Brittle stars (Ophiuroidea) are a useful group of marine invertebrates to fulfill these objectives, as they are abundant in the deep-sea and they colonized this environment several times independently, thus highlighting their strong adaptive abilities.
I investigated deep-sea adaptation using a comparative genomics approach and state-of-the-art analytic tools in three complementary work packages (WP):
• Work Package 1: The aim of WP1 was to test genomic adaptive evolution in the deep sea among distantly-related families. I examined the molecular evolution of ~400 genes in ~700 brittle stars species. I found that protein biogenesis (including protein folding and translation) is a key metabolic adaptation to deep-sea conditions. The results of this study have been published in the open access journal Genome Biology and Evolution.
• Work Package 2: The aim of WP2 was to uncover the drivers of genome size evolution in the deep ocean. I performed whole genome sequencing of ~80 species representative of all brittle stars and I examined the environmental, biological and genomic factors impacting the evolution of genome size. I found that the specific life-history traits of deep-sea species (i.e. high longevity, low metabolism) lead to generally increased genome sizes for these species. Furthermore, I uncovered that genome size is mediated by changes in repeat content, especially transposable elements, and not by changes in ploidy or whole-genome duplications. I completed data analyses of this WP, and will submit the corresponding manuscript to the diamond open-access journal 'Peer Community Journal' by the end of April 2022.
• Work Package 3: The aim of WP3 was to examine the genomic architecture of speciation along depth. I used a population genomics approach by generating a reference genome for the deep-sea species Ophiosphalma armigerum. Furthermore, I performed whole genome sequencing of 120 Ophiosphalma individuals from different localities worldwide and depths (~2500m and ~4000m) to uncover the genetic architecture of local adaptation. I uncovered an example of recent cryptic speciation along depth, as morphologically-similar populations from the same locality at different depths were showing convincing signatures of reproductive isolation. Furthermore, I uncovered that closely-related species were showing signatures of hybridization, suggesting that mechanisms of reproductive isolation are postzygotic in these species. There were unforseen delays in this WP, so I am currently running further analyses and I am planning to submit the corresponding manuscript to the open-access journal 'Science Advances' by the end of September 2022.
• DIssemination: To fulfill the dissemination and exploitation objectives of DeepAdapt, i.e. promoting my research and fostering interactions among deep-sea scientists, I took part in the organization of the 16th Deep-Sea Biology Symposium, a hyrbid conference with onsite and online attendance possible. This was not only an excellent opportunity to present my research to the deep-sea community, but also a strategic way to promote myself and develop my scientific network by interacting closely with international deep-sea experts. Given the current generalisation of the hybrid conference format, I led the publication of a manuscript about the challenges and opportunities of hybrid meetings. I am the senior author and sole corresponding author of this paper. This manuscript is under review in the open-access journal 'Frontiers in Marine Sciences', and a preprint is available on the BioRxiv preprint server:
https://doi.org/10.1101/2022.03.18.484941(odnośnik otworzy się w nowym oknie) In addition to open-access publications, I shared the results of my research by participating in 7 international conferences, I was invited to speak at 5 seminars, I participated in 5 outreach events and I wrote 3 blogposts for the general public, ensuring that the results of this project are widely disseminated in the scientific community and beyond.
