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DIVERSITY OF LIFE Chapter 12 Chapters 13-15 included ORGANIZING LIFE ON EARTH • To make sense out of life’s diversity organisms are classified and named based on their characteristics • Phylogeny • The evolutionary history and the relationships among a species or group of species • Systematics • The study of organisms with the purpose of deriving their relationships • Taxonomy • The science of classifying organisms ORGANIZING LIFE ON EARTH • Taxonomy is based on the work of Karl von Linne (Linnaeus) • Organisms are grouped based on shared characteristics • Individual organisms are identified as a species • Morphologically different from other groups • Do not interbreed with other groups ORGANIZING LIFE ON EARTH • Taxonomy • One or more species which share characteristics are placed in a group called a taxon (plural is taxa) • The first taxon is the genus • Each species is assigned a name based on their genus plus a descriptive specific epithet • Genus species • Italics • The genus is capitalized, species is not • Binomial naming system designed by Linneaus ORGANIZING LIFE ON EARTH • Taxonomy • Taxa are then placed in broader more inclusive categories (still based on shared characteristics ORGANIZING LIFE ON EARTH • Taxonomy • The levels of taxa from the most inclusive/broad to the most exclusive are: • Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species ORGANIZING LIFE ON EARTH • Taxonomy of a house fly • From most exclusive or specific to the most inclusive • Species = Musca domestica ORGANIZING LIFE ON EARTH • Taxonomy of a house fly • From most exclusive or specific to the most inclusive • Species = Musca domestica • Genus: Musca ORGANIZING LIFE ON EARTH • Taxonomy of a house fly • From most exclusive or specific to the most inclusive • Species = Musca domestica • Genus = Musca • Family = Muscidae ORGANIZING LIFE ON EARTH • Taxonomy of a house fly • From most exclusive or specific to the most inclusive • • • • Species = Musca domestica Genus = Musca Family = Muscidae Order = Diptera ORGANIZING LIFE ON EARTH • Taxonomy of a house fly • From most exclusive or specific to the most inclusive • • • • • Species = Musca domestica Genus = Musca Family = Muscidae Order = Diptera Class = Insecta ORGANIZING LIFE ON EARTH • Taxonomy of a house fly • From most exclusive or specific to the most inclusive • • • • • • Species = Musca domestica Genus = Musca Family = Muscidae Order = Diptera Class = Insect Phylum = Arthropoda ORGANIZING LIFE ON EARTH • Taxonomy of a house fly • From most exclusive or specific to the most inclusive • • • • • • • Species = Musca domestica Genus = Musca Family = Muscidae Order = Diptera Class = Insect Phylum = Arthropoda Kingdom = Animalia ORGANIZING LIFE ON EARTH • Taxonomy of a house fly • From most exclusive or specific to the most inclusive • • • • • • • • Species = Musca domestica Genus = Musca Family = Muscidae Order = Diptera Class = Insect Phylum = Arthropoda Kingdom = Animalia Domain = Eukarya DETERMINING EVOLUTIONARY RELATIONSHIPS • Organisms that share similar physical features (morphology) and genetic sequences tend to be more closely related than those that do not • Homologies • Features overlap morphologically and genetically • Arrangement of bones in the wing of a bird and the arm of a human DETERMINING EVOLUTIONARY RELATIONSHIPS • Organisms that share similar physical features (morphology) and genetic sequences tend to be more closely related than those that do not • Analogies • Characteristic is superficially similar, but is not genetically similar • Comparison of wings between birds and insects • Lead to mis-classification of organisms DETERMINING EVOLUTIONARY RELATIONSHIPS • Molecular comparisons • Relatedness is now determined on more than just morphology • Cell type, cell wall, reproduction, nutrition, motility, etc. • Most importantly—genetic similarities • Genetic relatedness • Genetic information is compared • Species A: AACTAGCGCGAT • Species B: AACTAGCGCCAT • Species C: T T CTAGCGG TAT • Shows evolutionary relatedness (phylogenetic) DETERMINING EVOLUTIONARY RELATIONSHIPS • Molecular comparisons • Genetic analysis of many organisms resulted in three distinct lineages or Domains • Bacteria • Archae • Eukarya QUESTIONS • • • • • • What is the correct way to write a scientific binomial name? What is taxonomy? Which is the most inclusive taxon? Which is the most exclusive taxon? Give an example of a homology Name one domain PHYLOGENETIC TREE • Cladogram (a type of phylogenetic tree) • Depicts relatedness of organisms which are arranged on “branches” • Those close to one another are more closely related PHYLOGENETIC TREE • Cladogram • Branch points represent where a single lineage evolved into distinct new ones • Common ancestor is represented by the single branch point at the base PHYLOGENETIC TREE • Cladogram • Organisms are indicated at the end of each branched line • Closely related: Rabbit and Lizard/3 and 4 • Less closely related: Rabbit and Lancelet/1 and 5 PHYLOGENETIC TREE • Cladogram • Significant character changes are indicated • Must be quantifiable and heritable (Physical, behavioral, physiological, or molecular trait) PHYLOGENETIC TREE • Cladogram • Shared ancestral character (symplesiomorphy) • All members of the lineage have this character • Vertebral column/Letter A PHYLOGENETIC TREE • Cladogram • Shared derived characters (synapomorphies) are traits that • Arose since common ancestry • Define each branching point • Hinged jaw, legs, etc/Letters B-H PHYLOGENETIC TREE • Cladogram • Outgroup shares only the ancestral character (symplesiomorphy) • Derived characters (synapomorphies) arose later evolutionarily • Lancelet/#5 • Clade: groups (taxa) that share a synapomorphy PHYLOGENETIC TREE • Cladogram • Idealy taxonomists will be able to create monophylogentic cladograms containing • A common ancestor • All the descendants • Many cladograms are still either poly- or paraphylogenetic as there is missing information about species, relatedness, and evolutionary history QUESTIONS • Symplesiomorphy Single ancestor and all its descendants • Synapomorphy Groups that share a synapomorphy • Outgroup Character common to all members of a lineage • Character Shares only the first character with the other group members • Monophylogenetic Character which has arisen since common ancestry with the outgroup • Clade Similar traits used to group organisms DICHOTOMOUS KEY • Dichotomous keys are used to identify organisms • Consist of a series of questions • Each question has two possible answers • Based on the answer, you will be directed to the next question or given the name of the organism DICHOTOMOUS KEY 1. Sex female Sex male ---------------------------------2 ---------------------------------5 2. Hair color red -----------------------------Sally Not red ---------------------------------3 3. Hair blond Hair black -----------------------------Julie ---------------------------------4 4. Glasses No glasses ----------------------Deanna --------------------------Leslie 5. High-tops ------------------------Joseph not high-tops--------------------------------6 6. Hair blond Hair brown -----------------------Michael --------------------------David •Who is the male student with brown hair wearing cowboy boots? •Start at #1: because he is male, we need to go to # 5 •#5: his shoes are not hightops, go to #6 •#6: brown hair would lead us to the name David DICHOTOMOUS KEY 1. Sex female Sex male ---------------------------------2 ---------------------------------5 2. Hair color red -----------------------------Sally Not red ---------------------------------3 3. Hair blond Hair black -----------------------------Julie ---------------------------------4 4. Glasses No glasses ----------------------Deanna --------------------------Leslie 5. High-tops ------------------------Joseph not high-tops--------------------------------6 6. Hair blond Hair brown -----------------------Michael --------------------------David • Imagine that you meet a blond male member of this class wearing sandals. Who is it? • Imagine that his girl friend has black hair but doesn't wear glasses. Who is he dating? BIODIVERSITY • Characters used to differentiate Domains and Kingdoms • Type of cell • Prokaryotic cells lack a nucleus, are very small, and are simple • Domains Archaea and Bacteria • Eukaryotic cells have a nucleus, tend to be larger, and are complex with multiple organelles and cellular structures • Domain Eukarya • Presence or absence of a cell wall • Material used to build the cell wall • Uni- or multi- cellular BIODIVERSITY • Characters used to differentiate Domains and Kingdoms • Nutrition (how they acquire energy) • Autotroph or heterotroph • Motility • Can they move on their own • What method do they use for movement BIODIVERSITY • Characters used to differentiate Domains and Kingdoms • Mode of reproduction • Sexual, asexual, both • Life cycle ARCHAEBACTERIA • Domain Archae: Kingdom Archaebacteria • Prokaryotic cells with a cell