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CHAPTER 10
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Taxonomy and Phylogeny of Animals
Order in Diversity
Evolution and Diversity
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Order in Diversity
Taxonomy
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More than __________________species of animals named with thousands being
described each year.
 Less than ____% of all extant animals known
 Less than _____% of extinct animals found
 Animal diversity is not random and has definite order.
 Natural system of order reflects relationships among animals in nature and
outside of human context
 Darwin’s theory of evolution serves as a guide.
Formal system for naming and classifying species following the principle of
__________descent
 Animals with recent __________ share many common features and are
grouped __________ together.
Biologist have organized animal diversity in __________ __________ of groups
within groups based on shared features.
However, taxonomy was based on pre-evolutionary practices so has issues
Order in Diversity
__________ and __________ biology
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Broader science of classifying organisms based on studies of variation among
populations that reveal their _______________ relationships
Need to accommodate various alternative taxonomic viewpoints
Systematic zoologists have three goals:
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Linnaeus and Taxonomy
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_______________ (384 to 332BC) - the Greek biologist /philosopher, who first classified
organisms based on structural similarities
Linnaeus and Taxonomy
The Linnaean system of classification
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Divided animal kingdom into _______________ and gave each a _______________
name
 Grouped species based on shared common essential properties into
_______________ , genera into _______________ , and orders into classes,
etc.
 Animals are arranged in an ascending series of groups with increased
inclusiveness
His original classification scheme was very limited and has been drastically altered,
but the basic principle is still followed today.
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Linnaeus and Taxonomy
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_______________(taxon)- major animal groups at each level in the hierarchy
Taxonomic ranks- indicate the general degree of inclusiveness per group
The _______________ mandatory major ranks
 _______________, _______________ , _______________ ,
_______________ , _______________ , _______________ , and
_______________
 All animals are placed in Kingdom _______________
 Each major rank can be further subdivided into smaller levels of taxa like
Superclass, suborder, etc.
 More than _______ taxonomic ranks are now recognized
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Linnaeus and Taxonomy
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Systematization versus Classification
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Introduction of the evolutionary theory into animal taxonomy changed the
taxonomist’s role from one of _______________ to that of _______________
Classification denotes the construction of classes and grouping of organisms
 Groups possess a _______________ feature called an _______________
which is used to define the group
 Static nature of groups are ill advised due to the constant evolution of species
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Linnaeus and Taxonomy
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_______________ places groups of species into units of _______________
evolutionary descent
 Include the most recent common ancestor and its descendants
Character _______________ is used to diagnose systems of common descent
 Not required as an essential character to be maintained throughout the system
for its recognition as a taxon
 Each successive taxon represents the descendants of an earlier ancestor.
_______________ and other features are used differently between classification and
systematization
In _______________
 Taxonomist asks whether a species being classified contains the defining
feature of a particular taxonomic class
In _______________
 Taxonomist asks whether the characteristics of a species confirm or reject the
hypothesis that it descends from the most recent common ancestor of a
particular taxon
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Linnaeus and Taxonomy
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_______________ _______________ _______________
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Scientific name of an animal consists of ______ words, normally in ___________
Scientific name should be printed in _______________ or _______________ if
handwritten
 First word is the _______________ and is capitalized
 The second, the _______________ _______________ , is written in lower
case
 for example Homo sapiens
 Latin is used in scientific nomenclature by scientists all around the world due
to its precise description compared to “common” names that may vary both
culturally and geographically.
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Linnaeus and Taxonomy
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A species epithet may be used in different genera
 ___________ ____________ (white-breasted nuthatch)
 ___________ ___________ (Carolina chickadee)
 ___________ ___________ (green anole lizard)
Thomas Henry Huxley (1825-1895) asked this famous question which has no clear
answer even till today.
There are numerous concepts about species which lead to enormous disagreements.
Biologists have repeatedly used certain criteria for identifying species.
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Species
___________ descent
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Same name can not be given to different animals
What is a species?
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_______________ _______________
 Usually an adjective that must agree in gender with the species and never used
alone
Species
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_______________ name
 Always a noun and must refer only to a single group of organisms
Central theme to all modern concepts of species trace their ancestry to a
___________ ___________ population but not necessarily the same exact pair of
parents
Smallest distinct groupings
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Species must be the smallest unit sharing patterns of ancestry and descent
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___________ has been traditionally used but now supplemented with ___________
and ___________ characteristics
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Species
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Reproductive community
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Species form reproductive groups that exclude other species.
___________ reproducing populations
 Interbreeding is critical for maintaining a reproductive community.
