarck proposed that by ________________________ use or disuse of organs, organisms
________________________ or ________________________ certain traits during their life time. These traits
could then be passed on to their offspring.
Over time, this process led to change in ________________________.
Scientists now know that some of Lamarck’s ideas were wrong. (You can’t control what traits
are passed on to the next generation)
 What’s right with Lamark’s hypothesis?
 Lamark was first to develop a scientific hypothesis about ________________________ and recognize
that organisms are ________________________________________________.
 Darwin Presents his Case
 After Darwin returned to England in 1836 he filled notebooks
with ideas about ________________________ ________________________and
the process he would later call ________________________.
 He did not rush to publish his ideas because they
________________________ with the fundamental scientific
________________________ of his day.
 In 1858 another naturalist, ________________________________________, wrote an essay describing his work
in ________________________ that summarized the same ideas ________________________ had been thinking
about for 25 years.
 Darwin’s observations led him to develop the scientific ________________________ ________________________,
which explains how modern organisms ________________________ over long periods of time by
________________________ ________________________.
 In 1859, Darwin published his work, ________________________________________.
 What was Darwin’s Theory?
 His ______________________________________ included the
following components:
 ________________________

________________________

________________________

________________________

________________________
 ________________________ - a species produce more offspring than can survive.
 Examples:
 ________________________________________________ – organisms in a population compete for scarce
resources.
 Examples:
 ________________________ – members of a population differ from each
other.
 Variation provides the “________________________” for evolution.

Helps a ________________________ survive in response to change.

Traits ________________________ in a habitat or different traits are

________________________.
Examples:

Genetically speaking ________________________ is a change in the frequency of ________________________

in a ________________________ over time.
Three sources of ________________________ ________________________:

________________________ – change in genetic material of a cell.
 Short-term results – most don’t show up in the next generation
 Long-term results – introduce new genes to the population.

________________________ ________________________ – result of meiosis
 Short-term results – one generation to the next see difference in phenotype that
affect underlying genotypes.
 Long-term results – not adding different genes to the population

________________________ ________________________ – passing of genes from one organism to
another (not including offspring)
 ________________________ ________________________ – individual organisms with characteristics more
________________________ to their ________________________ are more likely to ________________________ and
________________________ and pass characteristics to the next ________________________.
 How Natural Selection works
 ________________________ – individuals are adapted; using what they have; doing the best with
what they have.
 New ________________________ can appear in a population or a ________________________ over time.
 Examples:
 ________________________
 Over time the ________________________ favored by Natural Selection ________________________ so that
some members in the population are no longer able to breed with other members of a
population and produce viable (possible) offspring.
 ________________________ – a group of closely ________________________ organisms that are very
________________________ to each other and are capable of interbreeding and producing fertile
________________________.
 Hardy-Weinberg Equilibrium
 ________________________ ________________________ states that allele
frequencies will remain ________________________, or have genetic
equilibrium unless factors cause those frequencies to change.
 5 conditions in which evolution will NOT happen:

________________________________– no picking characteristics of each other.

________________________ – adding & subtracting genes (change in gene pool)

________________________ – consists of all genes, including all the different alleles, that are
present in a population.

________________________ ________________________ – predators eating anything, bad storm=chance of
survival, parasites, competition.

________________________ ________________________ – occurs when removed or added through
immigration, emmigration.

________________________ ________________________– if a change occurs it’s not as noticeable.
 Evidence of Evolution
 ________________________ ________________________ suggests that each species has ________________________,
with ________________________, from other species over time.
 This idea suggests that all living species are ________________________ ________________________, and that all
species, living and extinct, share a ________________________ ________________________.
 ________________________ ________________________
 In artificial selection, ________________________ provides ________________________ through
________________________ and ________________________ ________________________

and ________________________ ________________________ those traits they find ________________________.
Examples:
 Fossil record

The Fossil record – ________________________ are the
________________________________________________ found in layers of rock in Earth.

The layers of rock tell the history of the ________________________, while
________________________ found within the rock tell a history of

________________________.
The fossils are thought to be the ________________________ as the rock they are found in.
 ________________________ ________________________
 If Darwin’s theory is correct you would expect to find ________________________
________________________ yet ________________________ ________________________ living in a
________________________ region as they spread into nearby habitats and evolve.

Tortoises adapted to different habitats as they spread from the mainland to the different
islands.
= ________________________ ________________________ =
________________________ ________________________
 If Darwin’s theory is correct you would also expect to
find ________________________ ________________________ living
in ________________________ geographic regions but similar
habitats becoming ________________________ as they adapt

to ________________________ ________________________.
Whales and sharks have a ________________________ body
design even though they are very ________________________ organisms (one is a fish; the other is a
mammal) because they have ________________________ ________________________ to living in a
________________________ environment. = ________________________ ________________________

________________________ ________________________
 ________________________ ________________________
 Homologous body structures – Structures, like limbs of
vertebrates, look ________________________, but are made from the
________________________ ________________________, because they are
made from the same clump of ________________________ cells in the
________________________.

Some ________________________ ________________________ are
________________________ and have no useful function even though they are still
present, like ________________________ in whales and boa constrictors.
 ________________________
 Early stages or ________________________ of many
animals with backbones (vertebrates) are very
similar – suggesting that organisms share a
________________________ ________________________.