Many classic tests of ecological theory have involved populations and communities maintained for many generations in the laboratory under tightly controlled conditions. In spite of this, such “bottle experiments” now play only a minor role within the larger field of ecology, and their relevance to natural populations and communities is regarded with suspicion by many field ecologists. Here, we compare and critique several recent bottle experiments, which were designed to test open questions in ecological theory that could never feasibly be addressed in natural communities. Judging from this set of experiments, we suspect that it will be difficult to relate the qualitative results of bottle experiments to natural populations and communities. What we learn from these experiments depends heavily on the relationship between theoretical models and experimental design. If the demography of organisms is completely under experimental control, bottle experiments can teach us about the possible range of population dynamics, but not about what regulates dynamics in natural populations. Furthermore, if experimental results are not linked to a mechanistic model, we can support or refute broad generalizations, but there is no direct way to relate bottle experiments to natural communities. Consequently, we argue that the most informative bottle experiments must incorporate both mechanistic models and unmanipulated demography; such bottle experiments can generate new ideas and future directions for both empirical and theoretical research.
The conventional wisdom of most ecologists is that herbivores are generally incapable of strongly affecting plant populations in natural communities. Thus, ecologists have largely focused on the role of competition for limited resources but have ignored herbivory as a primary factor determining plant success. Here, we present a quantitative review of herbivore manipulations and find that herbivores do exert important effects on plant biomass—equally as important as those of plant competition. This result should alter the way plant communities are investigated. Furthermore, we find that the effects of invertebrate herbivores are significantly stronger than those of vertebrates; this is in contrast to widely held views. Quantitative syntheses of accumulated studies, such as the one presented here, can provide surprising answers to a broad scope of biological questions. This is especially important in fields lacking a strong theoretical basis, in which generalities are born from empiricism rather than deductive theorizing.
Phylogenetic systematics, as espoused in a recent book review by Harry W. Greene published in this journal, promotes the idea that paraphyly obscures the recognition of phylogenetic relationships and other aspects of organismic biology. I argue here that this viewpoint is not only without merit (what, in fact, do derived taxa tell us about paraphyletic taxa?), but that insistence on holophyly in itself may obscure ready appreciation of phylogenetic relationships. It has been recognized and accepted for the better part of this century that taxonomic groups at all levels may be derived from within other taxonomic groups, resulting in paraphyly. This phenomenon is becoming more and more evident as cladistic analyses of molecular and morphological data are more penetrating, and many well-defined taxa, including sponges, are now seen as probably paraphyletic. Computer-based cladistic analysis, integrating both molecular and morphological characters, is a powerful and increasingly essential approach for sorting out and establishing both sister-group and paraphyletic relationships. Paraphyletic taxa should be recognized as such for the fascinating perspective they provide in unraveling evolutionary patterns.
Self-organizing behavior is one of the most remarkable properties of regulative animal embryos. The reorganization of disarranged embryonic primordia to form an approximation of the "correct" structure by any number of abnormal pathways constitutes a form of goal-directed behavior. One might suppose that such anatomical "goals" are specified by genetic programs evolved through mutation and natural selection to produce useful structures. However, one might also ask the following questions: how can genes direct morphogenesis without specifying the pathways to be followed? How can genetic systems have evolved to specify the organization of the never-before-assembled structures reproducibly generated by abnormal tissue combinations? Experiments have shown that the layered structures generated in such experiments belong to the category of "inherently precise" machines, in which a specific pattern is generated with great precision by the constant repetition of a simple local behavior throughout the pattern-forming system. The organization characteristic of the chordate body plan—the "goal" of early development—also arises by very different developmental pathways in the various members of the phylum. Yet divergent evolution can hardly have altered the mechanisms governing gastrulation and neurulation while holding the end results essentially constant. Evidence suggests that the striking differences in these pathways may be understood less as fundamental alterations of morphogenetic mechanisms than as the physical consequences arising from heterochrony—differences in the times at which a shared set of underlying cellular changes are initiated.