___________ reproducing populations
 Entails occupation of a particular ecological habitat in a particular place so
that a reproducing population responds as a unit to evolutionary forces
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Species
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___________ distribution
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Species
Different Species Concepts
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All species differ greatly in their distribution through space and time
 ___________ range
 ______________________ species having very large geographic
ranges or worldwide distributions
 _____________________ species with very restricted geographic
distributions
 Range can either be ________________or _______________
 Evolutionary duration
 Distribution through time which is variable per species
_________________ Species Concept
 Before Darwin, a species was considered a distinct and immutable entity
derived from divinely created patterns
A ___________ ___________ was labeled and deposited in a museum
 New specimens were always compared to this previously described
representative specimen
 ___________ differences from the type are considered accidental
imperfections
 ___________ difference lead to formation of new species
Species
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Evolutionist discarded the Typological Species Concept
 Today, ___________ morphology is still important in recognizing species.
 However, species are no longer viewed as classes of organisms defined by
possession of certain morphological features.
 Type specimens serves only as a ___________ to general morphological features
that one might expect to find in a particular species.
 ___________ is not viewed as an imperfect manifestation of an eternal “type”.
Species
Biological Species Concept
 Proposed by Theodosius Dobzhansky and Ernst Mayr
 A species is a reproductive community of populations (reproductively isolated
from others) that occupies a specific niche in nature.
 Ability to ___________ ___________ is central to the concept
 Criteria of “___________ ” views members of a reproductive community to have
common ecological properties
Species
Modernized version states that a species is an interbreeding population of individuals
having common descent and sharing intergrading characteristics
Expect to maintain ___________ ___________ within similar species and discontinuous
between different species
 Sometimes species status can be evaluated directly by conducting ___________
experiments
 However, controlled breeding experiments can be difficult to conduct so character
variation is still used
Species
Variation in molecular characters is used to identify geographical boundaries of different
reproductive groups.
 Molecular studies may detect ___________ species which can be too similar in
morphology to be diagnosed as separate species by morphological characters alone.
Biological species is based on ___________ properties of populations rather than
organismal morphology, but ___________ can help us to diagnose biological species
Species
Problems with Biological species concept
 Lacks an explicit temporal dimension
 Gives little guidance regarding the species status of ancestral populations relative to
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Species
Evolutionary and Cohesion Species Concepts
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their evolutionary descendants
Disagreement on the degree of ___________ isolation necessary for considering two
populations separate species
___________ between species may be difficult to locate
___________ does not occur in asexual organisms which only do binary fission and
budding
George Gaylord Simpson (1902-1984) proposed the evolutionary species concept in
the 1940s.
Species
Advantages of the Evolutionary species concept
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Definition accommodates both sexual and asexual forms as well as fossils
Adds the evolutionary time dimension needed by the biological species concept
Allows the unbroken genealogical chain of populations to the point where sister
species converge on their common ancestor
The ability of geographic populations to evolve collectively as a single, genetically
cohesive unit through evolutionary time is critical to the evolutionary species
concept.
___________ Species Concept
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The most inclusive population of individuals having the potential for
phenotypic cohesion through intrinsic cohesion mechanisms.
Definition includes genetic changes in the population caused by gene flow, genetic
drift, and natural selection
Species
___________ Species Concept
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Phylogenetic species
 An irreducible (basal) grouping of organisms distinct from other such
groupings and within which there is a parental pattern of ancestry and descent.
Both ___________ and ___________ groups are covered
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Species
Emphasis of the _____________________ species concept :
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Permits future gene exchanges and possible merging of different populations
Views separate species as the smallest groupings of organisms that have undergone
independent evolutionary change
Discerns the greatest number of species more readily but may become impractical
Guarantees strict monophyletic units at the species level
Disregards details of evolutionary process intentionally
Allows the description of species without the need for detailed studies
Species
___________ ___________ concept
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Groups geographically disjoint populations into single species that show
phylogenetic divergence but have similar evolutionary tendencies
Emphasis of the ________________ species concept:
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Places greater emphasis on historically separated populations having biological
potential to merge into a single lineage
Species
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Phylogenetic species is a single population lineage with no detectable branching and
emphasizes common descent
Various species concepts have common underlying principles despite their
differences.
Species constitute a segment of the population level lineage
Emphasizes the common goal of identifying the phylogenetic history of population
level lineages
Still has issues with contrasting species concepts that may differ in how many
species are named
Species
Dynamism of various species concepts
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Disagreement is a sign of dynamic research and should not be considered
discouraging.
