Herpetology. An Introductory Biology of Amphibians and Reptiles

749 Pages·2013·102.86 MB·English

by  Laurie J. Vitt and Janalee P. Caldwell (Auth.)

Herpetology
An Introductory Biology of
Amphibians and Reptiles
Fourth Edition
Laurie J. Vitt and Janalee P. Caldwell
Sam Noble Museum and Biology Department
University of Oklahoma
Norman, Oklahoma
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Dedication
We dedicate this book to the many young scientists that have joined the
global herpetological community during the past 20 years, bringing new
perspectives, new techniques, and new data to a taxonomically delimited
field that impacts all conceptual areas of the biological sciences.
L.J.V. and J.P.C.
Foreword
The diversity of living creatures on our planet is extraordi- creatures being studied, not just on methods or concepts.
nary—and thus, trying to understand how those organisms So “herpetology” is a useful category: If we really want to
function, and how and why they do the things they do, is understand what animals do, we can’t ignore the history
an awesome challenge. To make the challenge a bit more behind each type of organism. Many of its features will be
manageable, we traditionally divide the study of biology determined by that history, not by current forces. Because
into many categories, some based on methodology (e.g., of that historical underpinning, the most effective way to
“microscopy” or “molecular biology”), some on function answer general questions in biology may be to work within
(e.g., “ecology” or “physiology”), and some on relatedness one or more of those major branches in the tree of life. Start-
among the things that are to be studied (e.g., “ornithology” ing from common ancestors, we can see with much greater
or “herpetology”). At first sight, this last way of slicing the clarity how evolutionary forces have created rapid change
cake seems a bit old-fashioned—surely we can simply ask in some cases (why are chameleons so incredibly weird
the same questions and use the same methods, regardless compared with other lizards?), have produced remarkably
of what kind of organism we might be studying? If so, are little change over vast timescales in others (can it really be
traditional taxonomy-based divisions just historical relics of true that crocodiles are more closely related to birds than to
the early naturalists, doomed to eventual extinction by the lizards?), and have even generated convergent solutions in
rise of powerful conceptual and methodological advances? distantly related species exposed to similar adaptive chal-
Nothing could be further from the truth. Entrancing as lenges (like horned lizards in the deserts of North America
the new approaches and conceptual divisions are, the reality compared with thorny devils in the deserts of Australia).
of life on Earth is that organisms do fall into instantly recog- Allied to the greater clarity that comes from compar-
nizable types. Few people would mistake a tree for a lizard, ing like with like, and including genealogy in our thinking,
or a whale for an insect. The reason is simple: evolution is are other great advantages to taxon-based categories like
a historical process that creates biodiversity by the accu- “herpetology.” Organisms are composites of many traits,
mulation of small changes along genealogies, with the vast and these need to work together for the creature to function
majority of species becoming extinct during that process. effectively. So we can’t really look at metabolic rate sepa-
So the end result at any time in Earth’s history is a series rately from foraging behavior, or social systems separately
of terminal branches from the great tree of life—terminal from rates of water loss. Biology forges functional links
branches that form larger branches, that in turn coalesce between systems that our conceptual and methodological
to form even larger branches, and so forth. All the species classification systems would treat in isolation from each
within each of those larger branches share common ances- other, ignoring their need for integration within a function-
tors not shared by any species on the other branches, and, ing individual. And there are many other advantages also.
