AN INTRODUCTION TO BIOLOGY

1
AN INTRODUCTION TO BIOLOGY
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WHAT WILL WE COVER?

• The nature of biology
• Levels of organization of life
• Diversity of life
• Unity of life
• Introduction to evolution and natural selection
• Nature of scientific inquiry

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WHAT IS BIOLOGY?

• Biology is a natural science
• Literally, the study of life
• Employs principles and methods common to all
  sciences
• Biological knowledge is consistent with our
  understanding of chemistry, physics, etc.

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WHAT IS BIOLOGY?

• Biology has many subfields
• Biochemistry
• Ecology
• Evolutionary biology
• Genetics
• Microbiology
• Molecular biology
• Primatology
• etc.

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WHAT IS BIOLOGY?

• Biology intersects with many other fields of
  study
• Anthropology
• Chemistry
• Geology
• Physics
• etc.

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WHAT IS SCIENCE?

• Science is more than just a collection of facts
• Science is a way of knowing or understanding the
  natural world
• Science is NOT the only way of understanding
• Philosophy, theology, and other disciplines
  provide their own type of understanding

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WHAT IS SCIENCE?

• Science is based on the fundamental assumption
  that all events have natural causes
• e.g., Lightning is the result of natural causes,
  not the result of Zeus having a bad day
• e.g., Storms and earthquakes are not caused by
  Poseidon
• e.g., The sun is not a fiery chariot driven
  across the sky
• We may potentially understand these causes

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WHAT IS SCIENCE?

• Or maybe it is

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BIOLOGICAL HIERARCHIES

• Biology is literally the study of life
• Extends from the microscopic scale to the global
  scale
• This range is divided into different levels of
  biological organization

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BIOLOGICAL HIERARCHIES

• Hierarchy of biological organization
• Biosphere
• Ecosystems
• Communities
• Populations
• Organisms
• Organ systems
• Organs
• Tissues
• Cells
• Organelles
• Molecules

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BIOLOGICAL HIERARCHIES

• Hierarchy of biological organization
• Biosphere
• Ecosystems
• Communities
• Populations
• Organisms

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BIOLOGICAL HIERARCHIES

• Hierarchy of biological organization
• The biosphere consists of all the environments on
  Earth that are inhabited by life
• Ecosystems include all of the living things in
  one area, as well as the nonliving environmental
  components with which they interact
• Communities include all organisms inhabiting a
  particular ecosystem
• A population consists of all the individuals of
  one species living within a specified area
• Organisms are individual living things

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BIOLOGICAL HIERARCHIES

• Hierarchy of biological organization
• Organisms
• Organ systems
• Organs
• Tissues
• Cells
• Organelles
• Molecules

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BIOLOGICAL HIERARCHIES

• Hierarchy of biological organization
• Multicellular organisms possess numerous organs
  arranged into organ systems
• A tissue is a group of cells similar in structure
  and function
• Cells represent the fundamental structural and
  functional unit of life
• Some organisms consist of one cell (unicellular)
• Some organisms consist of several cells
  (multicellular)
• Organelles are specialized structures within a
  cell
• Molecules are chemical structures consisting of
  multiple connected atoms

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BIOLOGICAL HIERARCHIES

• Hierarchy of biological organization
• Biosphere
• Communities
• Populations
• Organisms
• Organ systems
• Organs
• Tissues
• Cells
• Organelles
• Molecules

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DIVERSITY OF LIFE

• About 1.8 million different species have been
  identified to date
• Most living species remain unidentified
• Thousands are identified each year
• The actual number of living species is unknown
• Much higher than this number
• Estimates range from 10 200 million
• The vast majority of species ever having lived
  are now extinct

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DIVERSITY OF LIFE

• The 1.8 million identified species display
  significant diversity
• 1,000,000 insects
• 52,000 vertebrates
• 290,000 plants
• 100,000 fungi
• 5,200 prokaryotes

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UNITY OF LIFE

• Despite significant diversity, all life possesses
  certain unifying traits
• Composed of cell(s)
• Require energy
• Reproduce
• Possess genetic material (DNA)
• Evolve (characteristic of populations)
• etc.

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VIRUSES
?

• Blur the boundary between life and non-life
• Share some of the unifying features of life
• Differ from normal life in some of these
  characteristics
• Are viruses alive?

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VIRUSES

• Cellular life
• Composed of cell(s)
• Require energy
• Reproduce
• Possess DNA
• Evolution (of populations)
• etc.

