the-floating-lab-standard-operational-procedure-for-collecting

The Floating Lab: Standard Operational Procedure for Collecting and Filtering Seawater Samples from Operating Ferries for Environmental DNA Analysis

Genetic tools to retrieve information from environmental DNA traces are well-established for both targeted and taxonomically broad biodiversity ...

University of Milano-Bicocca

Marine Research and Higher Education Center (MaRHE Center)

National Biodiversity Future Centre (NBFC)

Maldives islands host a unique biodiversity, but their integrity is threatened by climate change and impacting land-uses (e.g. cemented or agricultural areas). As pollinators provide key services for the ecosystems and for the inhabitants, it is crucial to know which pollinators occur in the islands, to characterise their genetic identity and to understand which plants they visit and the size of the human impact. Given that no significant faunistic surveys of Hymenoptera have been published for the country in more than 100 years and that Syrphidae were only partly investigated, we sampled islands in the central part of the Maldives country (Faafu and Daahlu atolls) and hand-netted flower-visiting bees, wasps and hoverflies (Hymenoptera: Anthophila, Crabronidae, Sphecidae, Vespidae, Scoliidae and Diptera: Syrphidae). Overall, we found 21 species; 76.4% of the collected specimens were Anthophila (bees), 12.7% belonged to several families of wasps and 10.8% of individuals were Syrphidae. It seems that one third of species are new for the Maldives, based on the published literature. Human land-uses seem to shape the local pollinator fauna since the assemblages of bees, wasps and hoverflies from urbanised and agricultural islands differed from those in resort and natural ones. These pollinators visited 30 plant species in total, although some invasive plants hosted the highest number of flower visitor species. Biogeographically, this pollinating fauna is mostly shared with Sri Lanka and India. Genetically, the used marker hinted for a unique fauna in relation to the rest of the distribution ranges in most cases, although generally within the level of intraspecific genetic variation. This study significantly contributes to increasing the knowledge on the pollinator diversity and genetic identity in Maldives islands also considering the important implications for the islands' land-use and the role of invasive plants. This study will be pivotal for future pollination studies and biodiversity conservation efforts in the region.

Updating the list of flower-visiting bees, hoverflies and wasps in the central atolls of Maldives, with notes on land-use effects.

The major histocompatibility complex (MHC) is a multigene family responsible for pathogen detection, and initiation of adaptive immune responses. Duplication, natural selection, recombination, and their resulting high functional genetic diversity spread across several duplicated loci are the main hallmarks of the MHC. Although these features were described in several jawed vertebrate lineages, a detailed MHC IIβ characterization at the population level is still lacking for chondrichthyans (chimaeras, rays and sharks), i.e. the most basal lineage to possess an MHC-based adaptive immune system. We used the small-spotted catshark (Scyliorhinus canicula, Carcharhiniformes) as a case-study species to characterize MHC IIβ diversity using complementary molecular tools, including publicly available genome and transcriptome datasets, and a newly developed high-throughput Illumina sequencing protocol. We identified three MHC IIβ loci within the same genomic region, all of which are expressed in different tissues. Genetic screening of the exon 2 in 41 individuals of S. canicula from a single population revealed high levels of sequence diversity, evidence for positive selection, and footprints of recombination. Moreover, the results also suggest the presence of copy number variation in MHC IIβ genes. Thus, the small-spotted catshark exhibits characteristics of functional MHC IIβ genes typically observed in other jawed vertebrates.

Extensive MHC class IIβ diversity across multiple loci in the small-spotted catshark (Scyliorhinus canicula).

The major histocompatibility complex (MHC) constitutes a functionally relevant multigene family playing an essential role in the adaptive immune responses of jawed vertebrates, being directly involved in pathogen recognition. MHC diversity, driven by pathogen-mediated selection, is vital for species survival and is characterized by high genetic diversity in many taxa, namely at the sequence, allelic and haplotype levels. Chondrichthyans, the most basal jawed vertebrates with an adaptive immune system, exhibit a high diversity of MHC gene lineages conservatively organized in a compact region of the genome. Such genomic architecture suggests linkage among MHC genes, where alleles from different genes possibly co-segregate together. Such condition may have major implications on immune response, individual fitness and evolution. In this study, we examine MHC IIβ haplotype diversity in a model shark species, the small spotted catshark, Scyliorhinus canicula. Making use of pedigree data, we reconstructed MHC IIβ haplotypes to understand allele transmission from parent to offspring. Results indicate allele co-segregation consistent with tight linkage among MHC IIβ genes, suggesting the presence of functional stable haplotypes inherited from parents to offspring. The reconstructed haplotypes suggested extensive haplotype diversity characterized by variable allele numbers and allelic lineage composition, as well as marked allelic divergence, consistent with previous population-level data on this species. These findings underscore the complexity of MHC genetics (and of MHC evolution) in chondrichthyans. Accurate reconstruction of MHC haplotypes and assessment of its functional significance are crucial for better understanding adaptive immune responses and MHC evolutionary dynamics in chondrichthyans.

Article	Year
Updating the list of flower-visiting bees, hoverflies and wasps in the central atolls of Maldives, with notes on land-use effects. Biodiversity data journal\| PubMed ID: 36761651	2022
Extensive MHC class IIβ diversity across multiple loci in the small-spotted catshark (Scyliorhinus canicula). Scientific reports\| PubMed ID: 36882519	2023
Allele co-segregation and haplotype diversity of MHC IIβ genes in the small-spotted catshark Scyliorhinus canicula. Immunogenetics\| PubMed ID: 40164821	2025

Alessia Rota

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