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1.
Evol Appl ; 17(3): e13649, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38463749

RESUMO

Characterizing patterns of genetic connectivity in marine species is of critical importance given the anthropogenic pressures placed on the marine environment. For sessile species, population connectivity can be shaped by many processes, such as pelagic larval duration, oceanographic boundaries and currents. This study combines restriction-site associated DNA sequencing (RADseq) and passive particle dispersal modelling to delineate patterns of population connectivity in the pink sea fan, Eunicella verrucosa, a temperate octocoral. Individuals were sampled from 20 sites covering most of the species' northeast Atlantic range, and a site in the northwest Mediterranean Sea to inform on connectivity across the Atlantic-Mediterranean transition. Using 7510 neutral SNPs, a geographic cline of genetic clusters was detected, partitioning into Ireland, Britain, France, Spain (Atlantic), and Portugal and Spain (Mediterranean). Evidence of significant inbreeding was detected at all sites, a finding not detected in a previous study of this species based on microsatellite loci. Genetic connectivity was characterized by an isolation by distance pattern (IBD) (r 2 = 0.78, p < 0.001), which persisted across the Mediterranean-Atlantic boundary. In contrast, exploration of ancestral population assignment using the program ADMIXTURE indicated genetic partitioning across the Bay of Biscay, which we suggest represents a natural break in the species' range, possibly linked to a lack of suitable habitat. As the pelagic larval duration (PLD) is unknown, passive particle dispersal simulations were run for 14 and 21 days. For both modelled PLDs, inter-annual variations in particle trajectories suggested that in a long-lived, sessile species, range-wide IBD is driven by rare, longer dispersal events that act to maintain gene flow. These results suggest that oceanographic patterns may facilitate range-wide stepping-stone genetic connectivity in E. verrucosa and highlight that both oceanography and natural breaks in a species' range should be considered in the designation of ecologically coherent MPA networks.

2.
J Fish Biol ; 104(1): 125-138, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37728039

RESUMO

This study provides a regional picture of long-term changes in Atlantic salmon growth at the southern edge of their distribution, using a multi-population approach spanning 49 years and five populations. We provide empirical evidence of salmon life history being influenced by a combination of common signals in the marine environment and population-specific signals. We identified an abrupt decline in growth from 1976 and a more recent decline after 2005. As these declines have also been recorded in northern European populations, our study significantly expands a pattern of declining marine growth to include southern European populations, thereby revealing a large-scale synchrony in marine growth patterns for almost five decades. Growth increments during their sea sojourn were characterized by distinct temporal dynamics. At a coarse temporal resolution, growth during the first winter at sea seemed to gradually improve over the study period. However, the analysis of finer seasonal growth patterns revealed ecological bottlenecks of salmon life histories at sea in time and space. Our study reinforces existing evidence of an impact of early marine growth on maturation decision, with small-sized individuals at the end of the first summer at sea being more likely to delay maturation. However, each population was characterized by a specific probabilistic maturation reaction norm, and a local component of growth at sea in which some populations have better growth in some years might further amplify differences in maturation rate. Differences between populations were smaller than those between sexes, suggesting that the sex-specific growth threshold for maturation is a well-conserved evolutionary phenomenon in salmon. Finally, our results illustrate that although most of the gain in length occurs during the first summer at sea, the temporal variability in body length at return is buffered against the decrease in post-smolt growth conditions. The intricate combination of growth over successive seasons, and its interplay with the maturation decision, could be regulating body length by maintaining diversity in early growth trajectories, life histories, and the composition of salmon populations.