• Viruses
• Not cellular
• Only when infecting
• Only within host
• DNA or RNA
• Very rapid evolution

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UNITY AND DIVERSITY

• Evolution accounts for lifes unity
• Many similarities between organisms are due to
  shared ancestry

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UNITY AND DIVERSITY

• Evolution accounts for lifes diversity
• Differences between closely related species are
  the result of evolutionary change
• Often the result of adaptation to different
  environments

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EVOLUTION

• Evolution accounts for both the unity and the
  diversity of life
• Vast explanatory power
• Unifying theme of biology

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EVOLUTION

• except in Kansas

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EVOLUTION

• and in Dover, Pennsylvania

"breathtaking inanity"
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EVOLUTION

• and in other areas affected by various
  intellectually challenged school boards and
  legislative bodies in Arkansas, Georgia,
  Oklahoma, Wisconsin, etc.

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• Nothing in biology makes sense except in light
  of evolution
• -- Theodosius Dobzhansky

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EVOLUTION

• Our discussions of evolution will center on two
  main points
• Contemporary species arose from a succession of
  ancestors
• Descent with modification
• Inherited differences are the result of
  differences in reproductive success
• Natural selection is the mechanism of adaptive
  evolution
• Both of these topics will be covered in greater
  detail in future chapters

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EVOLUTION

• Differences in reproductive success will result
  in the evolution of adaptations in the
  population
• Traits of individuals reproducing more than
  average will increase in frequency in future
  generations
• Traits of individuals reproducing less than
  average will decrease in frequency in future
  generations

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EVOLUTION

• Differences in reproductive success will result
  in the evolution of adaptations in the population
• Traits of individuals reproducing more than
  average will increase in frequency in future
  generations
• Traits of individuals reproducing less than
  average will decrease in frequency in future
  generations

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CLASSIFICATION

• Taxonomy
• Branch of biology involved in the naming and
  classification of species
• Organisms are placed in groups based on
  similarities
• Morphological similarities
• Physiological / biochemical similarities
• Genetic similarities
• Multiple groups are combined into larger groups,
  again based on similarities

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CLASSIFICATION

• Taxonomic groupings reflect evolutionary
  relationships
• Similarities are due to shared ancestry

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CLASSIFICATION

• Taxonomic groupings reflect evolutionary
  relationships
• Similarities are due to shared ancestry

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CLASSIFICATION

• Taxonomic groupings reflect evolutionary
  relationships
• Similarities are due to shared ancestry

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CLASSIFICATION

• All living things are classified into one of
  three domains
• Bacteria
• Archaea
• Eukarya

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CLASSIFICATION

• Domain Bacteria and domain Archaea
• Two prokaryotic domains
• Organisms lacking a nucleus
• Most members are unicellular and microscopic
• Represent two very distinct branches of
  prokaryotes
• Formerly combined in a single kingdom (Monera)

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CLASSIFICATION

• Domain Eukarya
• Encompasses all eukaryotic cells
• Organisms possessing a nucleus
• Traditionally divided into four kingdoms
• Protista
• Fungi
• Animalia
• Plantae

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CLASSIFICATION

• Kingdoms animalia, plantae, and fungi are
  monophyletic groups
• Each kingdom consists of an ancestral species and
  all of its descendents

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CLASSIFICATION

• Kingdoms animalia, plantae, and fungi
• Distinguished partly by their modes of nutrition
• Plants produce foods through photosynthesis
• Fungi are mainly decomposers that absorb
  nutrients following the external breakdown of
  organic matter
• Animals obtain food by ingestion

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CLASSIFICATION

• Kingdom Protista is defined by exclusion
• Eukaryotes that are not animals, plants, or fungi
• Not a monophyletic group
• Should be split into multiple monophyletic
  kingdoms
• The number of kingdoms is currently unclear
• Most are unicellular
• Some are multicellular
• Some are very large

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CLASSIFICATION

• Each domain is divided into increasingly smaller
  groups
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

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CLASSIFICATION

• Each domain is divided into increasingly smaller
  groups
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

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CLASSIFICATION

• Each domain is divided into increasingly smaller
  groups
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

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CLASSIFICATION

• A specific scientific name is ultimately assigned
  to each species
• Genus species
• e.g., Homo sapiens
• e.g., Escherichia coli
• e.g., Bufonaria borisbeckeri
• e.g., Esox lucius
• etc.

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CLASSIFICATION

• DOMAIN Eukarya Bacteria
• KINGDOM Animalia
• PHYLUM Chordata Proteobacteria
• CLASS Mammalia Gammaproteobacteria
• ORDER Primata Enterobacteriales
• FAMILY Hominidae Enterobacteriacaea
• GENUS Homo Escherichia
• SPECIES sapiens coli
• STRAIN K12, O157H7, etc.

