Alan Love (Minnesota) and Gunter Wagner (Yale) (Virtual), The Hierarchical Basis of Serial Homology and Evolutionary Novelty

Alan Love is John M. Dolan Professor of Philosophy at the University of Minnesota (USA) and Director of the Minnesota Center for Philosophy of Science. His research focuses on conceptual issues in biology and has concentrated on evolutionary developmental biology (Evo-devo), developmental biology, molecular biology, and paleontology.

Günter Wagner is a Professor of Ecology and Evolutionary Biology at Yale University, USA and at the Department of Evolutionary Biology, University of Vienna. His main research interest is the evolution of gene regulation as it pertains to the origin of evolutionary novelties.

Both are members of the PhilInBioMed Network.

This talk is based on a paper with James DiFrisco (Crick Institute: https://www.crick.ac.uk/research/labs/james-difrisco) as first author. Link to paper: Paper The hierarchical basis of serial homology and evolutionary novelty.

Video of the talk:

Abstract

Given the pervasiveness of gene sharing in evolution and the extent of homology across the tree of life, why is everything not homologous with everything else? The continuity and overlapping genetic contributions to diverse traits across lineages seem to imply that no discrete determination of homology is possible. Although some argue that the widespread overlap in parts and processes should be acknowledged as “partial” homology, this threatens a broad base of presumed comparative morphological knowledge accepted by most biologists. Following a long scientific tradition, we advocate a strategy of “theoretical articulation” that introduces further distinctions to existing concepts to produce increased contrastive resolution among the labels used to represent biological phenomena. We pursue this strategy by drawing on successful patterns of reasoning from serial homology at the level of gene sequences to generate an enriched characterization of serial homology as a hierarchical, phylogenetic concept. Specifically, we propose that the concept of serial homology should be applied primarily to repeated but developmentally individualized body parts, such as cell types, differentiated body segments, or epidermal appendages. For these characters, a phylogenetic history can be reconstructed, similar to families of paralogous genes, endowing the notion of serial homology with a hierarchical, phylogenetic interpretation. On this basis, we propose a five-fold theoretical classification that permits a more fine-grained mapping of diverse trait-types. This facilitates answering the question of why everything is not homologous with everything else, as well as how novelty is possible given that any new character possesses evolutionary precursors.