Evolution is the process by which species change over time based on genetic variations and natural selection. Organisms must compete for limited resources and reproduce, so individuals with traits better suited to their environment are more likely to survive and pass on their genes. Evidence for evolution includes fossils that show how species have changed over millions of years, as well as anatomical and genetic similarities between organisms that indicate common ancestry. Darwin proposed that evolution occurs through natural selection, where individuals with advantageous traits are more likely to reproduce and leave more descendants.
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Evolution part 2
2. Evolution
• Process by which species of organisms change
over time
• Thing evolve around us all the time
• Based on scientific evidence such as…
– Fossils
– Comparative morphology/anatomy of organisms
– Embryology
– Analysis of genetic material (DNA analysis…DNA
fingerprinting!)
3. Terms to Know
• Species
– a group of organisms that share similar
characteristics and can interbreed to
produce fertile offspring
– As species EVOLVE, they produce new
traits and lose other traits….
• Adaptation
– Any physical or behavioral trait that
improves an organisms chance for
survival and reproduction
4. Fossil Evidence for
• Fossils: Evolution
– Remains or evidence of organisms that have
lived in the past
– Provided clues of when different species lived
• Law of Superposition
– States that in undisturbed sedimentary
rock, older rock layers lie beneath younger rock
layers
– By Identifying the fossils indifferent layers of
rock and applying the law of
superposition, scientists can determine:
• when the certain organisms lived
• The order in which things evolved
7. Biogeography
• Study of the distribution of Earth’s
organisms
• Continental Drift Hypothesis
– States that the continents were once joined
in a single, large landmass called PANGAEA
– Pangaea broke up over millions of years
and continents ended up where they are
today
– Fossil evidence shows that in addition to
changing Earth’s surface, continental drift
also changed the distribution of organisms
on Earth
9. Comparative
Anatomy/Morphology
• Do other organisms have arms like us?
• Many species share similar structures..
• Do flamingos and blue jays have
feathers?
– Yes…the presence of feathers suggest
that both groups of birds descended
from an animal with feathers
– Flamingos and blue jays are more closely
related than either one is to an animal
without feathers (like us)
10. Homologous
•
Structures
Body parts of different
organisms that have
similar structure but
NOT similar FUNCTION
• Homologous structures
DO indicate shared
ancestor
11. Analogous Structures
• Body parts that have a SIMIALR FUNCTION but NOT
similar structure
• Body parts with Different structure, same function
• Do NOT indicate shared ancestry
• An analogous structure found in two different species
14. Homologous vs. Analogous
Structures
• Homologous= Same structure, DIFFERENT
Function
• Analogous= Different Structure, SAME
Function
16. Vestigial Structures
• Structures that do not seem to play a role in the body
functions of the organism
– Appendix
• Rats digestion
• Humans no use…appendix is a vestigial structure
• It can be concluded that the common ancestor of the human and rat
had an appendix
17. Embryology
• Study of embryos
• Embryo early stage in the
development of an organism
• Scientists compare the development of
the embryos of different species
• Similarities in development =shared
ancestor
• More traits in common=more closely
related
Modern Organisms
EVOLVED from
COMMON Ancestors in
an Evolutionary Chain
19. Chemical Evidence of
Evolution
• Chemicals found in living things also
provide clues to ancestry..what
chemical?
– DNA!!!
• Comparisons of the sequences of the
nucleotides in DNA and the amino
acids in certain proteins can also be
used to show more common ancestry
• More similarities in two DNA
sequences or amino acid sequences =
the more closely related the organisms
are
– DNA fingerprinting
21. ALL organisms have DNA made up of the
same Amino Acids…
The only thing that’s different is the
ARRANGEMENT/sequence of amino
acids…
The More similar AA sequences= the
more closely related the organisms are!
22. Similarities in Molecular Biology
Common amino acid sequences suggest an
evolutionary relationships between various
species of organisms.
23. Observed Evolutionary Change
• Speciation
– Evolution of a new species from an existing species
• Occurs when a population is separated into groups
that cannot reach each other to interbreed
• Once groups are separated, environmental
conditions in each area influence which traits are
helpful or harmful to members of each population
– Less helpful traits disappear
– Helpful traits become more popular
• Overtime, these changes can produce 2 distinct
species that can no longer interbreed
27. Two Ways Evolution is believed to
have Occurred
• Gradualism
– Evolution occurring over a long period of time
– Slow and constant change
– Small difference between generations
– This is how Darwin believed NATURAL
SELECTION worked
• Punctuated Equilibrium
– Evolution occurs in spurts
– Changes occur rapidly followed by long period
without change
– Causes:
• random mutations in DNA
• Sudden Major changes in environment
28. Microevolution
• When evolution occurs quickly enough for
scientists to observe
• Bacteria
– Reproduce rapidly
– Trait for Resistance to antibiotics is passed down
to offspring
– This is how bacteria become resistant to certain
medicines…NOT GOOD
29. Convergent evolution
• organisms that descended from
different ancestors
• Evolve similar anatomies and/
or behaviors if they live in
similar environments
30. • Organisms from the Divergent
same ancestor have
developed different Evolution
anatomies/behavior
s (and eventually
form new species)
• Environment
influences their new
anatomy/behaviors
32. Ideas that shaped
Darwin
– Before Darwin people believed Earth was less than
10,000 years old and also relatively unchanged
• Buffon- Studied the fossil record which showed that the
Earth might be much older.(4.3 and 4.5 billion years old)
• Hutton - Layers of rock are moved by forces beneath
Earth’s surface. Most geological processes operate
extremely slowly.
