Colonization Routes Research Articles

The genetic legacy of the Quaternary ice ages for West Palearctic butterflies.

The interplay between geographic barriers and climatic oscillations over the past 2.6 million years structured genetic variation at the continental scale. The genetic legacy of the Quaternary ice ages (GLQ) hypothesis outlines this phenomenon for Europe, but a comprehensive data-driven assessment is lacking. Using innovative genetic landscape methods, we model the GLQ in the West Palearctic based on 31,653 Cytochrome c oxidase subunit 1 (COI) sequences from 494 butterfly species and three functional traits. Seven distinct bioregions with varying levels of genetic endemicity emerge, revealing a latitudinal gradient in variation that confirms the "southern richness, northern purity" hypothesis. Through shift from case studies to a comparative approach, we objectively identify the main glacial refugia, colonization routes, and barriers to dispersal. Our findings offer a quantitative model of the GLQ across Europe, North Africa, and neighboring Asia, with broader applicability to other taxa and potentially scalable to encompass life on Earth.

Urban air quality affects the apple microbiome assembly

Exposure to air pollution affects health of all organisms on earth but the impact on the plant microbiome is less understood. Here, we link the Air Quality Index with the dust and apple epiphytic and endophytic microbiome across the city of Graz (Austria). The microbiome of the apple episphere, peel endosphere and pulp endosphere, and surrounding dust was analyzed. Our results show that the fungal communities were more influenced by air quality than bacterial communities. Bacterial communities, instead, were more specific for the individual sample types, especially noticeable in the pulp endosphere. The microbiome of each sample type was comprised of distinct microbial communities. Overall, the bacterial communities were highly dominated by Proteobacteria followed by Bacteroidota and Actinobacteriota, and the fungal communities were dominated by Ascomycota followed by Basidiomycota. With lower air quality, the relative abundance of the fungal orders Hypocreales and Pleosporales decreased in the apple episphere and the peel endosphere, respectively. Interestingly, an unexpectedly high level of similarity was observed between the bacterial communities of dust and peel endosphere, while the epiphytic bacterial community was significantly different compared to the other samples. We suggested that dust served as a potential microbial colonization route for the fruit microbiome as most bacteria (55%) colonizing the peel endosphere originated from dust. In conclusion, air quality affects the microbiome of edible plants, which can cause health consequences in humans. Therefore, this knowledge should be considered in urban and horticultural farming strategies.

Phylogenomics and biogeography of sawflies and woodwasps (Hymenoptera, Symphyta)

Phylogenomic approaches have recently helped elucidate various insect relationships, but large-scale comprehensive analyses on relationships within sawflies and woodwasps are still lacking. Here, we infer the relationships and long-term biogeographic history of these hymenopteran groups using a large dataset of 354 UCE loci collected from 385 species that represent all major lineages. Early Hymenoptera started diversifying during the Early Triassic ∼249 Ma and spread all over the ancient supercontinent Pangaea. We recovered Xyeloidea as a monophyletic sister group to other Hymenoptera and Pamphilioidea as sister to Unicalcarida. Within the diverse family Tenthredinidae, our taxonomically and geographically expanded taxon sampling highlights the non-monophyly of several traditionally defined subfamilies. In addition, the recent removal of Athalia and related genera from the Tenthredinidae into the separate family Athaliidae is supported. The deep historical biogeography of the group is characterised by independent dispersals and re-colonisations between the northern (Laurasia) and southern (Gondwana) palaeocontinents. The breakup of these landmasses led to ancient vicariance in several Gondwanan lineages, while interchange across the Northern Hemisphere has continued until the Recent. The little-studied African sawfly fauna is likewise a diverse mixture of groups with varying routes of colonization. Our results reveal interesting parallels in the evolution and biogeography of early hymenopterans and other ancient insect groups.