Assuntos
Salmo salar , Humanos , Animais , Rios , Europa (Continente) , Evolução Biológica , Estações do Ano
3.
Genome Biol Evol ; 15(6)2023 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-37210218

RESUMO

Cold-water corals form an important part of temperate benthic ecosystems by increasing three-dimensionality and providing an important ecological substrate for other benthic fauna. However, the fragile three-dimensional structure and life-history characteristics of cold-water corals can leave populations vulnerable to anthropogenic disturbance. Meanwhile, the ability of temperate octocorals, particularly shallow-water species, to respond to adjustments in their environment linked to climate change has not been studied. This study reports the first genome assembly of the pink sea fan (Eunicella verrucosa), a temperate shallow-water octocoral species. We produced an assembly of 467 Mb, comprising 4,277 contigs and an N50 of 250,417 bp. In total, 213 Mb (45.96% of the genome) comprised repetitive sequences. Annotation of the genome using RNA-seq data derived from polyp tissue and gorgonin skeleton resulted in 36,099 protein-coding genes after 90% similarity clustering, capturing 92.2% of the complete Benchmarking Universal Single-Copy Orthologs (BUSCO) ortholog benchmark genes. Functional annotation of the proteome using orthology inference identified 25,419 annotated genes. This genome adds to the very few genomic resources currently available in the octocoral community and represents a key step in allowing scientists to investigate the genomic and transcriptomic responses of octocorals to climate change.


Assuntos
Antozoários , Ecossistema , Animais , Antozoários/genética , Genoma , Genômica , Água
4.
J Fish Biol ; 102(1): 258-270, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36281821

RESUMO

The rivers of southern England and northern France which drain into the English Channel contain several genetically unique groups of trout (Salmo trutta L.) that have suffered dramatic declines in numbers over the past 40 years. Knowledge of levels and patterns of genetic diversity is essential for effective management of these vulnerable populations. Using restriction site-associated DNA sequencing (RADseq) data, we describe the development and characterisation of a panel of 95 single nucleotide polymorphism (SNP) loci for trout from this region and investigate their applicability and variability in both target (i.e., southern English) and non-target trout populations from northern Britain and Ireland. In addition, we present three case studies which demonstrate the utility and resolution of these genetic markers at three levels of spatial separation:(a) between closely related populations in nearby rivers, (b) within a catchment and (c) when determining parentage and familial relationships between fish sampled from a single site, using both empirical and simulated data. The SNP loci will be useful for population genetic and assignment studies on brown trout within the UK and beyond.


Assuntos
Polimorfismo de Nucleotídeo Único , Rios , Animais , Irlanda , França , Truta/genética , Variação Genética
5.
PeerJ ; 10: e13509, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35651748

RESUMO

Species distribution models have become a valuable tool to predict the distribution of species across geographic space and time. In this study, maximum entropy models were constructed for two temperate shallow-water octocoral species, the pink sea fan (Eunicella verrucosa) and dead man's fingers (Alcyonium digitatum), to investigate and compare habitat suitability. The study area covered the north-east Atlantic from the Bay of Biscay to the British Isles and southern Norway; this area includes both the northern range of E. verrucosa and the middle-northern range of A. digitatum. The optimal models for each species showed that, overall, slope, temperature at the seafloor and wave orbital velocity were important predictors of distribution in both species. Predictions of habitat suitability showed areas of present-day (1951-2000) suitable habitat where colonies have not yet been observed, particularly for E. verrucosa, where areas beyond its known northern range limit were identified. Moreover, analysis with future layers (2081-2100) of temperature and oxygen concentration predicted a sizable increase in habitat suitability for E. verrucosa beyond these current range limits under the Representative Concentration Pathway 8.5 scenario. This suggests that projected climate change may induce a potential range expansion northward for E. verrucosa, although successful colonisation would also be conditional on other factors such as dispersal and interspecific competition. For A. digitatum, this scenario of projected climate change may result in more suitable habitat in higher latitudes, but, as with E. verrucosa, there is a degree of uncertainty in the model predictions. Importantly, the results from this study highlight present-day areas of high habitat suitability which, if combined with knowledge on population density, could be used to identify priority areas to enhance protection and ensure the long-term survival of these octocoral species in the region.


