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1.
J Evol Biol ; 2024 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-38306450

RESUMO

Insular biodiversity hotspots of Southeast Asia are remarkable for their biodiverse faunas. With a marine larval phase lasting up to several months, the freshwater fish subfamily Sicydiinae has colonized most islands of these hotspots. However, Sicydiinae diversity is still poorly understood in Southeast Asia. With the objective to estimate intraspecific genetic diversity and infer past demography, we conducted the molecular inventory of Sicydiinae species in Sundaland and Wallacea using 652 bp of the mitochondrial cytochrome oxidase I gene, species delimitation methods and Bayesian Skyline plot reconstructions. In total, 24 Molecular Operational Taxonomic Units are delimited among the 603 sequences belonging to 27 species and five genera. Two cases of discordance between morphology and mitochondrial sequence are observed suggesting ongoing speciation and/or introgression in two genera. Multiple new occurrences are reported, either for a single biodiversity hotspot or both, some of which corresponding to observations of a few individuals far from the range distribution of their conspecifics. Among the ten species or species group whose intraspecific diversity was examined, high levels of genetic diversity and past population expansion are revealed by Tajima's D tests and Bayesian Skyline Plot reconstructions. Together these results indicate that long-distance dispersal is common and suggest that most endemic species originated through founder events followed by population expansion. Patterns of sexual dimorphism and males' coloration among diverging species pair seem to point to sexual selection as an important mechanism contributing to speciation in the Sicydiinae of Sundaland and Wallacea.

2.
Proc Biol Sci ; 290(1991): 20221334, 2023 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-36695033

RESUMO

Pleistocene climate cycles are well documented to have shaped contemporary species distributions and genetic diversity. Northward range expansions in response to deglaciation following the Last Glacial Maximum (LGM; approximately 21 000 years ago) are surmised to have led to population size expansions in terrestrial taxa and changes in seasonal migratory behaviour. Recent findings, however, suggest that some northern temperate populations may have been more stable than expected through the LGM. We modelled the demographic history of 19 co-distributed boreal-breeding North American bird species from full mitochondrial gene sets and species-specific molecular rates. We used these demographic reconstructions to test how species with different migratory strategies were affected by glacial cycles. Our results suggest that effective population sizes increased in response to Pleistocene deglaciation earlier than the LGM, whereas genetic diversity was maintained throughout the LGM despite shifts in geographical range. We conclude that glacial cycles prior to the LGM have most strongly shaped contemporary genetic diversity in these species. We did not find a relationship between historic population dynamics and migratory strategy, contributing to growing evidence that major switches in migratory strategy during the LGM are unnecessary to explain contemporary migratory patterns.


Assuntos
Aves , Variação Genética , Animais , Densidade Demográfica , Aves/genética , Dinâmica Populacional , Geografia , América do Norte , Filogeografia , Filogenia , DNA Mitocondrial/genética
3.
BMC Bioinformatics ; 22(1): 115, 2021 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-33750296

RESUMO

BACKGROUND: Today an unprecedented amount of genetic sequence data is stored in publicly available repositories. For decades now, mitochondrial DNA (mtDNA) has been the workhorse of genetic studies, and as a result, there is a large volume of mtDNA data available in these repositories for a wide range of species. Indeed, whilst whole genome sequencing is an exciting prospect for the future, for most non-model organisms' classical markers such as mtDNA remain widely used. By compiling existing data from multiple original studies, it is possible to build powerful new datasets capable of exploring many questions in ecology, evolution and conservation biology. One key question that these data can help inform is what happened in a species' demographic past. However, compiling data in this manner is not trivial, there are many complexities associated with data extraction, data quality and data handling. RESULTS: Here we present the mtDNAcombine package, a collection of tools developed to manage some of the major decisions associated with handling multi-study sequence data with a particular focus on preparing sequence data for Bayesian skyline plot demographic reconstructions. CONCLUSIONS: There is now more genetic information available than ever before and large meta-data sets offer great opportunities to explore new and exciting avenues of research. However, compiling multi-study datasets still remains a technically challenging prospect. The mtDNAcombine package provides a pipeline to streamline the process of downloading, curating, and analysing sequence data, guiding the process of compiling data sets from the online database GenBank.


