Biology subjects

Litsios, G.

Publications and source records attributed to Litsios, G..

3 recordsLinked to original sources

bioRxiv2024

Specialization into Host Sea Anemones Impacted Clownfish Demographic Responses to Pleistocene Sea Level Changes

Fluctuating sea levels during the Pleistocene led to habitat loss and fragmentation, impacting the evolutionary trajectories of reef fishes. Species with specialized ecological requirements or habitat preferences, like clownfishes (Amphiprioninae), may have been particularly vulnerable due to their intricate dependence on sea anemones. The diverse host specializations within this group likely contributed distinct responses to sea-level fluctuations, differentially shaping their recent evolutionary histories. Leveraging a comprehensive genomic dataset, we reveal demographic patterns and connectivity dynamics across multiple populations of ten clownfish species under different host specializations. Host-generalist species demonstrated strong resilience to habitat perturbations, while those specialized on single hosts suffered dramatic bottlenecks linked to sea-level fluctuations. Spatial analyses revealed the significant role of oceanic currents in shaping clownfish genetic diversity landscapes. Dispersal barriers were driven by environmental variables, with the Coral Triangle emerging as a hub of genetic diversity. Our results reveal how clownfish associative behavior influences their population dynamics, holding major implications for their conservation such as the need to consider their mutualism with sea anemones, particularly on host-specialists, to ensure their survival in the face of climate threats. These findings extend broader principles of conservation, improving our understanding of species responses to ecological constraints and environmental changes over evolutionary timescales.

genomics↗

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↗

bioRxiv2017

First draft genome assembly of an iconic clownfish species (Amphiprion frenatus)

Clownfishes (or anemonefishes) form an iconic group of coral reef fishes, particularly known for their mutualistic interaction with sea anemones. They are characterized by particular life history traits, such as a complex social structure and mating system involving sequential hermaphroditism, coupled with an exceptionally long lifespan. Additionally, clownfishes are considered to be one of the rare group to have experienced an adaptive radiation in the marine environment.\n\nHere, we assembled and annotated the first genome of a clownfish species, the tomato clownfish (Amphiprion frenatus). We obtained a total of 17,801 assembled scaffolds, containing a total of 26,917 genes. The completeness of the assembly and annotation was satisfying, with 96.5% of the Actinopterygii BUSCOs (Benchmarking Universal Single-Copy Orthologs) being retrieved in A. frenatus assembly. The quality of the resulting assembly is comparable to other bony fish assemblies.\n\nThis resource is valuable for the advancing of studies of the particular life-history traits of clownfishes, as well as being useful for population genetic studies and the development of new phylogenetic markers. It will also open the way to comparative genomics. Indeed, future genomic comparison among closely related fishes may provide means to identify genes related to the unique adaptations to different sea anemone hosts, as well as better characterize the genomic signatures of an adaptive radiation.

genomics↗