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Used a hierarchical system
Kingdom, Phylum, Class, Order, Family, Genus, Species (later Domain was added)
Based on molecular evidence (DNA and protein sequences) its accepted to have 6 Kingdoms and have added 3 Domains
Latinized descriptive names of organisms -Binomial Nomenclature: 2 word scientific naming system ◦ First part of binomial – Genus – Always capitalized◦ Second part – species - always lower case.◦ Latin scientific names are always italicized (if word
processing) or underlined (if hand written)◦ Ex. Homo sapiens, “wise man”
• species – specific group of 1 type of organism that may interbreed and produce viable, fertile offspring.
• What do you call this?• Crawdad?• Crawfish?• Crayfish?• Prairie crayfish-Procambarus gracilis
Problems with common names1. Varies from area to area,
therefore, no commonality. 2. Does not specify a particular
species. Each animal has an unique binomial
name. Required for all animals by
International Code of Zoological Nomenclature.
Prokaryotic microbes, tiny
Live in extreme environments: high temps, salts, & acids (tough)
Anaerobic Most primitive
Prokaryotic microbes
Often called the “true bacteria”
Live in most environments
Anaerobic or aerobic
Eukaryotic Mainly aerobic but can be anaerobic Includes all other kingdoms (Protista, Plant,
Fungi, Animal)
36th found Phylum in 1995 In the Animal Kingdom Symbion pandora Found in mouthparts of Norwegian lobsters 0.3 mm long = 300 µm
Currently we use◦ Morphological, biochemical, fossil, and molecular
comparisons to infer evolutionary relationships
Though sedimentary fossils are the most common◦ Paleontologists study a wide variety of fossils
(a) Dinosaur bones being excavated from sandstone
(g) Tusks of a 23,000-year-old mammoth, frozen whole in Siberian ice
(e) Boy standing in a 150-million-year-old dinosaur track in Colorado
(d) Casts of ammonites, about 375 million years old
(f) Insects preserved whole in amber
(b) Petrified tree in Arizona, about 190 million years old
(c) Leaf fossil, about 40 million years old
In general, organisms that share very similar morphologies or similar DNA sequences◦ Are likely to be more closely related than organisms
with vastly different structures or sequences.◦ Not always true! Analogy vs. Homology
Homologous Structures – structures in different species that are similar because of commons ancestry.
• Analogous Structures – similarity in structures due to adaptations and not a common ancestor.
• a method that applies the scientific method to the construction of evolutionary relationships.
Diagram showing how organisms are related based on shared, derived characteristics
such as:◦ vertebrae◦ jaw bones◦ four legs◦ amniotic eggs◦ hair
Branch point◦ 2 species differ in shared derived characters
Ingroup◦ monophyletic group we are interested in
Outgroup◦ species or group of species that is most closely
related to an ingroup
Primate Primate CladogramCladogram
Each branch point◦ Represents the divergence (separation) of two
species
What shared derived character is common to:◦salmon◦lizard◦rabbit◦but not the lamprey?
1. Choose species2. Choose characters
◦ Each character has different character states (example: tail or no tail)
3. Determine order of character states primitive or derived? Use the fossil record Many simple parts came before fewer, more
specialized parts Vestigial organs –not functioning but present) Mutation rate of DNA nucleotides
4. Group species (or higher taxa) based on shared derived characteristics
5. Build a cladogram based on◦ All species are placed on tips in the
phylogenetic tree, not at branch points◦ Each cladogram branch point should have a list
of one or more shared derived characters that are common to all species above the branch point unless the character is later modified
◦ All shared derived characters appear together only once in a cladogram unless they arose independently during evolution more than once
6. Choose the most likely cladogram among possible options
Four limbs Fur No tail
Four limbs Fur Tail
Four limbs Tail
Tail
Four limbs Fur No tail
Tail is the most ancestral Four limbs is the oldest derived trait Fur is a later derived trait Loss of tail is the most derived trait
Gorilla
Tiger
Lizard
Fish
Four Limbs
Fur
Tail Lost
One Possible Cladogram
Chimpanzee
A Vertebrate CladogramBirds
MammalsReptile
Amphibian
Fish
Four Limbs
Amniotic Egg
Endothermic
Fur
Feathers
Vertebrae
LanceletO
utg
rou
p
The outgroup comparison◦ Enables us to focus on just those characters that
were derived at the various branch points in the evolution of a clade.
Sala
mand
er
TAXA
Turt
le
Leop
ard
Tuna
Lam
pre
y
Lance
let
(outg
roup
)0 0 0 0 0 1
0 0 0 0 1 1
0 0 0 1 1 1
0 0 1 1 1 1
0 1 1 1 1 1
Hair
Amniotic (shelled) egg
Four walking legs
Hinged jaws
Vertebral column (backbone)
Leopard
Hair
Amniotic egg
Four walking legs
Hinged jaws
Vertebral column
Turtle
Salamander
Tuna
Lamprey
Lancelet (outgroup)
(a) Character table. A 0 indicates that a character is absent; a 1 indicates that a character is present.
(b) Cladogram. Analyzing the distribution of these derived characters can provide insight into vertebrate phylogeny.
CH
AR
AC
TER
S