Download unit x - evolution

Name ____________________________________________________________
Test Date ____________________
UNIT X - EVOLUTION
I. THE THEORY OF EVOLUTION (pp. 418-386)
The theory of evolution is one of the most fundamental concepts in Biology. Evolution is defined as __________________
in a _______________________________________________ over time. The scientist considered as the founder of
modern evolutionary theory is _____________________________________.
A. History of Evolutionary Theory – During the 1700s, several scientists began challenging the idea of a world in which
changes did not occur. These scientists and their hypotheses were very important to Darwin’s work.
1. Gradualism - ______________________ first suggested that the planet was much ____________________ than
previously thought; began to find evidence that _________________ were slowly, but constantly taking place.
2. Malthus – Published an essay that had a huge impact on Darwin. Proposed that organisms _________- reproduce;
in other words, reproduce at a ______________________ rate than resources can supply.
3. Lamarck
Lamarck was one of the first scientists to propose a mechanism for evolution; that is, the _____________________
in a _________________________ of organisms over ____________. His major hypotheses included:
 Tendency Toward Perfection – Stated that organisms were continually changing in order to
_____________________________________.
 Use and Disuse – Changes in __________________ and/or __________________ of a structure in an
organism was a response to use or disuse. Structures used extensively ___________________________
and structures used less frequently ________________________________________________.
 Inheritance of _________________ Traits. Ex: Giraffes with long necks
B. Charles Darwin (1809 – 1882)
1. Darwin’s History
Darwin’s data was collected on a 5-year journey around the world on the HMS ________________. He made
observations and collected data throughout the journey. He used this data to propose a ______________________
to explain the diversity he saw. The area that had the greatest impact on Darwin was the _____________________
Islands due to the differences he saw in the same animals living on different islands.
2. Darwin’s Theory of Natural Selection
4 Principles:
 Variation - Members of a population often vary greatly in their ____________________________.
 Heritability - Traits are inherited from _________________________ to _____________________________.
 Overproduction - All species are capable of producing ____________________ offspring than
_________________________________. Due to a lack of _________________ or other resources, many of
the offspring ________________________.
 Reproductive Advantage - Organisms with favorable ____________________________ tend to survive and
____________________________; thereby leaving more descendants than other individuals. This will result in
an accumulation of these traits in the __________________________________, changing the original make-up
of the population.
3. Darwin’s Theory of Descent with Modification
 Each living species has descended (with changes) from other species over time.
 Implies that all living things are related to one another.
 Also known as common descent.
 According to this principle, there would be a single “tree of life” for all living things. This tree of life is commonly
known as a _______________________________________. These can also be referred to as cladograms.
4. Darwin’s Legacy
 Did not publish his findings for years
 Alfred Wallace – formed identical _______________________ based on his research. Sent his manuscript to
Darwin, and finally Darwin was persuaded to publish his own conclusions
 Released “_________________________________”, still considered one of the greatest scientific studies ever
II. THE PRINCIPLES OF EVOLUTIONARY THEORY (pp. 437-438)
A. Evolution occurs because of natural selection - a mechanism for change that occurs when organisms with
__________________________ characteristics for a particular environment __________________________________,
____________________________, and pass these characteristics on to ____________________________________.
B. The ability of an organism to survive and reproduce in its environment is known as ____________________________.
C. Fitness is based on _______________________________. An adaptation is any trait that aids in the
__________________________ and _____________________________ of an organism. Examples of adaptations are
_______________________________________________________________________________________________
D. As organisms __________________ and adapt, ______________________ may occur. Speciation is the formation of
new species - a group of similar organisms that _____________________________ with one another and produce
_______________________________________ that is, babies that can make babies!
Isolating Mechanisms allow for the gene pools to become ________________ so they can form a new ____________.
Reproductive Isolation-as a new _________________________evolves, population become ____________________
isolated from each other.
 Behavioral Isolation-Population is capable of _____________________________________, but have different
______________________________ rituals. EX: Eastern and Western Meadowlark
 Geographic Isolation-_____________ populations are separated by geographic barriers and evolve where they
can no longer ________________________________. EX: Abert and Kaibab squirrels of the Grand Canyon
 Temporal Isolation-______________________________ reproduce at different times even though capable.
EX: Three orchids of the rain forest, release pollen only 1 day and not the same day
E. The failure of an organism to ___________________________ to changes in its environment will ultimately lead to its
________________________ because of __________________________________________.
III. EVIDENCE FOR EVOLUTION (pp. 423-429)
A. Fossils – Fossils are _________________________________________________________________
Fossils provide a record of earlier life and evidence that evolution has occurred.