Spatial learning is necessary for most animals to survive in their natural environment. Spatial problems encountered by animals in nature are relatively constant across species, such as going to and from shelter or a food source. Most studies of orientation and spatial learning have been done in birds and mammals, but reptiles are particularly interesting because they have strong links between ecological factors, sensory processes, and behavior. Field studies suggest strongly that snakes can learn and remember spatial tasks encountered in the wild, including orientation, homing, and the localization of mates, shelter and foraging areas. Several sensory cues have been hypothesized to be used by snakes for orientation and navigation, with few direct tests of these hypotheses. A spatial learning and memory task has been developed that is relevant behaviorally to snakes and that they can learn rapidly. This open field escape task uses the natural behavior of snakes to address mechanistic hypotheses about their spatial learning and memory.
Integrative Biology: Issues, News, and ReviewsVolume 1, Issue 4 p. 113-114 In This Issue What was the natural condition of North America's first national park? Peter Kareiva, Peter Kareiva University of Washington, Seattle, WASearch for more papers by this author Peter Kareiva, Peter Kareiva University of Washington, Seattle, WASearch for more papers by this author First published: 07 January 1999 https://doi.org/10.1002/(SICI)1520-6602(1998)1:4<113::AID-INBI1>3.0.CO;2-5AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume1, Issue41998Pages 113-114 RelatedInformation
Integrative Biology: Issues, News, and ReviewsVolume 1, Issue 2 p. 45-48 News Innovative National Graduate Student Seminar analyzes habitat conservation plans Lisa Savage, Corresponding Author Lisa Savage savage@zoology.washington.edu Department of Zoology, University of Washington, Seattle, WA 98195-1800Department of Zoology, University of Washington, Seattle, WA 98195-1800Search for more papers by this author Lisa Savage, Corresponding Author Lisa Savage savage@zoology.washington.edu Department of Zoology, University of Washington, Seattle, WA 98195-1800Department of Zoology, University of Washington, Seattle, WA 98195-1800Search for more papers by this author First published: 07 January 1999 https://doi.org/10.1002/(SICI)1520-6602(1998)1:2<45::AID-INBI2>3.0.CO;2-5Citations: 5AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume1, Issue21998Pages 45-48 RelatedInformation
Lyme disease and gypsy moth outbreaks plague many temperate oak forests. Over the past decade, we have developed models and hypotheses designed to allow us to predict irruptions of both gypsy moths and the tick vector of Lyme disease. We have documented a web of connections involving mast production by oak trees, population responses by white-footed mice, habitat selection by white-tailed deer, and population dynamics of both tick parasites and defoliating insects. In patchy landscapes typical of the northeastern U.S., dispersal by mice, deer, and attached ticks between oak and nonoak forests creates dynamics that would not be predictable by focusing on a single patch type. We would not have uncovered these interactions without adopting a research approach that comprised: (1) the inclusion of diverse taxa of animals, plants, and microbes; (2) the integration of individual, population, community, and ecosystem levels of organization; (3) the incorporation of more than one patch type in a heterogeneous landscape; and (4) a combination of long-term monitoring and manipulative field experiments.
Integrative Biology: Issues, News, and ReviewsVolume 1, Issue 2 p. 73-75 Book Review Cells, embryos, and evolution: Toward a cellular and developmental understanding of phenotypic variation and evolutionary adaptability John Tyler Bonner, Corresponding Author John Tyler Bonner jtbonner@phoenix.princeton.edu Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544Search for more papers by this author John Tyler Bonner, Corresponding Author John Tyler Bonner jtbonner@phoenix.princeton.edu Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544Search for more papers by this author First published: 07 January 1999 https://doi.org/10.1002/(SICI)1520-6602(1998)1:2<73::AID-INBI6>3.0.CO;2-NAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume1, Issue21998Pages 73-75 RelatedInformation
Propagation of a modified form of the cellular prion protein is thought to be the primary cause of the transmissible spongiform encephalopathies, which include kuru, Creutzfeldt-Jakob disease (CJD), scrapie, and bovine spongiform encephalopathy (BSE). These highly unusual neurological maladies seem to arise spontaneously at extremely low rates. In addition, these diseases can be transmitted directly, in which case the incubation period is remarkably constant. The challenge is to understand these crucial features of prion diseases, without invoking the action of any viral agent. A simple model is developed in which the onset and progression of spongiform encephalopathies are explained by the kinetics of prion aggregate formation. Interestingly, ordered aggregations of proteins such as occurs in prion diseases are also associated with other neurological disorders such as Alzheimer's disease. Thus, insights developed about prion aggregation may have wide significance. © 1998 Wiley-Liss, Inc.