Traversing the Great Lakes: Post‐glacial colonization by a widespread terrestrial salamander

AbstractAimsGlacial retreat at the end of the Pleistocene epoch opened vast expanses of emergent habitat in the northern hemisphere that were colonized by opportunistic taxa. However, species that undergo post‐glacial expansion may have originated from one or several glacial refugia. We inferred the post‐glacial expansion history of the Eastern Red‐backed Salamander (Plethodon cinereus), a fully terrestrial species with a vast distribution despite severe dispersal limitations. Previous studies indicated populations south of the glacial boundary at the eastern and western limits of the distribution were closely related, suggesting either multiple refugia or an extraordinary post‐glacial expansion event.LocationEastern North America.Taxon Plethodon cinereus (Green, 1818), Caudata: Plethodontidae.MethodsWe collected ddRAD‐seq data from 106 individuals throughout the distribution of P. cinereus. We estimated phylogeographic structure, including finer‐scale structure among the post‐glacial populations. To test the origins and routes of colonization, we used ecological niche modelling, population trees and analyses of directional range expansion.ResultsAnalyses supported our hypothesis of a southeastern glacial refugium, with northward expansion along the Eastern Seaboard prior to westward invasion into the Great Lakes region, including southwestern expansion into unglaciated areas at the western end of the distribution. However, a distinct subgroup in the northwestern portion of the range raises the possibility of a second refugium near the ice‐free Driftless Area.Main ConclusionsBased on our results, we hypothesize a southeastern refugium from which most of today's northern populations undertook extensive post‐glacial colonization. Our results indicate a geographically non‐linear colonization history for P. cinereus.

Conservation Challenges Imposed by Evolutionary History and Habitat Suitability Shifts of Endangered Freshwater Mussels under a Global Climate Change Scenario

Climate change and associated shifts in temperature and precipitation patterns have become an increasing concern as drivers of ongoing biodiversity loss. The Mediterranean region is particularly vulnerable, being both a biodiversity hotspot and a region very prone to desertification. Freshwater mussels are amongst the most threatened invertebrate taxa worldwide. Unio tumidiformis is an endemic and endangered species restricted to the southern Iberian Peninsula, living in temporary Mediterranean-type streams. Freshwater mussels need a fish host for successful larval transformation, meaning U. tumidiformis must belong to the genus Squalius. The main objective of this study was to evaluate the vulnerability of U. tumidiformis to climate change, by studying its population genetics and evolutionary history, its current and future habitat suitability, and that of its hosts. Genetic population structure and diversity were assessed using Single-Nucleotide Polymorphisms through Genotyping by Sequencing and used to infer species evolutionary history. The species potential distribution was modeled using an ensemble forecasting approach, and future shifts in habitat suitability were assessed with the projected climate data layers from Worldclim. Most populations showed extreme genetic differentiation (Fst up to 0.745), even from close neighboring ones. Upper Guadiana populations were more diverse and less differentiated. We hypothesize that U. tumidiformis originated in Upper Guadiana and followed the same colonization routes as their hosts with numerous founder effects and bottlenecks. Our results also predicted a reduction of 99% of climatically suitable areas for U. tumidiformis in the Iberian Peninsula until 2040. For the fish hosts, a maximum 42% reduction in suitable areas was estimated throughout the century, with remaining adequate habitats in the north. Our results suggest that difficult conservation options are necessary, prioritizing the preservation of populations, translocations to the northern area of its historical range and stream engineering to increase resilience to droughts.

Phylogeography of Dolichophis Populations in the Aegean Region (Squamata: Colubridae) with Taxonomic Remarks

In this study, we investigate the phylogeographic patterns of Dolichophis species in the Aegean region, aiming to elucidate their genetic diversity and putative historical colonisation routes through mitochondrial and nuclear DNA data. Our findings revealed distinct phylogeographic patterns: D. caspius exhibited a higher level of haplotypes within two shallow mitochondrial lineages, contrasting with D. jugularis, which displayed lower genetic variability in the area. Additionally, we identified evidence showing possible human-mediated historical translocation of D. caspius populations to Karpathos from the Balkans mainland. The mitochondrial variability in D. jugularis remained relatively uniform across southwestern Anatolia and Dodecanese, except for Rhodes Island. The evidence from mitochondrial and nuclear data confirming the previously described morphological differentiation of the Rhodes snakes, and thus the name D. j. zinneri Cattaneo, 2012, described on the island, could be applied to this isolated population. This result addresses the first genetic view on the long-standing taxonomic uncertainties regarding the subspecies status of Rhodes D. jugularis. Our results also raise questions regarding possible historical hybridisations between D. caspius and D. jugularis in the Dodecanese islands, prompting the need for further investigation using extensive field studies and genomic approaches. Ultimately, the Aegean islands, particularly Kos and Rhodes, seem to be important sites for the evolution of these colubrid snakes and their historical dynamics.

