DISSERTATION RESEARCH: Phylogeny and the Evolution of Colony Organization in the Siphonophora, Cnidaria

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Non-technical abstract for NSF Proposal DEB-0408014Dr. Gunter Wagner and Mr. Casey Dunn of Yale University will study the systematics and diversity of siphonophores, a type of colonial jellyfish. Siphonophores live in the open ocean and are the longest animals in the world, sometimes exceeding 50 meters in length. They are also among the most complex of all colonial organisms. Rather than consisting only of specialized cells organized into tissues and organs, as humans do, they have entire animals, each specialized for a task such as feeding or reproduction, that are precisely organized into a colonial "super organism". The organization of siphonophores is the same from colony to colony of the same species but different between species. This grant will make it possible to describe this colony-level organization in a diversity of siphonophores for the first time, and to study the relationship of siphonophores to each other. This information will then be used to test hypotheses about the evolution of colony form in siphonophores. The results will bear directly on several important questions that have long been of general biological interest: when does evolution favor specialization in the units that make up an organism? How does complexity arise at different levels of biological organization? When is precise body organization favored by evolution? Even though it has long been recognized that siphonophores are particularly well suited to the investigation of these fundamental questions, it has been difficult to learn much about them because they are extremely fragile and the nets that have been historically used to collect oceanic organisms severely damage them. Recent advances in oceanographic technology have dramatically improved the situation, though. Ongoing collaborations with biological oceanographers will make it possible to collect siphonophores for this work by SCUBA diving from ocean-going research vessels and through the use of sophisticated samplers mounted on submarines. The specimens obtained using these new methods are often in pristine condition and are ideally suited to the work this grant will support.This grant has important broader implications. It will train a young scientist in siphonophore systematics and the methods used to study oceanic organisms. Siphonophores play a central role in the ecology of the open ocean and the results of this work will provide a strong foundation for the investigation of other aspects of siphonophore biology, including their interaction with their environment.