Biology subjects

Copilas-Ciocianu, D.

Publications and source records attributed to Copilas-Ciocianu, D..

8 recordsLinked to original sources

bioRxiv2023

Invasion is accompanied by dietary contraction in Ponto-Caspian amphipods

A species expansion beyond the native range is often assumed to be associated with an increased dietary niche breadth. However, empirical evidence remains limited due to a scarcity of studies comparing both the parental and invaded ranges. Here, we test the trophic niche expansion hypothesis by examining stable isotopes and functional morphology across native (NW Black Sea) and invaded (SE Baltic Sea) ranges of two amphipods, Dikerogammarus villosus and Pontogammarus robustoides, originating from the Ponto-Caspian region - a major source of species invading Holarctic inland waters. Stable isotopes revealed that both species underwent a twofold contraction of the dietary niche with a shift towards decreased carnivory in the invaded range. This dietary shift was morphologically mirrored by an overall reduction of prey grasping appendages, antennae, and mouthpart palps. The magnitude of dietary and morphological change was greater in D. villosus. Our findings indicate that previous experimental reports of aggressive predation in D. villosus reflect opportunistic foraging and align with local stable isotope studies which generally indicate a low trophic position. We conclude that Ponto-Caspian species can undergo rapid, if non-intuitive, changes in both diet and functional morphology outside the native range, likely contributing to their invasive potential.

ecology↗

bioRxiv2023

Climatic niche differentiation between native and non-native ranges is widespread in Ponto-Caspian amphipods

O_LINiche conservatism posits that a species non-native populations establish in areas that match the native environmental conditions. Although the Ponto-Caspian region is a major source of inland aquatic alien species, the extent to which their climatic niches diverged between the invasive and native ranges remains poorly understood. C_LIO_LIUsing an n-dimensional hypervolume approach, we quantified climatic niche overlap and inferred patterns of niche differentiation (shift, contraction, or expansion) among native and invaded ranges for 12 widespread Ponto-Caspian amphipod species (six genera in three families). C_LIO_LIOur results show that all investigated species experience substantially different climatic conditions in the invaded range. The invasive niche either contracted (five species), shifted (four species), expanded and shifted (two species), or shifted and contracted (one species) relative to the native niche. C_LIO_LIWe conclude that although the focal taxa share a common geographic origin and evolutionary history, they exhibit disparate patterns of climatic niche change outside the native range. The niche conservatism hypothesis receives mixed support given that half of the studied species underwent niche shifts/expansion. Furthermore, congeners exhibited both identical and contrasting patterns of niche differentiation, suggesting a limited phylogenetic effect. C_LIO_LIThe uncovered diversity of niche dynamics among closely related species indicates that each has a unique potential for invasiveness and long-term persistence. This has important implications for predicting invasion risk and refining management strategies. C_LI

ecology↗

bioRxiv2023

Distribution, diversity and diversification from a DNA barcoding perspective: the case of Gammarus radiation in Europe`s oldest inland waterbody - the ancient Lake Ohrid

AimA detailed, comparative DNA-barcoding and morphospecies based overview of the vertical and horizontal distribution of Lake Ohrid endemic Gammarus species-flock. Re-evaluation of the origin of the species-flock dating, identification of events that putatively influenced diversification patterns in the species-flock. LocationLake Ohrid: a deep and ancient lake of tectonic origin, biosphere reserve, UNESCO World Heritage Site, located on the Macedonia/Albania border. TaxonGammarus species-flock (Amphipoda, Crustacea) MethodsExtensive sampling and DNA barcoding of 600 individuals were carried out. DNA sequences were analysed using species delimitation methods, haplotype network reconstructions, Bayesian molecular dating and demographic analysis. The COI-based delimitation results were validated with nuclear 28S RNA data. ResultsThe species flock distribution has weak horizontal but clear vertical structure. The diversity across bathymetric gradients correlates with temperature and salinity; and the highest diversity with sublittoral and springs of lakes shore. Two new MOTUs representing putatively new species are revealed and supported also by the nuclear marker. The time of flock radiation overlaps with the time of lake formation. The COI gene shows signs of positive selection and an acceleration in substitution rate. The demographic changes of the flock happened during the last ky. Main conclusionsDistribution of the Gammarus species-flock is vertically structured, reflecting habitat zonation. Parapatric speciation as one of the mechanisms in flocks diversification is suggested. Detection of new MOTU suggests that the flocks diversity is still not fully revealed. Nevertheless, failure to recover three other MOTUs suggests the loss of gammarid diversity in the lake. This represents,together with the current threats to the lake ecosystem (i.e. climate changes, development of tourism), a clear call for conservation efforts. The speciation events and demographic changes within the flock relate presumably to glacial and postglacial water level changes and to colonisation of new depth ranges and the associated springs.

molecular biology↗

bioRxiv2023

Comparative mitogenomics of native European and alien Ponto-Caspian amphipods

European inland surface waters harbor an extensive diversity of native amphipod crustaceans with many species facing threats from invasive counterparts of Ponto-Caspian origin. Herein, we examine mitochondrial genomes to infer phylogenetic relationships and compare gene order and nucleotide composition between representative native European and invasive Ponto-Caspian taxa belonging to five families, ten genera, and 20 species (13 newly sequenced herein). We observe diverse gene rearrangement patterns in the phylogenetically disparate native species pool. Pallaseopsis quadrispinosa and Synurella ambulans show significant departures from the typical organization, with extensive translocations of tRNAs and the nad1 gene, as well as a tRNA-F polarity switch in the latter. The monophyletic alien Ponto-Caspian gammarids display a conserved gene order, mainly differing from the native species by a tRNA-E and tRNA-R translocation, which strengthens previous findings. However, extensive rearrangement is observed in Chaetogammarus warpachowskyi with translocations of six tRNAs. The alien corophiid, Chelicorophium curvispinum, displays a very conserved gene order despite its distant phylogenetic position. We also find that native species have a significantly higher GC and lower AT content than invasive ones. The observed mitogenomic differences between native and invasive amphipods need further investigation and could shed light on the mechanisms underlying invasion success.

molecular biology↗

bioRxiv2023

Comparative phylogeography of Ponto-Caspian amphipods throughout the invaded Baltic and native NW Black Sea donor ranges. Can introduction mode affect genetic diversity?