Assuntos
Antozoários , Mudança Climática , Humanos , Animais , Ecossistema , Temperatura , Noruega
6.
Mitochondrial DNA B Resour ; 6(11): 3309-3311, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34712818

RESUMO

The pink sea fan, Eunicella verrucosa (Pallas, 1766), inhabits rocky substrates across the northeast Atlantic and the western Mediterranean. Across much of its range it has been detrimentally affected by fishing. DNA from 17 E. verrucosa specimens was amplified by phi29-induced rolling circle amplification. Following purification by sodium acetate-ethanol precipitation, the circular genomic DNA was sequenced on an Illumina MiSeq v2. Specimens originated from sites along the west coast of Ireland, southwest Wales, southwest/southern England, northwest France, southern Portugal, and the Mediterranean coast of northeast Spain. All samples had identical mitochondrial genome sequences of 19,267 bp and included 14 protein-coding genes (including the mutS gene), two ribosomal RNA subunits (12S and 16S) and one methionine tRNA gene. Two genes (nad2 and nad5) overlapped by 13 bp; all other genes were separated by non-coding intergenic regions. All protein-coding genes had the same start codon (ATG) and a TAA or TAG stop codon, except for cox1 that terminated with the incomplete stop codon T--. The mitochondrial genome of E. verrucosa (MW588805) showed 99.72% similarity with that of a related sea fan species, Eunicella cavolini, with six SNPs and a 49 bp deletion between nad5 and nad4 in E. verrucosa distinguishing the two.

7.
Evol Appl ; 14(6): 1558-1571, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34178104

RESUMO

Maerl beds are vital habitats for a diverse array of marine species across trophic levels, but they are increasingly threatened by human activities and climate change. Furthermore, little is known about the genetic diversity of maerl-forming species and the population structure of maerl beds, both of which are important for understanding the ability of these species to adapt to changing environments and for informing marine reserve planning. In this study, we used a whole genome genotyping approach to explore the population genomics of Phymatolithon calcareum, a maerl-forming red algal species, whose geographical distribution spans the north-east Atlantic, from Norway to Portugal. Our results, using 14,150 genome-wide SNPs (single nucleotide polymorphisms), showed that P. calcareum maerl beds across the north-east Atlantic are generally structured geographically, a pattern likely explained by low dispersal potential and limited connectivity between regions. Additionally, we found that P. calcareum from the Fal Estuary, south-west England, is genetically distinct from all other P. calcareum sampled, even from The Manacles, a site located only 13 km away. Further analysis revealed that this finding is not the result of introgression from two closely related species, Phymatolithon purpureum or Lithothamnion corallioides. Instead, this unique diversity may have been shaped over time by geographical isolation of the Fal Estuary maerl bed and a lack of gene flow with other P. calcareum populations. The genomic data presented in this study suggest that P. calcareum genetic diversity has accumulated over large temporal and spatial scales, the preservation of which will be important for maximizing the resilience of this species to changes in climate and the environment. Moreover, our findings underline the importance of managing the conservation of maerl beds across western Europe as distinct units, at a site-by-site level.

8.
J Fish Biol ; 99(3): 980-989, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33991118

RESUMO

The stocking of hatchery-origin fish into rivers and lakes has long been used in fisheries management to try to enhance catches, especially for trout and salmon species. Frequently, however, the long-term impacts of stocking programmes have not been evaluated. In this study, the authors investigate the contribution of a stocking programme undertaken to support the rod catch of sea trout in the Shetland Islands, UK. Once a highly productive recreational fishery, Shetland sea trout catches crashed in the mid-1990s. Around the time that stocking began, increases in rod catches were also reported, with advocates of the stocking highlighting the apparent success of the programme. Using a suite of genetic markers (microsatellites), this study explores the contribution of the stocking programme to the Shetland sea trout population. The authors found that the domesticated broodstock and wild spawned brown trout from seven streams were genetically distinct. Despite extensive stocking, wild spawned brown trout dominated, even in those streams with a long history of supplementation. The majority of sea trout caught and analysed were of wild origin - only a single individual was of pure stocked origin, with a small number of fish being of wild × stocked origins. This study suggests that stocking with a domesticated strain of brown trout has made only a very limited contribution to the Shetland Islands rod catch, and that the revival of sea trout numbers appears to be driven almost exclusively by recovery of trout spawned in the wild.


