Download Name - Humble ISD

Name _____________________________________________________
Test Date ________________
UNIT X - EVOLUTION
I. THE THEORY OF EVOLUTION (pp. 369-386)
The theory of evolution is one of the most fundamental concepts in Biology. Evolution is defined as
________________ in a _______________________________________________ over time. The scientist
considered to be 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
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 Observations
 Members of a population often vary greatly in their ________________.
 Traits are inherited from __________________ to _________________.
 All species are capable of producing _________ offspring than ____________________________
 Due to a lack of ____________ or other resources, many of the offspring ___________________.
3. Darwin’s Theories – Based on his observations and the hypotheses of other scientists
 Organisms with favorable _______________ tend to survive and ______________________; thereby leaving
more descendents than other individuals
 This will result in an accumulation of these traits in the __________________________, changing the original
make-up of the population
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
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
__________________________________.
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: _____________________________________
 Geographic Isolation-__________ populations are separated by geographic barriers and evolve where
they can no longer _________________________. EX: ____________________________________
 Temporal Isolation-______________________ reproduce at different times even though capable.
EX:__________________________________________________________________________
E. The failure of an organism to _______________ to changes in its environment will ultimately lead to its
_______________ because of _________________________________.
III. EVIDENCE FOR EVOLUTION
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 _________________________________________.
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
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. Diploidy – Most organisms are diploid, which means ________________________________________.
This allows for increased genetic variation in a population.
 Heterozygote Advantage – Seen in _______________________________ and _______________.
 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 _______________
E. Single Gene Traits-Natural selection on __________ ________ traits can lead to changes in ___________
frequencies and therefore to evolution.
F. Polygenic Traits-Natural selection can affect the distributions of phenotypes in 3 ways:
 Directional Selection-Individuals at ____________ end of the bell curve have higher fitness than those in the
middle or other end. EX:___________________________________________________________________
 Stabilizing Selection-Individuals in the _______________ have the highest fitness causing the curve to narrow.
EX:____________________________________________________________________________________
 Disruptive Selection-when individuals at the ends of the curve have the higher fitness. If lasts long enough can
cause the curve to split in two and create _____ distinct phenotypes. EX: _____________________________
V. MACROEVOLUTION- 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
____________________________________________________________________________________________
 _____________extinction has occurred several times, wiping out entire _______________________.
 ____________________, volcanic action, and __________________________movement has been blamed.
 Mass extinctions clear the way for _______________________ of other species. EX:____________________
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. EX:_______________________________________________
D. ______________________________ is when a change in one organism leads to a ____________________________
change in another organism. EX: ______________________________________________________________________
E. _________________________ 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-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.
E. _______________________________- Comparisons of ___________can also be used to mark the passage of
evolutionary____________________________.
 A model known as a molecular clock uses DNA comparison to ________________________ the length of time
that_____ species have been evolving _________________________________________________.
 The molecular clock depends on a repeating process to mark time-___________________________________.
 ________________________ mutations (ones that cause no changes) accumulate in the DNA
of________________________________________ species at about the same rate.
 Comparing these sequences, with these mutations, can tell scientist how _______________________ the genes
are and in turn how long ago the two species shared a __________________________________________.