Ch 17

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Ch 17
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Classification the grouping of objects or
organisms based on a set of criteria
Linnaeus 1707-1778
Aristole 394-322 B.C.
Used observations of morphology and behavior of
organisms.
1st widely accepted classification system
Red Blood Bloodless
1st formal system of taxonomic organization.
Further divided by habitats and morphology
Taxonomy identifying, naming and classifying
species based on natural relationships.
Limitations assumed species were separate and
unchanging
Binomial nomencature gives species 2 names
Genus species Latin, unchanging language
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Scientific names are helpful 1. Eliminates
confusion with common names 2. Eliminates
confusion by misleading common names Ex.
starfish
Cardinalis cardinalis
Rules???
1. Genus capitalized species small case
2. Typed italicized Handwritten - underlined
3. Once written in full in a text, can be
abbreviated when appears after Ex. C.
cardinalis
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Current classification systems built on Linnaeus
but added evolutionary relationships.
Taxon a level in the classification system
General
Get more alike
Can have subgroups under each
Specific
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Dichotomous Key can be used to identify organisms
Determining Species
1. Typological species concept each species is
a distinctly different group of organisms based
on physical similarities (based on species being
unchanging, distinct, and natural types)
This has been replaced because

• Know members of some species vary greatly
• Know species change over time.

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2. Biological species concept
Theodosius Dobzhansky Ernst Mayr redefined the
term species in the 1930s and 1940s
Species group of organisms that is able to
interbreed and produce fertile offspring in a
natural setting.
Limitations

• Some organisms can interbreed and produce fertile
  offspring though classified as different species
• Does not account for extinct species or species
  that reproduce asexually

Still used today!!!
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3. Phylogenic concept
Phylogeny evolutionary history of a species
Phylogenic concept defines a species as a cluster
of organisms that is distinct from other clusters
and shows evidence of a pattern of ancestry and
descent.
Limitations
1. Evolutionary histories are not known for all
species
Benefits
1. Accounts for extinct species and considers
molecular data
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Characters inherited features that vary among
species
1. Morphological Characters
Homologous characters show an anatomical
similarity inherited from a common ancestor
analogous dont
2. Biochemical Characters
Ex. Chromosomes and nucleotides similarities
show common ancestor
The greater the number of shared DNA sequences
between species, the greater the number of shared
genes the greater the evidence that the species
share a common ancestor.
Molecular Clock model used to compare DNA
sequences from 2 different species to estimate
how long the species have been evolving since
they diverged from a common ancestor.
Differences between genes indicates the presence
of mutations. The more mutations, the more time
has passed since divergence. - Mutation rates
not constant but helpful when combined with the
fossil record.
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Cladistics method to classify organisms
according to the order that they diverged from a
common ancestor.
It reconstructs phylogenies (history) based on
shared characteristics.
2 characters used when doing cladistic analysis

• Ancestral character found within an entire line
  of descent of a group of organisms.

• Derived characters present in only one group of
  the line but not in the common ancestor

Cladogram (phylogenic tree) branching diagram
that represents the proposed phylogeny or
evolutionary history of a species or group.
Clade one branch of a cladogram
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Lilies are more like which species? How many
characters do they share?
Conifer
Lilies
Ferns
Mosses
Flowers (derived char)
Seeds (derived char)
Vascular tissue (derived char)
Ancestor with chloroplasts (ancestral Character)
Node common ancestor
Anchors or roots (ancestral char)
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1. Archae
Classified by cell type and structure
Domain
2. Bacteria
3. Eukarya
Kingdoms

• Bacteria
• Archae
• Protists
• Fungi
• Plantae
• Animalia

Classified by cell type, structure and nutrition
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Archaebacteria
Eubacteria
Kingdom
Moneran
Producer or consumer Number of cells Nucleus
present Can move Example
Both
Unicellular
No- prokaryote
No
Bacteria and Blue Green Bacteria
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Domain Archae
Kingdom Archae
More ancient than bacteria Prokaryote Cell wall
contains no peptidoglycan and have some of the
same proteins as eukaryotes Some autotrophs
most heterotrophs Extremophiles
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Domain Bacteria
Kingdom Bacteria
Prokaryote Cell wall contains
peptidoglycan Some aerobic some anaerobic Some
autotrophs most heterotrophs
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Domain Eukarya contains membrane bound
organelles
Protista
Kingdom
Producer or consumer Number of cells Nucleus
present Can move Example
Both
Unicellular, colonial, or multicellular
Yes, eukaryote
Yes Animal-like No Plant-like No Fungi
-like
Ameba and Paramecium
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Fungus Algae Lichen
Fungi
Kingdom
Producer or consumer Number of cells Nucleus
present Can move Example
Consumers absorbs nutrients from organic
material in environment
One - yeast but rest are multicellular
Yes, eukaryote
No
Mushrooms and Puff balls
Have cell walls with chitin. Hyphae are
thread-like filaments that make up fungus
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Plant
Kingdom
Producer or consumer Number of cells Nucleus
present Can move Example
Producers
Multicellular
Yes, eukaryote
No
Fern and Tree
Cell walls with cellulose. Have chloroplasts for
photosynthesis.
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Animal
Kingdom
Producer or consumer Number of cells Nucleus
present Can move Example
Consumer
Multicellular
Yes, eukaryote
Yes
Dog and Starfish
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Virus
Nucleic Acid surrounded by a protein coat.
No cells and not cellular
Not living
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Prokaryote Eukaryote Saprobe Parasite Heterotrophi
c Autotrophic Aerobic Anaerobic