What we did in this revision:
Ecology and Evolution
Professor Jonathan Losos, our colleague at Washington University, has revised
the Evolution and Ecology sections of the text, bringing more of everyday experimental
science into our discussions. Presentation of the experimental data used to
derive key conclusions and concepts is key to this revision. Our goal is to
better aid students to understand how the concepts arose from the research.
For this reason you will see that graphs and charts are more plentiful in these
Professor Susan Singer of Carleton College has revised the botany chapters.
The Botany sections have benefited from a new approach where plant development
takes center stage. A plant developmental biologist, she has placed the traditional
discussions of evolutionary influences on plant form and function into a developmental
context. Thus while evolution is still presented as the underlying explanation
for the character of vascular tissue, seeds, flowers, and fruits, the developmental
processes that produce these organs are now given more prominence. This does
not lessen the evolutionary character of the treatment, but rather serves to
amplify it. Throughout all the botany chapters, there is an enhanced emphasis
on the molecular aspects of plant life. Understanding the molecular underpinnings
of plant form and function allows students to more clearly understand the evolutionary
changes that have shaped them.
New Chapter: Conservation Biology (Chapter 31)
In the fifth edition, we presented a discussion of conservation biology on the
Biology web site, as an "enhancement chapter". The response was so
overwhelming that we have included such a chapter in this edition of our text.
In our own classroom teaching we find students to be keenly aware of the problems
of dwindling natural resources, and the need to tackle the issue concretely.
We feel a chapter focusing on conservation biology will be appreciated by students
and useful to professors.
Genomics "Enhancement Chapter"
The rapidly advancing field of Genomics is so key to the future of biology that
we felt it necessary to discuss it in some way in this sixth edition. Including
a chapter in the text seemed rather pointless--so much of what we would cover
will have changed after the first year. So, we turn again to an "enhancement
chapter." We used enhancement chapters to expand information for the fifth
edition of Biology and as you see from above, after fine-tuning the Conservation
Biology chapter, we now include it in this edition. The enhancement chapter
on Genomics can be found at http://auth.mhhe.com/raven6.
This new chapter expands upon the discussion of gene technology to present and
explain the advances now being made with genomics. While the chapter discusses
the technology involved and the genomes that have been uncoded, it focuses on
the significance of this information to biology as a science, and on what it
could mean to the future of medicine, agriculture and many other fields.
Real People Doing Real Science (Inquiry-Based Learning)
We have added an inquiry-based learning experience at the beginning of every
Part that walks a student through the process of scientific inquiry by examining
a particular experiment. After briefly reviewing the significance of the experimental
question being addressed, we take the student through the actual experiment,
discussing experimental design in depth, and then briefly describe the results
and conclusion. This is but the first part of the learning experience. The student
is then directed to the Biology, sixth edition web site for an in-depth examination
of the experiment. There a student can read the actual published research paper,
allowing students to become more familiar with the primary literature. Then
the student can carry out a "Virtual Experiment" where he or she is
able to manipulate the parameters of the experiment and obtain data for analysis.
We provide on-line questions and discussions to help the student better understand
the thought process behind the experiment.
A Thorough Revision
In addition to the extensive revisions of the Ecology, Evolution, and Botany
sections of the text, and new chapters on genomics and conservation biology,
we have thoroughly revised the rest of the text as well. Many chapters now sport
radically different organizations, benefiting from extensive reviewer input.
Pedagogy has been improved as well. We have included phylogenetic guideposts
throughout the discussions of diversity to clarify for the student where each
group fits in the tree of life (You will find these guideposts in chapters 35,
36, 37, and 44-48).
The Chemical Building Blocks of Life (Chapter 3)
The organization of this chapter has been turned on its head, presenting lipids
before carbohydrates. This gives a greatly improved sense of the relative biological
importance of these macromolecules, and actually makes the material easier to
The Origin and Early History of Life (Chapter 4)
The discussion of ideas about the origin of life is now much more open-ended,
stressing competing hypotheses and the key role of assumptions for which there
is little data.
Photosynthesis (Chapter 10)
The internal organization of this chapter has been reworked to make it easier
for students to understand how the many concepts covered in this chapter relate
to one another.
Patterns of Inheritance (Chapter 13)
This chapter has been reorganized to incorporate the discussion of human genetics
earlier in the chapter and then to use human examples as a means of explaining
Cellular Mechanisms of Development (Chapter 17)
We have moved the discussion of cellular development up earlier in the text,
immediately following the discussion of gene expression, to reinforce key molecular
Altering the Genetic Message (Chapter 18)
Many recent advances in cancer research are highlighted, with greater emphasis
on genes governing metastasis and angiogenesis.
Gene Technology (Chapter 19)
New topics such as Biochips and Transgenic rice have been included and rapidly
advancing areas such as Stem cells and Ethics and Regulations have been updated.
The Evidence for Evolution (Chapter 21)
We have expanded this chapter to include a complete discussion of the evolution
of the horse, and have expanded the discussion of artificial selection as a
means of showing the power of selection on the evolution of species.
Population Ecology (Chapter 24)
We have added and expanded the discussions of population distributions, ranges,
dispersal mechanisms and human effects in examples replete with actual data.
Animal Behavior (Chapter 26) and Behavioral Ecology (Chapter
We have amplified these two chapters, moving them to the ecology section, a
more logical place to teach these topics.
Dynamics of Ecosystems (Chapter 28)
We have greatly expanded discussions of interactions among trophic levels and
the controversial matter of how species richness influences community stability.
The Biosphere (Chapter 29)
We have expanded the discussion of evolutionary responses to environmental variation.
Evolutionary History of Plants (Chapter 37)
We now include a discussion of the "Deep Green Project" that demonstrated
the green algal origin of all plants.
The Plant Body (Chapter 38)
We included a discussion of the genes involved in development of stomata, trichomes,
root tissues and leaves.
How Plants Grow in Response to the Environment (Chapter 41)
This chapter was extensively reworked and many new topics were added and expanded
such as: acid growth hypothesis of auxin actions, plant defense responses, cytokinins
involvement in organ regeneration and crown gall tumors, brassinosteroids and
oligosaccharins, transgenic tomatoes, initiating flowering and circadian clocks.
The Noncoelomate Animals (Chapter 44)
This chapter now includes a molecular reevaluation of the evolution of the metazoan
Arthropods (Chapter 46)
New molecular data calls into question traditional classification of arthropods
based on external characteristics.
Locomotion (Chapter 50)
We have added a discussion of modes of locomotion that ties together the concepts
presented in the chapter.
Circulation (Chapter 52)
We have added a section on heart disease, explaining that heart disease is preventable
and begins with establishing a heart-healthy lifestyle early.
Sensory Systems (Chapter 55)
We have broadened the coverage in this chapter to include more examples of nonmammalian
The Immune System (Chapter 57)
This chapter has been completely reorganized to improve clarity and understanding.
The presentation of topics now more logically follows the process of the immune
response in the body.