as a result, the species within each branch resemble each In a purely pragmatic sense, the methods that we use to
other in many ways. For example, no amphibian embryo study animals—such as the ways we observe them, catch
grows up with an amniotic membrane around it in the egg, them, handle them, mark them, and follow them around—
whereas every reptile embryo has one. depend enormously on many of the traits that differ so con-
The evolutionary conservatism of major characteristics spicuously between major vertebrate lineages. A textbook
such as metabolic rates, reproductive modes, feeding struc- of herpetology can thus teach us more about how to study
tures, and the like, in turn have imposed evolutionary pres- these animals than can a textbook focused on any single
sures on myriad other features—and the end result is that functional topic. And lastly, the conservation challenges
the diversity of life is packaged into a meaningful set of facing reptiles and amphibians also are massively affected
categories. That is the reason why most of us can easily dis- by their small body sizes, low rates of energy use, primarily
tinguish a frog from any other kind of animal and can even tropical distributions, and the like—so that if we are to pre-
tell the difference between a crocodile and a lizard. And it serve these magnificent animals for future generations, we
is a major reason why there is immense value in defining need a new generation of biologists who can comprehend
a scientific field based on evolutionary relatedness of the the sophisticated functioning of these threatened creatures.
ix
x Foreword
This marvelous book captures the excitement of herpetol- from developed countries glean fragments of data during
ogy and will do much to instill that appreciation. brief trips to places far from home. Instead, locally born and
Much has happened in the world of herpetological locally based researchers are taking their studies to a whole
research since I wrote the Foreword to the Third Edition of new level, based upon a deep familiarity with the systems,
this book. The authors have updated their work to include and a perspective based upon living in an area rather than
those new insights, and the extent of the work required tells just visiting it. Herpetology is evolving as a discipline, and
us just how dramatically our understanding of reptile and the book you hold in your hands shows the rapid growth of
amphibian biology has advanced. One of the most striking our insights into the extraordinary world of amphibians and
features of this new generation of herpetological researchers reptiles.
is that so many of them come from developing countries—
especially in the tropics, which hold so much of the planet’s Rick Shine
herpetological diversity. Tropical fieldwork is no longer School of Biological Sciences, University of Sydney,
the province of “pith-helmet biology,” where researchers Sydney, Australia
Acknowledgments
We first acknowledge all herpetologists who have published R. Pianka, Michael Polcyn, Louis W. Porras, D. M. Portik,
results of their research, thus providing the basis for our Alan Pounds, Jennifer Pramuk, F. Rauschenbach, Chris
textbook. Several students and colleagues in our laboratory Raxworthy, Todd Reeder, Doug Ruby, Rudy Ruibal, Steve
have provided continual help and insight, often serving as M. Reilly, R. P. Reynolds, Stephen J. Richards, S tephen
crucial critics. In particular, Gabriel C. Costa, Donald B. Richter, Gordon H. Rodda, Santiago Ron, James Rorabaugh,
Shepard, Adrian A. Garda, Tim Colston, and Jessa Watters Herbert I. Rosenberg, C. A. Ross, Rodolfo Ruibal, Anthony
provided continual input. Many dedicated volunteers at the P. Russell, Marcello Ruta, Paddy Ryan, Diego San Mauro,
Sam Noble Museum at the University of Oklahoma have Ivan Sazima, Rainer R. Schloch, D. Schmidt, Cecil Schwalbe,
helped us put together information. Terry Schwaner, Kurt Schwenk, Bradley Shaffer, Wade
The following friends and colleagues provided photo- Sherbrooke, Antonio Sebben, Stephen C. Secor, Bradley
graphs, graphics, information, or read portions of the text: Shaffer, Donald B. Shepard, Rick Shine, Cameron Siler,
Andrés Acosta, G. Alexander, Ronald Altig, J. Pedro do Barry Sinervo, Jack Sites, U. Srinivasan, Koen Stein, James
Amaral, Stevan J. Arnold, Chris Austin, Teresa Cristina S. R. Stewart, R. Chris Tracy, Richard C. Tracy, Stanley E.