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SCIENTIFIC INQUIRY

• Scientific inquiry
• The search for information and explanation
• Drives progress in science

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SCIENTIFIC INQUIRY

• Two main processes of scientific inquiry in
  biology
• Discovery science
• Mainly concerned with describing nature
• Hypothesis-based science
• Mainly concerned with explaining nature

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SCIENTIFIC INQUIRY

• Recorded observations are called data
• May be quantitative
• May be qualitative

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SCIENTIFIC INQUIRY

• Discovery science
• Mainly concerned with describing nature
• Generalizations are derived based upon large
  numbers of specific observations
• Inductive reasoning
• e.g., The sun always rises in the east
• e.g., All organisms are made of cells

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SCIENTIFIC INQUIRY

• Discovery science involves observations and
  generalizations
• Provokes scientists to understand the natural
  causes and explanations for these observations
• Such inquiry generally involves the proposing and
  testing of hypothetical explanations
• Hypothesis testing

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SCIENTIFIC INQUIRY

• Hypothesis testing involves deductive reasoning
• Specific expected results are extrapolated from
  general premises
• Logic flows from the general to the specific
• Opposite direction from inductive reasoning

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SCIENTIFIC INQUIRY

• Hypothesis-based science employs the scientific
  method
• Idealized process of inquiry
• Orderly series of steps used to address
  scientific questions
• Elements of this process are used in most
  scientific research

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SCIENTIFIC INQUIRY

• Steps in the scientific method
• Make observations
• Ask a question
• Formulate a hypothesis (and predictions)
• Design an experiment to test this hypothesis
• Collect data
• Interpret the experimental results
• Support or reject the hypothesis

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SCIENTIFIC INQUIRY
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SCIENTIFIC INQUIRY

• Hypothesis
• Tentative answer to a well-framed question
• Generally an educated postulate
• Based on past experience and data of discovery
  science
• Based on observations
• Makes predictions that can be tested through
  additional observations or experiments

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SCIENTIFIC INQUIRY

• Hypotheses are commonly used to solve everyday
  problems
• Problems solved using hypotheses, predictions,
  and experiments
• Our thought processes are rarely formally
  dissected in this manner

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SCIENTIFIC INQUIRY

• A scientifically useful hypothesis must be
• Plausible
• Reasonable
• Testable
• There must be some way to test the validity of
  the idea
• Falsifiable
• There must be some observation or experiment that
  could reveal that the idea is not true
• A statement that is true by definition is not
  falsifiable

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SCIENTIFIC INQUIRY

• Certain predictions stem from a hypothesis
• A hypothesis and its predictions are often
  written as an if , then statement
• e.g., If cactus spines reduce herbivory, then
  herbivory will be more pronounced in cacti with
  fewer spines.
• Experiments can be designed to determine the
  validity of these predictions

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SCIENTIFIC INQUIRY

• Designing a controlled experiment
• An experimental group is compared to a control
  group
• Ideally differ in only one factor
• Independent variable

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SCIENTIFIC INQUIRY

• Designing a controlled experiment
• An experimental group is compared to a control
  group
• Ideally differ in only one factor
• Independent variable

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SCIENTIFIC INQUIRY

• Designing a controlled experiment
• Other potentially varying parameters are kept
  constant
• Controlled variables or constants
• What might be some constants in this experiment?

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SCIENTIFIC INQUIRY

• Designing a controlled experiment
• The dependent variable is the parameter that is
  measured
• Values of the dependent variable may differ
  between the experimental and control groups
• These differences are the result of differences
  in the independent variable
• The dependent variable is dependent upon the
  independent variable
• What is the dependent variable in this
  experiment?
• How would this be measured?

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SCIENTIFIC INQUIRY

• Review of variables
• The independent variable is the variable
  intentionally allowed to vary between the control
  and experimental groups
• Controlled variables (constants) are carefully
  controlled so as not to vary
• The dependent variable is the parameter that is
  measured
• Differences in the dependent variable are the
  result of differences in the independent variable

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SCIENTIFIC INQUIRY

• Designing a controlled experiment
• For each of these hypotheses, list the
• Independent variable
• Dependent variable
• Relevant constants

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SCIENTIFIC INQUIRY

• Presenting data
• Data can be organized and presented in tables and
  graphs

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SCIENTIFIC INQUIRY

• Presenting data
• Data can be organized and presented in tables and
  graphs

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SCIENTIFIC INQUIRY

• Interpreting results
• Useful results must be reproducible
• Experimental results must be viewed in light of
  the hypothesis being tested
• Results may support the hypothesis
• Note, the hypothesis is supported, not proven
• Results may refute the hypothesis
• Note that the hypothesis can be disproven
  (falsified)
• What results would support your hypothesis?
• What results would falsify your hypothesis?