Assuntos
Repetições de Microssatélites , Truta , Animais , Pesqueiros , Ilhas , Truta/genética , Reino Unido
9.
Environ Sci Technol ; 54(24): 15935-15945, 2020 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-33227200

RESUMO

Exposure of male fish to estrogenic substances from wastewater treatment works (WwTWs) results in feminization and reduced reproductive fitness. Nevertheless, self-sustaining populations of roach (Rutilus rutilus) inhabit river stretches polluted with estrogenic WwTW effluents. In this study, we examine whether such roach populations have evolved adaptations to tolerate estrogenic pollution by comparing frequency differences in single-nucleotide polymorphisms (SNPs) between populations sampled from rivers receiving either high- or low-level WwTW discharges. SNPs within 36 "candidate" genes, selected for their involvement in estrogenic responses, and 120 SNPs in reference genes were genotyped in 465 roaches. There was no evidence for selection in highly estrogen-dependent candidate genes, including those for the estrogen receptors, aromatases, and vitellogenins. The androgen receptor (ar) and cytochrome P450 1A genes were associated with large shifts in allele frequencies between catchments and in individual populations, but there is no clear link to estrogen pollution. Selection at ar in the effluent-dominated River Lee may have resulted from historical contamination with endocrine-disrupting pesticides. Critically, although our results suggest population-specific selection including at genes related to endocrine disruption, there was no strong evidence that the selection resulted from exposure to estrogen pollution.


Assuntos
Cyprinidae , Poluentes Químicos da Água , Animais , Cyprinidae/genética , Estrogênios , Estrona , Humanos , Masculino , Rios , Vitelogeninas , Poluentes Químicos da Água/análise
10.
Ecol Evol ; 10(12): 5631-5636, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32607179

RESUMO

Stocking is often used to supplement wild populations that are overexploited or have collapsed, yet it is unclear how this affects the genetic diversity of marine invertebrate populations. During the 1970s, a lobster stock enhancement program was carried out around the island of Corsica in the Mediterranean using individuals translocated from the Atlantic coast of France. This included the release of thousands of hatchery-reared postlarval lobsters and several adult individuals, but no monitoring plan was established to assess whether these animals survived and recruited to the population. In this study, we sampled European lobster (Homarus gammarus) individuals caught around Corsica and tested whether they showed Atlantic ancestry. Due to a natural marked phylogeographic break between Atlantic and Mediterranean lobsters, we hypothesized that lobsters with dominant (>0.50) Atlantic ancestry were descended from historical stocking releases. Twenty Corsican lobsters were genotyped at 79 single nucleotide polymorphisms, and assignment analysis showed that the majority (13) had dominant Atlantic ancestry. This suggests that the hatchery stocking program carried out in Corsica during the 1970s, using individuals translocated from the Atlantic coast of France, has likely augmented local recruitment but at a cost of altering the genetic structure of the Corsican lobster population.

11.
Ecol Evol ; 10(12): 5651-5669, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32607181

RESUMO

We used microsatellite markers to investigate levels and structuring of genetic diversity in trout (Salmo trutta L.) sampled from 16 rivers along the south coast of Cornwall in southwest England. This region is characterized by many small coastal streams with a few larger catchments. At a regional level, genetic structuring of contemporary populations has been influenced by a combination of events, including the last Ice Age and also more recent human activities over the last millennium. All populations are shown to have gone through strong genetic bottlenecks, coinciding with increased exploitation of mineral resources within catchments, beginning during the Medieval period. At more local levels, contemporary human-induced habitat fragmentation, such as weir and culvert construction, has disproportionally affected trout populations in the smaller catchments within the study area. However, where small catchments are relatively unaffected by such activities, they can host trout populations with diversity levels comparable to those found in larger rivers in the region. We also predict significant future loses of diversity and heterozygosity in the trout populations inhabiting small, isolated catchments. Our study highlights how multiple factors, especially the activity of humans, have and continue to affect the levels and structuring of genetic diversity in trout over long timescales.

