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5.3 Biodiversity of classification (Hierarchy of taxa (Phylum, Class,…
5.3
Biodiversity of classification
Terms used
Taxonomy
The science of identifying, naming and grouping of organisms
Binomial system of nomenclature
Genus
- indicates a group of species that are closely related and share a common ancestor
Must come first and
capitalised
Species
- a group of individuals that are capable of interbreeding to produce fertile offspring
Written in lower case
Some may have sub-species designation
Advantages
can show how closely related organisms are, allowing for the prediction of evolutionary links
makes it easier to collect, sort and group information about organisms
allows all organisms to be named according to a globally recognised scheme
Allows for the identification and comparison of organisms based on recognised characteristics
Classification
A method of organizing living organisms into groups to show similarities and differences between them
Types of classification
Natural
change of clasification
due to discovery of new information
advantages
To predict characteristics
To identify evolutionary relationships
To give each species a unique and universal name
involves
grouping organisms based on similarities first and then identifying shared characteristics
Artificial
advantage
easy to develop and relatively stable
disadvantage
evolutionary relationships are not generally shown
involves
arbitrarily selecting unifying characteristics first and then grouping organisms accordingly
Phylogenetic
now being used to differentiate organisms based on genetics
Dichotomous keys
How to do it
Consists of pairs of observable description
2 divisions
If clearly matched
it's decided or go to the next corresponding numbers
If clearly wrong
go to the next corresponding number
method of identification whereby groups of organisms are divided into two categories repeatedly
Hierarchy of taxa
Phylum
Class
Kingdom
Order
Domain
Family
Genus
Species
organisms that share a lower taxa must share all higher taxa
Living organisms classified into 3 groups
Archae
Examples - methanogens, thermophiles,
prokaryotic cells lacking a nucleus and consist of the extremophiles
Eubacteria
prokaryotic cells lacking a nucleus and consist of the common pathogenic forms
Examples - E. coli, S. aureus
Eukarya
eukaryotic organisms that contain a membrane-bound nucleus
Includes protist, plants, fungi and animals
Originally, Archae and Eubacteria were considered only as a single kingdom (Monera) but biochemical differences were discovered between the two groups
Plant Phyla
Plant Phyla Recognition Features table
Animal Phyla
Invertebrates
porifera, cnidaria, platyhelmintha, annelida, mollusca and arthropoda
Vertebrates
All vertebrates belong to the phylum chordata (however not all chordata are vertebrates)
Invertebrate Phyla Recognition Features Table