Chapter 17: Organizing Life’s Diversity

1. Chapter 17: Organizing Life’s Diversity Honors Biology Mrs. Toner

2. Section 17.1 – The History of Classification 1. How is classification used every day? 2. Why do scientists organize or classify living things? 3. Do you know the scientific names of any species? • Biologists use a system of classification to organize information about the diversity of living things. • Just as stores group CDs according to type of music and artist, biologists group living things by their characteristics and evolutionary relationships.

3. Early Systems of Classification • Classification – is the grouping of objects or organisms based on a set of criteria. • Biologists find it easier to communicate and retain information about organisms when the organisms are organized into groups. • One of the principal tools for this is biological classification.

4. Early Systems of Classification (cont.) • Aristotle’s System • Greek philosopher , Aristotle (394-322 B.C.) • Developed the first widely accepted system. • Classified organisms as either plants or animals. See page 484 Table 17.1 Aristotle’s Classification System

5. Early Systems of Classification (cont.) • Limitations of Aristotle’s System: • Viewed systems as being distinct, separate, and unchanging. • This was a common view until Darwin presented his theory of evolution which stated that organisms are always changing. Organisms share evolutionary relationships. • Nevertheless, many centuries passed before Aristotle’s System was replaced by a new one that was better suited to the increased knowledge of the natural world.

6. Early Systems of Classification (cont.) • Linnaeus’s System: • Linnaeus (Swedish Naturalist, 1707-1778) • Broadened Aristotle’s classification method • Concentrated on morphology and behavior of organisms • Categorized birds into three major groups (see page 485, Figure 17.1) • Linnaeus’s system of classification was the first formal system of taxonomic organization. • Taxonomy – is a discipline of biology primarily concerned with identifying, naming, and classifying species based on natural relationships.

7. Early Systems of Classification (cont.) • Linnaeus’s method of naming organisms called binomial nomenclature – gives each species a two-part name: genus and species • Latin • Cardinaliscardinalis

8. Taxonomic Categories (Created by Linnaeus) • Species and Genus • Taxon – a named group of organisms (plural, taxa). • Range from having broad diagnostic characteristics to having specific characteristics. • Think of taxa as a set of nesting boxes – one fitting inside the other. (See page 488, Fig. 17.4) • Domain • Kingdom • Phylum • Class • Order • Family • Genus • Species

9. The Taxonomic Categories • Species – a group of organisms that can interbreed and produce offspring. [Ursusamericanus (American black bear), Ursusthibetanus (Asiatic black bear)] • Genus – (pl. genera) a group of species that are closely related and share a common ancestor. (Ursus = black bear) • Family – is the next higher taxon, consisting of similar, related genera. (Ursidae = all bears, both living and extinct; brown bears, polar bears, giant pandas) • All members of the bear family share certain characteristics. They walk flatfooted, have forearms that can rotate to clasp prey.

10. The Taxonomic Categories (cont.) • Order – contains related families • Class – contains related orders • Phylum – (pl. phyla) or division (bacteria and plants) contains related classes • Kingdom - the taxon composed of related phyla or divisions • Domain – the broadest of taxa. • ACTIVITY: Classify a giant panda, Ailuropodamelanoleuca, completely from domain to species level by referring to Figure 17.4.

11. Answer to Activity: • Eukarya, Animalia, Chordata, Mammalia, Carnivora, Ursidae, Ailuropoda, melanoleuca

12. Section 17.2 - Modern Classification • Determining Species – the definition of species has “evolved” over the years. • Typological Species Concept • Biological Species Concept • Phylogenetic Species Concept • Phylogeny – the evolutionary history of a species. • Shows evidence of a pattern of ancestry and descent.

13. Characters • To classify a species, scientists often construct patterns of descent, or phylogenies, by using characters. • Characters – inherited features that vary among species. Characters can be: • Morphological - similarity in anatomy • Example – Darwin’s Finches • Biochemical (Molecular)- similarity of nucleic acids(DNA) and amino acids (proteins) • Developmental - similarity in developmental patterns • Behavioral – similarity in vocalization or mating behaviors

14. Phylogeny • The evolutionary history of a species or group of related species. • Organizes organisms based on their history and relation to one another. • A phylogenetic tree (or evolutionary tree) is a graphical hypothesis of the proposed phylogeny. • A phylogenetic tree is often called a cladogram. • A cladogram is a branching diagram that represents the evolutionary history of a species. • Cladistics – a method that classifies organisms according to the order that they diverged from a common ancestor.

15. Cladogram (Phylogenetic Tree) Clade Node