Ancient reindeer mitogenomes reveal island-hopping colonisation of the Arctic archipelagos

Climate warming at the end of the last glacial period had profound effects on the distribution of cold-adapted species. As their range shifted towards northern latitudes, they were able to colonise previously glaciated areas, including remote Arctic islands. However, there is still uncertainty about the routes and timing of colonisation. At the end of the last ice age, reindeer/caribou (Rangifer tarandus) expanded to the Holarctic region and colonised the archipelagos of Svalbard and Franz Josef Land. Earlier studies have proposed two possible colonisation routes, either from the Eurasian mainland or from Canada via Greenland. Here, we used 174 ancient, historical and modern mitogenomes to reconstruct the phylogeny of reindeer across its whole range and to infer the colonisation route of the Arctic islands. Our data shows a close affinity among Svalbard, Franz Josef Land and Novaya Zemlya reindeer. We also found tentative evidence for positive selection in the mitochondrial gene ND4, which is possibly associated with increased heat production. Our results thus support a colonisation of the Eurasian Arctic archipelagos from the Eurasian mainland and provide some insights into the evolutionary history and adaptation of the species to its High Arctic habitat.

Seed-to-Seed: Plant Core Vertically Transmitted Microbiota.

The plant core microbiota transmitted by seeds have been demonstrated to exist in seeds and adult plants of several crops for multiple generations. They are closely related to plants and are relatively conserved throughout evolution, domestication, and breeding. These microbiota play a vital role in the early stages of plant growth. However, information about their colonization routes, transmission pathways, and final fate remains fragmentary. This review delves into the concept of these microbiota, their colonization sources, transmission pathways, and how they change throughout plant evolution, domestication, and breeding, as well as their effects on plants, based on relevant literature. Finally, the significant potential of incorporating the practical application of seed-transmitted microbiota into plant microbial breeding is emphasized.

Balkan‐Anatolian biogeographic links and the evolutionary significance of Anatolian mountains, as evidenced by Cardamine (Brassicaceae)

AbstractAnatolia is a significant centre of biodiversity and endemism with diversity hotspots located mainly in mountain ranges. Its complex geological history and heterogeneous topography have generated natural barriers to gene flow that favour speciation, and migration corridors that accentuate its transitional biogeographic position. While more attention has been paid to the predominant Irano‐Turanian and Mediterranean xerophytic elements, the evolution of species adapted to wet habitats with limited occurrence is understudied in this area. Here, we investigated Cardamine representatives in northern Anatolia with the aims of resolving the taxonomically uncertain populations previously assigned to either C. uliginosa or C. tenera from northwestern Anatolia (Uludağ,) and elucidating the genetic structure of (sub)alpine C. uliginosa recorded mainly from the North Anatolian Mts. (Pontic Mts.). Using a combination of phylogenomic (Hyb‐Seq), morphometric, and flow cytometric analyses, we support a distinct position of the northwestern Anatolian populations, described here as a new species Cardamine anatolica. Apart from Uludağ, a few other sites were found in the montane to subalpine belts in the Marmara and Aegean regions. A sister phylogenetic position of C. anatolica to C. acris, a widespread and polymorphic Balkan species, supports the existence of biogeographic links between these areas and suggests a vicariance scenario. We revealed a pronounced intraspecific diversification of C. uliginosa with geographic structuring and admixture in the Pontic Mts., which highlights this area as a significant hotspot of biodiversity not only at the species level but also at the level of genetic variation. Due to the common misinterpretation of the species treated here, we revise their distributional data, provide details on their morphological differentiation, and present an identification key. The study highlights the evolutionary importance of Anatolian mountains, which promote speciation, favour accumulation of diversity, and serve as a meeting place of colonization routes.

