Assembly Models

by

Dominique Gravel

• LAST REVIEWED: 26 August 2013
• LAST MODIFIED: 26 August 2013
• DOI: 10.1093/obo/9780199830060-0040

Introduction

Understanding the processes that drive the assembly of a community has been a central theme of ecology since the foundation of the discipline. It concerns basic questions such as how do we start from a regional species pool to assemble a structured community? How many species should be found at a given location? What is the relationship between community structure and the environment? Studying the different drivers of community assembly is not only interesting for its own sake, but is also essential for a predictive ecology. The different processes involved in the assembly of a community will also be the ones driving the response to future environmental changes. The theme of community assembly is a huge area including an immense amount of theoretical, experimental, and observational studies. This article and bibliography will attempt to cover the main aspects of the discipline with a special attention to assembly models. It starts with a section defining the domain of the article and then sets the stage with the presentation of historical backgrounds. The next section addresses the community assembly dynamics in space and time. Conceptual aspects of the empirical investigation of community assembly are then presented with a section on the war over assembly rules, which launched the tradition of null model testing in community ecology. The article ends with the subject of the future of community assembly and an outlook on three fields that have gained considerable interest over the last decade: ecophylogenetics, trait-based assembly, and network ecology. The focus is mainly on the ecology of community assembly and therefore the reader interested by its evolutionary counterpart should consult the theme of adaptive radiation.

Definitions

Several definitions of community assembly have been proposed, some more stringent than others. Given its central role in ecology, the study of community assembly shares historical landmarks with several other themes such as the niche, the Competitive Exclusion Principle, and species distribution over environmental gradients (see Historical Background). The term “assembly rules” nonetheless came later, when Diamond 1975 introduced it to refer to a set of empirically derived regular aspects of community structure. After years of debate over the existence of such rules, the theme of community assembly became much broader in scope. Keddy 1992 generalized it as follows: “the objective of assembly rules is to predict which subset of the total species pool for a given region will occur in a specified habitat” (p. 158). The idea that communities are samples from a regional species pool gained further interest as it made its presence felt in the proposition of the Neutral Theory of biodiversity and Metacommunity Ecology. Nowadays the term “community assembly” is commonly employed to refer to “any constraint on species coexistence,” as in Götzenberger, et al. 2012. Fukami 2010 also emphasizes its dynamic aspects, with explicit consideration of the buildup of the community through sequential establishment of colonists and the development of their population. In his seminal book on biogeography, MacArthur 1972 proposed four essential ingredients of community assembly: the structure of the environment, species morphology, the economics of its behavior, and population dynamics. Vellend 2010 focuses on how these fundamental ingredients still hold today as major drivers of community assembly, with the addition of dispersal and evolutionary processes.

• Diamond, Jared. 1975. Assembly of species communities. In Ecology and evolution of communities. Edited by Martin L. Cody and Jared Diamond, 342–444. Cambridge, MA: Belknap.

  This book chapter launched the idea that there are some “assembly rules” based on an interpretation of years of field work on bird assemblages near New Guinea. Rules are derived from well-defined patterns of species co-occurrence and assume strong interspecific interactions.

• Fukami, T. 2010. Community assembly dynamics in space. In Community ecology: Processes, models, and applications. Edited by Herman A. Verhoef and Peter J. Morin, 45–54. Oxford: Oxford Univ. Press.

  Synthesizes the dynamics of community assembly with special attention to the effect of assembly history and spatial dynamics; distinguishes deterministic from historically contingent community assembly; and discusses the impact of patch size, patch isolation, and environmental heterogeneity on these types of assembly.

• Götzenberger, Lars, Francesco de Bello, Kari Anne Bråthen, et al. 2012. Ecological assembly rules in plant communities: Approaches, patterns and prospects. Biological Reviews 87.1: 111–127.

  DOI: 10.1111/j.1469-185X.2011.00187.x

  Critical and up-to-date review of the evidence for Diamond’s assembly rules in plant communities. A survey and a meta-analysis are reported and suggest that nonrandom co-occurrence of plant species is not a general phenomenon. Includes a discussion of methodological limitations and proposition of a set of guidelines for future research on assembly rules. Available online for purchase or by subscription.

• Keddy, Paul. 1992. Assembly and response rules: Two goals for predictive community ecology. Journal of Vegetation Science 3.2: 157–164.

  DOI: 10.2307/3235676

  Begins with a review of the controversy over assembly rules and the lack of generalities in community ecology. Develops the argument that assembly rules provide a unifying framework for community ecology, and emphasizes that functional traits should be used to make general predictions across systems with different species pools. Available online for purchase or by subscription.

• MacArthur, R. H. 1972. Geographical ecology: Patterns in the distribution of species. Princeton, NJ: Princeton Univ. Press.

  Last publication by MacArthur, this book presents a synthesis of his theoretical work on species coexistence and distribution. The most accessible and achieved description of the niche theory. Discusses the fundamental principles underlying species distribution.

• Vellend, Mark. 2010. Conceptual synthesis in community ecology. Quarterly Review of Biology 85.2: 183–206.

  DOI: 10.1086/652373

  Vellend asks: What are the fundamental processes in community ecology? Inspired by the ones found in population genetics, he proposes that selection, drift, speciation, and dispersal are sufficiently general to encompass all theoretical and conceptual models in community ecology. Interesting and potentially controversial perspective that is well suited for discussion in a journal club or in a graduate course. Available online for purchase or by subscription.