Assuntos
DNA Mitocondrial , Bases de Dados de Ácidos Nucleicos , Teorema de Bayes , DNA Mitocondrial/genética , Análise de Sequência de DNA
4.
Proc Biol Sci ; 288(1959): 20210957, 2021 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-34547905

RESUMO

Extinction has increased as human activities impact ecosystems, yet relatively few species have conservation assessments. Novel approaches are needed to highlight threatened species that are currently data-deficient. Many Madagascan plant species have extremely narrow ranges, but this may not have always been the case-it is unclear how the island's diverse flora evolved. To assess this, we generated restriction-site associated DNA sequence data for 10 Madagascan plant species, estimated effective population size (Ne) for each species and compared this to census (Nc) sizes. In each case, Ne was an order of magnitude larger than Nc-signifying rapid, recent population decline. We then estimated species' demographic history, tracking changes in Ne over time. We show that it is possible to predict extinction risk, particularly in the most threatened species. Furthermore, simulations showed that our approach has the power to detect population decline during the Anthropocene. Our analyses reveal that Madagascar's micro-endemics were not always rare, having experienced a rapid decline in their recent history. This casts further uncertainty over the processes that generated Madagascar's exceptional biodiversity. Our approach targets data-deficient species in need of conservation assessment, particularly in regions where human modification of the environment has been rapid.


Assuntos
Ecossistema , Espécies em Perigo de Extinção , Animais , Biodiversidade , Conservação dos Recursos Naturais , Extinção Biológica , Atividades Humanas , Humanos , Densidade Demográfica
5.
Mol Ecol ; 30(16): 3993-4004, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34152661

RESUMO

During the Quaternary, large climate oscillations impacted the distribution and demography of species globally. Two approaches have played a major role in reconstructing changes through time: Bayesian Skyline Plots (BSPs), which reconstruct population fluctuations based on genetic data, and Species Distribution Models (SDMs), which allow us to back-cast the range occupied by a species based on its climatic preferences. In this paper, we contrast these two approaches by applying them to a large data set of 102 Holarctic bird species, for which both mitochondrial DNA sequences and distribution maps are available, to reconstruct their dynamics since the Last Glacial Maximum (LGM). Most species experienced an increase in effective population size (Ne , as estimated by BSPs) as well as an increase in geographical range (as reconstructed by SDMs) since the LGM; however, we found no correlation between the magnitude of changes in Ne and range size. The only clear signal we could detect was a later and greater increase in Ne for wetland birds compared to species that live in other habitats, a probable consequence of a delayed and more extensive increase in the extent of this habitat type after the LGM. The lack of correlation between SDM and BSP reconstructions could not be reconciled even when range shifts were considered. We suggest that this pattern might be linked to changes in population densities, which can be independent of range changes, and caution that interpreting either SDMs or BSPs independently is problematic and potentially misleading.


Assuntos
Aves , DNA Mitocondrial , Animais , Teorema de Bayes , Aves/genética , DNA Mitocondrial/genética , Ecossistema , Variação Genética , Filogenia , Filogeografia , Densidade Demográfica
6.
Emerg Infect Dis ; 26(6): 1164-1173, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32441616

RESUMO

Salmonella enterica serovar Paratyphi B variant Java sequence type 28 is prevalent in poultry and poultry meat. We investigated the evolutionary relatedness between sequence type 28 strains from Europe and Latin America using time-resolved phylogeny and principal component analysis. We sequenced isolates from Colombia, Guatemala, Costa Rica, and the Netherlands and complemented them with publicly available genomes from Europe, Africa, and the Middle East. Phylogenetic time trees and effective population sizes (Ne) showed separate clustering of strains from Latin America and Europe. The separation is estimated to have occurred during the 1980s. Ne of strains increased sharply in Europe around 1995 and in Latin America around 2005. Principal component analysis on noncore genes showed a clear distinction between strains from Europe and Latin America, whereas the plasmid gene content was similar. Regardless of the evolutionary separation, similar features of resistance to ß-lactams and quinolones/fluoroquinolones indicated parallel evolution of antimicrobial resistance in both regions.


