Placozoan Comparative Genomics

The communities of coastal and marine ecosystems and the genetics of their species are still poorly understood compared to terrestrial systems. This lack of knowledge is particularly significant if we consider these communities taxonomic richness and the severe pressure today’s marine environments are facing from anthropogenic factors such as climate change or contamination. For example, very few is known about the genetic diversity, ecology and population dynamics of an entire phylum, the Placozoa, which is abundant throughout the world's tropical and temperate benthic communities [1-3]. Until today the phylum Placozoa consists of only one described species, Trichoplax adhaerens, which has drawn special attention as a model organism for evolutionary genetics  and other areas of biological research in the last two decades - mainly because of its simplistic morphology and basal position in the tree of life [e.g. 4-6].

However, despite the phylums morphological uniformity, recent research based on worldwide sampling and 16S genotyping has shown that the Placozoa consists of several deep branching clades and species which differ dramatically in their geographic distribution and show hotspots of diversity in coral reef and mangrove habitats [7-9]. Our lab therefor seeks to combine ecological research, evolutionary theory and modern genetic technology to investigate the enigmatic phylum Placozoa in its genetic diversity, phylogeny, population dynamics and the association of species/genotypes with environmental conditions. Using Next Generation Sequencing Techniques we are currently performing whole genome and transcriptome sequencing of 25 candidate species which allows us to determine the genetic diversity of an entire animal phylum.

 

1. Schierwater, B. (2005). My favorite animal, Trichoplax adhaerens. BioEssays : news and reviews in molecular, cellular and developmental biology 27, 1294-1302.

2. Pearse, V.B., and Voigt, O. (2007). Field biology of placozoans (Trichoplax): distribution, diversity, biotic interactions. Integrative and comparative biology 47, 677-692.

3. Eitel, M., Osigus, H.J., DeSalle, R., and Schierwater, B. (2013). Global diversity of the Placozoa. PloS one 8, e57131.

4. Dellaporta, S.L., Xu, A., Sagasser, S., Jakob, W., Moreno, M.A., Buss, L.W., and Schierwater, B. (2006). Mitochondrial genome of Trichoplax adhaerens supports placozoa as the basal lower metazoan phylum. Proceedings of the National Academy of Sciences of the United States of America 103, 8751-8756.

5. Srivastava, M., Begovic, E., Chapman, J., Putnam, N.H., Hellsten, U., Kawashima, T., Kuo, A., Mitros, T., Salamov, A., Carpenter, M.L., et al. (2008). The Trichoplax genome and the nature of placozoans. Nature 454, 955-960.

6. Schierwater, B., Kamm, K., Srivastava, M., Rokhsar, D., Rosengarten, R.D., and Dellaporta, S.L. (2008). The early ANTP gene repertoire: insights from the placozoan genome. PloS one 3, e2457.

7. Voigt, O., Collins, A.G., Pearse, V.B., Pearse, J.S., Ender, A., Hadrys, H., and Schierwater, B. (2004). Placozoa -- no longer a phylum of one. Current biology : CB 14, R944-945.

8. Signorovitch, A.Y., Dellaporta, S.L., and Buss, L.W. (2006). Caribbean placozoan phylogeography. The Biological bulletin 211, 149-156.

9. Eitel, M., and Schierwater, B. (2010). The phylogeography of the Placozoa suggests a taxon-rich phylum in tropical and subtropical waters. Molecular ecology 19, 2315-2327.

 

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