American Zoologist articles from December 1998

American Zoologist archives from December 1998

Effects of Ultraviolet Radiation on Amphibians: Field Experiments(1).
December 1, 1998... INTRODUCTION The fundamental problem in ecology is to determine the causes that limit the distribution and abundance of organisms (Krebs, 1994). Examining this problem is especially relevant today because populations of many organisms are...

Introduction to the Symposium: Evolutionary Relationships of Metazoan Phyla: Advances, Problems, and Approaches(1).
December 1, 1998... For the 1,033,614 species of living animals estimated by Wilson (1988), there are roughly 1 x [10.sup.6,000,000] possible unrooted phylogenetic trees. Despite this intimidating possibility, its many biologists have accepted the challenge to try...

Changing Patterns of Gene Regulation in the Evolution of Arthropod Morphology(1).
December 1, 1998... INTRODUCTION Remarkable similarities have been found in the gene networks that pattern basic cellular and developmental tasks in diverse metazoans. Examples from studies in development include similarity of the HOX genes in anteroposterior...

Major Transitions in Animal Evolution: A Developmental Genetic Perspective(1).
December 1, 1998... INTRODUCTION The range of body forms found across the animal kingdom is strikingly discontinuous. This discontinuity is reflected in taxonomy. For example, the taxonomic rank of phylum is used to divide the animal kingdom into sets of...

Are Platyhelminthes Coelomates without a Coelom? An Argument Based on the Evolution of Hox Genes(1).
December 1, 1998... INTRODUCTION "We are asked [by the supporters of the enterocoele theory] to believe that the Turbellaria have lost their coelom, lost their anus, lost their nephrostomes. This is asking too much of one's credulity." Libbie H. Hyman, (1959,...

Deciphering Metazoan Phylogeny: The Need for Additional Molecular Data(1).
December 1, 1998... INTRODUCTION The diversification of multicellular animals has resulted in major lineages each characterized by a unique body plan and classified as a separate phylum. A robust phylogenetic hypothesis of relationships among these lineages...

Early Metazoan Evolution: Reconciling Paleontology and Molecular Biology(1).
December 1, 1998... INTRODUCTION The question as to whether the fossil record, given its many and grievous imperfections, allows accurate insights into the history of life has a special force with respect to the Cambrian "explosion." This event, classically...

Evolution of the Multicellular Animals(1).
December 1, 1998... INTRODUCTION Despite more than a century of study, the evolutionary relationships among the 30+ phyla which comprise the multicellular animals (or Metazoa) is still unresolved. Much previous phylogenetic work has utilized anatomical,...

Metazoan Relationships on the Basis of 18S rRNA Sequences: A Few Years Later ...(1).
December 1, 1998... INTRODUCTION Despite several decades of morphological and anatomical research, numerous aspects of metazoan relationships have remained uncertain (for an overview see Brusca and Brusca, 1990; Willmer, 1990; Meglitsch and Schram, 1991). In...

The Essential Role of "Minor" Phyla in Molecular Studies of Animal Evolution(1).
December 1, 1998... INTRODUCTION What are "minor" phyla? Minor phyla are often referred to as enigmatic or problematic, are usually of uncertain affinity, and generally are treated superficially in invertebrate texts. Minor phyla are considered to be of...

Molecular Phylogeny of Arthropods and the Significance of the Cambrian "Explosion" for Molecular Systematics.
December 1, 1998... INTRODUCTION The phylogenetic relationships of the major arthropod lineages is a long-standing and contentious issue. This may stem from a level of taxonomic and morphological diversity within the phylum so high as to be beyond the ability...

Considerations for Reconstructing Metazoan History: Signal, Resolution, and Hypothesis Testing(1).
December 1, 1998... INTRODUCTION The resurgence of interest in higher-level metazoan phylogeny has sparked new and interesting debates, as well as rekindling long standing controversies. Unfortunately, an assessment of the field suggests that some issues...

Morphological Approaches to Phylogeny(1).
December 1, 1998... INTRODUCTION Morphology has been the basis of classification already long before the introduction of evolutionary theory and phylogenetic classification. It has the obvious advantage that many characters are immediately visible, and it is...

Recent Views on the Status, Delineation and Classification of the Annelida(1).
December 1, 1998... INTRODUCTION Through most of this century the Annelida has been split into two main groups; the Polychaeta and Clitellata, with myzostomatids being given class status by some workers (Jagersten, 1940; Prenant, 1959), or as members of the...

Evolution Within a Bizarre Phylum: Homologies of the First Echinoderms(1).
December 1, 1998... INTRODUCTION The familiarity of a seastar or a sea urchin belies their overall weirdness. Not only are they quite different from each other, together with all the other members of the Echinodermata, they form a clade very disparate from...

Interpreting the Earliest Metazoan Fossils: What Can We Learn?(1).
December 1, 1998... INTRODUCTION In 1947, Australian geologist Reginald C. Sprigg published a paper titled "Early Cambrian (?) jellyfishes from the Flinders Ranges, South Australia," describing some unusual impressions of unmineralized organisms that he had...

Species of Mind: The Philosophy and Biology of Cognitive Ethology.(Review)
December 1, 1998... Species of Mind: The Philosophy and Biology of Cognitive Ethology. COLIN ALLEN AND MARC BEKOFF. MIT Press, 1997, 232 pages, 9 illustrations. (ISBN 0-262-01163-8, Cloth; $35.00.) There is a somewhat tragic element overshadowing cognitive...

The Evolution of Sibling Rivalry.(Review)
December 1, 1998... The Evolution of Sibling Rivalry. DOUGLAS M. MOCK AND GEOFFRY A. PARKER. Oxford University Press, 1998, 464 pages. ISBN 0-19-8577443-5. cloth, $120, paper $55 In 1964, W. D. Hamilton introduced the concept of inclusive fitness and showed...

Motion Analysis of Living Cells.(Review)
December 1, 1998... Motion Analysis of Living Cells. DAVID R. SOLL AND DEBORAH WESSELLS, eds. Wiley-Liss, 1998. xii, 298 pages. (ISBN 0-471-15915-8, hardback $150.) This timely book is part of the series, "Techniques in Modern Biomedical Microscopy," and it...

Survival Strategies: Cooperation and Conflict in Animal Societies.(Review)
December 1, 1998... Survival Strategies: Cooperation and Conflict in Animal Societies. RAGHAVENDRA GADAGKAR. Harvard University Press, 1997, 196 pages. (ISBN 0-674-17055-5, $22.00.) This is a book about animal social behavior for the curious amateur, for the...

Molecular Evolution and Adaptive Radiation.(Review)
December 1, 1998... Molecular Evolution and Adaptive Radiation. THOMAS J. GIVNISH AND KENNETH J. SYTSMA, EDS. Cambridge University Press, Cambridge, 1997, xvii + 621 pages., (ISBN 0-521-57329-7). With the introduction of the polymerase chain reaction to...

Shapes of Time. The Evolution of Growth and Development.(Review)
December 1, 1998... Shape of Time. The Evolution of Growth and Development. KENNETH J. MCNAMARA. John Hopkins University Press, 1997, 342 pages, index. (ISBN: 0-8010-5571-3, $34.95.) Heterochrony (change in the timing or rate of development) is a major...

Avian Growth Development: Evolution within the Altricial-Precocial Spectrum.(Review)
December 1, 1998... Avian Growth Development: Evolution within the Altricial-Precocial Spectrum J. MATTHIAS STARCK AND ROBERT E. RICKLEFS. Oxford University Press, New York, 1998, x + 441 pp (ISBN 0-19-510608 cloth $70.00). Possibly because the embryos and...