Computers are increasingly being used in undergraduate biology teaching, but often their use seems more trendy than substantive. Simply putting textbooks and graphs on a computer does not accomplish much. The real value of computer-based teaching software lies with teaching the process of science — that is doing experiments and figuring out puzzles. A second major value is the ability to view large amounts of data in novel ways, for instance through 3-D visualization. Here I provide an idiosyncratic tour and review of biology teaching software, along with directions to Web sites that will take you deeper into this world. Computer software can greatly enhance biology teaching, but it is unlikely to replace flesh-and-blood professors or teaching assistants. The computer-in-the-classroom revolution has less to do with technology than with how to teach thinking.
Ecology analyzes the structure and function of ecosystems at all points along the continuum of human disturbance, from so-called pristine forests to urban backyards. Undisturbed systems provide reference points at one end of the spectrum, and nature reserves and parks are highly valued because they can provide unique examples of such ecosystems. Unfortunately the concept of “natural” or pristine is not that easy to define. Indeed, although ecologists have considered pre-Columbian, western-hemisphere ecosystems to have been largely unaltered by human action, and have termed their state “natural” or “pristine,” evidence from archaeology challenges this view. U.S. and Canadian national parks are charged with preserving the “natural,” and thus need to be able to understand and manage for the “natural.” A pivotal “natural” question in Yellowstone National Park management is the size of the northern-range, wintering elk population at Park establishment in 1872, argued both to have been small and large. Integrating and quantifying several sources of evidence provides a consistent picture of a low population (ca. 5,000–6,000), largely migrating out of the northern range in winter, with little vegetation impact. If we accept this conclusion about what is natural for the Yellowstone ecosystem, then it dramatically alters how we view management alternatives for the Park, which currently supports a northern wintering herd of up to ˜ 25,000 elk.
Ecotoxicology is a new discipline that supposedly melds the fields of ecology and toxicology. Yet as today's scientists grapple with wide-ranging environmental degradation, the field of ecotoxicology often seems an ineffectual, naïve and confused science, far from a seamless merger of two well-established and respected disciplines. We set out to examine the current state of ecotoxicology, paying special attention to some of the major simplifications and misunderstandings that underlie its weaknesses. By exposing major areas of needed improvement, we hope to point the way towards giving ecotoxicology a more prominent voice in the analysis of pressing contemporary environmental problems.
Humans have become such a dominant factor on the planet that they have shaped the evolution of many organisms. In some cases, the evolutionary response of the organisms in turn has profound implications for human and environmental health. Nowhere is this more apparent than in the case of bacteria and their evolutionary response to antibiotics, heavy metals and pesticides. This review examines bacterial responses to human-mediated selection on antibiotic and heavy metal resistances and pesticide degradation ability. Although there are differences in the fine details concerning the mechanisms, genetics, origins and selective pressures of these traits, taken as whole, their evolutionary paths are very similar to each other. However, those features which distinguish resistance traits are likely to be important for implementing intervention schemes to reduce the spread of antibiotic resistances and exploiting bacterial traits for bioremediation.
