John Damuth

Bio: John Damuth is an academic researcher from University of California, Santa Barbara. The author has contributed to research in topics: Allometry & Population. The author has an hindex of 33, co-authored 46 publications receiving 6378 citations. Previous affiliations of John Damuth include University of Chicago & University of California, Davis.

Population density and body size in mammals

Abstract: There seems to be an inverse relationship between the size of an animal species and its local abundance. Here I describe the interspecific seating of population density and body mass among mammalian primary consumers (herbivores, broadly defined). Density is related approximately reciprocally to individual metabolic requirements, indicating that the energy used by the local population of a species in the community is independent of its body size. I suggest that this is a more general rule of community structure.

Interspecific allometry of population density in mammals and other animals: the independence of body mass and population energy‐use

Abstract: Global regressions of ecological population densities on body mass for mammals and for terrestrial animals as a whole show that local population energy-use is approximately independent of adult body mass—over a body mass range spanning more than 11 orders of magnitude. This independence is represented by the slope of the regressions approximating –0.75, the reciprocal of the way that individual metabolic requirements scale with body mass. The pattern still holds for mammalian primary consumers when the data are broken down by geographic area, by broad habitat-type and by individual community. Slopes for mammalian secondary consumers are also not statistically distinguishable from –0.75. For any given body mass temperate herbivores maintain on average population densities of 1.5 to 2.0 times those of tropical ones, though slopes do not differ. Terrestrial animals of all sizes exhibit approximately the same range of population energy-use values. These results agree with those reported for population energy-budgets. It is suggested that rough independence of body mass and the energy-use of local populations is a widespread rule of animal ecology and community structure.

Terrestrial Ecosystems Through Time: Evolutionary Paleoecology of Terrestrial Plants and Animals

Abstract: Breathtaking in scope, this is the first survey of the entire ecological history of life on land--from the earliest traces of terrestrial organisms over 400 million years ago to the beginning of human agriculture. By providing myriad insights into the unique ecological information contained in the fossil record, it establishes a new and ambitious basis for the study of evolutionary paleoecology of land ecosystems. A joint undertaking of the Evolution of Terrestrial Ecosystems Consortium at the National Museum of Natural History, Smithsonian Institution, and twenty-six additional researchers, this book begins with four chapters that lay out the theoretical background and methodology of the science of evolutionary paleoecology. Included are a comprehensive review of the taphonomy and paleoenvironmental settings of fossil deposits as well as guidelines for developing ecological characterizations of extinct organisms and the communities in which they lived. The remaining three chapters treat the history of terrestrial ecosystems through geological time, emphasizing how ecological interactions have changed, the rate and tempo of ecosystem change, the role of exogenous "forcing factors" in generating ecological change, and the effect of ecological factors on the evolution of biological diversity. The six principal authors of this volume are all associated with the Evolution of Terrestrial Ecosystems program at the National Museum of Natural History, Smithsonian Institution.

A method for analyzing selection in hierarchically structured populations

Abstract: Individual fitness depends on the particular ecological, genetic, and social contexts in which organisms are found. Variation in individual context among subunits of a population thus raises interesting questions about selection in nature but also complicates its study. We present a method for analyzing phenotypic selection in hierarchically structured populations. Applying this method, called contextual analysis, to the study of selection allows explicit answers to two frequently controversial questions. First, must group membership be taken into account in explaining differences in individual fitness? Second, what particular group properties are associated with observable group-level effects? Contextual analysis is a generalization to structured populations of the "selection gradient" method developed by Lande and Arnold (1983). The aim of the gradient method is to distinguish characters that have a causal relationship with fitness from others that do not but are still subject to selection as a result o...

