Scientific Naming, Cladograms, Dichotomous Keys, Taxonomy, Natural Selection, & Evidence of Common Ancestry

Some organisms have several common names

This cat is commonly known as:

•Florida panther

•Mountain lion

•Puma

•CougarScientific name: Felis concolor

Scientific name means “coat of one color”

Why Scientists Assign Scientific Names to Organisms?

• Binomial Nomenclature - Allows scientists to give each organism a universally accepted two-part name. • The first part of the name is the Genus. • The second part of the name is the Species. • Example: “Homo” is the Genus, “sapiens” is

the species; The scientific name for humans is Homo sapiens

Binomial Nomenclature

Kingdom

Phylum

Class

Order

Family

Genus

Species

Levels of Classification

Most General

Most specific

King Philip came over for good

sweets!

Grizzly bear Black bear Giant panda

Red fox Abert squirrel

Coral snake

Sea star

KINGDOM Animalia

PHYLUM Chordata

CLASS Mammalia

ORDER Carnivora

FAMILY Ursidae

GENUS Ursus

SPECIES Ursus arctos

Hierarchical Ordering of Classification

As we move from the kingdom level to the

species level, more and more members are

excluded – species is least inclusive!

Cladogram• Diagram used to show the evolutionary

relationships among groups of organisms based on derived characteristics.

Derived Characteristics• Evolutionary descent is determined based on

derived characteristics, which are new traits that appear as organisms evolve over time

• The more derived characteristics that they share, the more closely related they are.

Jaws, lungs, claws, feathers, and fur are all examples of derived characteristics!

Dichotomous Keys

• A tool for identifying unknown organisms using a key consisting of paired questions based on observable characteristics.

• Steps:1. Always begin with

the first question2. Answer the paired

questions with yes or no

3. Based on your answers, follow the directions given by the key

Example of a Dichotomous Key

• Identify the unknown insect using the dichotomous key.

Example of a Dichotomous Key

• Identify the unknown insect using the dichotomous key.

Classifying OrganismsOrganisms are divided into 3 domains and 6 kingdoms based on the following characteristics

1. Cell Type: Prokaryotic vs. Eukaryotic• Prokaryotic - No nucleus• Eukaryotic - nucleus

2. Cell Structure: Components of Cell Wall3. Number of cells: Unicellular vs. Multicellular

• Unicellular - One cell • Multicellular - More than one cell

4. Nutrition: Autotrophic vs. Heterotrophic• Autotrophic - makes their own food• Heterotrophic - must consume food

Animalia Kingdom (Domain Eukarya)

• Cell Type: Eukaryotic• Cell Wall: No Cell Wall• Body Type: Multicellular• Nutrition: Heterotrophic• Examples: humans, dogs, sharks, fish, snakes

Plantae Kingdom (Domain Eukarya)

• Cell Type: Eukaryotic• Cell wall contains Cellulose• Body Type: Multicellular• Nutrition: Autotrophic• Examples: corn, ferns, roses, pine tree

Fungi Kingdom(Domain Eukarya)• Cell Type: Eukaryotic• Cell wall contains Chitin• Body Type: Multicellular, except yeast

which is unicellular• Nutrition: Heterotrophic• Are Immobile (cannot move around)• Examples: Yeast, morel, earthstar

puffball, bread mold, mushrooms• All fungi are heterotrophic

decomposers which externally digest dead matter

Protista Kingdom (Domain Eukarya)• Cell Type: Eukaryotic• Cell Wall: Cellulose (some)• Body Type: Unicellular, except algae

which are multicellular• Nutrition: Autotrophic &

Heterotrophic• Are Mobile (can move around)• Examples: Paramecium, euglena,

algae

Eubacteria Kingdom (Domain Bacteria)

• Cell Type: Prokaryote• Cell wall contains Peptidoglican• Body Type: Unicellular• Nutrition: Autotrophic and Heterotrophic• Examples: E. coli, streptococcus, & staphylococcus

Archaebacteria Kingdom (Domain Archae)• Cell Type: Prokaryote• Cell walls do not contain

peptidoglycan• Body Type: Unicellular• Nutrition: Autotrophic &

Heterotrophic• Examples: Live in extreme

environments• Thermophiles – Extreme

temperatures• Halophiles – Extreme salinity

Evolution Occurs by Natural Selection1. Struggle for existence exists in

nature • Competition among members of a species exist for

food, living space, and the other necessities of life.

2. Survival of the Fittest – Individuals that are better suited to their environment – that it, with adaptations that enable fitness –survive and reproduce more successfully; Darwin referred to this as natural selection

Natural Selection• Over time, natural selection

results in changes in the inherited characteristics of a population. These changes increase a species' fitness in its environment.

• Takes place without human control or direction.

• Natural selection cannot be seen directly; it can only be observed as changes in a population over many successive generations.

Evidence of Evolutioncomes primarily from these sources….

1. Fossil record 2. Geographical distribution of living species3. Structural similarities of related life forms4. Chemical similarities in DNA5. Embryology