1 Chapter 18: Classification

2 18–1 Finding Order in Diversity  Life on Earth has been changing for more than 3.5 billion years  1.5 million species named  between 2 and 100 million additional species have yet to be discovered

3 Why Classify?  Organize living things into groups that have biological meaning  Taxonomy = discipline of classifying organisms and assigning each organism a universally accepted name  Taxonomy: Life’s Filing System Taxonomy: Life’s Filing System Taxonomy: Life’s Filing System

4 Assigning Scientific Names  Common names are confusing and vary among languages or even regions –Ex: cougar, mountain lion, panther, puma –different species sometimes share a single common name  Ex: buzzard: hawk? Vulture?  Scientists have agreed to a single name for each species  Use Latin & Greek

5  Carolus Linnaeus, –Swedish botanist, 1700s  Hierarchical –Consists of levels  Includes seven levels –from smallest to largest—species, genus, family, order, class, phylum, and kingdom. –Each level is called a taxon or taxonomic category (plural: taxa) Linnaeus's System of Classification

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7 Humans  Kingdom = Animalia  Phylum (Division for plants) = Chordata  Class = Mammalia  Order = Primates  Family = Hominidae  Genus = Homo  species = sapiens

8  Also developed by Linnaeus  Classification system in which each species is assigned a two-part scientific name –written in italics –first word is capitalized (Genus), the second word is lower case (species) Binomial Nomenclature

9 Scientific Names  Grizzly bear is called Ursus arctos –Ursus — is the genus  Genus = group of closely related species –arctos – is the species  unique to each species within the genus  Often a Latinized description of some important trait of the organism or an indication of where the organism lives –Ursus maritimus, the polar bear  maritimus, referring to the sea

“Creative” Species Names 10 Cephise nuspesez - skipper butterfly Abra cadabra - clam...with magical properties? Agra vation - carabid beetle Cyclocephala nodanotherwon - scarab beetle Malo kingi - jellyfish named after Robert King, American tourist who died in Australia after being stung by it

11  Phylogeny: the study of evolutionary relationships among organisms  Biologists now group organisms into categories that represent lines of evolutionary descent, or phylogeny, not just physical similarities.  Evolutionary classification: method of grouping organisms together according to their evolutionary history

12  The higher the level of the taxon, the farther back in time is the common ancestor of all the organisms in the taxon.

Giant Panda vs. Red Panda   Share common ancestor that lived millions of years ago   Share the same habitat   Eat bamboo   Have extended wrist bone that functions almost like a thumb; aids their grip   Red pandas have been classified with the bear family and raccoon family   Today, Red Pandas are classified as the sole species in family Ailuridae. 13

14  Cladogram: diagram that shows the evolutionary relationships among a group of organisms

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16  Genes of many organisms show important similarities at molecular level  DNA used to help determine classification and evolutionary relationships.  The more similar the DNA sequences of two species, the more recently they shared a common ancestor; the more closely they are related in evolutionary terms.

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18 Dichotomous Key  Tool that allows user to determine the identity of organisms  Uses physical characteristics  A series of choices that lead user to the correct name of a given organism  "Dichotomous" means "divided into two parts“ = gives two choices in each step

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20 18–3 Kingdoms and Domains  There are now 6 Kingdoms – listed below.

21  Domain = most inclusive taxonomic category; larger than a kingdom

22 Eubacteria  Unicellular  Prokaryotic  Autotroph or heterotroph  Cell walls with peptidoglycan  Examples: E. coli, Streptococcus, Staph

23 Archaebacteria  Unicellular  Prokaryotic  Extreme environments –volcanic hot springs, brine pools, and black organic mud totally devoid of oxygen  Auto or heterotroph  Cell walls lack peptidoglycan peptidoglycan

24 Protista  Eukaryotic  Greatest variety  Most single-celled, some multi  Photosynthetic or heterotrophic  Ex: kelp, amoebas, slime mold, paramecium, euglena

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26Fungi  Heterotrophs –feed on dead or decaying organic matter organic matter  Eukaryotic  Most multicellular, some unicellular  Cell walls of chitin  EX: mushroom, yeast

27 Plantae  Multicellular  Photosynthetic autotrophs  Eukaryotic  Cells walls of cellulose

28 Animalia  Multicellular  Heterotrophic  Eukaryotic  No cell walls

29 Kingdom Animalia All members of this kingdom: Are multicellular Are heterotrophic Require oxygen for their metabolism

30 Phylum Chordata Chordates: Bilaterally symmetrical w/distinct heads Have a notochord (a rod-shaped supporting axis, or backbone) at some point in their development

31 Class Mammalia All mammals Have hair Are able to regulate body temperature Have females that can produce milk

32 Order Carnivora Not all eat meat but all have: Well-developed teeth for shredding foods Usually have: Strong limbs, claws and acute senses.

33 Family Ursidae Members of the bear family have: Five toes on each foot; some can walk upright for short distances Intelligent with a great sense of smell

34 Genus Ailuropoda Species melanoleuca Genus Ursus Species arctos

35 Ursus arctos (Grizzly Bear)  Kingdom – Animalia  Phylum – Chordata  Class – Mammalia  Order – Carnivora  Family –Ursidae  Genus –Ursus  species - arctos