Annette Ostling

Biodiversity conservation: Climate change and extinction risk

Arising from: C. D. Thomas et al. 427, 145–148 (2004)); see also communication from Thuiller et al. and communication from Buckley & Roughgarden; Thomas et al. replyThomas et al. have carried out a useful analysis of the extinction risk from climate warming. Their overall conclusion, that a large fraction of extant species could be driven to extinction by expected climate trends over the next 50 years, is compelling: it adds to the many other reasons why new energy policies are needed to reduce the pace of warming.

A THEORY OF SPATIAL STRUCTURE IN ECOLOGICAL COMMUNITIES AT MULTIPLE SPATIAL SCALES

A theory of spatial structure in ecological communities is presented and tested. At the core of the theory is a simple allocation rule for the assembly of species in space. The theory leads, with no adjustable parameters, to nonrandom statistical predictions for the spatial distribution of species at multiple spatial scales. The distributions are such that the abundance of a species at the largest measured scale uniquely determines the spatial- abundance distribution of the individuals of that species at smaller spatial scales. The shape of the species-area relationship, the endemics-area relationship, a scale-dependent com- munity-level spatial-abundance distribution, the species-abundance distribution at small spatial scales, an index of intraspecific aggregation, the range-area relationship, and the dependence of species turnover on interpatch distance and on patch size are also uniquely predicted as a function solely of the list of abundances of the species at the largest spatial scale. We show that the spatial structure of three spatially explicit vegetation census data sets (i.e., a 64-m 2 serpentine grassland plot, a 50-ha moist tropical forest plot, and a 9.68- ha dry tropical forest plot) are generally consistent with the predictions of the theory, despite the very simple statistical assumption upon which the theory is based, and the absence of adjustable parameters. However, deviations between predicted and observed distributions do arise for the species with the highest abundances; the pattern of those deviations indicates that the theory, which currently contains no explicit description of interaction mechanisms among individuals within species, could be improved with the incorporation of intraspecific density dependence.

ENDEMICS–AREA RELATIONSHIPS: THE INFLUENCE OF SPECIES DOMINANCE AND SPATIAL AGGREGATION

Patterns in the spatial distribution of endemic species are central to setting conservation priorities and estimating extinction rates due to habitat loss. We use quantitative models to isolate the effects of relative species abundances and conspecific spatial distributions on the endemics–area relationship. Using published abundance data from a tropical rain forest community, we apply these models to illustrate how species abundance distributions and species spatial distributions have a strikingly different influence on total and endemic species diversity patterns, respectively. Increased dominance and conspecific aggregation in a region will act to decrease the total species diversity of smaller sampled subregions, but to increase subregional endemic species diversity. Our results suggest that biotic or abiotic forces contributing to regional-scale species dominance and conspecific clustering may increase the risk of extinctions under habitat loss.

Self-Similarity and the Relationship between Abundance and Range Size

Patterns in the relationships among the range, abundance, and distribution of species within a biome are of fundamental interest in ecology. A self‐similarity condition, imposed at the community level and previously demonstrated to lead to the power‐law form of the species‐area relationship, is extended to the species level and shown to predict testable power‐law relationships between range size and both species abundance and area of census cell across scales of spatial resolution. The predicted slopes of plots of \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape

An integrative framework for stochastic, size-structured community assembly

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The consequences of spatial structure for the evolution of pathogen transmission rate and virulence.

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Self‐Similarity, the Power Law Form of the Species‐Area Relationship, and a Probability Rule: A Reply to Maddux

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