12.
Sci Rep ; 10(1): 7781, 2020 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-32385382

RESUMO

American lobsters (Homarus americanus) imported live into Europe as a seafood commodity have occasionally been released or escaped into the wild, within the range of an allopatric congener, the European lobster (H. gammarus). In addition to disease and competition, introduced lobsters threaten native populations through hybridisation, but morphological discriminants used for species identification are unable to discern hybrids, so molecular methods are required. We tested an array of 79 single nucleotide polymorphisms (SNPs) for their utility to distinguish 1,308 H. gammarus from 38 H. americanus and 30 hybrid offspring from an American female captured in Sweden. These loci provide powerful species assignment in Homarus, enabling the robust identification of hybrid and American individuals among a survey of European stock. Moreover, a subset panel of the 12 most powerful SNPs is sufficient to separate the two pure species, even when tissues have been cooked, and can detect the introduced component of hybrids. We conclude that these SNP loci can unambiguously identify hybrid lobsters that may be undetectable via basic morphology, and offer a valuable tool to investigate the prevalence of cryptic hybridisation in the wild. Such investigations are required to properly evaluate the potential for introgression of alien genes into European lobster populations.


Assuntos
Cruzamentos Genéticos , Hibridização Genética , Nephropidae/genética , Alelos , Animais , Cruzamento , Europa (Continente) , Genótipo , Nephropidae/classificação , Polimorfismo de Nucleotídeo Único
13.
Nat Rev Genet ; 21(7): 389-409, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32300217

RESUMO

Aquaculture is the fastest-growing farmed food sector and will soon become the primary source of fish and shellfish for human diets. In contrast to crop and livestock production, aquaculture production is derived from numerous, exceptionally diverse species that are typically in the early stages of domestication. Genetic improvement of production traits via well-designed, managed breeding programmes has great potential to help meet the rising seafood demand driven by human population growth. Supported by continuous advances in sequencing and bioinformatics, genomics is increasingly being applied across the broad range of aquaculture species and at all stages of the domestication process to optimize selective breeding. In the future, combining genomic selection with biotechnological innovations, such as genome editing and surrogate broodstock technologies, may further expedite genetic improvement in aquaculture.


Assuntos
Aquicultura , Cruzamento , Genômica , Adaptação Biológica , Animais , Animais Domésticos , Animais Selvagens , Biodiversidade , Domesticação , Meio Ambiente , Epigênese Genética , Edição de Genes , Interação Gene-Ambiente , Predisposição Genética para Doença , Genoma , Genômica/métodos , Seleção Genética , Seleção Artificial
14.
Evol Appl ; 12(10): 1881-1899, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31700533

RESUMO

Resolving stock structure is crucial for fisheries conservation to ensure that the spatial implementation of management is commensurate with that of biological population units. To address this in the economically important European lobster (Homarus gammarus), genetic structure was explored across the species' range using a small panel of single nucleotide polymorphisms (SNPs) previously isolated from restriction-site-associated DNA sequencing; these SNPs were selected to maximize differentiation at a range of both broad and fine scales. After quality control and filtering, 1,278 lobsters from 38 sampling sites were genotyped at 79 SNPs. The results revealed a pronounced phylogeographic break between the Atlantic and Mediterranean basins, while structure within the Mediterranean was also apparent, partitioned between lobsters from the central Mediterranean and the Aegean Sea. In addition, a genetic cline across the north-east Atlantic was revealed using both putatively neutral and outlier SNPs, but the precise driver(s) of this clinal pattern-isolation by distance, secondary contact, selection across an environmental gradient, or a combination of these factors-remains undetermined. Putatively neutral markers differentiated lobsters from Oosterschelde, an estuary on the Dutch coast, a finding likely explained by past bottlenecks and limited gene flow with adjacent North Sea populations. Building on the findings of our spatial genetic analysis, we were able to test the accuracy of assigning lobsters at various spatial scales, including to basin of origin (Atlantic or Mediterranean), region of origin and sampling location. The predictive model assembled using 79 SNPs correctly assigned 99.7% of lobsters not used to build the model to their basin of origin, but accuracy decreased to region of origin and again to sampling location. These results are of direct relevance to managers of lobster fisheries and hatcheries, and provide the basis for a genetic tool for tracing the origin of European lobsters in the food supply chain.