Assuntos
Salmonella enterica , Salmonella paratyphi B , África , Animais , Antibacterianos/farmacologia , Colômbia , Costa Rica , Farmacorresistência Bacteriana , Farmacorresistência Bacteriana Múltipla , Europa (Continente)/epidemiologia , Guatemala , Indonésia , América Latina/epidemiologia , Oriente Médio , Países Baixos , Filogenia , Aves Domésticas , Salmonella enterica/genética , Salmonella paratyphi B/genética
7.
J Fish Biol ; 97(4): 1039-1050, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32658333

RESUMO

In the present study we evaluate the population structure and potential colonization routes of the silverside Chirostoma humboldtianum through approximate Bayesian computations. Six microsatellite loci were amplified in a total of 288 individuals from six different locations covering the complete geographic distribution of the species. Additionally, two mitochondrial DNA markers, a D loop control region and cytochrome b were amplified in a subset of 107 individuals. The results found with microsatellites allow recovering well-structured populations that have experienced a drastic reduction in the effective population size. On the other hand, mtDNA sequences showed a moderate phylogeographic structure with shared haplotypes between geographic localities and signalsof a slight increase in the effective population size. Finally, the approximate Bayesian computation analysis performed with both datasets suggested a west-to-east colonization route for the species in Central Mexico.


Assuntos
Peixes/fisiologia , Genética Populacional , Filogeografia , Animais , Teorema de Bayes , Citocromos b/genética , DNA Mitocondrial/genética , Peixes/classificação , Peixes/genética , Marcadores Genéticos/genética , Variação Genética , Haplótipos , México , Repetições de Microssatélites/genética , Densidade Demográfica
8.
Clin Infect Dis ; 69(3): 405-413, 2019 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-30321294

RESUMO

BACKGROUND: The increase in multidrug-resistant tuberculosis (MDR-TB) severely hampers tuberculosis prevention and control in China, a country with the second highest MDR-TB burden globally. The first nationwide drug-resistant tuberculosis surveillance program provides an opportunity to comprehensively investigate the epidemiological/drug-resistance characteristics, potential drug-resistance mutations, and effective population changes of Chinese MDR-TB. METHODS: We sequenced 357 MDR strains from 4600 representative tuberculosis-positive sputum samples collected during the survey (70 counties in 31 provinces). Drug-susceptibility testing was performed using 18 anti-tuberculosis drugs, representing the most comprehensive drug-resistance profile to date. We used 3 statistical and 1 machine-learning methods to identify drug-resistance genes/single-nucleotide polymorphisms (SNPs). We used Bayesian skyline analysis to investigate changes in effective population size. RESULTS: Epidemiological/drug-resistance characteristics showed different MDR profiles, co-resistance patterns, preferred drug combination/use, and recommended regimens among 7 Chinese administrative regions. These factors not only reflected the serious multidrug co-resistance and drug misuse but they were also potentially significant in facilitating the development of appropriate regimens for MDR-TB treatment in China. Further investigation identified 86 drug-resistance genes/intergenic regions/SNPs (58 new), providing potential targets for MDR-TB diagnosis and treatment. In addition, the effective population of Chinese MDR-TB displayed a strong expansion during 1993-2000, reflecting socioeconomic transition within the country. The phenomenon of expansion was restrained after 2000, likely attributable to the advances in diagnosis/treatment technologies and government support. CONCLUSIONS: Our findings provide an important reference and improved understanding of MDR-TB in China, which are potentially significant in achieving the goal of precision medicine with respect to MDR-TB prevention and treatment.


