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Classification of Organisms Chapter 18. 18.1. Finding order in Diversity. Grouping organisms according to characteristics & evolutionary history Groups are called taxa/taxon. Taxonomy or Systematics. The History of Taxonomy? FYI.
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18.1 Finding order in Diversity
Grouping organisms according to characteristics & evolutionary history Groups are called taxa/taxon Taxonomy or Systematics
The History of Taxonomy? FYI • Started 2,000 years ago; Aristotle grouped living things by STRUCTURAL similarities • Greeks and Romans grouped into basic categories like OAKS, DOGS, HORSES
Then it got messy… FYI • Until mid 1700s, scientists just added descriptive Latin phrases to the group name • The honeybee’s scientific name (at the time) was Apis pubescens, thorace subgriseo, abdomine fusco, pedibus posticis glabis, untrinque margine ciliatus
Carolus Linnaeus • 1753 • Developed a 4 level system of classification and binomial nomenclature (two-name designation) • Most organisms he described still have the same scientific name, however there are now 7 levels of classification!
Levels of Classification • All organisms have the following: K – Kingdom (most general) P – Phylum (phyla) C – Class O – Order F – Family G – Genus (genera) S – species (most specific)
Phylum • Consists of groups of Classes
Class • Can you guess what is in a class?
What is a species? • a group of organisms that will only mate with themselves • Must produce fertile offspring
How many species do we recognize? • About 2 million identified FYI • Reptiles 8,163 • Amphibians 5,699 • Birds 10,000 • Mammals 4,629 • Insects 900,000 • Vascular Plants 270,000 • May be 5-100 million on earth
Binomial Nomenclature • Includes Genus and species (and sometimes subspecies) • italicized or underlined • Genus is Capitalized and species is not
Examples FYI • Canis lupus or Canis lupus • Pseudacris crucifer crucifer or Pseudacris crucifer crucifer • Falco sparverius or Falco sparverius
Examples FYI • Once a scientific name has been identified, the Genus can be abbreviated • C. lupus or C. lupus • P. crucifer crucifer or P. crucifer crucifer • F. sparverius or F. sparverius
Honey bee (Apis mellifera) FYI • Kingdom – Animalia • Phylum – Arthropoda • Class – Insecta • Order – Hymenoptera • Family – Apidae • Genus – Apis • Species – mellifera
Blue-banded bee (Amegilla cingulata) • Kingdom – Animalia FYI • Phylum – Arthropoda • Class – Insecta • Order – Hymenoptera • Family – Apidae • Genus – Amegilla • Species – cingulata
Green sea turtle (Chelonia mydas) • Kingdom – Animalia FYI • Phylum – Chordata • Class – Reptilia • Order – Testudines • Family – Cheloniidae • Genus – Chelonia • Species – mydas
Mexican mud turtle FYI (Kinosternon integrum) • Kingdom – Animalia • Phylum – Chordata • Class – Reptilia • Order – Testudines • Family – Kinosternidae • Genus – Kinosternon • Species – integrum
Chimpanzee (Pan troglodytes) FYI • Kingdom – Animalia • Phylum – Chordata • Class – Mammalia • Order – Primates • Family – Pongidae • Genus – Pan • Species – troglodytes
Human (Homo sapiens) FYI • Kingdom – Animalia • Phylum – Chordata • Class – Mammalia • Order – Primates • Family – Hominidae • Genus – Homo • Species – sapiens
Homework!!! • Classify any 2 organisms with all 7 levels of classification • Then write the organism’s binomial nomenclature with the correct format • Do NOT cut and paste text!!! • You may include pictures (optional) • Include citations for your work!
18.2 Modern Evolutionary Classification
The Debate! • DNA technology has turned classification upside down linking organisms that you wouldn’t expect to be related! • It is causing scientists to rethink the grouping of organisms.
Phylogeny • Evolutionary history of an organism • Similar traits may indicate a common ancestor!
Cladistics • Reconstructs phylogenies • In chronological order • Looks at traits and common ancestors • Often only indicates if a trait does or does not exist (ex: shell or no shell)
Cladogram Image: http://biology.unm.edu/ccouncil/Biology_203/Images/Phylogeny/ReptileCladogram1.jpg
18.3 Building the Tree of Life
Kingdoms or Domains? FYI Taxonomists traditionally used a 5 kingdom system to classify organisms Based on molecular information, today more taxonomists are leaning toward a 3 domain system
The 6 Kingdoms Archaebacteria Eubacteria Protista Fungi Plantae Animalia
Archaebacteria Unicellular prokaryotes that can survive harsh conditions Eubacteria • Unicellular prokaryotes that can not survive harsh conditions
Protista All unicellular eukaryotes AKA protozoa Catch all for misfits!!
Fungi Multicellular eukaryote Heterotrophic eats dead organic matter for nutrients
Plantae Multicellular eukaryotes that are autotrophic
Animalia Multicellular eukaryotes that are heterotrophic