The evolution of fish body shape is one of the central problems in vertebrate morphology. Models of fish body shape diversity have generally relied on functional morphology; for example Webb’s (Webb, 1982, 1984) seminal model of fish body shape as a compromise between endurance swimming, rapid bursts, and slow-speed maneuvering. Because of the apparently obvious form-function mapping of fish body shape, comparisons of shape among fishes have been central to many recent studies in local adaptation, adaptive plasticity, competition, and evolutionary constraints. Despite the plethora of research on variation in fish body shape and the role of this variation in many contemporary studies in ecology and evolution, very few of these studies appreciate that well tested explanatory functional models for this variation are wanting. The core of the problem is that fish body shape affects many, many functions, so asking “what is this body shape for” is a doomed approach, and that many different phenotype combinations can result in similar levels of performance (Ghalambor, Walker, & Reznick, 2003; Marks & Lechowicz, 2006; Wainwright, Alfaro, Bolnick, & Hulsey, 2005). These problems are compounded by (1) the many other phenotypic traits that affect these functions and (2) the feedback across generations between selected traits and the genetic and developmental processes that build the body. #1 confounds attempts to build simple models of form-function mapping because of intertrait correlations, functional compensation or redundancy, and interaction effects. #2 suggests that any explanation of fish body shape diversity must take into account the genetic and developmental architecture of fish body shape. Explanations of form or variation in form, then, are complicated by the different levels of organization in biological design, the complexity of the causal mapping (or regulatory control) from lower to higher levels, and the feedback from higher to lower levels of organization (Fig. 1). Identifying the mapping function at each of these levels is a major goal of the various disciplines focusing at these levels, including developmental and quantitative genetics, evo-devo, functional morphology, and evolutionary ecology. The organizer of this symposium integrated these mappings into a generalized, quantitative model of constraints on phenotypic evolution due to genetic, functional, and ecological architecture (Ghalambor et al., 2003; Walker, 2007). The utility of the model for any functional system critically depends on empirical measurements of the complexity of the architectures at each of the levels in Fig. 1. Given this need, the speakers in this symposium were invited to specifically address the genetic, developmental, functional and ecological architecture of fish body shape. Fish model systems, including threespine stickleback, the Trinidad guppy, North American salmonids, and East African cichlids provide perhaps the best current models for investigating the dynamics of and interactions between levels of biological organization from genes to natural habitats. This symposium will greatly facilitate the advancement of current models of the proximate and ultimate mechanisms regulating the development and evolution of fish body shape, specifically, and complex functional systems, more generally. In addition to review and synthesis of the different mappings in Fig. 1, specific areas of focus will include (1) some measure of the complexity of the architecture within each level including non-linear effects, redundancy, modularity, epistatic interactions, and trade-offs. (2) How organization at lower levels constrains the dynamics at higher levels. For example how genetic (McGuigan, Chenoweth, & Blows, 2005; Peichel et al., 2001; Schluter, 1996) and functional (Walker, 2007) influences the rate and direction of body shape evolution and the diversity of body shape among fishes. (3) How organization at higher levels feeds back to influence regulation and even architecture at lower levels. For example, performance (the force that muscles generate or the speed a fish swims) feeds back to development by modifying the environment experienced by the body while functional integration (Walker, 2007) influences patterns of selection on the genetic architecture of the next generation (Cheverud, 1996).

This symposium is sponsored by DVM and DCB.

Objectives
1. To explore an integrative “systems biology” type-thinking in addressing the question “what are the factors controlling or regulating fish body shape diversity”.

2. To encourage biologists and engineers working at different levels of organization, including genetic, developmental, functional, and ecological, to think about the “architecture” at their level and how this architecture influences and is influenced by the architecture at other levels.

3. Scientists from different disciplines vary in the way they approach and do science, from the fundamental organizing principles to the role of theory and experiment. This symposium will convene top researchers in a diverse array of disciplines together to facilitate the exchange of ideas, promote future collaboration, and to identify the best practices from the different disciplines working both within and among levels of biological organization related to fish body shape.

4. This symposium will stimulate the construction of more integrative, systems-biological models of biological shape and shape diversity more generally.

Organized by: Organizer Jeffrey A. Walker is in the Department of Biology, University of Southern Maine, Portland, ME. He is a regular member of the Society for Integrative and Comparative Biology and is the current Program Officer for the Division of Vertebrate Morphology.
Co-Organizer Rita Mehta is a Postdoctoral Research Associate in the Department of Ecology and Evolution at UC Davis and will be an Assistant Professor in Ecology and Evolutionary Biology at UC Santa Cruz starting September 2009.

Schedule