Integrated Principles of Zoology - Chapter 1

The Uses of Principles

Zoology:

• The scientific study of animal life

• Utilizes technologies and methods from all branches of science

• Seeks to document and systematically organize the diversity of animal life

Principles of Modern Zoology

Two important theories guide zoology research

• Theory of evolution

• Chromosomal theory of inheritance

Fundamental Properties of Life

• What is Life?

  • No simple definition

  • The history of life shows extensive and ongoing change called evolution

  • The answer must be based on the common history of life on the Earth

  • Life’s history of common descent with modification gives it an identity separate from the nonliving world

    • We trace this common history backward through time from the diverse forms observed today and in the fossil record to a common ancestor that must have arisen 4 billion years ago.

General Properties of Living Systems

Chemical Uniqueness

Living systems demonstrate a unique and complex molecular organization

Complexity and hierarchical organization

• Living systems demonstrate a unique and complex hierarchical organization

• In living systems, there exists a hierarchy of levels that includes:

  • Macromolecules

  • Cells

  • Organisms

  • Populations

  • Species

Reproduction

• Reproduction is a component of the definition of life

• At each level of the biological hierarchy, living forms reproduce to generate others like themselves:

  • Genes replicate to produce new genes

  • Cells divide producing new cells

  • Organisms reproduce, sexually or asexually, to produce new organisms

  • Populations fragment to produce new populations

  • Species split to produce new species

Possession of genetic program

A genetic program provides fidelity of inheritance

• Nucleic acids: encode the structures of the protein molecules needed for organismal development and functioning

• DNA: Long, linear chain of nucleotides

  • Stores genetic information

• Genetic code: Correspondence between base sequences in DNA and the sequence of amino acids in a protein

Metabolism

Living organisms maintain themselves by acquiring nutrients from their environments

• Metabolic processes include:

  • Digestion

  • Energy production (respiration)

  • Synthesis of molecules and structures required by organisms

Development

All organisms pass through a characteristic life cycle

• Development describes the characteristic changes that an organism undergoes from its origin to its final adult form

Environmental Interaction

All animals interact with their environments

• Ecology: the study of organismal interaction with an environment

• All organisms respond to environmental stimuli, a property called irritability

Movement

Living systems and their parts show precise and controlled movements arising from within the system

• Living systems extract energy from their environments permitting the initiation of controlled movements

Movement at the cellular level are required for:

• Reproduction

• Growth

• Responses to stimuli

• Development in multicellular organisms

On a larger scale:

• Entire populations or species may disperse from one geographic location to another over time

Movement of nonliving matter:

• Not precisely controlled by the moving objects

Often involves external forces

Life Obeys Physical Laws - Laws of Thermodynamics

First Law of Thermodynamics (Law of Conservation of Energy):

• Energy is neither created nor destroyed by can transformed from one form to another

• All aspects of life require energy and its transformation

Second Law of Thermodynamics:

• Physical systems tend to proceed toward a state of greater disorder or entropy

• The ultimate fate of materials in cells is the degradation and dissipation of their chemical bond energy as heat

• Organismal complexity is achieved and maintained only by the perpetual use of dissipation of energy flowing into the biosphere from the Sun

Zoology As Part of Biology

Animals originated in the Precambrian seas over 600 million years ago

Characteristics of animals:

• Eukaryotes: Cells contain membrane-enclosed nuclei

• Heterotrophs: Cannot make their own food and must rely on external food sources

• Animal cells lack cell walls

Principles of Science

Nature of science:

• Science is guided by natural law

• Has to be explained by reference to natural law

• Testable against their observable world

• The conclusions of science are tentative and therefore not necessarily the final word

• Falsifiable

The Scientific Method

• The hypothetico-deductive method

  • Requires the generation of hypotheses to potentially answer questions

• Using this method, in general, hypotheses may

  • Predict future observations

  • Be falsified

Hypothesis

• Potential answers to being asked.

• Derived from prior observations of nature or from theories based on such observations

• Often constitute general statements about nature that may explain a large number of diverse observations

• If a hypothesis is a very powerful in explaining a wide variety of related phenomena, it attains the level of theory

  • Theory - highest level in science, is generally accepted

    • Things can be a theory and a fact, example: evolution

Steps of the Scientific Method

Observation

Question

Hypothesis formation

Empirical test

• Controlled experiment

• Includes at least 2 groups

  • Test group

  • Control group

Conclusions

• Accept or reject hypothesis

Theories and Paradigms

Powerful theories that guide extensive research are called paradigms

The refutement and replacement of a paradigm is known as a scientific revolution

Two major paradigms that guide zoological research

• Darwin’s Theory of Evolution

• The Chromosomal Theory of Inheritance

Theories of Evolution and Heredity

Charles Darwin

Modern evolutionary theory is strongly identified with Charles Robert Darwin

Darwin’s Theory of Evolution

• Over 160 years old

• Published in On the Origin of Species by Means of Natural Selection in England in 1859

• Darwinism encompasses several different, although mutually compatible theories

• Alfred Russel Wallis - had the same idea as Darwin and sent him a letter

Theories of Darwinism

Ernst Mayr (Harvard University) proposed that Darwinism should be viewed as five major theories:

• Perpetual Change

  • The Living world is neither constant nor perpetually cycling but is always changing

    • The varying forms of organisms undergo measurable change across generations throughout time

    • Documented by the fossil record

    • Theory upon which the remaining four are based

• Common descent

  • All forms of life descend from a common ancestor through the branching of lineages

    • Life’s history has the structure of a branching evolutionary tree, known as phylogeny

    • Serves as the basis for our taxonomic classification of animals

      • All based on evolution

• Multiplication of the species

  • The evolutionary produces new species by splitting and transforming older ones

• Gradualism

  • Large differences in atomic traits that characterize disparate species originate through the accumulation of many small incremental changes over very long periods of times

• Natural Selection

  • A creative process that generates novel forms from the small individual variations that occur among organisms within a population

  • Adaptation - An anatomical structure, physiological process, or behavioral trait that evolved by natural selection and improves an organisms ability to survive and leave descendants

    • Ultimate goal - Leave behind descendants

Darwin’s Obstacle

Darwin’s theory of natural selection faced a major obstacle when first proposed because it lacked a successful theory of heredity

Neo-Darwinism

• Describes Darwin’s theories as modified by incorporating the Chromosomal Theory of Inheritance - based on Mendelian Laws of Genetics

Mendelian Heredity and the Chromosomal Theory of Inheritance

Foundation of current studies of genetics and evolution in animals

Genetic approach

• Mating populations of organisms that are true-breeding for alternative traits

• Following hereditary transmission of those traits to offspring

• Leads to evolution as desirable traits are passed on to offspring from one generation to the next

Transmission of traits via Gametes

Genes are regions of chromosomes that contain the recipe for a trait

Diploid individuals have two copies of each gene

Gamete Formation

During gamete formation, paired genes in the parent segregate from each other

Each gamete receives one copy of each gene

When fertilization occurs, the offspring receives one copy of each gene from each parent