The Cnidarian Tree of Life Project

Assistant Professor, School of Natural Sciences, University of California, Merced

Phylogeny and Evolution of Scyphozoa

Scyphozoa includes almost all of the large "jellyfish" with which most people are familiar. Scyphozoa has, at times, subsumed cubomedusae and stauromedusae, but modern systematic treatments usually include just the Coronatae, Rhizostomeae, and Semaeostomeae as scyphozoans. My lab is investigating the phylogeny and evolution of this enigmatic group. We are exploring the phylogenetic relationships of Coronatae, Rhizostomeae, and Semaeostomeae to each other as well as their relationships to other medusozoans, and we are particularly interested in asking, and answering, questions that elucidate the evolution of biodiversity within these three groups. Rhizostomeae, for example, is hypothetically both the most diverse and most highly derived order of Scyphozoa and is largely restricted to the Indo-West Pacific centre of marine biodiversity. Is the geographic pattern of diversity in the Rhizostomeae attributable to accumulation, origin, or overlap of taxa in the Indo-West Pacific? Did diversification of Rhizostomeae displace coronates and semaeostomes into peripheral environments, such as deep-water or temperate and polar seas? Have coronates and semaeostomes diversified in these challenging environments? Was the diversification of rhizostomes promoted by invasion of new ecological niches such as photosymbiosis, which is prevalent in tropical rhizostomes? If so, did photosymbiosis also promote diversification of tropical coronates? And is the high morphological diversity of rhizostomes matched by high molecular diversity (relative to other scyphozoans)? Through CnidToL we will generate the robust phylogenies that are necessary for answering these and many other intriguing questions about scyphozoan jellyfishes. Study areas include: behavior, morphology, phylogeography, biogeography, phylogenetics, rates of evolution, and symbiosis.