Meeting Abstract
Developmental regulatory networks govern the construction of morphology and structure how morphological features change through time. Highly conserved networks are often tightly associated with particular features, and similar regulatory patterns can specify similar morphological patterns and character arrangements. Developmental patterns can thus serve as a basis for studying living and fossil morphologies, and may be used to inform morphological character coding and models of character change. Using the fossil ecdysozoan lobopods as a case study, I describe how the developmental underpinnings of morphology may be used to reorganize discrete morphological character data, focusing on how gene network structure translates into a separation of character identity from character states. This reorganization recognizes the biological distinctiveness of “traditional” characters, such as appendages, and of patterning mechanisms which may be re-deployed across multiple body regions, and extends homology beyond a position-specific designation. The lobopods, thought to represent a basal grade leading to extant onychophorans and arthropods, are character-depauperate and difficult to resolve phylogenetically. I explore the contribution of developmental information to the problematic lobopod phylogeny by combining development-based character coding with a Bayesian phylogenetic approach. Because the complex wiring of developmental networks can impose lineage-specific constraints upon the pattern and rate of morphological character evolution, this approach provides a first step in forming a probabilistic model for the evolution of morphology, as well as future application to phylogenetic methods utilizing morphological characters.
