Biology subjects

Tettamanti, V.

Publications and source records attributed to Tettamanti, V..

6 recordsLinked to original sources

bioRxiv2026

A Deep Phylogenetic Split Between Short- and Long-Wavelength-Tuned Visual Systems in Surgeonfishes (Acanthuridae)

The light environment, coupled with ecology, is widely thought to drive visual adaptation, creating species-specific visual niches. However, coral reef ecosystems experience continuous spatiotemporal variations in light conditions, and mechanisms such as phenotypic plasticity may be essential for coral reef animals to adjust to such changing sensory requirements. It remains unclear how widespread colour vision plasticity is, or the extent to which ecology and phylogeny drive plasticity in coral reef fishes. Using a comparative transcriptomic approach across 22 species, we aimed to investigate visual plasticity within a prominent coral reef fish family, surgeonfishes (Acanthuridae), in response to changes in the light environment throughout development and across seasons in adults. Surprisingly, we uncovered a deep phylogenetic split (~42 mya) in visual opsin gene expression profiles, with Nasinae expressing a shorter-shifted palette than Acanthurinae, which coincides with the divide between water-column and benthic-feeding modalities during the speciation of their last common ancestor. However, opsin gene expression showed little variation in response to seasonal or ontogenetic shifts in the light environment, nor in the broad functional feeding groups extant species from both subfamilies fall under. Thus, the invariable visual gene expression observed in present-day surgeonfishes appears to be dictated by phylogenetic inertia, despite rapid diversification into a range of ecological niches. This suggests that spectral tuning into two main modalities, short and long, reduces the need for visual plasticity, allowing larger and more mobile coral reef fishes to conduct visually guided behaviours across the entire range of light environments they encounter.

evolutionary biology↗

bioRxiv2026

From deployment to functioning ecosystems: assessing taxonomic richness and community composition on modular shellfish reefs using environmental DNA metabarcoding

Ecological restoration success is commonly assessed against historical reference states that are often altered, poorly defined, or absent, particularly in marine systems. Reliance on taxon richness alone can further obscure changes in community structure, successional trajectories, and the emergence of functionally important taxa at restoration sites. We assessed biodiversity recovery on modular shellfish reef structures using environmental DNA (eDNA) metabarcoding, combining taxon-specific richness models with multivariate community composition analyses across a four-year age gradient (9, 21, and 42 months). Genus richness increased rapidly following reef deployment but differed strongly among taxon groups. Dominant groups, particularly Mollusca, showed similar richness in nine-month-old and 42-month-old reefs; crustaceans and fishes also showed high, consistent richness early in development. Five of nine taxon groups displayed significant richness changes through time, with increasing (flatworms and macroalgae) and decreasing (cnidarians, sponges, and roundworms) trajectories. Community composition showed pronounced age-related structuring: younger reefs were compositionally distinct from older reefs, and within-age variability declined markedly with age, consistent with convergent successional assembly. Trait-based patterns indicated shifts towards non-benthic crustaceans, larger-bodied fish, and free-living flatworms in older reefs. These results show that modular shellfish structures are rapidly colonised by a wide taxonomic range within 9 months, producing early richness gains. However, the identity and relative representation of those taxa continue to change, generating structured compositional shifts undetectable from richness alone. Integrated richness-composition frameworks focused on ecological trajectories provide a more robust basis for evaluating restoration success than strict reference states. Environmental DNA metabarcoding offers a scalable, non-invasive monitoring approach capable of capturing both early richness gains and longer-term community assembly dynamics in data-limited marine systems.

ecology↗

bioRxiv2024

Damsels in a hidden colour: development of ultraviolet sensitivity and colour patterns in damselfishes (Pomacentridae)

Damselfishes (Pomacentridae) are widespread and highly abundant on tropical coral reefs. They exhibit diverse body colouration within and between the [~]250 species and across ontogenetic stages. In addition to human visible colours (i.e., 400-700 nm), most adult damselfishes reflect ultraviolet (UV, 300-400 nm) colour patches. UV sensitivity and UV colour signals are essential for feeding and form the basis for a secret communication channel invisible to the many UV-blind predatory fish on the reef; however, how these traits develop across ontogenetic stages, and their distribution across the damselfish family is poorly characterised. Here, we used UV photography, phylogenetic reconstructions of opsin genes, differential gene expression analysis (DGE) of retinal samples, to investigate the development of UV vision and colour patterns in three ontogenetic stages (pre-settlement larval, juvenile, and adult) of eleven damselfish species. Using DGE, we found similar gene expression between juveniles and adults, which strongly differed from larvae. All species and all stages expressed at least one UV-sensitive sws1 opsin gene. However, UV body colour patterns only started to appear at the juvenile stage. Moreover, Pomacentrus species displayed highly complex UV body patterns that were correlated with the expression of two sws1 copies. This could mean that some damselfishes can discriminate colours that change only in their UV component. We demonstrate dramatic shifts in both UV sensitivity and UV colouration across the development stages of damselfish, while highlighting the importance of considering ontogeny when studying the coevolution of visual systems and colour signals.

