Biological Principles and the Science of Zoology Presentation

Biological Principles and the
Science of Zoology

Zoology
- Scientific study of animal life (Hickman et al. 2017)
- Zoo = animal; logy = to study
- Guided by principles
- Scientific method
- Guiding theories
- Natural selection and Mendelian Inheritance
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What is life?
- A trickier question than it seems.
- The properties of today’s living systems are undoubtedly different from those
when life first arose
- Criteria are more appropriate than succinct definitions.
- Eight (8) criteria have been proposed; living entities meet all. Non-living
do not.
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Properties of living systems
1. Chemical uniqueness - living systems demonstrate a unique and complex
molecular organization
- Living systems use the same atoms and chemical bonds as non-living,
but…
- These are arranged in more complex and larger molecules known as
macromolecules
- Nucleic acids
- Proteins
- Carbohydrates
- Lipids
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2. Complexity and hierarchical organization - living systems demonstrate a
unique and complex hierarchical organization
- Complexity increases in ascending order
- Cells are composed of macromolecules
- Organisms are composed of cell(s)
- Populations are composed of organisms
- Species are composed of populations.
- Even within a single organism:
- macromolecules
- cells
- tissues
- organs
- organ systems
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2. Complexity and hierarchical organization - living systems demonstrate a
unique and complex hierarchical organization
- New properties arise at successive levels (emergence)
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3. Reproduction - living systems can reproduce themselves
- Occurs at every level of organization (genes make copies, cells divide,
organisms reproduce, etc.)
- Reproduction among living systems balances heredity and variation
- Heredity is faithful transmission of traits
- Variation is unfaithful transmission of traits
- Too much of either can be negative
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4. Possession of a genetic program - a genetic program provides fidelity of
inheritance
- Nucleic acids encode the structure of proteins
- DNA (deoxyribonucleic acid) stores the genetic information
- Composed of four nitrogenous bases
- Adenine
- Cytosine
- Guanine
- Thymine
- Sequence of these base is the genetic code
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5. Metabolism - living organisms maintain themselves by acquiring
nutrients from their environments
- Study of metabolism is physiology
- Nutrients are the chemical energy and molecular components for
building and maintaining
- Breaking these down (catabolism) and then constructing (anabolism) is
metabolism
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6. Development - all organisms pass through a characteristic life cycle
- Usually entails some change in size and shape
- For some this is subtle (direct development)
- For other it is dramatic (indirect development, e.g., metamorphosis)
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7. Environmental interaction - all animals interact with their environments
- Study of interactions is ecology
- Response to environmental stimulation is irritability
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8. Movement - living systems and their parts show precise and controlled
movements arising from within the system
- Movement can be of the individual or its component parts
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A not so special life
Life plays by the rules of the universe
- Once thought not to (vitalism); but consistent show to
Physical laws governing energy are illustrative
1. 1st Law of Thermodynamics - conservation of energy
2. 2nd Law of Thermodynamics - entropy happens
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Principles of science
What is science?
- A way of knowing the world and a way of asking questions about it.
1. Guided by natural law (physical and chemical laws)
2. Explanatory by reference to natural law
3. Testable against the observable world
4. Conclusions are tentative
5. Falsifiable
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Principles of science
What is science?
- Knowing the world - not the only way; art, religion, rationalization...
- Science differs because it is data driven and based on objective criteria
- Asking questions - formalized methodology for constructing knowledge
- i.e., scientific method
- 1. Observation
- 2. Question
- 3. Hypothesis
- 4. Empirical test
- 5. Conclusion
- 6. Dissemination
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Guiding theories
Theory of Evolution by Natural Selection
- Evolution - change over time
- Natural selection - descent with modification
Best viewed as five separate theories
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Guiding theories
Theory of Evolution by Natural
Selection
1. Perpetual change - living world
neither constant or cycling
- Fossil record provides evidence
- Incomplete and biased
- But, no evidence that world is
static or cyclical
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Guiding theories
Selection
2. Common descent - all life
descends from a common
ancestor
- Evidenced in homology of
structures, conserved DNA
- Life represented as phylogeny
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Guiding theories
Selection
3. Multiplication of species -
evolution is a branching process.
- One species into two in many
cases
- More species over time
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Guiding theories
4. Gradualism - large differences are the result of the accumulation of
small changes over very long periods of time.
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Guiding theories
5. Natural selection
- Variation among organisms
- Variation is partially (or more) heritable
- Variants do not leave the same number of offspring
- Variants more likely to survive, leave more offspring and their traits
become more prevalent in population
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Guiding Theories
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Guiding Theories
- Prior to industrial revolution
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Guiding Theories
- During industrial revolution
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Guiding Theories
- Environmental era (clean up)
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Guiding Theories
Mendelian Heredity and the
Chromosomal Theory of Inheritance
- Gregor Mendel - experiments
with garden peas
- Crossed true-breeding
populations
- Observed offspring over
successive generations
- No blending
- Masking
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Biological Principles and the Science of Zoology Presentation

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