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Chapter 14 Table of Contents Classification of Organisms Table of Contents Section 1 Categories of Biological Classification Section 2 How Biologists Classify Organisms

Section 1 Categories of Biological Classification Chapter 14 Objectives Describe Linnaeus’s role in developing the modern system of naming organisms. Summarize the scientific system for naming a species. List the seven levels of biological classification.

Chapter 14 Classification Section 1 Categories of Biological Classification Chapter 14 Classification

Section 1 Categories of Biological Classification Chapter 14 Taxonomy The science of naming and classifying organisms is called taxonomy. Until the mid-1700s, biologists named a particular type of organism by adding descriptive phrases to the name of the genus.

Chapter 14 Taxonomy, continued A Simpler System Section 1 Categories of Biological Classification Chapter 14 Taxonomy, continued A Simpler System A simpler system for naming organisms was developed by the Swedish biologist Carl Linnaeus. Linnaeus’s two-word system for naming organisms is called binomial nomenclature. Over the past 250 years since Linnaeus first used two-part binomial species names, his approach has been universally adopted.

Section 1 Categories of Biological Classification Chapter 14 Species Name

Chapter 14 Taxonomy, continued Scientific Name Section 1 Categories of Biological Classification Chapter 14 Taxonomy, continued Scientific Name The unique two-part name for a species is now referred to as its scientific name. The first word is the genus to which the organism belongs. A genus is a taxonomic category containing similar species. The second word in a scientific name identifies one particular kind of organism within the genus, called a species. A species is the basic biological unit in the Linnaean system of classification.

Classifying Organisms Section 1 Categories of Biological Classification Chapter 14 Classifying Organisms Linnaeus worked out a broad system of classification for plants and animals in which an organism’s form and structure are the basis for arranging specimens in a collection. The genera and species that he described were later organized into a ranked system of groups that increase in inclusiveness.

Classifying Organisms, continued Section 1 Categories of Biological Classification Chapter 14 Classifying Organisms, continued Similar genera are grouped into a family. Similar families are combined into an order. Orders with common properties are united in a class. Classes with similar characteristics are assigned to a phylum. Similar phyla are collected into a kingdom. Similar kingdoms are grouped into domains.

Biological Hierarchy of Classification Section 1 Categories of Biological Classification Chapter 14 Biological Hierarchy of Classification

Linnaeus’s Levels of Classification Section 1 Categories of Biological Classification Chapter 14 Linnaeus’s Levels of Classification

Classification Hierarchy of Organisms Section 1 Categories of Biological Classification Chapter 14 Classification Hierarchy of Organisms

Classifying Organisms, continued Section 1 Categories of Biological Classification Chapter 14 Classifying Organisms, continued Classification of the Honeybee Each level of classification is based on characteristics shared by all the organisms it contains. The honeybee’s scientific name, Apis mellifera, indicates that it belongs to the genus Apis, which is classified in the family Apidae. All members of the family Apidae are bees that live either alone or in hives, as does Apis mellifera.

Classification of a Bee Section 1 Categories of Biological Classification Chapter 14 Classification of a Bee

Section 2 How Biologists Classify Organisms Chapter 14 Objectives List the characteristics that biologists use to classify organisms. Summarize the biological species concept. Relate analogous structures to convergent evolution. Describe how biologists use cladograms to determine evolutionary histories.

Chapter 14 What Is a Species? Section 2 How Biologists Classify Organisms Chapter 14 What Is a Species? In 1942, the biologist Ernst Mayr of Harvard University proposed a biologically based definition of species, which is called the biological species concept. Mayr defined a biological species as a group of natural populations that are interbreeding or that could interbreed, and that are reproductively isolated from other such groups. Sometimes individuals of different species interbreed and produce offspring called hybrids.

Section 2 How Biologists Classify Organisms Chapter 14 Species

What Is a Species?, continued Section 2 How Biologists Classify Organisms Chapter 14 What Is a Species?, continued Evaluating the Biological Species Concept The biological species concept works well for most members of the kingdom Animalia, in which strong barriers to hybridization usually exist. But the biological species concept fails to describe species that reproduce asexually, such as all species of bacteria and some species of protists, fungi, plants, and even some animals. In practice, modern biologists recognize species by studying an organism’s features.

What Is a Species?, continued Section 2 How Biologists Classify Organisms Chapter 14 What Is a Species?, continued Number of Species The number of species in the world is much greater than the number described. Only about 1.5 million species have been described to date. Scientists estimate that 5 million to 10 million more species may live in the tropics alone.

