“Understanding the origins and evolution of the highly diverse
body plans of the ~30 distinct phyla that make up the Animal
Kingdom is a major problem in biology. Recent research in my
lab has demonstrated the existence of a new phylum of
animals with a unique bodyplan - the Xenacoelomorpha whose evolutionary origins are particularly unusual and, as a
result highly contentious.
Our work has proved unusually controversial as our analyses elevate these very simple
worms from a lowly position at the base of the animal tree to a position right within the
group of highly complex animals called the deuterostomes. The deuterostome ‘superphylum’ includes three other major animal body architectures: the phyla Chordata
(including Humans), Echinodermata (starfish and sea urchins) and Hemichordata (acorn
worms).
All species within the phylum Xenacoelomorpha appear to have lost virtually everything
that defines them as deuterostomes revealing a history of extreme evolutionary
simplification and loss. The research I propose aims to understand the extraordinary
evolutionary path that led to the existence of this bizarre phylum of worms and so give
us deep new insights into the origins of phyla.
Exploiting our recent phylogenetic discoveries in a major new set of experiments, we
will use a diverse set of cutting edge techniques to study the morphology,
ultrastructure, embryogenesis and developmental genetics of the Xenacoelomorphs to
get a much clearer picture of the true extent to which their phenotype is simplified in
comparison to other deuterostomes.
In parallel, exploiting the possibilities of new technology, we will undertake ab initio
sequencing of the genomes of 3 species covering the diversity of the Xenacoelomorpha
and perform comparative genomics across all four deuterostome phyla to discover the
genotypic correlates of their phenotypic diversification.
In a reversal of the standard evolutionary approach which moves from morphology to
genetics, we will use our genomes to discover the genetic novelties associated with all
groups of deuterostome and then use data on gene function to link these clade specific
novelties back to their novel biological functions and phenotypes.
With a particular focus on the evolution of simplicity in the Xenacoelomorpha, our goal
is to uncover the links between genotypic and phenotypic novelty in the evolution of the
deuterostomes and ultimately, perhaps, to shed light on our own distant origins as
chordates.”