Baetidae (Insecta: Ephemeroptera) of Aurès Mountains (Algeria): A New Species of the Baetis alpinus Species Group, with Notes on Baetis Laech, 1815 Biogeography within Maghreb.

A new species, Baetis (Baetis) dihyaesp. nov., belonging to the Baetis alpinus species group, is described and illustrated based on larval material collected in the Aurès Mountains (northeastern Algeria) in 2020-2021. This new species is closely related to three European species, e.g., Baetis (B.) alpinus (Pictet, 1843); B. (B.) nubecularis Eaton, 1898; and B. (B.) pasquetorum Righetti & Thomas, 2002 by the combination of the following characteristics: (i) more than one short, stout bristle at the tip of segment II of the maxillary palp and (ii) a well-developed paracercus. However, the new species clearly differs from all congeners of the Baetis alpinus species group primarily by the (a) structure of mouthparts-with 14-18 long submarginal setae arranged in a single irregular row on the dorsal surface of the labrum; 2-6 short, stout bristles at the tip of segment II of the maxillary palp; and segment II of the labial palp without a considerably developed apico-internal lobe); (b) setation of abdominal terga, with a few triangular-shaped scales sparsely scattered near the posterior margin only; and (c) a well-developed paracercus, comprised of more than 50 segments. Primary data on the biology and distribution of this new species are provided, and molecular affinities are verified by the analysis of COI (barcode) sequences. Detailed notes on the distribution of mayfly species belonging to the Baetis alpinus species group common in Western Europe and the western part of North Africa are presented. The historical movement of Baetis representatives between Europe, North West Africa, and subsequently Algeria, with the land bridges 'Strait of Gibraltar' and 'Strait of Sicily' as colonization routes, is discussed in detail and identified in the present study as the Western Algeria colonization path and Eastern Algeria colonization path, respectively.

Bacteria Associated with Acute Oak Decline: Where Did They Come From? We Know Where They Go.

Acute oak decline is a high-impact disease causing necrotic lesions on the trunk, crown thinning and the eventual death of oak. Four bacterial species are associated with the lesions-Brenneria goodwinii, Gibbsiella quercinecans, Rahnella victoriana and Lonsdalea Britannica-although an epi-/endophytic lifestyle has also been suggested for these bacteria. However, little is known about their environmental reservoirs or their pathway to endophytic colonisation. This work aimed to investigate the ability of the four AOD-associated bacterial species to survive for prolonged periods within rhizosphere soil, leaves and acorns in vitro, and to design an appropriate method for their recovery. This method was trialled on field samples related to healthy and symptomatic oaks. The in vitro study showed that the majority of these species could survive for at least six weeks within each sample type. Results from the field samples demonstrated that R. victoriana and G. quercinecans appear environmentally widespread, indicating multiple routes of endophytic colonisation might be plausible. B. goodwinii and L. britannica were only identified from acorns from healthy and symptomatic trees, indicating they may be inherited members of the endophytic seed microbiome and, despite their ability to survive outside of the host, their environmental occurrence is limited. Future research should focus on preventative measures targeting the abiotic factors of AOD, how endophytic bacteria shift to a pathogenic cycle and the identification of resilient seed stock that is less susceptible to AOD.

A systematic evaluation on the relationship between hypo-osmoregulation and hyper-osmoregulation in decapods of different habitats.

