Taxonomy

Taxonomy

The systematic ordering and naming of organisms

Carl Linnaeus (1707-1778)

• Swedish botanist

• A christian who began his published works by praising God as the “Almighty Creator and Preserver of all things.”

• Published: Species Plantarum and Systema Naturae

Carl Linnaeus (pt. 2)

• proposed the binomial (2 part) naming system

• Developed the 1st workable classification system

• Kingdom - Species

Polynomial

Before the late 1700s plants and animals were named using Latin phrases with 8 or more words

Binomial system

All organisms have 1 binomial name and no other organism shares that name

Genus

First letter capitalized

Specific epithet

First letter always lower case

Genus & specific epithet

Both are either in italics or underlined

Species

Members must form a reproductive community that excludes members of other species

Sibling (cryptic) species

species that are too similar in morphology to be separated by morphological characters alone.

Morphology

The study of an organism’s structure

Characters

The features of an organism (wings, legs, tails, shells, etc.)

Type specimens

Specimens that are labeled and deposited in a museum at the time that the species is first described. Serve as guides to the general morphological features that are important in identifying the species.

Holotype

A single specimen that is clearly designated in the original description of the species (name bearing type) and is placed in a major museum.

Paratypes

Each type specimen other than the holotype referred to in the original species description. These are located in the museum’s research collection.

DNA Barcoding

A technique for identifying organisms to species using sequence information from a standard gene present in all animals.

The standard “barcode” region

The mitochondrial gene encoding cytochrome c oxidase subunit 1(COI)

COI

Varies among individuals of the same species but not as much as it varies between individuals of different species.

The two traditional science kingdoms

• Animalia: Protozoa, Sponges, and multicellular animals

• Plantae: everything else

Robert Whittaker (1969)

A plant ecologist who proposed a 5 kingdom classification system which is still used by many biologists.

The five kingdoms

• Monera (bacteria)

• Protista

• Fungi

• Plantae

• Animalia

Carl Woese (1980s)

A microbiologist proposed a 6 kingdom system which is becoming more and more widely adopted.

Six kingdoms

• archaea

• Bacteria

• Protista

• Fungi

• Plantae

• Animalia

Domain Archaea

Prokaryotes that differ from bacteria in membrane structure and ribosomal RNA sequences.

Domain Bacteria

Prokaryotes (lack organelles and nuclear membrane)

Domain Eukarya

Eukaryotes (has organelles and a nuclear membrane.

Kingdoms (in Domain Eukarya)

Protista, Fungi, Plantae, and Animalia

Classification categories (mostly proposed by Linnaeus)

Kingdom, Phylum, Class, Order, Family, Genus, Species

Category

Taxon (pl. taxa)

KPCOFGS

King Philip Came Over From Great Spain

Kings Play Chess On FiberGlass Stools

Taxonomists

People who specialize in identifying, naming and classifying organisms. Construct dichotomous keys to help others identify organisms.

Systematists

Taxonomists that use evolutionary theory to try and establish relationships between different groups.

Phylogenetic systematics (Cladistics)

A system of arranging taxa by analysis of evolutionarily derived characteristics so that the arrangement reflects phylogenetic relationships.

Phylogeny

The origin and diversification of a taxonomic group.

Phylogenetic tree

A diagram whose branches represent evolutionary lineages.

Ancestral character state

A character presumed to be present in the common ancestor of the entire taxon of interest.

Derived character state

A character presumed to have arose later within the taxon.

Clade

• A subset of species that share derived character states

• Forms a distinct branch on a phylogenetic tree

Synapomorphy

A derived character state shared by members of a clade.

Cladogram

A nested hierarchy of clades presented as a branching diagram.

Monophyletic taxon

Includes the most recent common ancestor of the group and all the descendants of that ancestor (the goal of cladistics)

Paraphyletic taxon

Includes the most recent common ancestor of all members of the group and some but not all descendants of that ancestor.

Polyphyletic taxon

Does not include the most common ancestor of all members of a group.

Phylogenetic analysis

Depends upon finding among organisms shared features that are proposed to have been inherited from a common ancestor.

Homologous structures

Structures that are proposed to have been passed on from a common ancestor because they are similar in structure. (Aka evidence of variations on a common design)

Analogous structures

Similar in function, but structurally unrelated.