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FACT AND THEORY

• The term fact does not convey absolute certainty
• Science rejects the concept of absolute certainty
• Scientists must always be willing to change their
  understanding in light of new information
• At best, our understandings are granted
  provisional acceptance
• A fact is confirmed to such a degree that it
  would be irrational to withhold provisional
  acceptance

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FACT AND THEORY

• The word theory has two very different meanings
• In everyday speech
• A theory can be little more than a hunch
• Unproven idea
• May or may not have supporting evidence
• Akin to a hypothesis in science
• In scientific communication (scientific
  theories)
• General set of principles
• Strongly supported by a large body of evidence
• Explains some aspect of nature

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FACT AND THEORY

• A scientific theory explains a great diversity of
  observations
• Supported by a massive body of evidence
• Supported by numerous facts
• Much broader in scope than a hypothesis
• General enough to generate numerous new, testable
  hypotheses
• Again, scientists must be willing to modify or
  reject any theory in light of new information

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FACT AND THEORY

• In science, the term theory does not imply that a
  concept is poorly supported
• Many scientific theories are so thoroughly
  supported and widely accepted that they form the
  foundation of fields of study

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FACT AND THEORY

• Examples of thoroughly supported and widely
  accepted scientific theories
• Cell Theory
• Darwins Theory of Evolution
• The Theory of Gravity
• The Big Bang Theory
• Einsteins Theory of Relativity
• Germ Theory

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FACT AND THEORY

• The Theory of Gravity is both fact and theory
• The occurrence of gravity is fact
• Supported by a vast body of evidence
• Sure, apples might begin levitating tomorrow, but
  considering events unsupported by any legitimate
  data is inappropriate
• The mechanism by which gravity occurs is a theory
• Isaac Newton explained rather well how gravity
  occurs
• Albert Einstein and others have refined our
  understanding of the nature of gravity

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FACT AND THEORY

• The Theory of Evolution is both fact and theory
• The occurrence of evolution is fact
• Supported by a vast body of evidence
• No competing scientific explanation for the unity
  and diversity of life exists
• The mechanism by which evolution occurs is a
  theory
• Charles Darwin described how evolution occurs by
  natural selection
• Other evolutionary biologists have refined our
  understanding of evolution by means of natural
  selection

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FACT AND THEORY

• Arguing that something is just a theory is
  based upon either dishonesty or ignorance
• Creationists commonly attempt to equate the two
  very different meanings of theory
• Stated plainly, they are being intentionally
  misleading
• Stated plainly, this is called dishonesty
• Many non-scientists assume that these arguments
  are honest and rational
• Mistakenly trust the untrustworthy
• Mistakenly conclude that evolution is a frivolous
  idea

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FACT AND THEORY

• Evangelical Scientists Refute Gravity With New
  Intelligent Falling Theory
• KANSAS CITY, KS As the debate over the
  teaching of evolution in public schools
  continues, a new controversy over the science
  curriculum arose Monday in this embattled
  Midwestern state. Scientists from the
  Evangelical Center For Faith-Based Reasoning are
  now asserting that the long-held theory of
  gravity is flawed, and they have responded to
  it with a new theory of Intelligent Falling.

For more on this imaginary yet profound article,
visit "theonion.com"
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FACT AND THEORY

• Students are expected to read Evolution as Fact
  and Theory, by Stephen Jay Gould, which can be
  found at the following website
• http//www.stephenjaygould.org/library/gould_fact-
  and-theory.html

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REFERENCES

• Audesirk, Teresa, Audesirk, Gerald, and Beyers,
  Bruce E. Biology, Life on Earth, 6th edition.
  Prentice Hall, Inc. 2002.
• Brooker, Robert J. Genetics, Analysis
  Principles, 2nd edition. McGraw-Hill Companies,
  Inc. 2005.
• Campbell, Neil A. and Reese, Jane B. Biology,
  7th edition. Pearson Education, Inc. 2005.
• Campbell, Neil A., Reese, Jane B., Taylor, Martha
  R., and Simon, Eric J. Biology, Concepts and
  Connections, 5th edition. Pearson Education,
  Inc. 2006.
• Gould, Stephen Jay. Evolution as Fact and
  Theory. Discover 2 (May 1981) p34 37.
• Nester, Eugene W., Anderson, Denise G., Roberts,
  C. Evans Jr., and Nester, Martha T.
  Microbiology, A Human Perspective, 5th edition.
  McGraw-Hill Companies, Inc. 2007.