Cannot predict which species concepts will remain useful in the future
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Possible disagreements regarding species boundaries may identify interesting cases
of evolution in action.
No single concept is comprehensive or final but all need to be understood so as to
understand future concepts
Species
___________ barcoding of species
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Technique used for identifying species using standard gene sequences present in all
animals
Mitochondrial gene encoding for the ___________ c oxidase subunit 1 (CO1)
normally varies between animals but the variation within species is smaller than
differences among species
Allows for the identification of the origin of a specimen within a given population
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Taxonomic Characters and Phylogenetic Reconstruction
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Major goal of systematics
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Infer the evolutionary tree or ___________ that relates all extant and extinct species
Accomplished by identifying organismal features called ___________ that vary
among species
 Characters are any features used to study variation within and among species.
 Identified by observing patterns of similarity in ________________ ,
________________ , and ________________ features
 Sometimes, ________________ and ________________ features are also
used
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Taxonomic Characters and Phylogenetic Reconstruction
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Phylogenetic analysis
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Depends upon finding shared features among organisms that are inherited from a
common ancestor
 ________________ character similarity resulting from common ancestry
Similarity may not always reflect common ancestry due to independent evolutionary
origin on different lineages.
 ________________ non-homologous similarities that may be found in various
organisms
Taxonomic Characters and Phylogenetic Reconstruction
Using Character Variation to Reconstruct Phylogeny
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Method used to examine the polarity of a variable character is called
________________ comparison
 ________________ - group that is phylogenetically close but not within the
group being studied
 Infer that any character state found both within the group being studied
and the outgroup is termed ________________
 All character states found in study groups and absent from appropriate
outgroups is considered ________________
 Organisms or species that share derived character states form
________________ within the study group called ________________ .
Taxonomic Characters and Phylogenetic Reconstruction
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Find ________________ of a character by identifying which one of its contrasting
states is ________________ and which one(s) is ________________
Taxonomic Characters and Phylogenetic Reconstruction
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First step is to determine which variant form of each character was present in the
common ancestor of the entire group
 ________________ character- the character state present in the common
ancestor
 ________________ derived character - all other variant forms of the character
that arose later within the group
A ________________ corresponds to a unit of evolutionary common descent that
includes ancestral lineage and all descendants.
 Synapomorphy- derived character shared by members of a clade
 Synapomorphies are used as evidence of homology and infers that a particular
group of organisms forms a clade.
 Plesiomorphic character states are ancestral for a taxon.
 Symplesiomorphy is the sharing of ancestral states.
Taxonomic Characters and Phylogenetic Reconstruction
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Nested hierarchy of clades within clades forms patterns of derived states of
characters within a study group.
 By identifying all of the clades nested within the study taxon, some patterns of
common descent can be formed.
________________ nested hierarchy of clades presented as a branching diagram
 Not similar to phylogenetic tree which represents real lineages in evolutionary
history
 Normally act as the first approximation of the branching structure of the
corresponding phylogenetic tree
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Taxonomic Characters and Phylogenetic Reconstruction
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Requirements for a ________________ tree:
 Additional information concerning ancestors
 Duration of evolutionary lineages
 Amount of evolutionary change within the lineage
Characters used to construct the first cladograms come from a variety of sources:
 _______________________________________
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Taxonomic Characters and Phylogenetic Reconstruction
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Sources of ________________ Information
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Comparative ________________
 Analyzes sequences of amino acids in proteins and nucleotides sequences in
nucleic acids
 Recent studies show comparative biochemistry can be applied to determine
the age of fossils.
Taxonomic Characters and Phylogenetic Reconstruction
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Comparative ________________
 Examines shapes, sizes, and development of organisms
 Macroscopic and microscopic characters
 Living specimens and fossils are used
Comparative ________________ (Karyology)
 Examines variation in number, shape, and size of chromosomes
 Used almost exclusively on ________________ specimens.
We can calibrate the evolution of proteins and DNA sequences by measuring their
divergence between species whose common ancestor has been dated in the fossil
record.
The age of branches can then be estimated by molecular calibration.
Theories of Taxonomy
Taxonomic theories establish the principles to recognize and rank groups
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Two currently popular theories:
 ________________(traditional)taxonomy
 ________________ systematics (cladistics)
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Relationship between taxonomic group and phylogenetic tree can be one of three forms:
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________________
 A monophyletic taxon includes the most recent common ancestor and all
descendants of that ancestor.
