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The Tree of Life Chapter 17. The Linnaean System of Classification Living things must be described 1.5 million identified and named species Identification.

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Presentation on theme: "The Tree of Life Chapter 17. The Linnaean System of Classification Living things must be described 1.5 million identified and named species Identification."— Presentation transcript:

1 The Tree of Life Chapter 17

2 The Linnaean System of Classification Living things must be described 1.5 million identified and named species Identification and naming requires organization Classification systems provide this organization Taxonomy – science of naming and classifying organisms

3 The Linnaean System of Classification Each group of organisms is called a taxon (taxa) Basic level is the species –Any group of animals that can interbreed In the Linnean System, each species got a name –Still in use today

4 The Linnaean System of Classification Carolus Linnaeus – Father of taxonomy Developed two word naming system – Binomial Nomenclature Always written in italics or underlined –Musca domestica or Musca domestica First word is the genus, second is the species

5 The Linnaean System of Classification Common names vary too much First attempts described physical characteristics What are the flaws of this method? –Too long of descriptions –Too many varying observations

6 The Linnaean System of Classification Linnaeus’s system consisted of 7 levels –Domain (Largest) –Kingdom –Phylum –Class –Order –Family –Genus –Species (Smallest) Each level is called a taxon (taxa)

7 The Linnaean System of Classification Levels up always group more organisms together Families are grouped into orders Classes are composed of similar orders Classes make up phylums

8 The Linnaean System of Classification Linneaus created his system based on physical similarities –Flaws? Today scientists genetic information to be sure of similiarities

9 Classification Based on Evolutionary Relationships Anything above species has been “invented” How would Linnaeus classify these: –Dolphin –Hermit crab –Sparrow –Cow –Snake –Monkey –Bull Shark

10 Classification Based on Evolutionary Relationships Phylogeny – evolutionary relationships among organisms Used now instead of physical similarities Evolutionary classification Species in the same genus are more related than species from another genus

11 Classification Based on Evolutionary Relationships All members of genus share a common ancestor This can be traced through a phylogenic tree The higher the level, the farther back the ancestor The more recent the common ancestor, the more related

12 Classification Based on Evolutionary Relationships

13 Cladogram – using derived characters to determine evolutionary relationships –Clade – group of species that share a common ancestor –Derived Characters – characters in recent members, but not older members –Result of evolution Demands force new innovations

14 Classification Based on Evolutionary Relationships Cladogram Interpretation –Derived characters –Nodes – where a branch splits off –Identifying clades – snip rule –What is the derived character of: Amphibians Crocodiles and birds

15 Classification Based on Evolutionary Relationships A lot of classification methods are based on appearance USUALLY, this works…why? DNA/RNA/Proteins are similar in related species These substances are used to make comparisons

16 Classification Based on Evolutionary Relationships

17 Molecular Clocks Evolutionary time can also be measured with DNA Molecular Clock – use DNA mutations to estimate the length of time species have been evolving –Scientists have found mutations tend to occur at constant rates for a species –Relies on mutations to repeat The more time has passed between two species diverging from a common ancestor, the more mutations there will be Not just one clock running at a time

18 Molecular Clocks Molecular Clocks and Real Time –Linking of mutations occurs with geological events and fossil evidence Amino acid differences along with geological splits determines the evolutionary time

19 Molecular Clocks Different genetic molecules mutate at different rates –Some sequences of DNA mutate rapidly, while others are relatively slow Mitochondrial DNA Ribosomal RNA Found only in mitochondria Mutation rate is 10x faster than nuclear DNA Good for closely related species due to speed Always inherited from mother Used to study human lineage for 200,000 years Contained in ribosomes Good for distantly related species Low mutation rate

20 Domains and Kingdoms Linnaeus started with two kingdoms: –Plantae –Animalia Scientists realized they needed more This lead to five kingdoms

21 Domains and Kingdoms Domains – larger and includes the kingdoms Three domains –Eukarya –Archaea –Archaebacteria As more discoveries are made, more kingdoms may be made

22 Domains and Kingdoms Domain Bacteria –Unicellular –Prokaryotic –Thick, rigid cell walls around a cell membrane –Cell wall made of peptidoglycan

23 Domains and Kingdoms Domain Archaea –Unicellular –Prokaryotic –Live in extreme environments Volcanic hot springs Brine pools Black mud devoid of oxygen –Lack peptidoglycan

24 Domains and Kingdoms Domain Eukarya –All organisms have a nucleus –Consists of four kingdoms ProtistaFungiPlantaeAnamalia

25 Domains and Kingdoms Kingdom Protista –Members have the greatest diversity –Cannot be classified as animals, plants, or fungi –Most single celled organisms –Some are multi-celled algae –Some are photosynthetic

26 Domains and Kingdoms Kingdom Fungi –All are heterotrophs –Feed on dead or decaying organic matter –Most recognizable is the mushroom –Most are multicellular, others (Yeast) are unicellular

27 Domains and Kingdoms Kingdom Plantae –Multicellular –All are photosynthetic autotrophs –Non-mobile

28 Domains and Kingdoms Kingdom Anamalia –Multicellular –Heterotrophs –Mobile –Incredible diversity


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