Chapter 14 Evolutionary History Section 2 How Biologists Classify Organisms Chapter 14 Evolutionary History Classification based on similarities should reflect an organism’s phylogeny, that is, its evolutionary history. Through the process called convergent evolution, similarities evolve in organisms not closely related to one another, often because the organisms live in similar habitats. Similarities that arise through convergent evolution are called analogous characters.

Section 2 How Biologists Classify Organisms Chapter 14 Phylogeny

Phylogenic Diagram of Mammals Section 2 How Biologists Classify Organisms Chapter 14 Phylogenic Diagram of Mammals

Comparing Convergent and Divergent Evolution Section 2 How Biologists Classify Organisms Chapter 14 Comparing Convergent and Divergent Evolution

Chapter 14 Analogous Features Section 2 How Biologists Classify Organisms Chapter 14 Analogous Features

Evolutionary History, continued Section 2 How Biologists Classify Organisms Chapter 14 Evolutionary History, continued Cladistics Cladistics is a method of analysis that reconstructs phylogenies by inferring relationships based on shared characters. With respect to two different groups, a character is defined as an ancestral character if it evolved in a common ancestor of both groups. A derived character evolved in an ancestor of one group but not of the other.

Section 2 How Biologists Classify Organisms Chapter 14 Cladistics

Evolutionary History, continued Section 2 How Biologists Classify Organisms Chapter 14 Evolutionary History, continued Cladistics Cladistics is based on the principle that shared derived characters provide evidence that two groups are relatively closely related. A biologist using cladistics constructs a branching diagram called a cladogram, which shows the evolutionary relationships among groups of organisms. Organisms that share derived characters, are grouped together on the cladogram.

Section 2 How Biologists Classify Organisms Chapter 14 Cladograms

Cladogram: Mammals, Reptiles, and Birds Section 2 How Biologists Classify Organisms Chapter 14 Cladogram: Mammals, Reptiles, and Birds

Cladogram: Major Groups of Plants Section 2 How Biologists Classify Organisms Chapter 14 Cladogram: Major Groups of Plants

Evolutionary History, continued Section 2 How Biologists Classify Organisms Chapter 14 Evolutionary History, continued Considering Characters The great strength of cladistics is objectivity. If a computer is fed the same set of data repeatedly, it will make exactly the same cladogram every time. The disadvantage of cladistics is that the degree of difference between organisms is not considered. Cladistic analysis does not take into account variations in the “strength” of a character, such as the size or location of a fin or the effectiveness of a lung. Each character is treated equally.

Evolutionary History, continued Section 2 How Biologists Classify Organisms Chapter 14 Evolutionary History, continued Evolutionary Systematics In evolutionary systematics, taxonomists give varying degrees of importance to characters and thus produce a subjective analysis of evolutionary relationships. In this type of analysis, evolutionary relationships are displayed in a branching diagram called a phylogenic tree. Evolutionary systematics involves the full observational power of the biologist, along with any biases he or she may have.

Evolutionary Systematics and Cladistic Taxonomy Section 2 How Biologists Classify Organisms Chapter 14 Evolutionary Systematics and Cladistic Taxonomy

Section 2 How Biologists Classify Organisms Chapter 14 Systematics

Chapter 14 Multiple Choice Standardized Test Prep Multiple Choice The diagram below shows seven levels of biological classification from kingdom to species. Use the figure below to answer questions 1–3.

Multiple Choice, continued Chapter 14 Standardized Test Prep Multiple Choice, continued 1. Which letter on the diagram represents the phylum level of classification? A. A B. B C. C D. D

Multiple Choice, continued Chapter 14 Standardized Test Prep Multiple Choice, continued 1. Which letter on the diagram represents the phylum level of classification? A. A B. B C. C D. D

Multiple Choice, continued Chapter 14 Standardized Test Prep Multiple Choice, continued 2. What level of classification does F represent? F. class G. family H. genus J. order

Multiple Choice, continued Chapter 14 Standardized Test Prep Multiple Choice, continued 2. What level of classification does F represent? F. class G. family H. genus J. order

Multiple Choice, continued Chapter 14 Standardized Test Prep Multiple Choice, continued 3. What can you infer about different species that belong to the same group at level D? A. They belong to the same group at level E. B. They belong to different groups at level E. C. They belong to the same group at level C. D. They belong to different groups at level C.

Multiple Choice, continued Chapter 14 Standardized Test Prep Multiple Choice, continued 3. What can you infer about different species that belong to the same group at level D? A. They belong to the same group at level E. B. They belong to different groups at level E. C. They belong to the same group at level C. D. They belong to different groups at level C.