The Baltic countries harbor a diverse assemblage of alien amphipods of Ponto-Caspian origin. The composition of this fauna was shaped by three invasion waves: 1) pre-20th century dispersals via watershed-connecting canals, 2) deliberate introductions in the 1960s, and 3) new dispersals during the last decade via shipping and pre-existing canals. Given this rich invasion history, we test whether genetic diversity (mitochondrial and nuclear) differs between the native and invaded ranges and between the deliberately introduced species and the ones that dispersed on their own. Our results show a significant decrease in mitochondrial but not nuclear genetic diversity in the invaded Baltic range. We also find that in the invaded range the introduced species exhibit a higher mitochondrial and nuclear genetic diversity than the species that dispersed on their own, while in the native range only the nuclear diversity is higher in introduced species. Mitochondrial diversity was more structured geographically in the native range and the dominant invasive haplotypes were detected in the native populations of all but one species, further highlighting the utility of this marker in tracing invasion sources. Our comparative approach provides important insight into the inter-range genetic diversity of Ponto-Caspian invaders, highlighting the role of introduction mode.

evolutionary biology↗

bioRxiv2021

Global distribution and diversity of alien Ponto-Caspian amphipods

The Ponto-Caspian region is an important donor of aquatic alien species throughout the Northern Hemisphere, many of which are amphipod crustaceans. Despite decades of ongoing spread and negative effects on native biota, a complete picture of the global diversity and distribution of these amphipods has yet to emerge, hampering efficient monitoring and predictions of future invasions. Herein, we provide a comprehensive summary of alien species taxonomic and ecomorphological diversity, as well as high-resolution distribution maps and biogeographical patterns based on >8000 global records. We find that up to 39 species in 19 genera and five families, belonging to all four currently recognized ecomorphs, are potentially alien, their diversity gradually decreasing with distance from the native region. Most species (62%) have limited distributions, 15% are widespread, and 23% exhibit intermediate ranges. We also find that regions adjacent to the native areal are comparatively less well-sampled than more distant regions. Biogeographical clustering revealed three faunal provinces that largely correspond with the Southern, Central and Northern invasion corridors. We conclude that 1) alien amphipods are a representative subsample of the native Ponto-Caspian phylogenetic and ecomorphological diversity, and 2) that their biogeographical patterns are driven by anthropogenic factors acting on distinct native regional species pools.

zoology↗

bioRxiv2021

Taxonomic, ecological and morphological diversity of Ponto-Caspian gammaridean amphipods: a review

Thanks to its dynamic geological history the Ponto-Caspian region harbors a unique and unusually adaptable fauna, notorious for its invasive species. Gammarid amphipods attained considerable diversity, becoming the worlds second most speciose ancient-lake amphipod radiation. Nonetheless, apart from a few invasive species, this group remains poorly studied. Herein, we review and quantify the taxonomic, morphological and ecological diversity, as well as phylogenetic context of Ponto-Caspian gammarids within the adaptive radiation framework. Published molecular phylogenies indicate that this radiation has a monophyletic mid-Miocene Paratethyan origin, and is nested within the morphologically-conserved Atlanto-Mediterranean genus Echinogammarus. We find extensive disparity in body shape, size, ornamentation and appendage length, along a broad ecological gradient from mountain springs to depths exceeding 500 m, on virtually all substrate types (including symbiosis). We propose four putative ecomorphs that appear convergent with distantly related oceanic and Baikal Lake taxa. Thus, the identified patterns support the adaptive radiation model, although extensive further research is needed. A checklist and provisional key to all known endemic species are provided to facilitate taxonomic research. Ponto-Caspian gammarids could be a potentially powerful model for studying adaptive radiations and invasive species evolution.

zoology↗

bioRxiv2019

The late blooming amphipods: global change promoted post-Jurassic ecological radiation despite Palaeozoic origin

The ecological radiation of amphipods is striking among crustaceans. Despite high diversity, global distribution and key roles in all aquatic environments, little is known about their ecological transitions, evolutionary timescale and phylogenetic relationships. It has been proposed that the amphipod ecological diversification began in the Late Palaeozoic. By contrast, due to their affinity for cold/oxygenated water and absence of pre-Cenozoic fossils, we hypothesized that the ecological divergence of amphipods arose throughout the cool Late Mesozoic/Cenozoic. We tested our hypothesis by inferring a large-scale, time-calibrated, multilocus phylogeny, and reconstructed evolutionary patterns for major ecological traits. Although our results reveal a Late Palaeozoic amphipod origin, diversification and ecological divergence ensued only in the Late Mesozoic, overcoming a protracted stasis in marine littoral habitats. Multiple independent post-Jurassic radiations took place in deep-sea, freshwater, terrestrial, pelagic and symbiotic environments, usually postdating deep-sea faunal extinctions, and corresponding with significant climatic cooling, tectonic reconfiguration, continental flooding, and increased oceanic oxygenation. We conclude that the profound Late Mesozoic global changes triggered a tipping point in amphipod evolution by unlocking ecological opportunities that promoted radiation into many new niches. Our study also provides a solid, time-calibrated, evolutionary framework to accelerate research on this overlooked, yet globally important taxon.

evolutionary biology↗