Assuntos
Antituberculosos/uso terapêutico , Farmacorresistência Bacteriana Múltipla/genética , Genoma Bacteriano , Mycobacterium tuberculosis/genética , Tuberculose Resistente a Múltiplos Medicamentos/epidemiologia , Adolescente , Adulto , Idoso , Antituberculosos/farmacologia , Teorema de Bayes , China/epidemiologia , Estudos Transversais , Feminino , Humanos , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Mutação , Mycobacterium tuberculosis/efeitos dos fármacos , Polimorfismo de Nucleotídeo Único , Escarro/microbiologia , Tuberculose Resistente a Múltiplos Medicamentos/microbiologia , Sequenciamento Completo do Genoma , Adulto Jovem
9.
Syst Biol ; 65(3): 449-64, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26683588

RESUMO

The molecular clock hypothesis is fundamental in evolutionary biology as by assuming constancy of the molecular rate it provides a timeframe for evolution. However, increasing evidence shows time dependence of inferred molecular rates with inflated values obtained using recent calibrations. As recent demographic calibrations are virtually non-existent in most species, older phylogenetic calibration points (>1 Ma) are commonly used, which overestimate demographic parameters. To obtain more reliable rates of molecular evolution for population studies, I propose the calibration of demographic transition (CDT) method, which uses the timing of climatic changes over the late glacial warming period to calibrate expansions in various species. Simulation approaches and empirical data sets from a diversity of species (from mollusk to humans) confirm that, when compared with other genealogy-based calibration methods, the CDT provides a robust and broadly applicable clock for population genetics. The resulting CDT rates of molecular evolution also confirm rate heterogeneity over time and among taxa. Comparisons of expansion dates with ecological evidence confirm the inaccuracy of phylogenetically derived divergence rates when dating population-level events. The CDT method opens opportunities for addressing issues such as demographic responses to past climate change and the origin of rate heterogeneity related to taxa, genes, time, and genetic information content.


Assuntos
Evolução Molecular , Genética Populacional/métodos , Mudança Climática , Filogenia , Dinâmica Populacional , Fatores de Tempo
10.
J Hered ; 108(2): 163-175, 2017 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-28003372

RESUMO

Population genetic variation and demographic history in Danaus plexippus (L.), from Mexico were assessed based on analyses of mitochondrial cytochrome c oxidase subunit I (COI; 658 bp) and subunit II (COII; 503 bp) gene segments and 7 microsatellite loci. The sample of 133 individuals included both migratory monarchs, mainly from 4 overwintering sites within the Monarch Butterfly Biosphere Reserve (MBBR) in central Mexico (states of Michoacán and México), and a nonmigratory population from Irapuato, Guanajuato. Haplotype (h) and nucleotide (π) diversities were relatively low, averaging 0.466 and 0.00073, respectively, for COI, and 0.629 and 0.00245 for COII. Analysis of molecular variance of the COI data set, which included additional GenBank sequences from a nonmigratory Costa Rican population, showed significant population structure between Mexican migratory monarchs and nonmigratory monarchs from both Mexico and Costa Rica, suggesting limited gene flow between the 2 behaviorally distinct groups. Interestingly, while the COI haplotype frequencies of the nonmigratory populations differed from the migratory, they were similar to each other, despite the great physical distance between them. Microsatellite analyses, however, suggested a lack of structure between the 2 groups, possibly owing to the number of significant deviations from Hardy-Weinberg equilibrium resulting from heterzoygote deficiencies found for most of the loci. Estimates of demographic history of the combined migratory MBBR monarch population, based on the mismatch distribution and Bayesian skyline analyses of the concatenated COI and COII data set (n = 89) suggested a population expansion dating to the late Pleistocene (~35000-40000 years before present) followed by a stable effective female population size (Nef) of about 6 million over the last 10000 years.


Assuntos
Borboletas/genética , DNA Mitocondrial , Variação Genética , Genética Populacional , Repetições de Microssatélites , Animais , Teorema de Bayes , Biodiversidade , Borboletas/classificação , Amplificação de Genes , Genes Mitocondriais , Haplótipos , Densidade Demográfica
11.
BMC Evol Biol ; 16(1): 268, 2016 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-27927166

