Bio Lecture 2 Basic Classification and taxonomy

taxonomy

The science of classifying organisms

Why should we classify organisms?

• gives some order to the estimated 9 million species of organisms alive on earth

• Only 2 millions species have been identified/ named

• Groups organisms in a logical manner. similoiratities based on physical traits, molecular signatures, evolutionary history (phylogeny), etc.

• Gives organisms a universal name

• prevents misnomers

• The species name is usually the same in different languages

• Organisms with multiple common names will have a single species name .

Carolus Linnaeus (1707-1778): The Father of Modern Taxonomy

• Swedish biologist who developed a simple system for naming organisms

• Categorized organisms based on morphology (structure and function).

hierarchy of Biological Classification

• Kingdom (Bottom)

• phylum

• class

• order

• family

• genus

• species (top)

Taxon

A single level in the taxonomic classification system

Binomial nomenclature

• developed by carols linnaeus

• still the basis for modern taxonomy

• a two name system for naming all species

• 1st word= genus name

• 2nd word= specific epithet( descriptor) aka scientific name

• ALWAYS italicized (or underlined if hand written)

Canis lupus

Today’s system of taxonomic classification

• based on evolutionary relationships or organisms

• Phylogeny: evolutionary history and relationships of an organism or a group of organisms

• Today: phylogeny is the basis of biological classification

How can we study evolutionary history?

• can look at extinct and living (extant) species

• fossil record

• Morphology

• DNA/ molecular analyses

Homologus structures

structures in different organisms that share a common ancestor

analogous structures

structures in different organisms that share a similar function

homoplasy

structures that in different organisms that look similar

Homolongus structures

structures that share a common ancestor

Analogus structures

Structures that share a similar function

• structures may differ in size, shape, number, etc

• Analogous structures may or may not share a common ancestor

Homoplasy

structure that look similar

• structures may differ in size, shape, number, function, etc

• Organisms with homoplasy may or may not share a common ancestor