Ávila-Pires, R. W. Barbour, Richard D. Bartlett, Aaron M. Trauth, Linda Trueb, R. G. Tuck, Jr., H. I. Uible, R. Wayne
Bauer, Dirk Bauwens, S. D. Biju, Daniel Blackburn, David Van Devender, Karthikeyan Vasudevan, Miguel Vences,
C. Blackburn, James Bogart, Franky Bossuyt, William R. Nicolas Vidal, Harold Voris, J. Visser, David Wake, Marvalee
Branch, A. Britton, Chris Brochu, Edmond D. Brodie, III, Wake, Dan Warner, Richard Wassersug, Graham Webb, Peter
Edmond D. Brodie, Jr., Rafe M. Brown, Samuel (Buddy) Weish, R. Whitaker, Martin Whiting, John J. Wiens, Steve
Brown, Frank Burbrink, Andrew C ampbell, Jonathan Wilson, Chris A. Wolfe, Yuchi Zheng, and George R. Zug.
A. Campbell, David Cannatella, Karen Carr, L. Chirio, Organizations permitting us to use their illustrative
R. S. Clarke, Guarino R. Colli, James P. Collins, Suzanne materials include: Academic Press, American Associa-
L. C ollins, Tim Colston, Justin D. Congdon, William E. tion for the Advancement of Science, American Museum
Cooper, Jr., Gabriel C. Costa, E. G. Crespo, Orlando Cuellar, of Natural History, American Society of Ichthyologists
Indraneil Das, K. P. Dinesh, C. Ken Dodd, Jr., R obert and Herpetologists, American Society of Integrative Biol-
C. Drewes, William E. Duellman, Carl H. Ernst, Robert ogy, Blackwell Science, Inc., Cambridge University Press,
Espinoza, Richard Etheridge, Danté B. Fenolio, April Fink Charles University Press, Chelonian Research Founda-
Dalto, Darrel Frost, Chris Funk, Tony Gamble, Adrian A. tion, Cornell University Press, CRC Press, Inc., Ecologi-
Garda, Luis G asparini, Varad Giri, J. Whitfield Gibbons, B. cal Society of America, Elsevier Science, Ltd. (TREE),
Göçmen, David J. Gower, Harry W. Greene, L. Lee Grismer, Ethology Ecology & Evolution, Herpetological Natural
W. Grossman, Celio Haddad, S. Harikrishnan, Blair Hedges, History, Harvard University Press, The Herpetologist’s
Robert H enderson, W. Ronald Heyer, David Hillis, Walter League, Kluwer Academic Publisher, The McGraw-Hill
Hödl, Marinus Hoogmoed, J effrey M. Howland, Raymond Companies, Muséum National d’Historie Naturelle, Paris,
B. Huey, Victor H. Hutchison, Kate Jackson, Karl-Heinz Museum of Natural History, University of Kansas, Divi-
Jungfer, Ken Kardong, J. Karney, Daryl R. Karns, Michael sion of Amphibians and Reptiles, National Museum of
Kearney, A. Kwet, Jeffrey W. Lang, Christopher Leary, Twan Natural History, Princeton University Press, Smithsonian
Leenders, William Leonard, Randy Lewis, Albertina Lima, Institution, National Research Council of Canada, Savan-
Jonathan B. Losos, William Magnusson, John H. Malone, nah River Ecology Laboratory, University of Georgia,
Michael A. Mares, Otavio A. V. Marques, Iñigo Martínez- Museum of Comparative Zoology (Harvard University),
Solano, Brad Maryan, Chris M attison, Roy W. McDiarmid, Selva, Smithsonian Institution Press, Society for the Study
James McGuire, D. Bruce Means, G. J. Measey, Phil A. of Amphibians and Reptiles, Society for the Study of Evo-
Medica, Peter Meylan, Ken Miyata, Edward O. Moll, Donald lution, Society of Systematic Biologists, Springer Verlag,
Moll, Robert W. Murphy, D. Nelson, K. Nemuras, Cristiano University of Chicago Press, John Wiley & Sons, Inc.,
Nogueira, Brice P. Noonan, Ronald A. Nussbaum, N ikolai Cambridge University Press, National Academy of Sci-
Orlov, Mark T. O’Shea, David Pearson, David Pfennig, Eric ences (USA), and others.