RESUMO

BACKGROUND: Evolutionary histories of parasite and host populations are intimately linked such that their spatial genetic structures may be correlated. While these processes have been relatively well studied in specialist parasites and their hosts, less is known about the ecological and evolutionary consequences of relationships between generalist ectoparasites and their hosts. The aim of this study was to investigate the genetic structure and demographic history of a bat ectoparasite, Cimex adjunctus, whose host affinity is weak but the biology of the potential hosts have been well studied. This ectoparasite has been hypothesized to rely on its hosts for dispersal due to its low inherent dispersal potential. Here we describe genetic diversity and demographic history in C. adjunctus through most of its range in North America. We investigated variation at the cytochrome c oxidase 1 mitochondrial gene and nine microsatellite markers, and tested the prediction that genetic diversity in C. adjunctus is spatially structured. We also tested the prediction that demographic history in C. adjunctus is characterized by range and demographic expansion as a consequence of post-Pleistocene climate warming. RESULTS: We found stronger spatial structuring of genetic diversity in C. adjunctus than has been quantified in two of its hosts, but contrast in amount of variation explained by host association with different genetic markers (i.e., nuclear vs mitochondrial DNA). Also, C. adjunctus' history is not primarily characterized by demographic and range expansion, as is the case with two of its key hosts. CONCLUSIONS: Our study shows different patterns of genetic structure and demographic history in C. adjunctus than have been detected in two of its key hosts. Our results suggest an effect of a loose parasite-host relationship and anti-parasitism strategies on genetic structure and post-Pleistocene recovery of population size.


Assuntos
Percevejos-de-Cama/genética , Quirópteros/parasitologia , Filogeografia , Animais , Evolução Biológica , Quirópteros/classificação , DNA Mitocondrial/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Genes de Insetos , Variação Genética , Interações Hospedeiro-Parasita , Desequilíbrio de Ligação , Repetições de Microssatélites , América do Norte
12.
BMC Evol Biol ; 16: 61, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26975876

RESUMO

BACKGROUND: Models that predict changes in the abundance and distribution of fauna under future climate change scenarios often assume that ecological niche and habitat availability are the major determinants of species' responses to climate change. However, individual species may have very different capacities to adapt to environmental change, as determined by intrinsic factors such as their dispersal ability, genetic diversity, generation time and rate of evolution. These intrinsic factors are usually excluded from forecasts of species' abundance and distribution changes. We aimed to determine the importance of these factors by comparing the impact of the most recent climate regime change, the late Pleistocene glacial-interglacial transition, on two sympatric, ice-dependent meso-predators, the emperor penguin (Aptenodytes forsteri) and Weddell seal (Leptonychotes weddellii). METHODS: We reconstructed the population trend of emperor penguins and Weddell seals in East Antarctica over the past 75,000 years using mitochondrial DNA sequences and an extended Bayesian skyline plot method. We also assessed patterns of contemporary population structure and genetic diversity. RESULTS: Despite their overlapping distributions and shared dependence on sea ice, our genetic data revealed very different responses to climate warming between these species. The emperor penguin population grew rapidly following the glacial-interglacial transition, but the size of the Weddell seal population did not change. The expansion of emperor penguin numbers during the warm Holocene may have been facilitated by their higher dispersal ability and gene flow among colonies, and fine-scale differences in preferred foraging locations. CONCLUSIONS: The vastly different climate change responses of two sympatric ice-dependent predators suggests that differing adaptive capacities and/or fine-scale niche differences can play a major role in species' climate change responses, and that adaptive capacity should be considered alongside niche and distribution in future species forecasts.


Assuntos
Caniformia/genética , Mudança Climática , DNA Mitocondrial/genética , Evolução Molecular , Spheniscidae/genética , Animais , Regiões Antárticas , Teorema de Bayes , Evolução Biológica , Caniformia/fisiologia , Ecossistema , Genética Populacional , Camada de Gelo , Spheniscidae/fisiologia , Simpatria
13.
Biol Lett ; 12(6)2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27330168

RESUMO

The Coral Triangle in the Indo-Pacific is a region renowned for exceptional marine biodiversity. The area could have acted as a 'centre of origin' where speciation has been prolific or a 'centre of survival' by providing refuge during major environmental shifts such as sea-level changes. The region could also have acted as a 'centre of accumulation' for species with origins outside of the Coral Triangle, owing to it being at a central position between the Indian and Pacific oceans. Here, we investigated support for these hypotheses using population-level DNA sequence-based reconstructions of the range evolution of 45 species (314 populations) of Indo-Pacific reef-associated organisms. Our results show that populations undergoing the most ancient establishment were significantly more likely to be closer to the centre of the Coral Triangle than to peripheral locations. The data are consistent with the Coral Triangle being a net source of coral-reef biodiversity for the Indo-Pacific region, suggesting that the region has acted primarily as a centre of survival, a centre of origin or both. These results provide evidence of how a key location can influence the large-scale distributions of biodiversity over evolutionary timescales.


