BASICS OF BIOLOGICAL CLASSIFICATION

Prokaryotic Cell

Eukaryotic Cell

Autotrophs capture the light energy from sunlight and convert it to chemical energy they use for food.

Heterotrophs must get energy by eating autotrophs or other heterotrophs.

Decomposers, aka saprobes, are heterotrophs that recycle dead organisms by breaking them down.

• Phylogeny• Systematics Hypothesis

• Cladistics • Derived character

• Cladogram • Dichotomous Key

• Classification

• Taxonomy• Aristotle• Linnaeus • Kingdom• Phylum • Class

• Order• Family • Genus• Species• Common name• Scientificname• Binomial nomenclature

• Taxonomy is the science of grouping

and naming organisms.

• Classification the grouping of information or objects based on similarities.

Why use a dead language?

•We only know about a fraction of the

organisms that exist or have existed on Earth.

•Taxonomists give a unique scientific name to

each species they know about whether it’s alive today or extinct.

• The scientific name comes from one of two

“dead” languages – Latin or ancient Greek.

Devil Cat

Ghost Cat

Mountain Lion

Screaming Cat

Puma

Florida Panther

Cougar

•There are at least 50 common names for the animal shown on the previous 7 slides.

•Common names vary according to region.

•Soooo……why use a scientific name?

    • a two name system for writing scientific names.

• The genus name is written first (always Capitalized).    

• The species name is written second (never capitalized).    

• Both words are italicized if typed or underlined if hand

written.

Example: Felis concolor or F. concolor

Which is the genus? The species?    

Binomial Nomenclature

"Formal" scientific names should have a third part, the authority.     The authority is not italicized or underlined.

The authority is written as an abbreviation of the last name of the person responsible for naming the organism. Since Carolus Linnaeus was the first person to name many plants, the L. for Linnaeus is very common in plant scientific names.

An example is Quercus alba L.

Phylogeny, the evolutionary history of an organism, is the cornerstone of a branch of biology called systematic taxonomy.

Systematics, as systematic taxonomy is commonly called, is the study of the evolution of biological diversity.

                        

A phylogenetic tree is a family tree that shows a hypothesis about the evolutionary relationships thought to exist among groups of organisms. It does not show the actual evolutionary history of organisms.

Why a hypothesis?

Phylogenetic trees are usually based on a combination of these lines of evidence:

    Fossil record

    Morphology

    Embryological patterns of development

    Chromosomes and DNA

Fossil

Morphology

Homologous Structures

Adaptive Radiation -

modifies

homologous

structures

Modifies homologous structures

http://www.sciencecartoonsplus.com/

These animals have evolved similar adaptations for obtaining food because they occupy similar niches. What can you infer about their phylogeny from their geographic locations?

Convergent Evolution

Analogous Structures  - 

•Traits that are morphologically and

functionally similar even though there is no common ancestor.

Convergent evolution leads to……….

Embryology

Cladistics - is a relatively new system of phylogenetics classification that uses shared derived characters to establish evolutionary relationships. A derived character is a feature that apparently evolved only within the group under consideration.

DNA

There are three basic assumptions in cladistics:

1.Organisms within a group are descended from a common ancestor.

2.There is a bifurcating pattern of cladogenesis.

3.Change in characteristics occurs in lineages over time.

A phylogenetic tree based on a cladistic analysis is called a cladogram.

What derived character is shared by all the animals on the cladogram on the next slide?

The acacia and its ants are an example of coevolution. Eachinfluences the others evolution.

Can you think of any other examples ofcoevolution?

Punctuated Equilibrium

“instead of a slow, continuous movement, evolution tends to be characterized by long periods of virtual standstill ("equilibrium"), "punctuated" by episodes of very fast development of new forms”

The "punctuated equilibrium" theory of Niles Eldredge and Stephen Jay Gould was proposed as a criticism of the traditional Darwinian theory of evolution…what is it called?

• A key is a device for easily and quickly identifying

an unknown organism.

• The dichotomous key is the most widely used type in biological sciences.

• The user is presented with a sequence of choices between two statements, couplets, based on characteristics of the organism. By always making the correct choice, the name of the organism will be revealed.

The Dichotomous Key

                                                         

   

1.  

A. one pair of wings

B. Two pairs of wings

The Three Domains• Domain Archaea– Includes newly discovered cell types – Contains 1 kingdom – the Archaebacteria

• Domain Bacteria– Includes other members of old kingdom

Monera – Has 1 kingdom – the Eubacteria

• Domain Eukarya– Includes all kingdoms composed of organisms

made up of eukaryotic cells

– Protista – Fungi – Animalia – Plantae

The major classification levels,from most general to most specific

(several of these have subdivisions)

A group at any level is a taxon.

Kingdoms are divided into groups called phyla Phyla are subdivided into classes

Classes are subdivided into orders

Orders are subdivided into families

Families are divided into genera Genera contain closely related species

Species is unique

Categories within Kingdoms