Diversity of shallow and deep-sea foraminifera

Foraminifera are a very diverse group of unicellular eukaryotes (protists). Occurring mainly in the marine bethic environment, they also colonized the pelagic environment, but also freshwater and even soils. Their biology and diversity (especially at the genetic level) is largely understudied.

During my Master, I worked on two different projects in Prof. Pawlowski’s Lab, the first one aiming at assessing the link between sequence and organism abundance in a heterogeneous community, and the second one investigating the extent of intragenomic polymorphism in foraminifera.

There, we showed that sequence abundance is an accurate proxy of organism abundance, but only when it is corrected for gene copy number (Weber and Pawlowski, 2013). In addition, we showed that intragenomic variability is widespread, challenging the existence of a barcoding gap in foraminifera, as well as the consensus idea that concerted evolution maintains sequence homogeneity over time (Weber and Pawlowski, 2014).

Shortly after defending my PhD, in February and March 2015, I had the opportunity to participate in the oceanographic deep-sea research cruise ABYSSLINE02, in order to establish a foraminiferal biodiversity baseline in the Clarion-clipperton zone (Pacific ocean). Due to its difficulty of access, the abyss remains an environment largely understudied. During this cruise, many new foraminiferal species were discovered, in particular many xenophyophores (Gooday et al, 2017a, 2017b, 2017c). These delicate giant foraminifera, reaching several centimeters in height and width, agglutinate sediment grains to form their shell, or test.