Assuntos
Biodiversidade , Recifes de Corais , Peixes/classificação , Invertebrados/classificação , Animais , Evolução Biológica , Mudança Climática , Simulação por Computador , Peixes/genética , Oceano Índico , Invertebrados/genética , Oceano Pacífico , Análise de Sequência de DNA
14.
Mol Ecol ; 24(11): 2686-701, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25891855

RESUMO

We estimated the effective population sizes (Ne ) and tested for short-term temporal demographic stability of populations of two Lake Malawi cichlids: Maylandia benetos, a micro-endemic, and Maylandia zebra, a widespread species found across the lake. We sampled a total of 351 individuals, genotyped them at 13 microsatellite loci and sequenced their mitochondrial D-loop to estimate genetic diversity, population structure, demographic history and effective population sizes. At the microsatellite loci, genetic diversity was high in all populations. Yet, genetic diversity was relatively low for the sequence data. Microsatellites yielded mean Ne estimates of 481 individuals (±99 SD) for M. benetos and between 597 (±106.3 SD) and 1524 (±483.9 SD) individuals for local populations of M. zebra. The microsatellite data indicated no deviations from mutation-drift equilibrium. Maylandia zebra was further found to be in migration-drift equilibrium. Temporal fluctuations in allele frequencies were limited across the sampling period for both species. Bayesian Skyline analyses suggested a recent expansion of M. zebra populations in line with lake-level fluctuations, whereas the demographic history of M. benetos could only be estimated for the very recent past. Divergence time estimates placed the origin of M. benetos within the last 100 ka after the refilling of the lake and suggested that it split off the sympatric M. zebra population. Overall, our data indicate that micro-endemics and populations in less favourable habitats have smaller Ne , indicating that drift may play an important role driving their divergence. Yet, despite small population sizes, high genetic variation can be maintained.


Assuntos
Ciclídeos/genética , Variação Genética , Genética Populacional , África Oriental , Animais , Teorema de Bayes , DNA Mitocondrial/genética , Evolução Molecular , Frequência do Gene , Deriva Genética , Genótipo , Lagos , Repetições de Microssatélites , Dados de Sequência Molecular , Densidade Demográfica , Análise de Sequência de DNA , Análise Espaço-Temporal
15.
Am J Bot ; 102(4): 609-20, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25878093

RESUMO

PREMISE OF STUDY: Molecular population genetics is a powerful tool to infer how species responded to past environmental change. In the northern hemisphere, interest is increasing in how species responded to changes in ice coverage and temperature during the last glaciation maximum (LGM, between 18000-21000 yr ago) with a common assumption that glacial refugia were located at the southern edge of a species range. METHODS: We reconstructed the glacial and postglacial phylogeography of Sabatia kennedyana, a member of the Atlantic Coastal Plains Flora with a current distribution from Nova Scotia (NS) to South Carolina, using both cpDNA and nuclear markers. We also examined clinal variation in morphological traits, in particular relative investment in asexual vs sexual growth. KEY RESULTS: We find strong evidence that the species did not reside in southern glacial refugia, but rather in primary glacial refugia off the exposed continental shelf extending from Cape Cod and that this area was responsible for the founding of modern populations across the range from Nova Scotia (NS) to the United States. Additionally, based on the finding of higher cpDNA diversity and older cpDNA lineages in NS, we propose that multiple founder events occurred in NS, while only a single lineage gave rise to current populations in the United States. CONCLUSIONS: By understanding how S. kennedyana responded to past shifts in climate and by identifying areas of high genetic diversity in the northern range edge, we discuss the potential response of the species to future climate change scenarios.