• Lyell - geologic process that shaped the Earth in the past
still continue today.
33. Ideas that shaped Darwin
Before Darwin people believed that species were fixed,
plants and animals had always been the way they are
today
Cuvier – based fossils from different rock layers gave
evidence that organisms from the past differed greatly
from living species
34. Ideas that shaped Darwin
Lamark’s
Use or disuse
1st to suggest that species change
evolve or evolve over time.
But his explanation was flawed.
He thought characteristics acquired
through your life could be passed
down from parent to offspring.
37. • Malthus – suggested that if the human population
continued to grow unchecked, eventually there
wouldn’t be enough food and living space for everyone.
38. • As Malthus predicted, world
population growth is exponential:
• 1 billion in 1830
• 2 billion in 1930
• 3 billion in 1960
• 4 billion in 1974
• 5 billion in 1987
• 6 billion in 1999
• 7 billion in 2013
• 8 billion in 2028
• 9 billion in 2048
39. Voyage of the Beagle
• Darwin made a voyage around the word collecting
thousands of plant and animal specimens.
• His observations and collected evidence led him to
propose hypothesis that living things change over time
• Theory of Evolution through natural selection.
40. Voyage of
the Beagle
• Darwin noticed that plants and
animals on the Galapagos
islands of the coast of Ecuador
were different from those on
the mainland and also from
island to island
44. Darwin’s Theory
• In 1859, Darwin published a book titled,
• “On the Origin of Species”
• In this book he presented all the evidence he had
gathered over the past several years supporting his
theory that evolution has been taking place for millions
of years—and continues in all living things.
• In his book he also proposed a mechanism for
evolution called
• Natural Selection
45. Summary of Evolution
• DNA is the blue-print for building ALL living things on planet Earth.
• DNA sequences are changed by:
• random mutations
• Radiation
• Viruses
• Chemicals
• sexual reproduction
• Migration
• geological events
• As a result there is variation within populations of a species.
• Those individuals of a particular species with a phenotype (as a result
of their genotype) that is more fit to survive in a given environment
has a better chance to reproduce.
• Those individuals who reproduce more pass-on their genes at a
higher frequency than those who do not.
• EVERYTHING is trying to SURVIVE and REPRODUCE
46. NATURAL SELECTION
The ability of an organism to survive and
reproduce in its specific environment is
called fitness.
• Individuals with characteristics that are not
well suited to their environment either die or
leave few offspring
• Individuals that are better suited to their
environment survive and reproduce most
successfully.
• Darwin called this process Survival of the
Fittest, or Natural Selection.
47. 4 Principles of Natural Selection
• Variation
• Competition
• Excess offspring
• Survival of the Fittest
48. 4 Main Principles of
Natural Selection
1. Variation exists within
a population
2. Organisms compete
for limited resources
3. Organisms produce
more offspring than
can actually survive
4. Individuals with
variations suitable for
their habitat are the
ones that SURVIVE
and REPRODUCE
49. • Three species of lizard.
• B- The ones at the bottom live in the shrubland, and are colored to
blend in.
•The top pictures show the
same species of lizard, but the
variety that lives in the White
Sands
•They all evolved to become
white (camouflage)
•The DNA on the bottom shows
the location of the mutation
that gives the white color
50. 1. Inherited Variation
Individual organisms within the population differ. Most of this
variation is determined by genetic inheritance (recombination), but
sometimes it is the result of genetic mutations.
51. 2. Struggle for Existence
Because so many offspring are produced, many will die due to a
lack of resources, predation, disease, or other unfavorable
conditions.
52. 3. Overproduction of Offspring
Organisms produce more offspring than can survive.
Many of the offspring do not survive to reproductive age.
53. 4. Differential Reproduction
Individuals best suited to their environment survive and reproduce
most successfully. Therefore these organisms pass their
advantageous traits to their offspring while offspring with
disadvantageous traits die or produce fewer offspring.
54. Descent with Modification
• Natural selection
causes species to
change over time.
• Species alive today
descended with
modification from
ancestral species.
55. Evolution of populations
• Genetic Drift
• Sometime changes in the allele frequency within a
population occur by chance. This is called genetic drift.
Before After
• The genes of the next generation will be the genes of
the “lucky” individuals, not necessarily the healthier
or “better adapted” individuals.
56. Gene Flow
• genes from one population are introduced
into the gene pool of another population
– Gene Pool: the combined genetic information of ALL
members of a population
– Biggest Factor that Effects Gene Flow: MOBILITY
For example:
The immigration and emigration of organisms.
The dispersal of seeds or spores.
Editor's Notes
The fact that this process of making proteins is common to all living things suggests that it has been passed down from an ancient ancestor.Ask students to share their interpretations of the data table.
The genes of the next generation will be the genes of the “lucky” individuals, not necessarily the healthier or “better adapted” individuals. That, in a nutshell, is genetic drift.