xi
Introduction
It is an admirable feature of herpetologists that they are able to population increase is reflected in the exponential increase
cross the boundaries between different aspects of their subject, in environmental effects. We consider it imperative that
which remains, perhaps more than other branches of zoology, a students understand the basis for life around them and the
single coherent discipline.
connections between our survival and the survival of other
A. d’A. Bellairs and C. B. Cox, 1976. species. The biology of amphibians and reptiles provides a
unique opportunity to achieve that goal, for several rather
We are now in the Fourth Edition of Herpetology, and obvious reasons. Amphibians and reptiles live in water, on
advances in the field have been remarkable. The global and under the surface of the land, or in vegetation cover-
interest in herpetology has increased dramatically, with new ing the Earth. As a result, they are exposed to all chemicals
professional societies emerging in nearly every country and that are released into the environment, either directly or
literally thousands of bright, enthusiastic herpetologists indirectly. Because many, if not most, have special habi-
entering the field. Perusal of nearly every scientific jour- tat requirements, modifications of their habitats usually
nal reveals author lines with new names, many of which result in loss of populations or species. Some species are
will make significant contributions to the field throughout harvested commercially for food or cultural medicines, and
their entire careers. Technological and analytical advances those with considerable monetary value are rapidly being
in phylogenetics have not only resulted in new phylogenetic overexploited. Amphibians (frogs in particular) have gained
hypotheses for clades of amphibians and reptiles, but have enormous popularity in the arts and crafts trade, partly
resulted in reinterpretations of ecological and behavioral because they are colorful and diverse, and partly because
phenomena. Most striking is the impact of phylogenetics they are non-threatening. The pet trade has brought amphib-
on historical biogeography and related fields. Not only can ians and reptiles into the homes of millions of people and
we trace the history of clades on a global level, we can also sparked their interest in these remarkable animals. Harvest-
add a time component to the divergence histories of clades ing of these animals for the pet trade has had local effects
based on evolutionary rates of genes. These independently on populations, but captive breeding has offset some of that
derived divergence histories can then be used to integrate impact. The pet trade has directly or indirectly resulted in
the evolution of clades with the geological history of the the introduction of exotic species, many of which cause
planet. major problems for endemic faunas. It is our hope that we
Herpetology is a rapidly evolving field, and, although it can use the interest in these fascinating animals to draw stu-
is a taxonomically delimited field, research on amphibians dents into understanding general biological concepts, all of
and reptiles has set new directions, defined new fields, and which apply to the biodiversity surrounding us that helps
led to major discoveries in all conceptual areas of biology— sustain life on Earth.
discoveries that have changed the way we think about life Our primary goals in revising Herpetology—An Intro-
on Earth. We know more now than we ever did, and we ductory Biology of Amphibians and Reptiles are to (1) update
will continue to know and understand more as innovative the text to reflect some of the truly exciting discoveries that
technologies allow us to explore new ideas in ways never have been made since about 2008 when we completed the
before thought possible. At the same time, we are losing third edition (published in 2009), (2) update the taxonomy,
species and habitats at a rate unparalleled in the history of which in some cases has changed radically as the result of
life, and much of it can be tied directly to human activity much more sophisticated evolutionary analyses (e.g., squa-
and indirectly to human population growth. When Coleman mates and anurans), and (3) introduce the reader to some
and Olive Goin published Introduction to Herpetology in of the leading herpetological researchers by featuring them
1962, the population of the Earth was nearly 3 billion; when throughout the book. In doing the latter, we emphasize that
George Zug published the first edition of Herpetology—An many truly phenomenal researchers make major discover-
Introductory Biology of Amphibians and Reptiles in 1993, ies every day—we have selected a few from the many, and
the population was 5.4 billion; today, the world population with future editions, our selections will vary. Our intent is
has reached more than 7 billion! The exponential rate of not to slight any researcher by non-inclusion, but rather to
xiii
xiv Introduction
highlight a few of the many in an attempt to make research physiological, and ecological data (total evidence) demon-