The Theory of Island Biogeography

Abstract: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

Phylogenies and the Comparative Method

Abstract: Recent years have seen a growth in numerical studies using the comparative method. The method usually involves a comparison of two phenotypes across a range of species or higher taxa, or a comparison of one phenotype with an environmental variable. Objectives of such studies vary, and include assessing whether one variable is correlated with another and assessing whether the regression of one variable on another differs significantly from some expected value. Notable recent studies using statistical methods of this type include Pilbeam and Gould's (1974) regressions of tooth area on several size measurements in mammals; Sherman's (1979) test of the relation between insect chromosome numbers and social behavior; Damuth's (1981) investigation of population density and body size in mammals; Martin's (1981) regression of brain weight in mammals on body weight; Givnish's (1982) examination of traits associated with dioecy across the families of angiosperms; and Armstrong's (1983) regressions of brain weight on body weight and basal metabolism rate in mammals. My intention is to point out a serious statistical problem with this approach, a problem that affects all of these studies. It arises from the fact that species are part of a hierarchically structured phylogeny, and thus cannot be regarded for statistical purposes as if drawn independently from the same distribution. This problem has been noticed before, and previous suggestions of ways of coping with it are briefly discussed. The nonindependence can be circumvented in principle if adequate information on the phylogeny is available. The information needed to do so and the limitations on its use will be discussed. The problem will be discussed and illustrated with reference to continuous variables, but the same statistical issues arise when one or both of the variables are discrete, in which case the statistical methods involve contingency tables rather than regressions and correlations.

Toward a metabolic theory of ecology

Abstract: Metabolism provides a basis for using first principles of physics, chemistry, and biology to link the biology of individual organisms to the ecology of populations, communities, and ecosystems. Metabolic rate, the rate at which organisms take up, transform, and expend energy and materials, is the most fundamental biological rate. We have developed a quantitative theory for how metabolic rate varies with body size and temperature. Metabolic theory predicts how metabolic rate, by setting the rates of resource uptake from the environment and resource allocation to survival, growth, and reproduction, controls ecological processes at all levels of organization from individuals to the biosphere. Examples include: (1) life history attributes, including devel- opment rate, mortality rate, age at maturity, life span, and population growth rate; (2) population interactions, including carrying capacity, rates of competition and predation, and patterns of species diversity; and (3) ecosystem processes, including rates of biomass production and respiration and patterns of trophic dynamics. Data compiled from the ecological literature strongly support the theoretical predictions. Even- tually, metabolic theory may provide a conceptual foundation for much of ecology, just as genetic theory provides a foundation for much of evolutionary biology.

A simple practice guide for dose conversion between animals and human.

Abstract: Understanding the concept of extrapolation of dose between species is important for pharmaceutical researchers when initiating new animal or human experiments. Interspecies allometric scaling for dose conversion from animal to human studies is one of the most controversial areas in clinical pharmacology. Allometric approach considers the differences in body surface area, which is associated with animal weight while extrapolating the doses of therapeutic agents among the species. This review provides basic information about translation of doses between species and estimation of starting dose for clinical trials using allometric scaling. The method of calculation of injection volume for parenteral formulation based on human equivalent dose is also briefed.

Taphonomic and Ecologic Information Form Bone Weathering

Abstract: Bones of recent mammals in the Amboseli Basin, southern Kenya, exhibit distinctive weathering characteristics that can be related to the time since death and to the local conditions of temperature, humidity and soil chemistry. A categorization of weathering characteristics into six stages, recognizable on descriptive criteria, provides a basis for investigation of weathering rates and processes. The time necessary to achieve each successive weathering stage has been calibrated using known-age carcasses. Most bones decompose beyond recognition in 10 to 15 yr. Bones of animals under 100 kg and juveniles appear to weather more rapidly than bones of large animals or adults. Small-scale rather than widespread environmental factors seem to have greatest influence on weathering characteristics and rates. Bone weathering is potentially valuable as evidence for the period of time represented in recent or fossil bone assemblages, in- cluding those on archeological sites, and may also be an important tool in censusing populations of animals in modern ecosystems.