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1 Chapter 18: Classification. 2 18–1 Finding Order in Diversity Life on Earth has been changing for more than 3.5 billion years Life on Earth has been.

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Presentation on theme: "1 Chapter 18: Classification. 2 18–1 Finding Order in Diversity Life on Earth has been changing for more than 3.5 billion years Life on Earth has been."— Presentation transcript:

1 1 Chapter 18: Classification

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

3 3 Why Classify? organize living things into groups that have biological meaning organize living things into groups that have biological meaning Taxonomy = discipline of classifying organisms and assigning each organism a universally accepted name Taxonomy = discipline of classifying organisms and assigning each organism a universally accepted name

4 4 Assigning Scientific Names Common names are confusing and vary among languages or even regions 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? Ex: buzzard: hawk? Vulture? Scientists have agreed to a single name for each species Scientists have agreed to a single name for each species Use Latin & Greek Use Latin & Greek

5 5 Binomial Nomenclature Carolus Linnaeus, Carolus Linnaeus, –a Swedish botanist, 1700s binomial nomenclature = classification system in which each species is assigned a two-part scientific name binomial nomenclature = classification system in which each species is assigned a two-part scientific name –written in italics –first word is capitalized, the second word is lower case

6 6 Scientific Names grizzly bear is called Ursus arctos grizzly bear is called Ursus arctos –Ursus is the genus Genus = group of closely related species Genus = group of closely related species –arctos – is the species unique to each species within the genus 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 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 maritimus, referring to the sea

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8 8 Linnaeus's System of Classification Hierarchical - it consists of levels Hierarchical - it consists of levels includes seven levels includes seven levels –from smallest to largestspecies, genus, family, order, class, phylum, and kingdom. –Each level is called a taxon or taxonomic category

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10 10 Ursus arctos (Grizzly Bear) Kingdom – Animalia Kingdom – Animalia Phylum – Chordata Phylum – Chordata Class – Mammalia Class – Mammalia Order – Carnivora Order – Carnivora Family –Ursidae Family –Ursidae Genus –Ursus Genus –Ursus species - arctos species - arctos

11 11 Humans Kingdom = Animalia Kingdom = Animalia Phylum (Division for plants) = Chordata Phylum (Division for plants) = Chordata Class = Mammalia Class = Mammalia Order = Primates Order = Primates Family = Hominidae Family = Hominidae Genus = Homo Genus = Homo species = sapiens species = sapiens

12 12 Taxonomic groups above the level of species are invented by researchers who decide how to distinguish between one genus, family, or phylum, and another. Taxonomic groups above the level of species are invented by researchers who decide how to distinguish between one genus, family, or phylum, and another.

13 13 Phylogeny = the study of evolutionary relationships among organisms 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. Biologists now group organisms into categories that represent lines of evolutionary descent, or phylogeny, not just physical similarities.

14 14 evolutionary classification = method of grouping organisms together according to their evolutionary history evolutionary classification = method of grouping organisms together according to their evolutionary history

15 15 The higher the level of the taxon, the farther back in time is the common ancestor of all the organisms in the taxon. The higher the level of the taxon, the farther back in time is the common ancestor of all the organisms in the taxon.

16 16 Cladogram = diagram that shows the evolutionary relationships among a group of organisms Cladogram = diagram that shows the evolutionary relationships among a group of organisms

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20 20 The genes of many organisms show important similarities at the molecular level. The genes of many organisms show important similarities at the molecular level. Similarities in DNA can be used to help determine classification and evolutionary relationships. Similarities in DNA can be 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, and the more closely they are related in evolutionary terms. The more similar the DNA sequences of two species, the more recently they shared a common ancestor, and the more closely they are related in evolutionary terms.

21 21 Dichotomous Key A dichotomous key is a tool that allows the user to determine the identity of items in the natural world, such as trees, wildflowers, mammals, reptiles, rocks, and fish. A dichotomous key is a tool that allows the user to determine the identity of items in the natural world, such as trees, wildflowers, mammals, reptiles, rocks, and fish. Keys consist of a series of choices that lead the user to the correct name of a given item. Keys consist of a series of choices that lead the user to the correct name of a given item. "Dichotomous" means "divided into two parts". Therefore, dichotomous keys always give two choices in each step. "Dichotomous" means "divided into two parts". Therefore, dichotomous keys always give two choices in each step.

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23 23 18–3 Kingdoms and Domains There are now 6 Kingdoms – listed below. There are now 6 Kingdoms – listed below.

24 24 Domain = most inclusive taxonomic category; larger than a kingdom Domain = most inclusive taxonomic category; larger than a kingdom

25 25 Eubacteria Unicellular Unicellular Prokaryotic Prokaryotic Autotroph or heterotroph Autotroph or heterotroph Cell walls with peptidoglycan Cell walls with peptidoglycan Examples: E. coli, Streptococcus, Staph Examples: E. coli, Streptococcus, Staph

26 26 Archaebacteria unicellular unicellular prokaryotic prokaryotic extreme environments extreme environments –volcanic hot springs, brine pools, and black organic mud totally devoid of oxygen Auto or heterotroph Auto or heterotroph cell walls lack cell walls lack peptidoglycan peptidoglycan

27 27 Protista eukaryotic eukaryotic greatest variety greatest variety Most single-celled, some multi Most single-celled, some multi photosynthetic or heterotrophic photosynthetic or heterotrophic Ex: kelp, amebas, slime mold, paramecium, euglena Ex: kelp, amebas, slime mold, paramecium, euglena

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29 29 Fungi heterotrophs heterotrophs –feed on dead or decaying organic matter organic matter Eukaryotic Eukaryotic Most multicellular, some uni Most multicellular, some uni Cell walls of chitin Cell walls of chitin EX: mushroom, yeast EX: mushroom, yeast

30 30 Plantae multicellular multicellular photosynthetic autotrophs photosynthetic autotrophs Eukaryotic Eukaryotic Cells walls of cellulose Cells walls of cellulose

31 31 Animalia multicellular multicellular heterotrophic heterotrophic Eukaryotic Eukaryotic No cell walls No cell walls


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