Integrative Biology: Issues, News, and ReviewsVolume 1, Issue 3 p. 108-111 Book Review We are primates and we are fish: Teaching monophyletic organismal biology Harry W. Greene, Corresponding Author Harry W. Greene is Curator of Herpetology in the Museum of Vertebrate Zoology and Professor of Integrative Biology at the University of California, BerkeleyHarry W. Greene is Curator of Herpetology in the Museum of Vertebrate Zoology and Professor of Integrative Biology at the University of California, BerkeleySearch for more papers by this author Harry W. Greene, Corresponding Author Harry W. Greene is Curator of Herpetology in the Museum of Vertebrate Zoology and Professor of Integrative Biology at the University of California, BerkeleyHarry W. Greene is Curator of Herpetology in the Museum of Vertebrate Zoology and Professor of Integrative Biology at the University of California, BerkeleySearch for more papers by this author First published: 07 January 1999 https://doi.org/10.1002/(SICI)1520-6602(1998)1:3<108::AID-INBI5>3.0.CO;2-TCitations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat Citing Literature Volume1, Issue31998Pages 108-111 RelatedInformation
Human beings have a natural interest in their origins. We are vertebrates, within the craniates, within the chordates. Fossils indicate how the chordates separated, in early Palaeozoic times or before, from their latest common ancestor with the echinoderms. The most primitive known fossil chordates retained a calcitic skeleton of echinoderm type (calcichordates) and some of these, the mitrates, were like giant calcite-plated tunicate tadpoles, consisting of a head and a tail with no trunk region. Some mitrates are themselves craniates in the broad sense and represent the ancestral group (stem group) from which extant craniates descended. In this paper, we describe such a stem-craniate mitrate, and reconstruct, from the shared characteristics of the extant craniates supplemented by evidence from fossils, the latest common ancestor of extant craniates which we call “animal x”. (In most respects animal x would resemble a hagfish, but its larva would filter-feed like a lamprey larva.) We then list the changes involved in transforming a mitrate into animal x and describe the probable changes in development in early embryos that converted a mitrate into animal x. During this transition, our ancestors took to swimming forwards rather than crawling rearwards, lost the calcitic skeleton, and acquired the trunk region, the notochordal region to the head, kidneys, and neural-crest cartilage. An important developmental mechanism involved was forward extension of the notochord, caused by anteriorly directed convergent extension movements.
There is great interest in the invention of multicellularity because it is one of the major transitions during the course of early evolution.1 Most of the emphasis has been on why it occurred. For instance, recently Gerhart and Kirschner2 have argued that a multicellular organism has gained the advantage of a unicellular ancestor because it can more effectively shield itself from the vagaries of the environment by producing its own internal environment. In broader terms, this is Dawkins'3 argument that a competitively effective way of carrying the genes from one generation to the next is by building a complex soma that safely sees to it that the germ plasm survives. © 1998 Wiley-Liss, Inc.
Society invests heavily in science and research aimed at providing guidance on how to manage biological resources, yet the world is filled with too many management failures. Why is this? One reason is that the task itself is so difficult—the environment varies, we never really know the underlying processes that drive population change, and observation errors can be very large when we study populations in the wild. But worse than uncertainty itself is the fact that we tend to underestimate uncertainty. We place too much confidence in our assessment and forecasting models. Fisheries, conservation, and pest control have much to gain by embracing so-called adaptive management. Adaptive management forces us to acknowledge uncertainty, and to follow a plan by which decisions are modified as we learn by doing. Indeed, we can expect little more than continued failures if adaptive management is not adopted in a determined and widespread fashion. © 1998 Wiley-Liss, Inc.
Insect outbreaks have attracted a great deal of attention from ecologists, but an understanding of outbreaks has been elusive. We argue that a major reason for this lack of understanding is that most ecologists focus on single factor explanations, while most outbreaks are probably determined by multiple factors. This focus on single factors is not just due to investigator bias, but seems to be inherent in the major approaches used to study outbreaking insects. Theoreticians have focused on fitting mathematical models to time series of densities; we show, however, that this method is not capable of distinguishing among mechanisms. Field biologists typically rely on experiments that test only one factor at a time, probably due to the difficulty of performing experiments on an appropriate scale. We suggest that a way out of this problem may be to closely integrate models and experiments so that moderately complex mathematical hypotheses may be tested in the field without too great expense.
Integrative Biology: Issues, News, and ReviewsVolume 1, Issue 1 p. 1-2 Explaining the mysteries of prion diseases Peter Kareiva, Corresponding Author Peter Kareiva University of Washington, Seattle, WAUniversity of Washington, Seattle, WASearch for more papers by this author Peter Kareiva, Corresponding Author Peter Kareiva University of Washington, Seattle, WAUniversity of Washington, Seattle, WASearch for more papers by this author First published: 07 January 1999 https://doi.org/10.1002/(SICI)1520-6602(1998)1:1<1::AID-INBI1>3.0.CO;2-ECitations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume1, Issue11998Pages 1-2 RelatedInformation
