How We Name Living Things
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How We Name Living Things Invention of the Linnaean System Classification - Multilevel grouping of individuals. Organisms first classified by Aristotle over 2,000 years ago. Eventually groups started to be formed and referred to as genera (singular, genus). Starting in middle ages, names began to be systematically written down using Latin. Invention of the Linnaean System Classification scheme of the Middle Ages (polynomial system) was used replaced with a binomial system by Linnaeus about 250 years ago. Polynomial - Strings of latin words and phrases containing up to 12 words. Binomial - Two-part name for each species. Species Names Taxa - Group of organisms at a particular level in a classification system (Taxonomy). By convention: First word of binomial name is genus and is always capitalized. Second word refers to particular species and is not capitalized. Together form Scientific Name, written in italics. Species Definition Biological Species Concept (Ernst Mayr) Species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups. Problems Assumes regular outcrossing Assumes strong reproductive barriers Hybrids ? Higher Categories Species Genus Family Order Class Phylum Kingdom Kindly Pay Cash Or Furnish Good Security. Hierarchical Classification System Kingdoms of Life Most Biologists use a six-kingdom system. Animalia Plantae Fungi Protista Archaebacteria Eubacteria Domains - taxonomic level above kingdoms. Evolutionary Relationship Domain Bacteria (Eubacteria) Most abundant organisms on earth. Most taxonomists recognize 12-15 major groups. Domain Eukarya (Eukaryotes) Appear in fossil record only about 1.5 billion years ago. Complex cellular organization. Fungi, Plants, and Animals are well-defined evolutionary groups. Largely multicellular Domain Eukarya (Eukaryotes) With few exceptions, all modern eukaryotic cells possess energy-producing organelles (Mitochondria). Some protist phyla have also acquired chloroplasts and are photosynthetic. Mitochondria and chloroplasts are both believed to have entered early eukaryotic cells by endosymbiosis. Advent of The Eukaryotes Endosymbiosis Most biologists believe mitochondria originated as symbiotic, aerobic eubacteria (endosymbiosis). Bacteria thought to have been engulfed by ancestral eukaryotic cells early in the history of eukaryotes. Endosymbiosis Kingdoms of Life Most Biologists use a six-kingdom system. Animalia Plantae Fungi Protista Archaebacteria Eubacteria Multicellular Organisms Individuals composed of many cells that interact and coordinate their activities. Classifying Protists Most diverse of four kingdoms in the domain Artificial group formed for convenience. Five general groups according to major shared characteristics. Presence or absence of cilia / flagella Presence and kind of pigment Type of mitosis Kinds of cristae in mitochondria Protist Reproduction Multicellularity - Composed of many permanently associated cells with integrated activities. Allows for specialization. Occurs only in eukaryotes Colonies - Permanent association, but no integration of cell activities. Aggregates - Transient collection of cells. Movement accomplished by various means. Flagella Lobopodia Filopodia Axopodia Heterotrophs Lacking Permanent Locomotor Apparatus Largest of the five groups. Amoebas - Lack flagella and cell walls, and move with pseudopodia. Forams - Possess rigid shells and move by cytoplasmic streaming (podias). Marine with pore-studded shells (tests). Radiolarians - Phylum Actinopoda Glassy skeletons with many needlelike pseudopods. Heterotrophs With Flagella Zoomastigotes Ancestor of all animals appears to have been a member of this group. All have at least one flagellum. Heterotrophs With Flagella Ciliates Possess large number of cilia, fixed cell shape, and two nuclei per cell. Reproduction usually by fission. Move by beating cilia. Photosynthetic Protists Dinoflagellates Photosynthetic unicellular protists, most with two flagella of unequal lengths. One flagella beats in a groove circling body, while the other beats in a groove perpendicular to it. Copyright © McGraw-Hill Companies Permission required for reproduction or display Photosynthetic Protists Euglenoids Freshwater protists with two flagella. One-third are photosynthetic, while others are heterotrophic. Reproduction by mitotic cell division. Copyright © McGraw-Hill Companies Permission required for reproduction or display Photosynthetic Protists Diatoms Photosynthetic unicellular protists with unique double shell of silica. Golden Algae Named for yellow and brown accessory pigments in chloroplasts. Photosynthetic Protists Green Algae Ancestor of true plants is a member of this group. Contain chlorophyll a and b. Most are microscopic and unicellular. Photosynthetic Protists Red Algae Contain red pigments (phycobilins). Almost all multicellular and live at sea. Brown Algae Life cycle employs alteration of generations. (Kelp)
