The Origin and Evolution of Species
Early Earth and the Origin of Living Things
Young Earth Theories
• Theorists estimate that the Earth formed ___________ years ago.
• The early atmosphere probably contained ___________________
_____________________________________________________.
• Volcanic activity, lightning, and UV radiation were intense.
• Fossilized prokaryotes date back to _______________ years ago.
• Life may have formed from ___________________________
_________________________________________years ago.
Young Earth Timeline
• Life may have developed from nonliving materials as early as 3.9
billion years ago
• Remember _____________________________? Francesco Redi
disproved the theory using fruit flies, meats, jars, maggots, etc.
• The _________________________________________ resulted.
• _________________________________________________
SO WHERE DID THE FIRST ORGANISM COME FROM?
• 1920s Oparin and Haldane suggested that the Earth’s early
atmosphere has a certain mix of gases that could _____________
_____________________________________________________.
• 1953 Miller and Urey proved that __________________________
_____________________________________________________.
1. ______________________________________________________
2. ______________________________________________________
______________________________________________________
3. ______________________________________________________
4. ______________________________________________________
5. ______________________________________________________
Forming Polymers from the Monomers
• Proteins
• Miller & Urey Experiment: The amino acids formed
_________________ for short periods of time to form very
short protein strands, but the bonds broke quickly.
_________________________________________________
_________________________________________________
• Theoretical explanation: Early amino acids were deposited
on __________. The amino acids stuck to the clay and
others deposited on the same piece of clay. Eventually,
bonds formed between the amino acids since they were all
“stuck” on the clay.
• Nucleic Acids:
• ________________ is considered to have been early life’s
genetic code.
• RNA can be replicated using clay crystals.
• Scientists believe that resulting RNA molecules developed
their own replication system over time.
Forming Cells from the Polymers
• Researchers have tested ways of enclosing molecules in membranes.
• The path from molecules to cells __________________________.
Origin of Species
Example of Speciation
• The origin of new species is called _________________________.
• Evolution has generally been thought of as a very gradual process
• However, examples of rapid evolution have been observed
• One example of rapid evolution occurred ____________________
______________________________________________________
______________________________________________________
• In less than 150 years, Culex pipiens evolved into a new mosquito
species, Culex molestus.
• The isolated mosquitoes adapted to their new underground
environment.
– They altered their prey, mating habits, and breeding
patterns
• _______________________________________ that isolate
populations are just one of many mechanisms in the evolution of
species.
What is a species?
• Linnaeus used _____________________________________ to
identify species when he developed the binomial system of
naming organisms.
• But appearance alone does not always define a species.
• Example: ________________________________________
• Similarities between some species (Meadowlarks) and variation
within a species (Humans) can make defining species difficult
• Humans exhibit extreme physical diversity
Species
• ______________________________________________________
______________________________________________________
Difficult to Establish a New Species
• Two types of reproductive isolation prevent new species:
• _______________________________: (BEFORE A ZYGOTE
FORMS) prevent reproduction by making fertilization
unlikely
• _______________________________: (AFTER A ZYGOTE
FORMS) hybrid offspring cannot reproduce
Prezygotic vs. Postzygotic Reproductive Isolation
Let’s Identify the Type of Reproductive Isolation Illustrated
1) Eastern and Western Meadowlark
• Very similar appearance but different mating songs
• TYPE: ____________________________________
2) Blue-footed boobies
• Courtship ritual specific to one area
• TYPE: ____________________________________
3) Plant species
• Flower structures fit specific pollinators
• TYPE: ____________________________________
4) Liger (Lion/tiger hybrid)
• Ligers cannot reproduce.
• TYPE: ____________________________________
5) Mule (Horse/donkey hybrid)
• Mules cannot reproduce.
• TYPE: ____________________________________
MECHANISMS OF SPECIATION
______________________ and _______________________ Speciation
Allopatric Speciation: ________________________________________
• Allopatric speciation: ___________________________________
______________________________________________________
• When a population is cut off from its parent stock, species
evolution may occur.
• An isolated population may become ___________________
as its gene pool is changed by natural selection, genetic drift,
or mutation.
• As enough genetic differences are established, the two
populations _______________________________________.
Allopatric Speciation: Islands
• On the Galápagos Islands, repeated isolation and adaptation have
resulted in adaptive radiation of __________ of Darwin’s finches.
• __________________________: a pattern of evolution; one
species gives rise to many species in response to the creation of a
new habitat or other ecological opportunity.
Sympatric Speciation
• Sympatric Speciation: ___________________________________
______________________________________________________
• In sympatric speciation, a new species may arise without
geographic isolation.
• Example: Polyploidy in Plants
• A failure in meiosis can produce diploid gametes
• Self-fertilization can then produce a tetraploid zygote
A Few Patterns in Species Evolution
• Three patterns common when new species evolve:
• Adaptative Radiation: (discussed earlier)
• Coevolution: ______________________________________
_________________________________________________
• Example: Moth and Comet Orchid –As the foot-long
flowers of the Comet Orchid developed, a moth with a
foot-long tongue evolved to pollinate them.
• Convergent Evolution: ______________________________
_________________________________________________
_________________________________________________
• Example: Mara and a rabbit – unrelated genetically
but developed similar body type, etc. because they
inhabit similar niches
Two Theories on Rate of Speciation
• ____________________________________ – Most scientists
believe that evolution proceeds in small, gradual steps.
• _________________________________________________ –
rapid spurts of genetic change cause species to diverge quickly;
these periods punctuate longer periods when little changes in a
species.
Tracing Evolutionary History
Earth History
• The fossil record chronicles _______________________________,
which is evolution on a grand scale.
• A ___________________________________ has been established
using the fossil record to organize the BIG PICTURE of how the
earth and its inhabitants have evolved over millions of years.
