Raposo, Débora

Lessepsian foraminiferal migration as a model for marine invasion in a warming climate

The last few decades have witnessed a dramatic and rapid change in the composition of marine biota in the Eastern Mediterranean due to invasion of alien species from the Red Sea, known as the “Lessepsian” migration. I will use the Larger Benthic Foraminiferal (LBF) species Amphistegina lobifera, a successful Lessepsian invader, and their algal symbionts, as a model system for assessing factors promoting and suppressing biological invasions. The aim is to understand the mechanisms of invasion of this species, if traits facilitating invasions were already developed in the invasive populations and what is the role of their microbiome (symbionts) in this process. For this, I will perform culturing experiments to test the tolerance (growth, photosynthetic activity, mortality) of the invasive and source populations to low temperatures, as such the ones found in the invasion front in Sicily. Also, molecular analyses will be conducted to determine the population structure (genetic divergence across locations analysed by the SSU and ITS rDNA) and the microbiome composition (metabarcoding) of A. lobifera and the surrounding environment (sediment and water samples).

I would like to understand: (1) if the different populations (invasion front in Sicily; pioneer invaders from the Levantine Basin/Eastern Mediterranean and source population from the Red Sea) show signs of adaptation by performing distinct physiological responses to thermal stress; (2) if the symbionts has an important role in mediating invasion success; (3) if the invaders keep the same microbiome associations as the source population or make new associations with the environmental microbiome available; and finally, (4) if after ca. 150 years, the invasive populations already display traits of genetic adaptation when compared to the source population. This combined approach will allow us to answer whether traits facilitating invasions are the property of the host and/or of the symbionts.