discovery a little more personal. After all, successful her- strates the complexity of the evolutionary history of amphib-
petologists are really just normal people driven by their ians and reptiles. At the same time, it brings us much closer
interest in herpetology just as rock stars are normal people to constructing phylogenetic hypotheses that accurately
driven by their interest in music and the performing arts. reflect evolutionary relationships. At times, molecular data
We have explicitly tried to keep the text at a level that are at odds with morphological data (fossil or otherwise),
will be of use to undergraduates with a basic background in and when new and different phylogenetic hypotheses emerge
biology as well as those with a much broader background. based on solid molecular data and analyses, we have to ask
Because color is so important in the lives of amphibians whether morphological traits that we have so long believed
and reptiles, we use it throughout the text, which we believe reflect homology may have misled us. Most striking is the
aids significantly in showcasing how special these animals observation that classical Linnean taxonomy presents a false
are. Color is also useful in chapters in which we discuss impression about relationships of taxa. For example, Lin-
crypsis, aposomatic coloration, and social behaviors medi- nean taxonomy implies that all Families are equal age, that
ated by visual displays. We remind the reader that not only all Orders are equal age, and so on. Although some elements
are amphibians and reptiles part of our own evolutionary of Linnean taxonomy are useful in allowing us to talk about
history, but also they are an integral part of our natural heri- amphibians and reptiles, the basic notion that organisms
tage. They, along with all other animal and plant species, can be placed in arbitrary groups and given names is highly
comprise life on Earth. misleading. Our classification contains a mix of lower
Readers will note that the taxonomies that we present taxonomic-level Linnean taxonomy (to facilitate discussion)
in Chapters 15–22 differ from those in past editions. This and phylogenetic taxonomy (to reflect relationships). We use
in itself is a testament to the rapid advances being made in species, genus, subfamily, and family as labels, emphasiz-
phylogenetics. In addition, many new species, genera, and ing that each does not correspond to a given phylogenetic
families have been described since the last edition, and this distance or evolutionary time period (e.g., not only are dif-
will continue. Indeed, between the time that we completed ferent “families” different ages, they are nested within each
this revision and the release date (approximately 8 months), other). We have attempted to be as current as possible and
additional taxa will be described and new phylogenies will our classification sections reflect published interpretations
appear rendering some of our taxonomies dated. A num- through August 2012. Numerous phylogenetic hypotheses
ber of websites can be used to track changes as they occur, exist for most groups of amphibians and reptiles, resulting in
and we recommend that users of this text refer to these different classifications, sometimes strikingly different. We
periodically for updates. For amphibians, two websites, have selected a single cladistic interpretation for each group
AmphibiaWeb (http://amphibiaweb.org/) and the American or combined the results of two interpretations when a single
Museum’s Amphibian Species of the World (http://research. cladistic analysis for all members of the group (clade) was
amnh.org/vz/herpetology/amphibia/) are particularly use- not available. We discuss other interpretations and analy-
ful. For reptiles, The Reptile Database (http://www.reptile- ses, but not necessarily all available studies, to ensure that
database.org/) maintained by Peter Uetz and supported by readers are aware that other interpretations exist. We use
the Systematics working group of the German Herpetologi- Latinized familial and subfamilial group names for mono-
cal Society and the European Union through the Catalogue phyletic groups and Anglicized or Latinized names in quotes
of Life Project is continually updated. for groups that are of uncertain monophyly. Some authors
Classification and nomenclature continue to change, and, have not assigned family names to some species and groups
if anything, the rate of change is greater than it ever has been. of species that represent a sister taxon to another family;
New fossils, new techniques for obtaining and interpreting where Latinized familial names are available, we have used
phylogenetic data, and the beginnings of a truly phylogenetic the available name or elevated a subfamilial name if that lat-
taxonomy and its associated nomenclature are changing ter taxon includes the same set of species. Distributions are
amphibian and reptilian classification monthly. The ability an important component of an organism’s biology; our maps
to recover relationships among taxa at all levels based on show the natural (nonhuman dispersed) distribution as best
combinations of morphological, gene sequence, behavioral, as we were able to determine it.
