Transcript kingdom
Organizing Life’s Diversity 17 The Big Idea Evolution underlies the classification of life’s diversity. Main Idea #1 Biologists use a system of classification to organize information about the diversity of living things. Classification Biologists use a system of classification to organize information about the diversity of living things. Classification is the grouping of objects or organisms based on a set of criteria. Early Systems of Classification Aristotle More than 2000 years ago, Aristotle developed the first widely accepted system of biological classification. Aristotle classified organisms as either Animals were classified according to absence of “red blood.” Animals were further grouped according and morphology. Plants were classified by average size trees, shrubs, or herbs. animals or plants. the presence or to their habitats and structure as Aristotle’s classification system was believed to be accurate until rapid scientific exploration caused many new species to be discovered. Using common names for so many organisms was causing problems since names varied from one location to the next. Early Systems of Classification Linnaeus In an attempt to organize the system, a Swedish naturalist named Carolus Linnaeus, came up with a system that grouped organisms into hierarchical categories. Linnaeus’s system of classification was taxonomy. He used the organisms’ morphology His system consisted of seven levels kingdom, family, genus, and species. the first formal system of (form and function) of organization: phylum (or division), class, order, Early Systems of Classification Linnaeus’s method of naming organisms, called binomial nomenclature, gives each species a scientific name with two parts. The first part is the genus name, and the second part is the specific epithet, or specific name, that identifies the species. Ursus americanus (AKA the “Rebel” Black Bear) Rules for Scientific Names The first letter of the genus name always is capitalized, but the rest of the genus name and all letters of the specific epithet are lowercase. If a scientific name is written in a printed book or magazine, it should be italicized (e.g., Homo sapiens). When a scientific name is written by hand, both parts of the name should be underlined (e.g., Homo sapiens). After the scientific name has been written completely, the genus name will be abbreviated to the first letter in later appearances (e.g., H. sapiens). Taxonomic Categories The taxonomic categories used by scientists are part of a hierarchy system. Each category is contained within another, and they are arranged from broadest to the most specific, or largest to smallest. Each named group is called a taxa. Main Idea #2 Classification systems have changed over time as information has increased. What is a species? How are things classified? To classify a species, scientist construct patterns of descent by using characters. These characters may morphological or biochemical. Morphological Characters Shared morphological characters suggest that species are related closely and evolved from a recent common ancestor. Analogous characters may have similar functions but different underlying construction , while homologous characters may appear similar but have differing functions. Compare birds and dinosaurs: Theropods have leg, wrist, hip, and shoulder structures similar to birds. Both have hollow bones. Some theropods may have had feathers. Biochemical Characters Scientists use biochemical characters, such as amino acids and nucleotides, to help them determine evolutionary relationships among species. Scientists will also compare the DNA and RNA between species to determine how similar or different they are. The similarity between the chromosomes of the chimpanzee, gorilla, and orangutan suggests a common ancestor. Molecular Clocks Scientists use molecular clocks to compare the DNA sequences or amino acid sequences of genes that are shared by different species. The differences between the genes indicate the presence of mutations. The more mutations that have accumulated, the more time that has passed since divergence. Phylogenic Reconstruction Cladistics reconstructs phylogenies based on shared characters. A cladogram can be used to show the amount of shared characters. The greater the number of derived characters shared by groups, the more recently the groups share a common ancestor. Main Idea #3 The most widely used biological classification system has six kingdoms within 3 domains. Domains & Kingdoms Grouping Species The broadest category in the classification used by most biologists is the domain. The most widely used biological classification system has six kingdoms and three domains. The three domains are Bacteria, Archaea, and Eukarya. The six kingdoms are Bacteria, Arcahea, Protisits, Fungi, Plantae, and Animalia. Domain Bacteria Typical Bacteria Prokaryote Unicellular Most have a cell wall Most make own food by photosynthesizing Reproduce by conjugation and binary fission Used to make antibiotics and flavor for some foods Domain Archaea Bacteria Extremophiles Prokaryote Unicellular Have a cell wall Make own food Reproduce by conjugation and binary fission Ribosomal RNA holds genetic code Domain Eukarya Classifies all eukaryotes. Contains kingdoms protista, fungi, plantae, and animalia. Kingdom Protista Uni/Multicellular Some make food via photosynthesis Reproduce through conjugation, binary fission, mitosis, or meiosis. Some have a cell wall made of cellulose Most diverse kingdom Amoebas, Euglena, Diatoms, 3 Groups Algae Plantlike Animallike Funguslike Kingdom Fungi Uni/Multicellular Cannot make its own food Reproduce through fission, fragmentation, budding, spores (sexual/asexual) Cell wall made of chitin or cellulose Can be fatal to humans Mushrooms, Yeast, Lichen Kingdom Plantae Multicellular Makes food via photosynthesis Reproduce through vegetative propagation, sexual spores, and pollination Cell wall made of cellulose Mossess, grasses, trees, flowers Kingdom Animalia Multicellular No cell wall Does not make its own food. Internal/External Fertilization Vertebrates/Invertebrates Symmetrical Symmetry Asymmetry Bilateral Radial No Symmetry Can be divided into 2 equal halves with only one line Grouped around a central point, can be divided many ways to get mirror images. Types of Sexual Reproduction Types of Asexual Reproduction