1. Essentials of the Living World Exploring Biological Diversity
Second Edition
George B. Johnson
Jonathan B. Losos
Chapter 16
Exploring Biological Diversity
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 16.1 The Invention of the Linnaean System
To talk about and to study organisms it is necessary to give them names
biologists use a kind of multilevel grouping of individuals called classification
the earliest classification scheme grouped animals and plants into basic units called genera (singular, genus)
early biologists added a series of non-standardized descriptions to the genus name
this created a string of subjective names called a polynomial

3. 16.1 The Invention of the Linnaean System
A much simpler system than the polynomial for the naming of organisms was developed by Carolus Linnaeus
Linnaeus assigned organisms a two-part name called a binomial
he also grouped similar organisms into higher-level categories based on similar characteristics
this would have important, though unintended, applications to evolutionary connections

4. Figure 16.1 How Linnaeus named two species of oaks

5. 16.2 Species Names
Taxon (plural, taxa) is a group of organisms at a particular level in a classification system
the branch of biology that identifies and names such groups is called taxonomy
no two kinds of organisms can have the same name and all names are given in Latin

6. 16.2 Species Names
The scientific name for an organism is comprised of the two-part binomial
the first part is the genus, which is always capitalized
the second part is the specific epithet and is not capitalized
the two words together are written in italics or underlined

7. 16.3 Higher Categories
the binomial has been expanded into a Linnaean system of classification
genera with similar properties are grouped together into a family
families that share similar characteristics are put into the same order
orders with common properties are placed into the same class
classes with similar characteristics are placed into the same phylum
phyla are assigned to one of several gigantic groups called kingdoms
kingdoms are sometimes assigned to an additional level of classification, called domains

8. Figure 16.3 The hierarchical system used to classify an organism

9. 16.4 What Is a Species?
Since the time of Linnaeus, about 1.5 million species have been named
the actual number of species is much greater
the biological species concept is widely applied to animals but not as frequently to plants
it does not apply to some kingdoms at all
molecular data are causing a reevaluation of traditional classification systems

10. 16.5 How to Build a Family Tree
Phylogeny is the evolutionary history of an organism and its relationship to other species
Systematics is the study of and reconstruction of phylogenetic trees
it also includes the naming and classifying of organisms

11. 16.5 How to Build a Family Tree
Cladistics is the systematic approach that infers phylogeny according to similarities derived from a common ancestor
derived characters are characters that are present in a group of organisms that arose from a common ancestor that lacked the character
a clade is a group of organisms, related by descent, that share a derived character
by examining the distribution of derived traits among related organisms, it is possible to construct a cladogram, a branching diagram that represents the phylogeny

12. Figure 16.5 A cladogram of vertebrate animals

13. 16.5 How to Build a Family Tree
Cladograms convey comparative information about relative relationships
organisms that are closer together on a cladogram simply share a more recent common ancestor than those that are farther apart
each cladogram must have an outgroup, a rather different organism to serve as a basis for comparisons among the other organisms being evaluated, called the ingroup

14. 16.5 How to Build a Family Tree
Cladistics is a relatively new but popular approach to studying evolution because it is objective and portrays the order in which a series of evolutionary events have occurred

15. 16.5 How to Build a Family Tree
An alternative approach to constructing phylogenies is traditional taxonomy
both ancestral and derived characters are used to build trees
this wealth of additional information is often weighted by its biological significance but this is a more subjective process than cladisitics

16. Figure 16.6 Two ways to classify terrestrial vertebrates

17. 16.6 The Kingdoms of Life
Most biologists use a six-kingdom system first proposed by Carl Woese
four kingdoms consist of eukaryotes
Animalia, Plantae, Fungi, and Protista
two kingdoms consist of prokaryotes
Archaea and Bacteria
Recognizing that there are further differences among the prokaryotes, the domain level above kingdom was created
Domain Archaea contains the Kingdom Archaea
Domain Bacteria contains the Kingdom Bacteria
Domain Eukarya contains the eukaryotic kingdoms

18. Figure 16.8 Different approaches to classifying living organisms

19. 16.7 Domain Bacteria
The bacteria are the most abundant organisms on earth
there are many different types of bacteria and the evolutionary links between them are not well understood
most taxonomists recognize 12 to 15 major groups of bacteria
although archaea are also prokaryotic like bacteria, the archaea are more closely related to eukaryotes

20. 16.8 Domain Archaea
The Archaea branched off from a line of prokaryotic ancestors that lead to the evolution of eukaryotes
modern Archaea live in some of the most extreme environments on earth and, although a diverse group, share some of the same key characteristics
their cell walls lack the peptidoglycan that is characteristic of bacterial cell walls
they possess unique lipids and rRNA sequences
some genes in the archaea have introns

21. Figure 16.9 A tree of life

22. 16.8 Domain Archaea Archaea are grouped into three general categories
methanogens obtain their energy by using hydrogen gas (H2) to reduce CO2 to methane gase (CH4)
extremophiles are able to grow under extreme conditions, such as extreme heat, salt, pH or pressure
nonextreme archaea grow in the same environments that bacteria do

23. 16.9 Domain Eukarya
Eukaryotes have a complex cellular organization but are fairly uniform in metabolism, when compared to prokaryotes
there are three largely multicellular kingdoms (fungi, plants, and animals)
the remaining eukaryotic kingdom, Protista, is a diverse array of mostly unicellular forms that basically don’t fit into the other kingdoms

24. 16.9 Domain Eukarya
Endosymbiosis may explain the origin of eukaryotes from prokaryotes
Figure Endosymbiosis

25. Inquiry & Analysis
Three great innovations in the jaw and tail occur during the history of the bony fishes, producing the superorders represented by strurgeons, then gars, then teleost fishes. In what period did each innovation occur?
Graph of The Rate New Forms of Fish Have Appeared