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