Ecological Modelling 251 (2013) 32–43 Contents lists available at SciVerse ScienceDirect Ecological Modelling jo u r n al hom ep age : www.elsevier.com/locate/ecolmodel Trait contributions to fish community assembly emerge from trophic interactions in an individual-based model Henrique C. Giacomini a,∗ , Donald L. DeAngelis b , Joel C. Trexler c , Miguel Petrere Jr. a,1 a Departamento de Ecologia, Universidade Estadual Paulista “Júlio de Mesquita Filho”, Campus de Rio Claro, Avenida 24-A, 1515, CEP 13506-900, Rio Claro, SP, Brazil b U.S. Geological Survey, Department of Biology, University of Miami, 271 Cox Science Center, 1301 Memorial Drive, Coral Gables, FL 33146, USA c Department of Biological Sciences, Florida International University, 3000 NE 151 St, North Miami, FL 33181, USA a r t i c l e i n f o Article history: Received 28 May 2012 Received in revised form 11 November 2012 Accepted 4 December 2012 Available online 9 January 2013 Keywords: Community dynamics Fish diversity Life history Environmental gradients Tradeoffs Priority effects a b s t r a c t Community ecology seeks to understand and predict the characteristics of communities that can develop under different environmental conditions, but most theory has been built on analytical models that are limited in the diversity of species traits that can be considered simultaneously. We address that limi- tation with an individual-based model to simulate assembly of fish communities characterized by life history and trophic interactions with multiple physiological tradeoffs as constraints on species perfor- mance. Simulation experiments were carried out to evaluate the distribution of 6 life history and 4 feeding traits along gradients of resource productivity and prey accessibility. These experiments revealed that traits differ greatly in importance for species sorting along the gradients. Body growth rate emerged as a key factor distinguishing community types and defining patterns of community stability and coexis- tence, followed by egg size and maximum body size. Dominance by fast-growing, relatively large, and fecund species occurred more frequently in cases where functional responses were saturated (i.e. high productivity and/or prey accessibility). Such dominance was associated with large biomass fluctuations and priority effects, which prevented richness from increasing with productivity and may have limited selection on secondary traits, such as spawning strategies and relative size at maturation. Our results illustrate that the distribution of species traits and the consequences for community dynamics are inti- mately linked and strictly dependent on how the benefits and costs of these traits are balanced across different conditions. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Community assembly is the process by which immigrants sur- vive to form a local assemblage of coexisting species. This process is dynamic, with the resultant community at any point in time depending on the previous balance between successful invasions and deterministic or stochastic extinctions (Drake, 1990; Tilman, 2004). Assembly studies – and community studies in general – are much more interesting when functional traits are explicitly accounted for, assuming they are relevant to species adjustment to environmental conditions and to resource partitioning, working as a signature of niche differentiation and structuring by inter- actions (McGill et al., 2006). Accordingly, compelling arguments have been made for a trait-based approach in community ecology ∗ Corresponding author. Present address: Department of Ecology and Evolution- ary Biology, University of Toronto, Office RW 520B, 25 Harbord St., Toronto, ON, Canada M5S 3G5. Tel.: +1 416 978 7338; fax: +1 416 978 5878. E-mail address: hgiacomini@gmail.com (H.C. Giacomini). 1 Present address: UNISANTA - Mestrado em Ecologia, Rua Doutor Oswaldo Cruz, 266, Boqueirão, 11045-907 Santos, SP, Brazil. (McGill et al., 2006; Mims et al., 2010). Many trait-based stud- ies of animal community assembly have searched for evidence of regular niche spacing among co-occurring species (i.e. trait overdis- persion), based on a variety of morphological traits (Gotelli and Graves, 1996). But trait overdispersion is not expected to occur in studies encompassing large spatial scales or very heterogeneous landscapes (Weiher and Keddy, 1995), in which case the search for trait-environment associations is the usual and most interesting aspect of assembly theory. For fish, especially in freshwater, the trilateral classification of Winemiller and Rose (1992) among opportunistic, periodic and equilibrium strategies has been a good predictor of general associ- ations between species life history and environmental conditions (Mims et al., 2010; Mims and Olden, 2012). In this case, and in many empirical investigations, habitat predictability and the strength of biotic interactions are the main factors driving selection of life history traits such as fecundity, life span, and offspring size (e.g. Reznick and Endler, 1982; Roff, 1992; Lamouroux et al., 2002; Mims and Olden, 2012). For studies interested in the outcomes of biotic interactions, as in the present paper, two key gradients influencing species traits and diversity are resource productiv- ity and predation pressure (Sih et al., 1985; Rosenzweig, 1995; 0304-3800/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ecolmodel.2012.12.003