15.
J Fish Biol ; 95(1): 304-310, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30281146

RESUMO

In this work, patterns of geographical genetic diversity in Atlantic salmon Salmo salar were studied across the whole Atlantic Arc; whether these patterns (and thus genetic population structure) were affected by water temperatures was also evaluated. Salmo salar populations were characterized using microsatellite loci and then analysed with reference to ocean surface temperature data from across the region. Analysis showed the presence of a latitudinal cline of genetic variability (higher in northern areas) and water temperatures (sea surface temperatures) determining genetic population structure (the latter in combination with genetic drift in southern populations). Under the current global change scenario, northern areas of Europe would constitute refugia for diversity in the future. This is effectively the inverse of what appears to have happened in glacial refugia during the last glacial maximum. From this perspective, the still abundant and large northern populations S. salar should be considered as precious as the small almost relict southern ones and given appropriate protection. Careful management of the species, coordinated across countries and latitudes, is needed in order to avoid its extinction in Europe.


Assuntos
Mudança Climática , Variação Genética , Salmo salar/genética , Animais , Oceano Atlântico , Clima , Demografia , Espécies em Perigo de Extinção , Europa (Continente) , Genética Populacional , Geografia , Repetições de Microssatélites , Filogeografia , Densidade Demográfica , Refúgio de Vida Selvagem , Temperatura
16.
PeerJ ; 6: e5684, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30280047

RESUMO

BACKGROUND: Comparative phylogeography enables the study of historical and evolutionary processes that have contributed to shaping patterns of contemporary genetic diversity across co-distributed species. In this study, we explored genetic structure and historical demography in a range of coastal marine species across the northeast Atlantic to assess whether there are commonalities in phylogeographic patterns across taxa and to evaluate whether the timings of population expansions were linked to the Last Glacial Maximum (LGM). METHODS: A literature search was conducted using Web of Science. Search terms were chosen to maximise the inclusion of articles reporting on population structure and phylogeography from the northeast Atlantic; titles and abstracts were screened to identify suitable articles within the scope of this study. Given the proven utility of mtDNA in comparative phylogeography and the availability of these data in the public domain, a meta-analysis was conducted using published mtDNA gene sequences. A standardised methodology was implemented to ensure that the genealogy and demographic history of all mtDNA datasets were reanalysed in a consistent and directly comparable manner. RESULTS: Mitochondrial DNA datasets were built for 21 species. The meta-analysis revealed significant population differentiation in 16 species and four main types of haplotype network were found, with haplotypes in some species unique to specific geographical locations. A signal of rapid expansion was detected in 16 species, whereas five species showed evidence of a stable population size. Corrected mutation rates indicated that the majority of expansions were estimated to have occurred after the earliest estimate for the LGM (∼26.5 Kyr), while few expansions were estimated to have pre-dated the LGM. CONCLUSION: This study suggests that post-LGM expansion appeared to be common in a range of marine taxa, supporting the concept of rapid expansions after the LGM as the ice sheets started to retreat. However, despite the commonality of expansion patterns in many of these taxa, phylogeographic patterns appear to differ in the species included in this study. This suggests that species-specific evolutionary processes, as well as historical events, have likely influenced the distribution of genetic diversity of marine taxa in the northeast Atlantic.

17.
J Phycol ; 54(5): 762-764, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29981276

RESUMO

The binary designation Symbiodinium thermophilum was invalid due to the absence of an illustration as required by Article 44.2 of the ICN. Herein, it is validated. This species is the most common symbiont in reef corals in the southern Persian/Arabian Gulf, the world's hottest body of water sustaining reef coral growth.


Assuntos
Dinoflagellida/classificação , Terminologia como Assunto , Recifes de Corais , Oceano Índico , Simbiose
18.
Int J Parasitol ; 48(7): 569-584, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29544703

