Exploring Diatoms Functional and Taxonomic Diversity on a Global Scale Through an Integrative Approach

Busseni, Greta (2019). Exploring Diatoms Functional and Taxonomic Diversity on a Global Scale Through an Integrative Approach. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000e7af

Abstract

Diatoms are a fundamental component of the oceanic ecosystem. Because of the massive primary production they are responsible for they play a pivotal role in several biogeochemical cycles as well as in the marine food web. This high relevance is due to their global distribution together with their seasonal dominance in many of the planktonic communities. This ecological ‘success’ is granted by their diversity, being diatoms the most diverse microalgae taxa. Notwithstanding the relevant role of this taxa, little is known about their biology and ecology, given the lack of large scale observations and the large number of uncultured species. Here I describe global scale diatom diversity exploring in parallel their taxonomic and their functional diversity. Different methodological frameworks were developed to measure both classes of diversity from meta-omic data. As results, herein it is described the first assessment of diatom taxonomic richness at a global scale together with its statistical modeling using a machine-learning approach. Moreover, a completely new approach to characterize the functional diversity is provided. It is based on the phylogenies of nitrogen transporter marker gene families that proved to be optimal markers of functional traits such as size and resource utilization traits. Finally, the outcome of a numerical modeling exercise was compared to omic taxonomic data with the aim of improving the diatom model types. The whole work has been developed exploiting the unprecedented amount of data provided by the Tara Oceans expedition.