"Evolution of the Metazoa"

Daniel Jackson’s group

Daniel Jackson’s research group is focused on understanding the events that accompanied and drove the diversification of the Metazoa during the early Cambrian. One prominent feature of this expansion is the widespread adoption of various biomineralisation strategies during a relatively narrow geological window. Currently, little is known about the genetic basis of invertebrate biomineralisation, and the way in which these processes evolved. For many metazoans, biomineralisation begins very early in life, often during a larval phase, and is a fundamental feature of the developmental process. An understanding of the developmental pathways and biochemical reactions that generate larval shells, spicules and other skeletal elements is therefore essential to our interpretation of metazoan evolution. To address these questions we are currently focusing on the Mollusca, a highly diverse group of Lophotrochozoans whose success can in part be attributed to an incredibly varied range of shell morphologies. By combining wet-lab studies on animals such as the freshwater pond snail Lymnaea stagnalis, the tropical abalone Haliotis asinina and the South Sea pearl oyster Pinctada maxima with the bioinformatic wealth of metazoan genomic data, we can begin to dissect the molecular events that generated this shelled diversity.

An advantage to studying the Mollusca is that this group is one of the most morphologically diverse of the animal kingdom, and is a representative of the much understudied Lophotrochozoa. With representative model organisms established for outgroups such as the Ecdysozoa (Drosophila, C. elegans), deuterostomes (urchins, mouse, frog, chicken) and early branching metazoan taxa (cnidarians, sponges and Trichoplax) we hope that in developing L. stagnalis as an accessible model for molecular studies we will gain insight into how the regulation of molluscan development differs from other taxa, and how these differences supported the generation of such immense diversity.

We are also interested in a relatively recent finding that is emerging from genomic analyses. Vast regions of eukaryotic genomes, previously thought to be inactive or ‘junk DNA’, are now known to play critical roles in developmental procesess. These regions of repetitive, mobile DNA, known as transposable elements (TEs), have been suggested to drive the generation of morphological novelty, and hence speciation. We are isolating evolutionarily conserved TEs from L. stagnalis, and plan to characterise their role in molluscan development and their potential for use as phylogenetic markers.

Our tools include molecular techniques (gene isolation, in situ hybridisation, confocal microscopy, in vitro protein expression), and various in silico methods such as genome mining, EST sequencing and phylogenetic reconstruction of molecular and organismal evolutionary relationships.