• The geologic time scale is a model that expresses the major
geological and biological events in Earth’s history.
• Organization of the Time Scale
• __________________________________
• ____________________________________
• _____________________________________
• ____________________________________
• Development of the Time Scale
• As geologists study the ____________________________,
they collect fossils.
• _______________________________________ uses
chemistry of the rocks to measure an approximate age.
• Scientists have built the geological time scale based upon
_________________________________________________.
Macroevolution Cause: Continental Drift
• _____________________________________ has played a major
role in macroevolution.
• Continental drift is the ___________________________________
of Earth’s crustal plates on the hot mantle.
• This movement has influenced the distribution of organisms and
greatly affected the history of life.
• _________________________________________________
_________________________________________________
• _________________________________________________
• Example of _______________________________________ :
• Continental drift explains the distribution of ____________,
which are freshwater fish that use a modified swim bladder
to breathe air.
• Lungfishes evolved when ____________________________
was intact during the ____________________________ Era.
• They were distributed around the world as crustal plates
shifted during the Mesozoic Era.
• ___________________________________ as plates shifted
to new climates.
• Plate tectonics, the movements of Earth’s crustal plates, are also
associated with volcanoes and earthquakes.
• By forming new islands, volcanoes can ______________________
______________________________________________________
• Example: Galápagos
• But volcanic activity can also ______________________________
– Example: Krakatau
Macroevolution: Mass Extinctions
• Mass extinctions were __________________________________.
• At the end of the Cretaceous period (Mesozoic Era), many lifeforms disappeared, including the dinosaurs.
• These mass extinctions may have been a result of an
_________________________________________________.
• Every mass extinction ___________________ the diversity of life.
• But each was followed by a __________________________.
• ____________________ filled the void left by the dinosaurs.
• ________________________________________________ may
enable species to proliferate after mass extinctions.
• Adaptations that have evolved in one environmental context may
be able to perform new functions when conditions change.
• Example: Plant
species with
catch basins, an
adaptation to dry
environments
CONNECTION: You may be living through a Mass Extinction Event
right now…
• Many scientists think a Mass extinction event is happening now.
• A decrease in _______________________________ is a threat to
us all.
• Humans are responsible for much of the problem due to _______
_____________________________________________________.
Cladistics
What is Cladistics?
• A method of analyzing organisms that classifies them based on
______________________________________________________
______________________________________________________
Necessary Vocabulary:
Phylogenic Species Concept
_____________________________________________________
• Phylogeny is the evolutionary history of a species.
• The phylogenic species concept defines a species as a cluster of
organisms that is distinct from other clusters and _____________
_____________________________________________________.
Necessary Vocabulary:
Typological Species Concept
______________________________________________________
• Aristotle and Linnaeus thought of each species as a distinctly
different group of organisms based on ________________
_________________________________________________.
• Based on the idea that species are unchanging, distinct, and
natural types.
Necessary Vocabulary:
Biological Species Concept
______________________________________________________
• The biological species concept defines a species as a group
of organisms that is able to ___________________________
_________________________________________________
Necessary Vocabulary:
Characters
• Characters: ___________________________________________
• To classify a species, scientists construct patterns of descent by
using characters.
• Characters can be ______________________________________.
Necessary Vocabulary:
Morphological Characters
• Shared morphological characters suggest that species are related
closely and ____________________________________________.
• _____________________________________ are those that have
the same function but different underlying construction.
• _____________________________________ might perform
different functions, but show an anatomical similarity inherited
from a common ancestor.
Necessary Vocabulary:
Evolutionary Characters
Compare birds and dinosaurs:
• Hollow bones
• Theropods have leg, wrist, hip, and shoulder structures similar to
birds.
• Some theropods may have had feathers.
Necessary Vocabulary:
Biochemical Characters
• Scientists use biochemical characters, such as ________________
and ________________________________, to help them
determine evolutionary relationships among species.
• DNA and RNA analyses are powerful tools for reconstructing
phylogenies.
• Example: The similar appearance of chromosomes among
chimpanzees, gorillas, and orangutans suggests a shared ancestry.
• __________________________ even share entire gene sequences
with other organisms; again, suggesting shared ancestry.
Necessary Vocabulary:
Molecular Clock
 Cladistics organizes organisms based upon _______________ they
diverged from a common ancestor.
 Scientists use molecular clocks to __________________________
______________________________________________________
______________________________________________________
 The data helps to put organisms in chronological order.
• How Molecular Clocks Work:
• Differences in the amino acid sequences between DNA of
related organisms indicate the presence of
_________________.
• The more mutations are present, _____________________
_________________________________________________.
• Simple – If organism A has more mutations (more
differences from the ancestor), then it diverged more
recently. More difference = more time = “newer”
organism
• In the 1960s, scientists developed molecular clocks. They
thought that mutations occur at regular intervals (like time).
• They were wrong…lots of factors affect the rate of
mutations.
• Therefore, molecular clocks aren’t very reliable on their
own. When used in conjunction with other resources like
the fossil record, they are useful.
• Factors that Affect the Rate of Mutation:
• Type of mutation
• Where the mutation is in the genome
• Type of protein that the mutation affects
• Population in which the mutation occurs
Necessary Vocabulary:
Phylogenetic Reconstruction
• Cladistics reconstructs phylogenies (“family trees) based upon
shared characters.
• Scientists consider two main types of characters:
• ______________________________: a character found
within the entire line of descent of a group of organisms
• ______________________________: a character that is
present in members of one group of the line but not in the
common ancestor
Cladograms
• The greater the number of derived characters shared by groups,
____________________________________ a common ancestor.
Using Molecular Biology to Create a Cladogram
(Human, fish, frog, chicken, shark)