________________ A taxon is paraphyletic if it includes the most recent common
ancestor of all members of a group and some but not all descendants of that ancestor.
Polyphyly
 A taxon is polyphyletic if it does not include the most recent common
ancestor of all members of a group.
 The group has at least two separate evolutionary origins
Monophyletic and paraphyletic groups share the property of ________________ and
distinguishes these from polyphyletic group.
 A group is ________________ if you can trace a path between any two
members of the group on a cladogram without leaving the group.
Theories of Taxonomy
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Evolutionary taxonomy predates phylogenetic systematics.
Theories of Taxonomy
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Both are based on evolutionary principles but differ in how these are used.
Similarities of ________________ and cladistic ________________
 ________________ monophyletic groups
 ________________ polyphyletic groups
 ________________ on accepting paraphyletic groups which has important
evolutionary implications
Evolutionary taxa must have a single evolutionary origin, and must show unique
adaptive features.
George Gaylord Simpson and Ernst Mayr were influential in the development and
formalization of evolutionary taxonomy.
Theories of Taxonomy
________________ Taxonomy incorporates two main principles for ranking taxa:
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________________ descent
Amount of adaptive evolutionary change
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Theories of Taxonomy
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Entering a new adaptive zone with new organismal and behavioral changes will
allow populations to use environmental resources in a new way.
 A taxon that represents a distinct adaptive zone is a ________________ .
 The broader the adaptive zone when fully occupied by a group of organisms,
the higher the rank given to it.
Evolutionary taxonomy has been challenged in many ways:
 ________________ taxonomy
 ________________ systematics/ cladistics
Theories of Taxonomy
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________________ taxonomy uses a more easily measured feature; the overall
similarity of organisms is evaluated without regard to phylogeny.
 Has contributed some useful analytical methods but did not have a strong
impact on animal taxonomy, such that scientific interest in this approach has
declined
 Zoologists still prefer to reconstruct phylogeny as the central goal of
systematics and are unwilling to compromise
Theories of Taxonomy
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A particular branch on an evolutionary tree is considered a higher taxon if it
represents a distinct ________________ zone
 Described as a characteristic reaction and mutual relationship between
environment and organism, a way of life and not a place where life is led
Stronger challenge to evolutionary taxonomy
Willi Hennig (1913-1976)
 First proposed cladistics or phylogenetic systematics such that it also calledHennigian systematics
Emphasizes ________________ properties of taxa and not their differences to other
related groups
Theories of Taxonomy
Current State of Animal Taxonomy
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________________ animal taxonomy
 Established using evolutionary systematics and recent cladistic revisions
________________
 New taxonomic system that is being developed as an ________________ to
Linnaean taxonomy
 Replaces Linnaean ranks with codes that denote the nested hierarchy of
monophyletic groups conveyed by cladograms
 Nevertheless, Linnaean ranks are still widely used by many other taxonomists.
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Theories of Taxonomy
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Taxonomist must always be careful to specify which type of taxonomy they use.
Early attempts at taxonomy
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Aristotle’s two kingdom system
 Included plants and animals
 Fungus and single-celled organisms became problems
Ernst Haeckel (1866)
 Proposed a new kingdom called-Protista for single-celled organisms
 Separated bacteria and blue green algae from other single celled organisms
R.H. Whittaker (1969)
 Proposed a five-kingdom system to distinguish prokaryotes from eukaryotes
Major Division of Life
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When discussing patterns of descent, we must avoid the use terms like:
 “mammals evolved from reptiles”
 “basal” group
Major Division of Life
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The terms “________________ ,” “________________ ,” “specialized” and
“generalized” must be avoided as all groups have a combination of all of the terms
 Can be used for specific characteristics and not for groups as a whole
Modern classification systems take phylogenetic relationships into account to
construct evolutionary branches.
Woese, Kandler, and Wheelis
 Proposed three monophyletic ________________ above kingdom level—
________________ (all eukaryotes), ________________ (true bacteria) and
________________ (variant bacteria) —based on ________________ RNA
sequences.
 All animal-like ________________ were traditionally grouped as Protozoans
but recent systematics have modified this to reflect several separate phyla that
provide context for animal diversity.
Major Subdivisions of the Animal Kingdom
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Phylum is the largest formal taxonomic category in the Linnaean classification of the
animal kingdom.
 ________________ includes all animal phyla except Porifera and Placozoa
 Major groups are ________________ (Cnidaria and Ctenophora) and
________________ (all other animal groups)
 Bilateria is further divided into ________________ and ________________
 Phylum ________________ is still a controversial group within Eumetazoa