Transcript Classification & Phylogeny of Animals Zoology Chapter 4

Classification & Phylogeny of
Animals
Zoology Chapter 4
Homework:
Read pages 72-76 (up to Taxonomic char…)
Do Questions 1, 2, 3, 4 page 86
Due: Tuesday 2/16/10
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Linnaeus & Classification
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Carolus Linnaeus (1707-1778)
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Botanist who introduced a comprehensive
classification system for naming organisms
It is important to classify (group) organisms
b/c it makes learning about them easier
This system based on hierarchy of major to
minor groups (taxa, taxon) having certain
characteristics
The characteristics used to group organisms
vary; this will be discussed in a later slide
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Hierarchy of the system
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The major classification ranks are:
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Kingdom
Phylum
Class
Order
Family
Genus
species
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Binomial Nomenclature
(2 Name Naming System)
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Every organism has a scientific name that is the
Genus + species name (which is italicized or
underlined); uppercase Genus, lowercase species
Naming system uniform throughout world
Often the species epithet (name) may be similar for
several organisms b/c the species epithet is usually
descriptive (adjective) , therefore, the genus name
must always be included!
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For example:
Anolis carolinensis (green anole) &
Poecile carolinensis (Carolina chickadee) & Sitta
carolinensis (White-breasted nuthatch)
Note there are 3 organsims all with the same species name
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Criteria for Recognition of Species
(But what is a species?)
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We defined it as a group of individuals in a
population which successfully breed producing
fertile offspring.
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B/c the naming system relies on “what is a
species”, defining it properly matters
So, biologists have several definitions of what
constitutes a species, we will look at those:
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Biological species concept
Evolutionary species concept
Phylogenetic species concept
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Biological Species Concept
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Introduced by Theodosius Dobzhansky & Ernst
Mayr in 1983.
“A species is a reproductive community of
populations that occupies a specific niche in nature.”
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Note that species here is defined according to reproductive
properties of populations, not based on morphology
A species is an interbreeding population of
individuals having a common descent inhabiting a
particular niche in nature.
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Evolutionary Species Concept
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Proposed by George Simpson in the 1940s.
“A species is a single lineage of ancestordescendant populations that maintains its
identity from other such lineages and that has
its own evolutionary tendencies and historical
fate.”
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Applies to both sexually & asexually reproducing
organisms
Common descent is a factor in this definition
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Phylogenetic Species Concept
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“A species is an irreducible grouping of
organisms diagnosably distinct from other
such groupings and within which there is a
parental pattern of ancestry and descent.”
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This definition implies common descent, as well
as, referring to both sexually & asexually
reproducing organisms
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Sources of Phylogenetic Information
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In order to construct phylogenetic relationships,
information is gathered from many sources:
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Comparative morphology
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Comparative biochemistry
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Amino acid sequences (proteins); nucleotide sequences (RNA
& DNA)
Comparative cytology
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Organism structure & developmental origins
Variation in #, shape, & size of chromosomes
Fossil Record
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Fossil remains showing appearance of morphological
characteristics
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5 Kingdoms
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Monera
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Protista
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Uni- & Multicellular eukaryotic heterotrophs (decomposers)
Animalia
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Unicellular eukaryotes
Fungi
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Unicellular prokaryotes
Now broken into Eukarya (true bacteria) & Archaebacteria
Multicellular eukaryotic heterotrophs
Plantae
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Multicellular eukaryotic autotrophs
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