Assuntos
DNA de Cloroplastos/genética , Variação Genética , Gentianaceae/genética , Dispersão Vegetal , Refúgio de Vida Selvagem , Canadá , Mudança Climática , DNA de Cloroplastos/metabolismo , Evolução Molecular , Haplótipos/genética , Dados de Sequência Molecular , Filogenia , Filogeografia , Análise de Sequência de DNA , Estados Unidos
16.
J Hered ; 106(4): 333-46, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25926628

RESUMO

Sequence mismatch analysis (MMA) and Bayesian skyline plots (BSP) are commonly used to reconstruct historical demography. A survey of 173 research articles (2009-2014), which included estimates of historical population sizes from mtDNA or cpDNA, shows a widespread genetic signature of demographic or spatial population expansion in species of all major taxonomic groups. Associating these expansions with climatic events can provide insights into the origins of lineage diversity, range expansions (or contractions), and speciation. However, several variables can introduce error into reconstructions of demographic history, including levels of sequence polymorphism, sampling scheme, sample size, natural selection, and estimates of mutation rate. Most researchers use substitution rates estimated from divergences in phylogenetic trees dated with fossils, or geological events. Recent studies show that molecular clocks calibrated with phylogenetic divergences can overestimate the timings of population-level events by an order of magnitude. Overestimates disconnect historical population reconstructions from climatic history and confound our understanding of the factors influencing genetic variability. If mismatch distributions and BSPs largely reflect demographic history, the widespread signature of population expansion in vertebrate, invertebrate, and plant populations appears to reflect responses to postglacial climate warming.


Assuntos
Mudança Climática , Genética Populacional , Modelos Genéticos , Análise de Sequência de DNA/métodos , Teorema de Bayes , DNA de Cloroplastos/genética , DNA Mitocondrial/genética , Deriva Genética , Variação Genética , Taxa de Mutação , Filogenia , Densidade Demográfica , Seleção Genética
17.
Bull Entomol Res ; 105(1): 92-100, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25336385

RESUMO

Population genetics of invading pests can be informative for understanding their ecology. In this study, we investigated population genetics of the invasive alfalfa weevil Hypera postica in Fukuoka Prefecture, Japan. We analyzed mitochondrial tRNALeu-COII, nuclear EF-1α gene fragments, and Wolbachia infection in relation to three leguminous host plants: Vicia angustifolia, Vicia villosa, and a new host Astragalus sinicus cultivated as a honey source and green manure crop. A parsimony network generated from mitochondrial gene sequences uncovered two major haplotypic groups, Western and Egyptian. In contrast to reported Wolbachia infection of the Western strain in the United States, none of our analyzed individuals were infected. The absence of Wolbachia may contribute to the stable coexistence of mitochondrial strains through inter-strain reproductive compatibility. Hypera postica genetic variants for the mitochondrial and nuclear genes were associated neither with host plant species nor with two geographic regions (Hisayama and Kama) within Fukuoka. Mitochondrial haplogroups were incongruent with nuclear genetic variants. Genetic diversity at the nuclear locus was the highest for the populations feeding on V. angustifolia. The nuclear data for A. sinicus-feeding populations indicated past sudden population growth and extended Bayesian skyline plot analysis based on the mitochondrial and nuclear data showed that the growth of A. sinicus-feeding population took place within the past 1000 years. These results suggest a shorter history of A. sinicus as a host plant compared with V. angustifolia and a recent rapid growth of H. postica population using the new host A. sinicus.


Assuntos
Fabaceae/fisiologia , Cadeia Alimentar , Variação Genética , Espécies Introduzidas , Gorgulhos/fisiologia , Animais , Núcleo Celular/genética , DNA Mitocondrial/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Comportamento Alimentar , Proteínas de Insetos/genética , Japão , Dados de Sequência Molecular , Fator 1 de Elongação de Peptídeos/genética , Reação em Cadeia da Polimerase , Densidade Demográfica , RNA de Transferência de Leucina/genética , Análise de Sequência de DNA , Especificidade da Espécie , Gorgulhos/genética , Gorgulhos/microbiologia , Wolbachia/isolamento & purificação
18.
Anim Genet ; 45(6): 782-90, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25308478

