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My research interests are in the field of evolution and development,
and more specifically the evolution of the deuterostomes. This major
metazoan lineage is made up of four major groups; chordates,
echinoderms, hemichordates, and Xenoturbellida . The early
evolutionary history of the deuterostomes remains poorly understood
and surprisingly even the evolutionary origins of our own phylum,
the chordates, remains a major puzzle for zoologists. This
uncertainty is partly due to a poor early fossil record for this
lineage, but also due to the enormous morphological disparity in
adult body plans between the major groups. Reconstructing the body
plan of a plausible common ancestor based on extant forms is fraught
with difficulties. My work attempts to make some headway in this
area, and has focused on investigating the role of developmental
genes that underlie these divergent body plans and morphologies in
hemichordates and echinoderms. By comparing the expression and roles
of these genes to their orthologues in chordates I am trying to gain
insights into early events in deuterostome evolution.
We have largely focused on the origins
and early evolution of the vertebrate brain and central nervous system.
While the brain is clearly a key innovation of our phylum, we understand
very little about its evolutionary origins outside of the chordates.
Much progress has been made in identifying the early molecular genetic
program of brain patterning and morphogenesis in vertebrate model
systems. However, gene interactions in vertebrate central nervous system
development are themselves very complex: widespread duplication and
expansion of developmental regulatory gene families have led to
functional redundancy, making functional studies sometimes difficult to
interpret. We have been developing the hemichordate Saccoglossus
kowalevskii as a less complex developmental model for addressing
early evolution and origins of the vertebrate nervous system. As a
phylum closely related to chordates, hemichordates are the most
promising group for addressing issues of chordate brain evolution and
development. Unlike chordates, their nervous system is organized on the
basis of a nerve net rather than a centralized structure. We have been
investigating conserved gene regulatory networks involved in the
regionalization of the vertebrate brain during hemichordate development
and find a remarkable conservation of gene expression, despite the
organizational disparity between the nervous systems of both groups. I
plan to establish the earliest, and most fundamental aspects of the
molecular genetic networks that were involved in early brain evolution.
This approach should not only help elucidate the early patterning events
leading to chordate brain evolution, but also be generally informative
about how conserved regulatory networks can generate such amazing
neuroanatomical diversity during animal evolution.
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