Abstract. Sponges are likely to be the earliest evolved animal lineage, making them key models in studies aimed at understanding evolutionary history of animal genomes. From the morphological and developmental perspectives, sponges combine features of single-cell eukaryotic organisms and the complex multicellular animals. Analysis of the first sequenced sponge genome demonstrated a limited number of homologues of genes involved in eumetazoan development, suggesting a gradual assembly of the complex animal developmental toolkit. However, sponges are a diverse phylum, composed of four distinct lineages. Taking advantage of the accessibility of next generation sequencing technologies, we have sequenced genomes of seven additional sponge species, including six calcareous sponges. For some of these species, we have generated an extensive collection of transcriptome datasets representing embryonic and postembryonic development and regeneration. Comparisons of gene content, with emphasis on developmental regulatory genes, demonstrated unexpected complexity and diversity of developmental toolkits among sponges, suggesting a signifi­cant gene loss and family expansions occurring independently in various sponge lineages. Usage of developmental regulatory genes demonstrated deep conservation of body plan patterning and regeneration mechanisms between sponges and other animals, while several conserved and novel genes are involved in formation of calcareous sponge skeletal elements.

Biography. Maja Adamska studied biology in Krakow, Poland, and carried PhD work on function of homeobox genes in inner ear development in Braunschweig and Halle, Germany. During postdoctoral work at the University of Michigan she followed complex crosses of mouse mutants to reveal genetic interactions involved in limb patterning. At that time, she became convinced that the origin of complex developmental toolkits and processes is as exciting as their current function, so in her second postdoc at the University of Queensland she focused on analysis of developmental signalling pathways in the first sequenced sponge, Amphimedon queenslandica. This work revealed surprising similarities in patterning of sponge and higher animal embryos. Maja was a group leader during 2007-2015 at the Sars International Centre for Marine Molecular Biology in Bergen, Norway; in 2015 she became Senior Lecturer/Lab Leader and in 2017 ARC Future Fellow/Associate Professor in the Research School of Biology of the Australian National University. Her group uses calcareous sponges to gain insight into the evolutionary origin of a variety of key developmental processes, including segregation of germ layers and axial patterning of embryos and adults. Maja is also interested in major transitions in animal evolution, such as emergence of multicellularity and morphological complexity, their relationship to genomic complexity as well as effects of environment on animal development.