wall (built with pseudomurine or other) • Microscopic uni-cellular organisms • Many are autotrophs • chemosynthesis and some forms of photosynthesis • Those that can move use flagella • Reproduce asexually using prokaryotic fission ARCHAEBACTERIA • Classification is based on • Extreme habitats • Halophiles • Thermophiles • Physiology • Energy source Two types of archaebacteria from a hydrothermal vent BACTERIA • Domain Bacteria: Kingdom Bacteria • • • • • Prokaryotic cells with a cell wall (built with peptidoglycan) Microscopic uni-cellular organisms Diverse forms of acquiring energy Those that can move use flagella mostly Reproduce asexually using prokaryotic fission BACTERIA • Classification is based on • Form of nutrition • Autotroph • Heterotroph • Habitat • Shape • Coccus • Bacillus • Spirillium BACTERIA • Classification is based on • Gram stain • A staining method that results in two different colors depending on the thickness of the bacteria’s cell wall • Thick = Purple (called Gram+) • Thin = Pink (called Gram-) PROTISTA • Domain Eukarya: Kingdom Protista • Eukaryotic cells • Some protists have cell walls (constructed with a variety of molecules) • They do not represent a monophylogenetic group • Taxonomy is changing • All of Domain Eukarya can be divided into six supergroups containing all the protists, animals, plants, and fungi PROTISTA • Most are microscopic and uni-cellular • Even though unseen, they play a significant role in life • Photosynthesis • Diatoms • Green, red, and brown algae • Diseases • Trypanosomes cause African Sleeping Sickness, Chagas Disease, and Leishmaniasis • Plasmodium causes malaria PROTISTA • Most are microscopic and uni-cellular • Even though unseen, they play a significant role in life • Pond life • Paramecium • Commercial use • Diatomaceous earth • Toothpaste, reflective paint • Carrageenan • Gelling, thickening, stabilizing • Agar PLANTAE • Domain Eukarya: Kingdom Plantae • Eukaryotic cells • cell walls constructed with cellulose • • • • Plants are multi-cellular and macroscopic Photosynthetic autotrophs Non-motile Reproduce sexually • Form spores or seeds PLANTAE • Classification is based on • Absence or presence of • Vascular tissues • Conduct water (xylem) and photosynthesized sugars (phloem) through the plant • Seeds • Flowers and fruit PLANTAE • Taxa of the Plantae • Bryophytes • Mosses: simple small plants • No vascular tissue, seeds, or flowers PLANTAE • Taxa of the Plantae • Ferns • Have vascular tissue • No seeds or flowers PLANTAE • Taxa of the Plantae • Gymnosperms (evergreen, cone bearing) • Have vascular tissue and seeds (develop in cones) • No flowers or fruit PLANTAE • Taxa of the Plantae • Angiosperms (flowering plants) • Have vascular tissue, seeds, and flowers and fruit FUNGI • Domain Eukarya: Kingdom Fungi • Eukaryotic cells • cell walls constructed with chitin • Some fungi are microscopic but most are larger • Most are multicelled • Yeasts are uni-cellular • Heterotrophs • Non-motile • Reproduce sexually and asexually • Release spores following reproduction FUNGI • Important impacts of fungi • Disease • Mold • Mycoses • Ring worm • Coccidiodomycosis • Histoplasmosis • Ecosystems • Decomposition • Lichens (fungus + algae) • Food • Yeast (bread, fermentation) • Mushrooms ANIMALIA • Domain Eukarya: Kingdom Animalia • Eukaryotic cells • No cell walls • Range in size from microscopic rotifers up to the blue whale • All are multicellular • Heterotrophs • Movement based on contractile tissues (muscles) and a skeleton • Reproduce sexually • Form ova and sperm for reproduction • A few species can reproduce asexually ANIMALIA • Classification is based on • Level of development • tissues, organs, organ systems • Symmetry • Type of skeleton • Several other criteria ANIMALIA • Taxa of animalia • Sponges • Simplest and least complex • Cnidarians • Jelly fish, anemones • Flat worms • Tape worms • Round worms • Hook worms, filarial worms, ascaris • Segmented worms • Earthworm ANIMALIA • Taxa of animalia • Mollusca • Clams, snails, squid • Arthropoda • Spiders, crustaceans, insects • Echinodermata • Sea Stars, Sea Urchins • Chordata • Vertebrates • Fish, amphibians, reptiles, birds, and mammals QUESTIONS • Archaebacteria Chitin cell walls • Bacteria Photosynthetic • Protista Peptidoglycan cell walls • Plantae Extreme habitats • Fungi No cell walls • Animalia Includes plasmodium which causes malaria SUMMARY • Classification • Nomenclature • Taxonomy • Dichotomous keys • Cladograms • Biodiversity • Kingdoms