Decapods occupy all aquatic, and terrestrial and semi-terrestrial environments. According to their osmoregulatory capacity, they can be osmoconformers or osmoregulators (hypo or hyperegulators). The goal of this study is to gather data available in the literature for aquatic decapods and verify if the rare hyporegulatory capacity of decapods is associated with hyper-regulatory capacity. The metric used to quantify osmoregulation was the osmotic capacity (OC), the gradient between external and internal (hemolymph) osmolalities. We employ phylogenetic comparative methods using 83 species of decapods to test the correlation between hyper OC and hypo OC, beyond the ancestral state for osmolality habitat, which was used to reconstruct the colonization route. Our analysis showed a phylogenetic signal for habitat osmolality, hyper OC and hypo OC, suggesting that hyper-hyporegulators decapods occupy similar habitats and show similar hyper and hyporegulatory capacities. Our findings reveal that all hyper-hyporegulators decapods (mainly shrimps and crabs) originated in estuarine waters. Hyper OC and hypo OC are correlated in decapods, suggesting correlated evolution. The analysis showed that species which inhabit environments with intense salinity variation such as estuaries, supratidal and mangrove habitats, all undergo selective pressure to acquire efficient hyper-hyporegulatory mechanisms, aided by low permeabilities. Therefore, hyporegulation can be observed in any colonization route that passes through environments with extreme variations in salinity, such as estuaries or brackish water.

Detection of Aeromonas salmonicida subsp. salmonicida infection in zebrafish by labelling bacteria with GFP and a fluorescent probe based on the siderophore amonabactin

Zebrafish (Danio rerio) is an excellent model to study bacterial infections in fish and their treatment. We used zebrafish as a model of infection for Aeromonas salmonicida subsp. salmonicida (hereinafter A. salmonicida), the causative agent of fish furunculosis. The infection process of A. salmonicida was studied by immersion of zebrafish larvae in 2 different doses of the bacteria and the fish mortality was monitored for three days. The bacterium caused a high mortality (65 %) in zebrafish larvae only when they were exposed to a high bacterial concentration (107 bacterial cells/mL). To evaluate the use of fluorescence microscopy to follow A. salmonicida infection in vivo, two different fluorescent strains generated by labeling an A. salmonicida strain with either, the green fluorescent protein (GFP), or with a previously reported siderophore amonabactin-sulforhodamine B conjugate (AMB-SRB), were used. The distribution of both labeled bacterial strains in the larvae tissues was evaluated by conventional and confocal fluorescence microscopy. The fluorescent signal showed a greater intensity with the GFP-labeled bacteria, so it could be observed using conventional fluorescence microscopy. Since the AMB-SRB labeled bacteria showed a weaker signal, the larvae were imaged using a laser scanning confocal microscope after 48 h of exposure to the bacteria. Both fluorescent signals were mainly observed in the larvae digestive tract, suggesting that this is the main colonization route of zebrafish for waterborne A. salmonicida. This is the first report of the use of a siderophore-fluorophore conjugate to study a bacterial infection in fish. The use of a siderophore-fluorophore conjugate has the advantage that it is a specific marker and that does not require genetic manipulation of the bacteria.

Colonization routes uncovered in a widely introduced Mediterranean gecko, Tarentola mauritanica

In this study, we aimed to understand the contemporary and ancient colonization routes of the Moorish gecko, Tarentola mauritanica, using simple sequence repeats. By analyzing the genetic diversity of populations in different regions, we found that Morocco is the genetic diversity hotspot for the species, followed by the Iberian Peninsula. However, historical gene flow estimates identified the Iberian Peninsula, not Morocco, as the primary contributor of colonizing individuals, along with continental Italy to a lesser extent. Currently, mainland Italy is the main source of introduced individuals, likely due to the plant nursery trade. The study suggests that human-facilitated introductions from various geographical origins, with numerous regions colonized through continental Italy during two distinct periods, are responsible for the recurrent entry of individuals belonging to the European lineage of T. mauritanica into the Mediterranean and Macaronesia. These findings can inform better monitoring surveys and conservation programs by identifying putative current colonization routes of alien species.

