Date post: | 18-Dec-2015 |
Category: |
Documents |
Upload: | alice-chrystal-hopkins |
View: | 222 times |
Download: | 2 times |
Chapter 18
Classification
Taxonomy - the science of classifying organisms and giving them a universally accepted name.
Aristotle (384 - 322BC)
Aristotle’s Groups He divided all living things into 2
major groups 1. Plants
classified by size and structure
2. Animals classified by habitat (where they
lived)
HISTORY: Aristotle Problems with his system:
Frogs live in both water and on land
HISTORY: Aristotle Problems with his system:
Bats, birds and flying insects were grouped together
HISTORY: Carolus
Linnaeus- developed the modern system of classification
Father of Taxonomy
Carolus Linnaeus (1707-1778)
MODERN CLASSIFICATION SYSTEM Organisms are grouped
together on the basis of: Similarity in structure
Felis domesticus
Felis rufusPanthera leo
Similarity in structure
Canis lupus
Similarity in structure
Canis latrans
Similarity in structure
Canis domesticus
Organisms are grouped together on the basis of:
Similarity of embryonic development
Organisms are grouped together on the basis of:
Similarity in evolutionary history
Phylogeny: the evolutionary
history of a species based on comparing relationships between species using the fossil record
Organisms are grouped together on the basis of:
Similarity in behavior
Classification is based on close evolutionary relationships of organisms.
Organisms classified in the same taxa (pl.) (taxon, sing.) share a common ancestry. They have evolved from the same common ancestral organism.
Binomial nomenclature - classification system developed by Carolus Linnaeus that assigns each organism a two-part name.
-Scientific name is ALWAYS in italics.
-Scientific name is ALWAYS in Latin.
-First word- CAPITALIZED, second word- lowercase
The first word is the genus in which the animal belongs to and the second word is the species in which the animal belongs to.
-Example- Homo sapiens (Humans)
Binomial Nomenclature
Scientific Name: Rudbeckia hirta
Common Name: Gloriosa daisy
or Black-eyed Susan
Binomial Nomenclature
Scientific Name: Pinus virginianis
Common Name: Virginia Pine
Binomial Nomenclature
Scientific Name: Harmonia axyridis Common Name: Asian Ladybug
Binomial Nomenclature
Scientific Name: Ophiophagus hannahCommon Name: King Cobra
Species Organisms that belong to the
same species can mate AND produce FERTILE offspring.
Horses and donkeys can mate. They produce a mule.
Mules are INFERTILE
+ =
Lions and tigers can mate. They produce a liger.
Ligers are INFERTILE
+ =
Why use scientific names? Common names do not indicate how
organisms are related or classified.
Common names can be misleading.
(e.g., seahorse, weeping willow)
Organisms with more than one common name leads to mass confusion.
Why Latin? Latin is no longer spoken, and
therefore, does not change as spoken languages do.
So, scientific names remain the same forever.
Linnaeus's System of Classification -hierarchical Kingdom Phylum Class Order Family Genus Species -Each of these levels is called a taxon
(taxa)
KingdomPhylum
ClassOrderFamilyGenusSpeci
es
K__________ p__________ c_________
o___________ f________ g_________ s________.
Kings play chess on fine gold sets.
K__________ p__________ c_________
o___________ f________ g_________ s________.
King Phillip came over for great soup.
-The kingdom is the largest of Linnaeus's taxonomic categories.
(Linnaeus named two kingdoms- Animalia and Plantae)
-His system was based on visible similarities and differences
Can you think of any problems with this?
All organisms, living or extinct, are descendants of the first cells. Because they all share a common ancestor, all organisms are related to one another, no matter how different they seem.
Relationships among taxa can be illustrated on a family, or phylogenetic tree.
-The tips of the branches represent the most modern organisms to evolve.
-The base represents common ancestors from which the organisms at the tip evolved.
-Each time a branch divides, it show the emergence of a new ancestral species.
Cladistic analysis - scientific search for ancestral relationships among species.
Cladogram - phylogenetic trees constructed from a two-way branch points that show the evolutionary relationships among a group of organisms.
Derived characters - homologous characteristics that unite the organisms in a group.
When a scientist is in the field and finds an organism they do not recognize, he/she uses a dichotomous key to identify it.
This key is a list of observable traits that eventually lead you to the name of the organism.
The observations are presented as choices.
Kingdoms and Domains Six kingdom system of classification: -Bacteria (Eubacteria) -Archaebacteria -Protist -Fungi -Plant -Animal
Domain Bacteria -polymerases are small and
simple -cell walls contain
peptidoglycan
Domain Archaea comes from a Greek work meaning
"ancient" live in extreme environments polymerases are complex and
similar to eukaryotes cell wall does not contain
peptidoglycan
Domain Eukarya all organisms have a nucleus
(eukaryotes) Protist, Fungi, Plant, and Animal.