RESUMO

Trypanosoma rangeli and Trypanosoma cruzi are generalist trypanosomes sharing a wide range of mammalian hosts; they are transmitted by triatomine bugs, and are the only trypanosomes infecting humans in the Neotropics. Their origins, phylogenetic relationships, and emergence as human parasites have long been subjects of interest. In the present study, taxon-rich analyses (20 trypanosome species from bats and terrestrial mammals) using ssrRNA, glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH), heat shock protein-70 (HSP70) and Spliced Leader RNA sequences, and multilocus phylogenetic analyses using 11 single copy genes from 15 selected trypanosomes, provide increased resolution of relationships between species and clades, strongly supporting two main sister lineages: lineage Schizotrypanum, comprising T. cruzi and bat-restricted trypanosomes, and Tra[Tve-Tco] formed by T. rangeli, Trypanosoma vespertilionis and Trypanosoma conorhini clades. Tve comprises European T. vespertilionis and African T. vespertilionis-like of bats and bat cimicids characterised in the present study and Trypanosoma sp. Hoch reported in monkeys and herein detected in bats. Tco included the triatomine-transmitted tropicopolitan T. conorhini from rats and the African NanDoum1 trypanosome of civet (carnivore). Consistent with their very close relationships, Tra[Tve-Tco] species shared highly similar Spliced Leader RNA structures that were highly divergent from those of Schizotrypanum. In a plausible evolutionary scenario, a bat trypanosome transmitted by cimicids gave origin to the deeply rooted Tra[Tve-Tco] and Schizotrypanum lineages, and bat trypanosomes of diverse genetic backgrounds jumped to new hosts. A long and independent evolutionary history of T. rangeli more related to Old World trypanosomes from bats, rats, monkeys and civets than to Schizotrypanum spp., and the adaptation of these distantly related trypanosomes to different niches of shared mammals and vectors, is consistent with the marked differences in transmission routes, life-cycles and host-parasite interactions, resulting in T. cruzi (but not T. rangeli) being pathogenic to humans.


Assuntos
Quirópteros/parasitologia , Filogenia , Trypanosoma cruzi/genética , Trypanosoma rangeli/genética , Tripanossomíase/veterinária , Animais , Genoma de Protozoário , Guiné-Bissau/epidemiologia , Tripanossomíase/epidemiologia , Tripanossomíase/parasitologia
19.
Front Plant Sci ; 9: 1796, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30619388

RESUMO

Hybridization and polyploidy are major forces in the evolution of plant diversity and the study of these processes is of particular interest to understand how novel taxa are formed and how they maintain genetic integrity. Sorbus is an example of a genus where active diversification and speciation are ongoing and, as such, represents an ideal model to investigate the roles of hybridization, polyploidy and apomixis in a reticulate evolutionary process. To elucidate breeding systems and evolutionary origins of a complex of closely related Sorbus taxa, we assessed genotypic diversity and population structure within and among taxa, combining data from nuclear DNA microsatellite markers and flow cytometry. Clonal analysis and low genotypic diversity within the polyploid taxa suggest apomixis is obligate. However, genetic variation has led to groups of 'clone-mates' within apomictic taxa that strongly suggest mutation is responsible for the genotypic diversity of these apomictic lineages. In addition, microsatellite profiles and site demographics suggest hybridization events among apomictic polyploid Sorbus may have contributed to the extant diversity of recognized taxa in this region. This research demonstrates that both macro- and micro-evolutionary processes are active within this reticulate Sorbus complex. Conservation measures should be aimed at maintaining this process and should therefore be prioritized for those areas of Sorbus species richness where the potential for interspecific gene flow is greatest.

20.
Parasitology ; 145(5): 563-573, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29168449

RESUMO

Trypanosomes (genus Trypanosoma) are parasites of humans, and wild and domestic mammals, in which they cause several economically and socially important diseases, including sleeping sickness in Africa and Chagas disease in the Americas. Despite the development of numerous molecular diagnostics and increasing awareness of the importance of these neglected parasites, there is currently no universal genetic barcoding marker available for trypanosomes. In this review we provide an overview of the methods used for trypanosome detection and identification, discuss the potential application of different barcoding techniques and examine the requirements of the 'ideal' trypanosome genetic barcode. In addition, we explore potential alternative genetic markers for barcoding Trypanosoma species, including an analysis of phylogenetically informative nucleotide changes along the length of the 18S rRNA gene.


Assuntos
Código de Barras de DNA Taxonômico/métodos , Trypanosoma/genética , Marcadores Genéticos , Filogenia , Reação em Cadeia da Polimerase , RNA Ribossômico 18S/genética , Trypanosoma/classificação
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