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Zoology
 Zoon = animal
 Logos = study of
 Zoology = study of animals
 Zoology is the study of animal diversity,
the way they function, live, reproduce
and interact.
History and Evolution
 Animal life existed more than 600
million years ago
 From earliest animals to millions of
animal species present today, history
demonstrates perpetual change we call
evolution.
phylogeny
 We depict the history of animal life as a
branching geneological tree called a
phylogeny.
 Earliest species, ancestral to all animals are
at the trunk, then all living animals species fall
at the growing tips of the branches.
 Each successive branching event represents
formation of a new species from an ancestral
one.
Two goals of scientific study of
animal diversity
 1. Reconstruct a phylogeny of animal life and
find where in evolutionary history we can
locate the origins of features that comprise
animal diversity as we know it.
 2. Understand historical processes that
generate and maintain diverse species and
adaptations throughout evolutionary history.
Principles of Science
 Using scientific method
 Characteristics
of scientific hypotheses:
Testable against the empirical world
 Relying on or derived from observation or
experiment
 Verifiable or provable by means of observation
or experiment
 Conclusions are tentative
 It is falsifiable

Scientific Method
 Generate hypothesis (based on prior
observations)
 State your methods. Methods are the
blueprint for your experiment such as
sample size, number of replications, etc.
 Gather and analyze data
 Draw conclusions.
Theory

If a hypothesis is very powerful in
explaining a large variety of related
phenomena, it may be called a theory.

This differs from the common use of
the word theory which basically means
speculation.
Experimental and Evolutionary
Sciences
 Questions about animal life can be grouped
into two major categories:


1. Questions which seek to understand proximate
causes that underlie functioning of biological
systems at all levels of complexity.
2. Questions addressing ultimate causes that
have generated biological systems and their
properties through evolutionary time.
 Questions of the first type represent
experimental science.
 Include problems of explaining how
animals perform their metabolic,
physiological and behavioral functions
at molecular, cellular, organismal and
population levels. These use the
experimental method.
 Questions of the second type are
examples of evolutionary science.
 Include questions such as:
 What
factors have caused some birds to
acquire complex patterns of seasonal
migration between temperate and tropical
regions?
 Answering these questions requires the
comparative methods.
Examples of experimental
sciences:
 Molecular biology
 Cell biology
 Endocrinology
 Immunology
 Physiology
 Developmental biology
 Community ecology
Examples of evolutionary
sciences
 Comparative biochemistry
 Molecular evolution
 Comparative cell biology
 Comparative anatomy
 Comparative physiology
 Phylogenetic systems
Early evolutionary theory
 In mid-1600’s Archbishop James Ussher fixed
year 4004 B.C. as time of life’s creation.
 French Naturalist Georges Louis Buffon
(1707-1788) stressed environmental
influences on modifications of animal type.
 Jean Baptiste de Lamarck


Inheritance of acquired characteristics
Transformational Evolution

Giraffe example
Charles Lyell
 1797 – 1875
 Established principles of geology – the
principle of uniformitarianism
 Uniformitarianism encompasses two
principles:



Laws of physics and chemistry remain consistent
throughout earth’s history.
Past geological events occurred by natural
processes similar to those that we observe in
action today.
He concluded that earth’s age must be reckoned
at millions of years.
Charles Darwin
 Noticed that though many islands
similar in climate and topography, there
were differences in flora and fauna.
 Recognized that Galapagos plants and
animals related to those of South
America but differed in curious ways.
 They had undergone modification to
environment.
Darwin’s theory of evolution
 Five major theories that make it up:
 Perpetual
change
 Common descent
 Multiplication of species
 Gradualism
 Natural selection
Perpetual Change
 Living world is neither constant nor
perpetually cycling but constantly
changing
 Characteristics of organisms undergo
modification across generations
throughout time
Common Descent
 All forms of life descended from a common
ancestor through a branching of lineages.
 An opposing argument that different forms of
life arose independently and descended to
the present in linear unbranched geneologies
has been refuted by comparative studies of
organismal form, cell structure and
macromolecular structures.
Multiplication of species
 Evolution produces new species by
splitting and transforming older ones.
 Individual
species do not interbreed
Gradualism
 Large differences in anatomical traits
that characterize different species
originate by accumulation of many small
incremental changes over very long
periods of time.
Natural Selection
 Natural selection explains why
organisms are constructed to meet the
demands of their environments –
adaptation.
 Darwin developed his theory of natural
selection as a series of five
observations and three inferences from
them.