Phylogeny and evolution of edible sea urchins (Echinoidea: Camarodonta)

Sea urchins of the order Camarodonta are among the most important components of shallow-water marine communities. They are intensively used in scientific studies on reproduction and development and serve as model organisms in classroom education. Their reproductive organs are considered a delicacy and thus sea urchins are heavily exploited by a multimillion-dollar fisheries industry. Many research papers on various aspects of their biology exist, yet their evolution and species relationships are still poorly understood, mainly due to a lack of studies merging data from fossils and living members. The proposed project aims to decipher the origin and evolutionary history of camarodont sea urchins. In order to achieve this goal, genetic information at the genome level, will be combined with an in depth morphological analysis. In contrast to previous studies this will provide significantly more genetic data, allowing for more robust results. The first occurrences of camarodont sea urchins in the geological record (i.e., fossils) will be used to infer minimum ages of individual groups within camarodonts. New analytical methods, subsumed under the name Next Generation Sequencing, have drastically increased the amount of genetic information that can be generated. To infer robust and accurate phylogenetic trees (a representation of the evolutionary relationship between the studied species), however, large sequence data alone are insufficient as the problem often lays in sorting and matching the relevant sequences among the different samples to facilitate meaningful comparisons. Within the proposed project, an innovative method will be used to solve this problem. By targeting and enriching special stretches of the DNA so-called Ultra Conserved Elements, which are highly similar in all members of a particular group comparable portions of the genome will be identified. The flanking regions of which will then be used for the genetic analyses. A similar approach, first used in 2012 to study vertebrate relationships, has been proven highly successful in subsequent studies. Few of these, however, were conducted on invertebrates, and none targeted echinoderms. The research is planned as a three-year project to be carried out at the Natural History Museum Vienna by Andreas Kroh, Elisabeth Haring and Omri Bronstein, with the help of an international collaborators team of experts. Within the first half year, the new method will be adapted to the study of echinoids. In the following year-and-half the genetic analyses will be conducted and the oldest members of the camarodont sea urchins identified. In the final year, the two sets of data will be brought together. Genetic and morphological data will then be merged to construct a robust tree, which will allow to infer when and where the different groups first appeared.