ecology↗

bioRxiv2023

Gene flow throughout the evolutionary history of a polymorphic and generalist clownfish

Even seemingly homogeneous on the surface, the oceans display high environmental heterogeneity across space and time. Indeed, different soft barriers structure the marine environment, which offers an appealing opportunity to study various evolutionary processes such as population differentiation and speciation. Here, we focus on Amphiprion clarkii (Actinopterygii; Perciformes), the most widespread of clownfishes that exhibits the highest colour polymorphism. Clownfishes can only disperse during a short pelagic larval phase before their sessile adult lifestyle, which might limit connectivity among populations, thus facilitating speciation events. Consequently, the taxonomic status of A. clarkii has been under debate. We used whole-genome resequencing data of 67 A. clarkii specimens spread across the Indian and Pacific Oceans to characterise the species population structure, demographic history, and colour polymorphism. We found that A. clarkii spread from the Indo-Pacific Ocean to the Pacific and Indian Oceans following a stepping-stone dispersal and that gene flow was pervasive throughout its demographic history. Moreover, edge populations exhibited more similar colouration patterns compared to central populations. However, we demonstrate that colour polymorphism is not associated with population structure, thus, colour phenotype is unreliable in assessing the taxonomic status of A. clarkii. Our study further highlights the power of whole-genome comparative studies to determine the taxonomy of geographically wide-ranging and phenotypically diverse species, supporting the status of A. clarkii as a single species.

evolutionary biology↗

bioRxiv2020

CRISPR/CAS9-mediated generation of biallelic G0 anemonefish (Amphiprion ocellaris) mutants

Genomic manipulation is a useful approach for elucidating the molecular pathways underlying aspects of development, physiology, and behaviour. However, a lack of gene-editing tools appropriated for use in reef fishes has meant the genetic underpinnings for many of their unique traits remain to be investigated. One iconic group of reef fishes ideal for applying this technique are anemonefishes (Amphiprioninae) as they are widely studied for their symbiosis with anemones, sequential hermaphroditism, complex social hierarchies, skin pattern development, and vision, and are raised relatively easily in aquaria. In this study, we developed a gene-editing protocol for applying the CRISPR/Cas9 system in the false clown anemonefish, Amphiprion ocellaris. Microinjection of eggs at the one-cell stage was used to demonstrate the successful use of our CRISPR/Cas9 approach at two separate target sites: the rhodopsin-like 2B opsin encoding gene (RH2B) involved in vision, and Tyrosinase-producing gene (tyr) involved in the production of melanin. Analysis of the sequenced target gene regions in A. ocellaris embryos showed that uptake was as high as 50% of injected eggs. Further analysis of the subcloned mutant gene sequences revealed that our approach had a 75% to 100% efficiency in producing biallelic mutations in G0 A. ocellaris embryos. Moreover, we clearly show a loss-of-function in tyr mutant embryos which exhibited typical hypomelanistic phenotypes. This protocol is intended as a useful resource for future experimental studies that aim to elucidate gene function in anemonefishes and reef fishes in general.

molecular biology↗

bioRxiv2019

Neoteny in visual system development of the spotted unicornfish, Naso brevirostris (Acanthuridae)

Ontogenetic changes of the visual system are often correlated to shifts in habitat and feeding behaviour of animals. Coral reef fishes begin their lives in the pelagic zone and then migrate to the reef. This transition of habitat frequently involves a change in diet and light environment as well as major morphological modifications. The spotted unicornfish, Naso brevirostris, is known to shift diet from zooplankton to algae and back to zooplankton when transitioning from larval to juvenile and then to adult stages. Concurrently, N. brevirostris also moves from an open pelagic to a coral-associated habitat before migrating up in the water column when reaching adulthood. Using retinal mapping techniques, we discovered that the distribution and density of ganglion and photoreceptor cells in N. brevirostris do not change with the habitat or the feeding habits of each developmental stage. Instead, fishes showed a neotenic development with a slight change from larval to juvenile stages and not many modifications thereafter. Visual gene expression based on RNA sequencing mirrored this pattern; independent of stage, fishes mainly expressed three cone opsin genes (SWS2B, RH2B, RH2A), with a quantitative difference in the expression of the green opsin genes (RH2A and RH2B) when transitioning from larvae to juveniles. Hence, contrary to the ontogenetic changes found in many animals, the visual system is fixed early on in N. brevirostris development calling for a thorough analysis of visual system development of the reef fish community.

evolutionary biology↗