Citation: Gao, F., Thompson, J. R., Petsios, E., Erkenbrack, E., Moats, R. A., Bottjer, D. J., & Davidson, E. H. (2015). Juvenile skeletogenesis in anciently diverged sea urchin clades. Developmental biology, 400(1), 148-158.
This work provides direct evidence of evolutionary rewiring of gene-regulatory circuitry accompanying divergence of two subclasses of echinoderm, the cidaroid and euechinoid sea urchins. These forms descend from a known common Paleo- zoic ancestor, and their embryos develop differently, offering an opportunity to probe the basic evolutionary process by which clade divergence occurs at the gene-regulatory net- work (GRN) level. We carried out a systematic analysis of the use of particular genes participating in embryonic skeleto- genic cell specification, building on an established euechinoid developmental GRN. This study revealed that the well-known and elegantly configured regulatory circuitry that underlies skeletogenic specification in modern sea urchins is largely a novel evolutionary invention. The results dramatically dis- play extensive regulatory changes in a specific developmental GRN, underlying an incidence of cladistic divergence at the subclass level.
Diverse sampling of organisms across the five ma- jor classes in the phylum Echinodermata is beginning to reveal much about the structure and function of gene regulatory net- works (GRNs) in development and evolution. Sea urchins are the most studied clade within this phylum, and recent work suggests there has been dramatic rewiring at the top of the skeletogenic GRN along the lineage leading to extant mem- bers of the euechinoid sea urchins. Such rewiring likely ac- counts for some of the observed developmental differences between the two major subclasses of sea urchins—cidaroids and euechinoids.
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