The Living World Fourth Edition GEORGE B. JOHNSON Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display PowerPoint ® Lectures prepared by Johnny El-Rady 14 How We Name Living Things

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 14.1 The Invention of the Linnaean System To name organisms, biologists use a multilevel grouping of individuals called classification Organisms were first classified more than 2,000 years ago by Aristotle Living things were either plants or animals Later groups started to be formed and referred to as genera (singular genus) Animals were either land, water, or air dwelling Plants were distinguished based on their stems

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display The classification system of the Middle Ages was known as the polynomial system Polynomials were a string of Latin words or phrases consisting of up to 12 or more words This system was cumbersome and confusing In the 1750s, the Swedish biologist Carolus Linnaeus developed the binomial system Binomials are two-part names They have become our standard way of designating species

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig How Linnaeus named two species of oaks

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 14.2 Species Names A group of organisms at a particular level in a classification system is called a taxon (plural, taxa) Taxonomy is the branch of biology that identifies and names organisms Organisms are named using Latin and in such a way that no two have the same name Using common names can be misleading

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig Common names make poor labels Corn BearsRobins

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 14.2 Species Names By convention, the binomial name consists Genus The first word and is always capitalized Epithet The second word which refers to the species and is not capitalized The two words are written in italics Together, they form the scientific name Example: Apis mellifera The honeybee

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 14.3 Higher Categories Taxonomists use a hierarchical system to classify organisms Species Genus Family Order Class Phylum Kingdom Information gets more and more general spaghetti green for over came Philip King

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig. 14.3

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 14.4 What Is a Species? Since the time of Linnaeus, about 1.5 million species have been named However, scientists estimate that at least 10 million species exist At least two-thirds of these occur in the tropics

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 14.5 How to Build a Family Tree Taxonomy also enables us to glimpse the evolutionary history of life on earth The evolutionary history of an organism and its relationship to other species is called phylogeny

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display A clade is a group of organisms related by descent Cladistics is the construction of phylogeny based on similarities derived from a common ancestor Examination of these derived characters allows the construction of a branching cladogram Cladograms are not true family trees They convey comparative relationship information 14.5 How to Build a Family Tree

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig A cladogram of vertebrate animals Ingroup Outgroup

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Modern cladistics attempts to assign extra weight to the evolutionary significance of key characters Weighting characters lies at the heart of traditional taxonomy Phylogenies are constructed based on a large amount of information about the organism gathered over the years To construct their trees traditional taxonomists use both ancestral and derived characters Cladists use only derived characters 14.5 How to Build a Family Tree

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig Two ways to classify terrestrial vertebrates Birds are lumped with reptiles Birds have their own Class

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display So which approach is better? 14.5 How to Build a Family Tree Traditional taxonomy, when a lot of information is available to guide character weighting Cladistics, when little information is available about how the character affects the life of the organism

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig The cat family tree

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig The cat family tree

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 14.6 The Kingdoms of Life The designation of kingdoms has changed over the years Originally there were only two kingdoms As more information about organisms was obtained, the number of kingdoms increased! Indeed, a taxonomic level higher than kingdom has been recognized Domain

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 14.6 The Kingdoms of Life Fig Different approaches to classifying living organisms

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig A tree of life More closely related to each other than either is to bacteria

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 14.7 Domain Archaea Consists of only one kingdom, the Archaebacteria Archaebacteria inhabit some of the most extreme environments on earth They share certain key characteristics Cell walls lacking peptidoglycan Unusual lipids and unique rRNA sequences Some archaebacterial genes possess introns

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Archaebacteria are grouped into three general categories Methanogens Obtain energy by using hydrogen gas to reduce carbon dioxide to methane gas Extremophiles Grow under extreme conditions Thermophiles (heat) Halophiles (salt) pH-tolerant Pressure-tolerant Nonextreme archaebacteria Grow in the same environments as bacteria do

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 14.8 Domain Bacteria Consists of only one kingdom, Bacteria Bacteria are the most abundant organisms on earth They play critical roles throughout the biosphere Most taxonomists recognize major groups Bacteria are as different from archaebacteria as they are from eukaryotes

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display 14.9 Domain Eukarya Appeared about 1.5 billion years ago Consists of four kingdoms Animalia Plantae Fungi Protista Well defined evolutionary groups Largely muticellular Very diverse Unicellular

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14.9 Domain Eukarya The hallmark of eukaryotes is complex cellular organization This is highlighted by the presence of organelles Mitochondria and chloroplasts most likely entered early eukaryotic cells by endosymbiosis Mitochondria are descendants of purple bacteria Chloroplasts are descendants of cyanobacteria

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Fig Diagram of the evolutionary relationship among the six kingdoms Symbiotic events

Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display Interestingly, other types of photosynthetic protists are endosymbionts of some eukaryotic organisms Fig Zooxanthellae algae Coral animal