Transcript File - Mr.Nolan`s Science Class`s

Taxonomy
Taxonomy
• Common names
• Have evolved over centuries in a multitude of
languages
• Sometimes used only in a limited geographical
area
• Problem with common names:
• One plant may be known by several names in
different regions, and the same name may be
used for several different plants…
The science of classification
Taxonomy - study of classifying organisms
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Taxonomists are scientists who study classifying
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Taxon ( taxa-plural) is a category into which
related organisms are placed
Why do we need a system of classification?
- brings order
- logical means of naming organisms
- scientific names are understood globally
common names are regional, not specific, and can be
misleading
ex) puma, cougar and mountain lions are the same
organism
ex) ringworm and mealworms are not actually worms
Mountain lion
cougar
puma
Ringworm
Mealworms
Aristotle
divided organisms into two groups
plants: classified them on the basis of structure and size
animals: subdivided them on the basis of where they live
Carolus Linnaeus
Swedish botanist who developed a classification system based on structural
features.
seven taxa
Kingdom: broadest category
Phylum (division in plants)
Class
Order
Family
Genus
Species: most specific; one type of organism
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A sentence to help remember these taxa is
--- "King Phillip Came Over For Gooseberry Soup."
Carolus Linnaeus
• Swedish scientist – Carl von Linne
(doctor and botanist)
born in 1707.
• Called the “Father of Systematic Botany”
• Established modern system of nomenclature
Linnaeus
• Carolus Linnaeus used risque language for his
time…
• Classifying plants by their flowers, he compared
flower parts to human sexuality: stamens were
husbands (many) and the pistil was the wife – the
flower was the bed!
• Many were shocked. Dr. Johann Siegesbeck:
“such loathesome harlotry as several males to one
female would not be permitted by the creator…
Who would have thought that bluebells, lilies and
onions would be up to such immorality?”
Linnaeus legacy
His binomial system of nomenclature, in
which the genus and species names are
used.
He classified 12,000 plants and animals,
published Systema Naturae in 1753, and
many of the names he first proposed are still
in use today…
Species name
Each species has a single correct scientific name in
Latin called a binomial (two names) – it is always
italicized or underlined.
First name is genus name.
Second name is species name
Human: Homo sapiens
Cat:
Felis catus
Dog: Canis familiaris
Wolf: Canis lupus
Examples
Genus of maple trees is Acer
It has many species including:
Common name
“Red maple”
“Sugar maple”
“Black maple”
Scientific name
Acer rubrum
Acer saccharum
Acer nigrum
4 Basis for Modern taxonomy:
Modern taxonomists classify organisms based on their evolutionary relationships
1. Homologous structures have the same structure, but different
functions & show common ancestry
The bones in a bat's wing, human's arm, penguin's flipper are the
same (homologous), but the function is different
2. Analogous structures have the same function, but different
structures & do not show a close relationship (insect wing & bird's
wing)
3. Similarity in embryo development shows a close relationship
(vertebrate embryos all have tail & gill slits)
4. Similarity in DNA & amino acid sequences of proteins show
related organisms
Homologous structures
Analogous structures
6 KINGDOMS
• Living organisms are classified in five
kingdoms:
• Animalia: animals
• Plantae: plants
• Fungi: fungi
• Protista: algae
• Monera: 2 bacteria kingdoms
– Eubacteria and Archaebacteria
What is a species?
Species: a set of individuals that are closely
related by descent from a common ancestor
and ordinarily can reproduce with each other,
but not with members of any other species.
Biological species: a group of interbreeding
populations. Offspring are fertile.
Species
Some members of same species look very
different…
Same species, are capable of interbreeding, but
Morphologically look very different.
All these are same species!
Examples in plants: species of oaks and sycamores;
Broccoli, kale, cabbage, califlower: members same
species! Brassica olearea
Definition of species
• However, some plants look the same, but
due to polyploidy
(more than the diploid number of
chromosomes), they cannot interbreed.
• For example: Ferns; evening primrose