Part I
Evolutionary History
Although amphibians and reptiles are not closely related evolutionarily, they are usually studied together, largely
because they often occur side by side and share many physiological, behavioral, and ecological similarities. More-
over, both are very ancient groups with fascinating histories. What we see today are the successful remnants of a
few groups that avoided extinction for various historical reasons. Major extinction events reduced global diversity
of amphibians and reptiles several times, only to be followed by relatively rapid diversification events within some
of the surviving groups.
Chapter 1
Tetrapod Relationships and
Evolutionary Systematics
Chapter Outline
Amphibians and Reptiles—Evolutionary History 5 Early Amniotes 18
Relationships Among Vertebrates 7 Radiation of Diapsids 19
Origin of Tetrapods 7 Linnean Versus Evolutionary Taxonomy 21
Key Fossils 8 Rules and Practice 22
Major Features of Early Tetrapod Evolution 9 Evolution-Based Taxonomy 25
Respiration 9 Systematics—Theory and Practice 26
Movement 13 Systematic Analysis 26
Feeding 13 Types of Characters 26
Skin 14 Morphology 27
Sense Organs 14 Molecular Structure 28
Evolution of Early Anamniotes 14 Methods of Analysis 29
Ancient Amphibians 14 Numeric Analyses 30
Modern Amphibians—The Lissamphibia 15 Phylogenetic Analyses 31
Evolution of Early Amniotes 15
Early Tetrapods and Terrestriality 15
Herpetology is the study of amphibians and reptiles. We Amphibians have successfully exploited most terrestrial
focus on the biology of extant amphibians and reptiles environments while remaining closely tied to water or
throughout much of the text. Nevertheless, we provide an moist microhabitats for reproduction. Most amphibians
introduction to what is currently known about the fascinat- experience rapid desiccation in dry environments, but
ing history of these animals. Reconstructing this history some species have evolved spectacular adaptations that
has been a challenge, largely because the fossil record is so permit existence in extreme habitats.
incomplete, but also because methods used to reconstruct During the Carboniferous, about 320 Ma, the ances-
relationships (phylogenies) continue to change. Living tors of modern reptiles (including birds) and mammals
amphibians and reptiles are representatives of a small num- appeared. They not only were able to reproduce on land
ber of the many historical tetrapod radiations (Fig. 1.1). in the absence of water but also had an effective skin bar-
Living amphibians are descendants of the first terres- rier that presumably reduced rapid and excessive water
trial vertebrates. Their ancestors were lobe-finned fishes loss. Higher taxonomy of early tetrapods remains unsta-
(Sarcopterygii), a group of bony fishes (Osteichtyes). ble. Anthracosaura and Reptiliomorpha have been used to
These fishes appeared in the Lower Devonian Period include reptile ancestors, but definitions of each, in terms
(more than 400 million years ago [=400 Ma, where 1 mega- of fossil taxa included, varies from author to author. We
annum = 1 million years ago]) and radiated in fresh and use anthracosaur to include modern amniotes and extinct
salt water. The earliest fossils assigned to Tetrapoda (from tetrapods that cannot be considered amphibians. The study
Greek, tetra = four, poda = foot) included Elginerpeton, of birds and mammals, formally called Ornithology and
Ventastega, Acanthostega, and Ichthyostega, all of which Mammalogy, respectively, are beyond the scope of this
were completely aquatic but had four distinct limbs. They book.
appeared as fossils in the late Devonian (about 360 Ma) Amphibians and reptiles (collectively, herps) are not
but may have been present much earlier (see below). They each other’s closest relatives evolutionarily, yet they
are in a group of tetrapods referred to as ichthyostegalians. have traditionally been treated as though they are related
3
Herpetology. http://dx.doi.org/10.1016/B978-0-12-386919-7.00001-0
Copyright © 2014 Elsevier Inc. All rights reserved.