B. Biogeography – Variations are seen in the same types of animals based on their ___________________________.
In addition, there are some organisms that live in very different locations but they have similar characteristics because
_____________________________________________, for example, climate, food sources, etc.
C. Homologous Structures – Scientists use anatomical studies of different organisms for evidence of evolutionary
relationships. For example, appendages that are very similar in structure, but differ in function are known as
___________________________ structures. Examples of homologous structures are
__________________________________________________________________________________________.
D. Vestigial Structures - A structure that is reduced in function in a living organism, but may have been used by an
ancestor is known as a _______________________ structure. A structure may become vestigial when an organism
changes in form or behavior. Examples are __________________________________________________________.
E. Embryology – Similarities in the structures of developing ___________________________ of different organisms are
considered to be proof of a close evolutionary relationship.
F. DNA Sequencing – Scientists use DNA studies to determine the evolutionary relationship between organisms. The
more similar the DNA, __________________________________________________
IV. MECHANISMS FOR EVOLUTION (pp. 431-439)
Evolution does not occur in an individual; instead it refers to ________________ that occur in a ____________________
over time. There must be mechanisms available for _______________________ changes to occur:
A. Mutation – A mutation is a _____________________________________. Although mutations are most often
_________________________, sometimes the resulting change in _____________________________ may be
beneficial to an organism under certain conditions. If the change occurs in the ____________________, this change
will be passed onto the offspring of that organism. A positive mutation that provides a survival advantage is known as
an __________________________.
B. Recombination – Leads to increased genetic variation as a result of ______________________________ during
______________________________ of ____________________________.
C. Gene Flow – Gene flow occurs when organisms from one
community migrate to another. This introduces new
__________________________ into the
____________________________ which can lead to a change in
the genetic make-up of the population.
D. Genetic Drift – This describes a situation in which change in a
population is magnified because the population size is
very __________________________________.
Causes of genetic drift include:
 Bottleneck effect – large portion of population
______________________________________________
 Founder effect – segment of population moves to new
________________________
V. MACROEVOLUTION (pp. 439-440)
Refers to large-scale evolutionary pattern and processes that
occur over long periods of time.
A. Extinction-More than _______% of all species that have ever
lived are now ____________________, which means the
species has died out. Darwin proposed possible reasons with
competition for ___________________and environmental change.
 ________________extinction has occurred several times, wiping out entire __________________________.
 _____________________, volcanic action, and __________________________movement has been blamed.
 Mass extinctions clear the way for _______________________ of other species.
B. Adaptive radiation-the process where a ____________________species has evolved through
_________________________ into diverse forms that live in _________________________ways. EX: ____________
______________________________________________________________
C.____________________ _____________________can have an evolutionary “side effect”, producing unrelated species
that ________________ similar to one another. This process is known as ____________________________________
and occurs in ________________________ and animals. These organisms have _____________________________
structures. EX:_____________________________________________
D. _________________________ Equilibrium is another pattern of evolution. Unlike ___________________________
punctuated equilibrium is characterized with long periods of _________________________ interrupted by brief periods
of ______________________change. It is controversial but known that evolution does occur at different rates.
VI. Modern Evolutionary Classification (pp. 440-441)
Linnaeus tried to group organisms according to biologically important characteristics, but his system had limitations and
problems.
A. Darwin’s ideas about descent with modification gave rise to the study of _______________________________, or
evolutionary relationships among organisms.
 Biologists now group organisms into categories that represent lines of _______________________________, or
phylogeny, not just physical similarities.
B. Cladistic Analysis-identifies and considers only those characteristics of organisms that are
_____________________________________________ -new characteristics that arise as lineages evolve over time.
 These recent characteristics are called ______________________________________________.
C. Derived characters can be used to construct a ______________________________________, a diagram that shows
the evolutionary relationships among a group of organisms.


Cladograms-are useful tools that help scientists understand how
one lineage ____________________________ from another in
the course of evolution.
Think of them as a family tree showing
__________________________________relationships among a
group of organisms.
D. Similarities in Genetic Material
 ____________ and _____________ are so similar across all
forms of life, these molecules provide an excellent way of
comparing organisms at their most basic level_____________________________________________.
 _________________________________________ in DNA can
be used to help determine classification and
_______________________________________relationships.
 DNA___________________________________ using
________________________________________ is a technique
that can be used to analyze DNA and determine these
evolutionary relationships.
 ________________________________________________ or
reading of the DNA of organisms allow for comparison of the
DNA of different organisms to trace the history of genes over ________________ of years.
VII. THE EVOLUTION OF THE CELL – THE ENDOSYMBIOTIC THEORY (pp. 406-407)