Varieties of modules: Kinds, levels, origins, and behaviors

Abstract

This article began as a review of a conference, organized by Gerhard Schlosser, entitled "Modularity in Development and Evolution." The conference was held at, and sponsored by, the Hanse Wissenschaftskolleg in Delmenhorst, Germany in May, 2000. The article subsequently metamorphosed into a literature and concept review as well as an analysis of the differences in current perspectives on modularity. Consequently, I refer to general aspects of the conference but do not review particular presentations. I divide modules into three kinds: structural, developmental, and physiological. Every module fulfills none, one, or multiple functional roles. Two further orthogonal distinctions are important in this context: module-kinds versus module-variants-of-a-kind and reproducer versus nonreproducer modules. I review criteria for individuation of modules and mechanisms for the phylogenetic origin of modularity. I discuss conceptual and methodological differences between developmental and evolutionary biologists, in particular the difference between integration and competition perspectives on individualization and modular behavior. The variety in views regarding modularity presents challenges that require resolution in order to attain a comprehensive, rather than a piecemeal and fragmentary, evolutionary developmental biology.

The Sum of the Parts: Large-Scale Modeling in Systems Biology

“…Modularity is a rich concept, and different kinds of modules have been discussed in different fields of biology (Callebaut and Rasskin-Gutman, 2005). Winther (2001) distinguishes between structural, physiological, and developmental modules. Modular reductionism, as we understand it, concerns modularity both in a structural and a physiological sense since it assumes that the behavior of a system is produced by the individual activities of structurally distinct parts.…”

Natural Kinds in Evolution and Systematics: Metaphysical and Epistemological Considerations

“…Thus, an important aspect of the developmental properties determining the identity of a homologue is the way in which this structure is partially developmentally dissociated from other structures so as result in distinct (semi-autonomous) units of evolutionary change. The growing literature on modularity (Bolker 2000;Rieppel 2005a;Schlosser and Wagner 2004;von Dassow and Munro 1999;Winther 2001) offers a partial explanation of how structures that are developmentally and functionally related can be sufficiently dissociated so as to permit morphological change. Furthermore, homologues exist on several levels of organization (homology among genes, developmental processes, adult morphological structures, behavioral patterns); and homology on different levels can be dissociated, e.g., a homologous structure can develop by different developmental processes and by the action of non-homologous genes.…”

Aristotelian essentialism: essence in the age of evolution

“…22 Müller (2008: 10). 23 See Winther (2001), Bolker (2000), and Von Dassow & Munro (1999). accordingly, are individuated with respect to the structure whose development they are causally responsible for, evidence for which is gathered either by ectopic expression experiments 24 , or else by the principled decomposition of genotype-phenotype mappings. 25 Indeed, although discovering the niceties of the regulatory architecture which comprises these developmental modules is an interesting and thus far fruitful research programme (especially with respect to its prowess in establishing molecular-based phylogenetic lineages), what is most important is their generative specificity with respect to particular morphological structures.…”