ORGANIZING BIODIVERSITY

A SPECIES

How do we define a species?A reproductive population that occupies a specific niche (plays a role) in natureIndividuals within a species share DNA with other individuals within that species, but not outside of itUsually look similar, but not always

SAME SPECIES?

Eastern Meadowlark Western Meadowlark

http://www.nature.com/scitable/content/western-meadowlark-and-eastern-meadowlark-two-distinct-4257520

SAME SPECIES?Chihuahua

Tiny dog

Great Dane

St Bernard

HOW ARE THESE ANIMALS RELATED?Horse Donkey

Mule (and chicken)

http://www.diffen.com/difference/Donkey_vs_Mule

A species is a “reproductive community” (?) – a bunch of living things - that occupy a specific niche in nature. They share DNA with each other (i.e. “interbreed”) and not other species.Some species show such a wide range of phenotypic variations that it is not initially obvious that they share a common gene

pool.Mules are sterile and cannot reproduce.

They are therefore not considered a species – they are hybrids.

SystematicsSystematics is the branch of biology that deals with classifying living things, both current and prehistoric. There are three components:

Taxonomy –describing and naming new taxonomic groupsClassification – organizing information about organisms by arranging them into a hierarchical systemPhylogenetics – determining the evolutionary history and relationships among the various forms of life through time. Relationships among organisms are expressed through diagrams known as cladograms.

THE EVOLUTION OF THE BIOLOGICAL

CLASSIFICATION SYSTEM

ARISTOTLE (384-322 BCE)

created the first widely used classifications system by dividing all organisms into two groups; plants and animals.

Carolus Linnaeus (1707-1778) developed the hierarchical

categorization system: Kingdom

PhylumClass

– Order• Family• Genus• Species

grouped organisms based on their resemblance to other life forms

Linnaeus

Developed the binomial nomenclature system of naming organisms, that is still in use today

The first word of the 2-word name is the Genus nameThe second word is the species nameEg. Homo sapiens (genus is capitalized, species is not)

Anton van Leeuwenhoek (1632-1723)

Invented the light microscopeled to the discovery of a great number of single-celled organisms. – Kindgom Protista.

Electron microscope --mid 1900’s

Led to the discovery of two different types of cells; prokaryotes (bacteria) and the eukaryotes(plants, animals, fungi, protists)five kingdom system 1959:

PlantsAnimalsFungiProtistsMonerans (Bacteria)

Carl Woese (1970s)

Analysis of the base sequence of ribosomal RNA in various bacteria led him to suggest that bacteria be subdivided into two distinct groups, the eubacteria and archaebacteria At first, a six kingdom system was suggested: Kingdom Monera was split into 2 – Kingdom Eubacteria (true bacteria) and Kingdom Archaebacteria

What was the difference that caused the split?

Bacteria ArchaeaAntibiotics kill them Not killed by antibiotics

Heterotrophs Autotrophs

One kind of RNA Several kinds of RNA

Differences in what cell walls are made of

In 1990, Woese proposed the now widely accepted, three domain scheme of classification consisting of:

P la n ts A n im a ls F u n g i P ro tis ts

Eu karya

T ru e B a c te ria

Ba cte ria A rchae

3 D o m a in S ys tem

Domain Archaea (ancient bacteria – think “archaic”) consists of anaerobic bacteria that live in extreme environments such as high temperature or extreme salinity (salty), acidic environments, or produce methane gas

They are all unicellular prokaryotes

Domain Bacteria – “true” bacteria including E.coli, Lactobacillus bulgaris, S. aureus (MRSA) – these are different from Archaea in that their cell walls contain different proteins.

Unicellular, prokaryotes

What about the Kingdoms for the bacteria domains?

Conflicting information online:The original bacteria kingdom, Kingdom Monera, is no longer really a kingdomDomain Archaea – Kingdom ArchaeaDomain Bacteria – Kingdom Bacteria/EubacteriaKingdom names are no longer being used in either domainhttp://www.fossilmall.com/Science/Domains.htm

EukaryaDomain Eukarya – most advanced – contain eukaryotic cells having nuclei and organelles such as mitochondria and chloroplasts

Traditional classification was based on similarities in morphology (structures) among speciesThe fossil record, homologous structures, and embryology determined relationships between organismsCurrent classifications use knowledge of evolutionary relationships. This method is called cladistics – it uses cladograms (branching diagrams based on ancestral traits)

Phylogenetic trees are also used…

http://en.wikipedia.org/wiki/Image:Phylogenetic_tree.svg