Environmental suitability and potential range expansion of the Eurasian beaver in Italy

AbstractReintroduction and rewilding initiatives are key strategies to reverse human impacts on ecosystems and re‐establish natural processes. However, rewilding may involve complex management scenarios, because many expanding species can have economic impacts and cause human–wildlife conflicts. Conflicts can be particularly challenging when carnivores, large herbivores and ecosystem engineers are involved. The Eurasian beaver (Castor fiber) is a key ecosystem engineer that was once present in a large part of the Palearctic, but in Medieval times underwent a severe decline due to the joint effects of habitat loss and hunting. Subsequent legal protection and reintroductions triggered the recovery of the species through most of its original range. Eurasian beavers recently started the recolonization of Italy, because of the joint effects of natural dispersal (from Austria to northern Italy) and illegal reintroductions (central Italy). The lack of data on the most likely colonization routes hampers appropriate management of this species. Here, we identified the areas where beaver populations are most likely to arrive in the near future within Europe, with a specific focus on Italy. First, we developed spatially cross‐validated species distribution models to identify the areas with the highest suitability for the Eurasian beaver in Europe. Second, we used connectivity modelling to assess the possible expansion routes of this species in Italy. Large areas of Europe are suitable for the beaver and may soon be colonized. The connectivity model showed a high potential for expansion from central Italy to surrounding areas, while the high isolation of northern Italy populations suggests a slower expansion. Our results can help environmental managers to understand where to focus both the future monitoring of beaver populations and actions aimed at preventing and mitigating possible human–wildlife conflicts that could arise from the expansion of an environmental engineer such as the beaver.

Palaeoclimatic niche modelling reveals the phylogeographic history of the South African shrew Myosorex varius and the colonisation route of the genus Myosorex (Mammalia, Soricidae) from East Africa

Myosorex varius is a South African generalist shrew, which has been found to consist of several genetic clades across its range. A northern clade inhabits the more mesic, summer-rainfall areas of grassland and savannah in the east of South Africa. A southern clade occupies areas of fynbos in the south, and can be further divided into a western subclade occupying winter-rainfall areas and an eastern subclade occupying areas with aseasonal rainfall. Non-South-African members of the African genus Myosorex primarily are limited to isolated montane habitats along the East African Rift System. Here, we used palaeoclimatic niche modelling to examine the effects of Pliocene and Pleistocene climate change on the distributions of M. varius, its clades and the genus as a whole. Results indicate that repeated cycles of range expansion during glacial periods and fragmentation during interglacials are responsible for current phylogeographic patterns within M. varius. Based on their close alignment with rainfall zones and lack of genetic mixing despite areas of contact, it is likely that these (sub)clades are locally adapted to their respective areas. Earlier climatic fluctuations allowed the genus to ‘island hop’ south from East Africa along the East African Rift System, expanding in range during cooler periods and retreating to montane refugia during warmer periods. Areas currently occupied by Myosorex species largely correspond with predicted montane refugia that have allowed them to survive previous warm periods.

Phylogenetic relationships of Cuban and Caribbean Plumeria (Apocynaceae) based on the plastid genome

Abstract Plumeria L. (Apocynaceae) is a Neotropical genus mostly restricted to the Caribbean, which is cultivated in tropical gardens worldwide. Almost all ~27 species are endemic to the Caribbean Islands, except for four (Plumeria inodora Jacq., Plumeria obtusa L., Plumeria pudica Jacq., and Plumeria rubra L.) that are native to Central America and northern South America. Cuba harbours the largest diversity of the genus, with 13 endemic species. We present the first molecular phylogeny of the genus based on the nucleotide sequences of the complete plastid genome. Partial plastid genomes of 11 Plumeria species and one closely related species (Himatanthus sp.) were sequenced using long-PCR and next-generation sequencing. The recovered clades mostly grouped by single islands or closely neighboring islands. The phylogenetic relationships indicate patterns of adaptive radiation, with ecological shifts within these island-based clades and a west-to-east colonization route in the region. Plumeria rubra and Himatanthus sp. were resolved as sister to the rest of the genus. One unexpected finding was that P. pudica, a species restricted to the southern Caribbean Basin mainland, was recovered within the clade containing the Caribbean Island endemics, rendering the endemic group polyphyletic. Our study provides a phylogenetic framework for future studies that will need to include nuclear molecular markers and a more extensive sampling.

