Presentation on theme: "Linnaeus’ System of Taxonomy"— Presentation transcript:
1 Linnaeus’ System of Taxonomy Used a hierarchical systemKingdom, Phylum, Class, Order, Family, Genus, Species (later Domain was added)Based on molecular evidence (DNA and protein sequences) its accepted to have 6 Kingdoms and have added 3 Domains
2 Latinized descriptive names of organisms - Binomial Nomenclature: 2 word scientific naming system First part of binomial – Genus – Always capitalizedSecond part – species - always lower case.Latin scientific names are always italicized (if word processing) or underlined (if hand written)Ex. Homo sapiens, “wise man”species – specific group of 1 type of organism that may interbreed and produce viable, fertile offspring.
3 Binomial Nomenclature – Who cares? What do you call this?Crawdad?Crawfish?Crayfish?Prairie crayfish-Procambarus gracilis
4 Why use Binomial Nomenclature? Problems with common namesVaries from area to area, therefore, no commonality.Does not specify a particular species.Each animal has an unique binomial name.Required for all animals by International Code of Zoological Nomenclature.
7 Domain Archaea Domain Eubacteria Prokaryotic microbes, tinyLive in extreme environments: high temps, salts, & acids (tough)AnaerobicMost primitiveProkaryotic microbesOften called the “true bacteria”Live in most environmentsAnaerobic or aerobic
13 Most recently described Phylum - Cycliophora 36th found Phylum in 1995In the Animal KingdomSymbion pandoraFound in mouthparts of Norwegian lobsters0.3 mm long = 300 µm
14 Currently we useMorphological, biochemical, fossil, and molecular comparisons to infer evolutionary relationships
15 Though sedimentary fossils are the most common Paleontologists study a wide variety of fossils(a) Dinosaur bones being excavated from sandstone(g) Tusks of a 23,000-year-old mammoth, frozen whole in Siberian ice(e) Boy standing in a 150-million-year-old dinosaur track in Colorado(d) Casts of ammonites, about 375 million years old(f) Insects preserved whole in amber(b) Petrified tree in Arizona, about 190 million years old(c) Leaf fossil, about 40 million years old
16 Morphological and Molecular Homologies In general, organisms that share very similar morphologies or similar DNA sequencesAre likely to be more closely related than organisms with vastly different structures or sequences.Not always true! Analogy vs. Homology
17 HomologyHomologous Structures – structures in different species that are similar because of commons ancestry.
18 AnalogyAnalogous Structures – similarity in structures due to adaptations and not a common ancestor.
20 Cladisticsa method that applies the scientific method to the construction of evolutionary relationships.
21 CladogramDiagram showing how organisms are related based on shared, derived characteristicssuch as:vertebraejaw bonesfour legsamniotic eggshair
22 Cladogram Vocabulary Branch point Ingroup Outgroup 2 species differ in shared derived charactersIngroupmonophyletic group we are interested inOutgroupspecies or group of species that is most closely related to an ingroup
26 What shared derived character is common to: salmonlizardrabbitbut not the lamprey?
27 Constructing a cladogram Choose speciesChoose charactersEach character has different character states (example: tail or no tail)Determine order of character statesprimitive or derived?Use the fossil recordMany simple parts came before fewer, more specialized partsVestigial organs –not functioning but present)Mutation rate of DNA nucleotidesGroup species (or higher taxa) based on shared derived characteristics
28 Constructing a cladogram Build a cladogram based onAll species are placed on tips in the phylogenetic tree, not at branch pointsEach cladogram branch point should have a list of one or more shared derived characters that are common to all species above the branch point unless the character is later modifiedAll shared derived characters appear together only once in a cladogram unless they arose independently during evolution more than onceChoose the most likely cladogram among possible options
29 Construct a Cladogram for Us Construct a Cladogram for Us! Let’s use the characters of tail, fur, and # of limbs
38 Characteristics (Traits) for Constructing this Cladogram Tail is the most ancestralFour limbs is the oldest derived traitFur is a later derived traitLoss of tail is the most derived trait
39 One Possible Cladogram GorillaChimpanzeeTigerLizardFishTail LostFurFour Limbs
40 A Vertebrate Cladogram BirdsMammalsReptileAmphibianFishFour LimbsAmniotic EggEndothermicFurFeathersVertebraeLanceletOutgroup
41 The outgroup comparison Enables us to focus on just those characters that were derived at the various branch points in the evolution of a clade.SalamanderTAXATurtleLeopardTunaLampreyLancelet (outgroup)1HairAmniotic (shelled) eggFour walking legsHinged jawsVertebral column (backbone)Amniotic eggVertebral column(a) Character table. A 0 indicates that a character is absent; a 1 indicates that a character is present.(b) Cladogram. Analyzing the distribution of these derived characters can provide insight into vertebrate phylogeny.CHARACTERS
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