A. Taxonomy Defined1. Grouping of organisms - the science of

classifying living organisms based on sharedfeatures

2. Principles of classification – the practice or principles of classification

3. Study of classification – the study of the rules and practice of classifying living organisms

QUESTION:

Would you also consider that taxonomy deals with IDENTIFICATION of living organisms? Why or why not?

Taxonomy involves: 1. Classification – ranking of groups of

organisms in some hierarchical relationship

- based on their similarities in their characteristics (genetic relationship, internal and external anatomy, physiology or evolutionary history)

2. Identification – separation of one group from other groups according to their uniquecharacteristics

Identifying organisms based on their morphology, anatomy, physiology, cytology, biochemistry and geographic distribution

WHAT ARE THE ROLES of TAXONOMISTS and SYSTEMATICISTS?

To classify, identify and make a census of the unique characteristics of each species.

To reconstruct the evolutionary history of the present classified species based on morphology, anatomy, chemical composition, geographic distribution, breeding behavior, and chromosome number

To determine which traits are advanced(derived in time from primitive traits) or primitive

To discover all species of animals.

To reconstruct their evolutionary relationships.

To classify animals according to their evoutionary relationships.

Unexplored areas, only an estimation could be done

Continuous evolution process (diversification)

Continuous extinction

How about in local settings?

300 BCAristotle – used dichotomies or polar opposites Ex. Animals with blood and without blood

(vertebrates and invertebrates) - wrote extensively on both plants

and animals but his writings on plants were lost

Theophrastus – Aristotle’s pupil and applied his approach to the study of plants in his work “Inquiry into Plants”

Theophrastus – subdivided plants based on shape, and into broad categories as trees, shrubs, and herbs

Dioscorides – developed a more practical approach

- Ex. Medicinal herbs were separated from those used in making perfumes

Polynomial System

-translation of the common names of organisms into Latin

-each species was described in Latin by a sentence limited to 12 words that begins with the genus name

-Ex. Spiderwort -Tradescantia ephemerum phalangoides tripetalum non repens virginianum gramineum

Common name: Tradescantia virginiana

Translation: The annual, upright Tradescantia from Virginia which has a grasslike habit, 3 petals, and stamens with hairs like spider legs, common name Tradescantia of Virginia

But the polynomial system was simplified into a two-word or BINOMIAL naming system in the mid-16th century to mid-17th century by a group of naturalists known as herbalists.

Andrea Cesalpino – first scientist to classify plants primarily according to structuralcharacteristics, such as their fruits and seeds

Caspar Bauhin – adapted Cesalpino’s method; catalogued an extensive list of plants

Animal Classification Advanced

Pierre Belon

– extensively studied and catalogued birds

-first to use adaptation to habitat to divide birds as AQUATIC, WADING, PERCHING, and LAND BIRDS and BIRDS of PREY

John Ray – used key characteristics such as the shape and size of the birds’ beak to classify birds

MID 1700s

Carolus Linnaeus

Binomial system of nomenclature – similar organisms are grouped into a genus, and each organism is given a two-word Latin name

Carolus Linnaeus

Binomial nomenclature

first name – genus name

second name – adjective describing the organism, its geographic location or the person who discovered it

Ex. domestic dog

Canis familiaris

Canis – genus name for the group of animals that includes dogs, wolves, coyotes, and jackals

familiaris – acts as a descriptor to further differentiate the domestic dog from its wild cousins

Carolus Linnaeus – also designed the HIERARCHICAL classification scheme

Kingdom

Phylum

Class

Order

Family

Genus

Species

Development and use of microscopes presented new classification problems which still relied on a 2-kingdom classification system (Plantae and Animalia

Charles Darwin

-published “On the Origin of Species” in 1859

-argued that classification system should reflect the history of life; species should be related based on their shared ancestry

-emphasis on taxonomy shifted to:

a. A search for characters which reflected genetic (evolutionary) relationships; and

b. The construction of a phylogenetic classification scheme

Phylogenetic – based on genetic, evolutionary relationships

- which traits are primitive or advanced

Ernst Haeckel

-proposed placing the unicellular forms in kingdom Protista; placed bacteria within this kingdom

1930s

Edouard Chatton – distinguished prokaryotes and eukaryotes

Herbert Copeland

-prokaryotes in the 4th kingdom, Monera

1950s

Robert Whittaker

-proposed adding a 5th kingdom, Fungi

1970s

Advances in molecular systematics

Polymerase chain reaction – permits easy analysis and comparison of DNA structures

Carl Woese – determined that archaebacteria were found to have unique molecular structures and physiological characteristics from bacteria

-proposed a 6-kingdom classification system

Other scientists propose an 8-kingdom system

Modern animal taxonomy was established using evolutionary systematics and recent cladistic revisions.

PhyloCode

-new taxonomic system

-being developed as an alternative to Linnaean taxonomy

-replaces Linnaean ranks with codes that denote nested hierarchy of monophyletic groups converged by cladograms

The terms “primitive”, “advanced”, “specialized”, and “generalized” are used for specific characteristics and not for groups as a whole.