Neutral genetic diversity follows a latitudinal gradient in the endangered plant Arnica montana L.: a range-wide study

Arnica montana is a clonal, self-incompatible herb of economic and intrinsic ecological value which is declining in large parts of its range. With the employment of microsatellite markers, we characterized the population structure and distribution of genetic diversity of 40 populations of A. montana sampled throughout Europe. We detected a clear geographical pattern of isolation and strong population structure, indicating limited gene flow. We also observed a negative latitudinal gradient in genetic diversity. Such patterns can be explained by paleo-historical colonization routes following the last glacial maximum, with regions characterized by higher genetic diversity corresponding to former glacial refugia. We recommend the implementation of conservation measures such as assisted gene flow in the populations characterized by low genetic diversity under consideration of the observed population structure. For the populations where high levels of genetic diversity are still retained, we recommend the maintenance of suitable habitat conditions. Our study emphasises the importance of conducting large-scale population genetic studies that consider postglacial recolonization history when planning active conservation measures such as assisted gene flow.

Hepcidin and piscidin modulation and antibacterial response in gilthead seabream (Sparus aurata) infected with Vibrio harveyi.

Vibriosis is an infectious disease that generates large economic losses in Mediterranean aquaculture. Vibrio harveyi is one of the marine bacteria causing this disease, it is widespread in the Mediterranean Sea and causes ulcers on the skin of the fish it infects. In addition, the skin is a route of entry and colonization of this pathogen. In this study, one group of fish was injected intraperitoneally with phosphate buffered saline (control group) and another with V. harveyi (infected group). At 4h after injection, samples of skin mucus, blood, skin, head kidney, liver, and spleen were collected to study the immune response generated. Liver histology showed notable alterations in hepatocyte morphology, such as increased vacuolization. Bactericidal activity was measured in skin mucus and serum against V. harveyi and V. anguillarum, different changes in this activity were recorded depending on the bacteria target and sample (skin mucus or serum) used. Gene expression of genes encoding hepcidins and piscidins (antimicrobial peptides) was performed in the mentioned organs. The results indicated a different expression according to the type of AMP and the tissue studied. Hepcidin appeared involved in all tissues studied while piscidins were in the spleen. In this study we have integrated hepcidin-piscidin modulation with the effects of infection on skin mucosa, serum and hepatocyte morphology. Knowing the changes produced in all these parameters improves the understanding of the infection in the first hours in sea bream and could have applications in the diagnosis or treatment of vibriosis in fish farms.

Phylogeography and demographic history of the cyprinid fish Barbodes semifasciolatus: implications for the history of landform changes in south mainland China, Hainan and Taiwan

Hainan Island and Taiwan Island are adjacent to the southern margin of mainland China and Vietnam. During glacial periods, global sea levels dropped, allowing that the land bridges connected the continental island and mainland, connecting rivers and providing dispersal opportunities that shaped the origin and diversification of freshwater fishes. Barbodes semifasciolatus is distributed in various water systems of Vietnam, Hainan, Taiwan, and southern mainland China and is restricted to the southern region of the Min River. Our study aimed to evaluate the genetic diversity and phylogeography of B. semifasciolatus using the mtDNA cyt b gene (1,141 bp). A total of 107 haplotypes were identified from 395 specimens in 23 populations, and high haplotype diversity (1.000) and low nucleotide diversity (0.0134) were detected. Mitochondrial phylogenetic analysis and haplotype network analyses revealed three major lineages according to geographical distribution. Lineage A was mainly distributed in Hainan Island, Vietnam and the southern region of the Pearl River in mainland China. Lineage B was distributed only in southeastern Hainan Island. Lineage C was distributed in the coastal rivers of mainland China and Taiwan. We suggest that the river in the Guangdong region is a colonization route in South Taiwan and that the populations distributed in the Pearl River region moved southward to Hainan Island and Vietnam based on the network and Bayesian binary MCMC (BBM) analysis. Our demographic history results indicated that the populations of B. semifasciolatus experienced a bottleneck event following a recent population expansion (DECINC model) supported by ABC analysis. We suggest that sea-level changes exerted pronounced effects on the demography of B. semifasciolatus on the continental island and in the mainland during the late Pleistocene glacial cycles.