RESUMO

Butana and Kenana breeds from Sudan are part of the East African zebu Bos indicus type of cattle. Unlike other indigenous zebu cattle in Africa, they are unique due to their reputation for high milk production and are regarded as dairy cattle, the only ones of their kind on the African continent. In this study, we sequenced the complete mitochondrial DNA (mtDNA) D-loop of 70 animals to understand the maternal genetic variation, demographic profiles and history of the two breeds in relation to the history of cattle pastoralism on the African continent. Only taurine mtDNA sequences were identified. We found very high mtDNA diversity but low level of maternal genetic structure within and between the two breeds. Bayesian coalescent-based analysis revealed different historical and demographic profiles for the two breeds, with an earlier population expansion in the Butana vis a vis the Kenana. The maternal ancestral populations of the two breeds may have diverged prior to their introduction into the African continent, with first the arrival of the ancestral Butana population. We also reveal distinct demographic history between the two breeds with the Butana showing a decline in its effective population size (Ne ) in the recent past ~590 years. Our results provide new insights on the early history of cattle pastoralism in Sudan indicative of a large ancient effective population size.


Assuntos
Bovinos/genética , DNA Mitocondrial/genética , Variação Genética , Genética Populacional , África Oriental , Animais , Teorema de Bayes , Cruzamento , Bovinos/classificação , Haplótipos , Densidade Demográfica , Análise de Sequência de DNA
19.
Mol Ecol ; 22(16): 4177-4195, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23844700

RESUMO

Anthropogenic global climate change is expected to cause severe range contractions among alpine plants. Alpine areas in the Mediterranean region are of special concern because of the high abundance of endemic species with narrow ranges. This study combined species distribution models, population structure analyses and Bayesian skyline plots to trace the past and future distribution and diversity of Linaria glacialis, an endangered narrow endemic species that inhabits summits of Sierra Nevada (Spain). The results showed that: (i) the habitat of this alpine-Mediterranean species in Sierra Nevada suffered little changes during glacial and interglacial stages of late Quaternary; (ii) climatic oscillations in the last millennium (Medieval Warm Period and Little Ice Age) moderately affected the demographic trends of L. glacialis; (iii) future warming conditions will cause severe range contractions; and (iv) genetic diversity will not diminish at the same pace as the distribution range. As a consequence of the low population structure of this species, genetic impoverishment in the alpine zones of Sierra Nevada should be limited during range contraction. We conclude that maintenance of large effective population sizes via high mutation rates and high levels of gene flow may promote the resilience of alpine plant species when confronted with global warming.


Assuntos
Conservação dos Recursos Naturais , Aquecimento Global , Linaria/classificação , Linaria/genética , Modelos Genéticos , Teorema de Bayes , Ecossistema , Genética Populacional , Dados de Sequência Molecular , Plantas/classificação , Plantas/genética , Densidade Demográfica , Análise de Sequência de DNA , Espanha , Especificidade da Espécie
20.
Evol Appl ; 16(4): 895-910, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37124086

RESUMO

The human activity impact on wild animal populations is indicated by eco-evolutionary and demographic processes, along with their survival and capacity to evolve; consequently, such data can contribute toward enhancing genetic-based conservation programs. In this context, knowledge on the life-history and the eco-evolutionary processes is required to understand extant patterns of population structure in Prochilodus costatus a Neotropical migratory fish that has been threatened due to loss and fragmentation of its natural habitat since 1960s promoted by the expansion of hydroelectric power plant construction programs. This study evaluated the eco-evolutionary parameters that cause oscillations in the demography and structure of P. costatus populations. An integrated approach was used, including temporal and spatial sampling, next-generation sequencing of eight microsatellite loci, multivariate genetic analysis, and demographic life-history reconstruction. The results provided evidence of the complex interplay of ecological-evolutionary and human-interference events on the life history of this species in the upper basin. In particular, spawning wave behavior might have ecological triggers resulting in an overlapping of distinct genetic generations, and arising distinct migratory and nonmigratory genetic patterns living in the same area. An abrupt decrease in the effective population size of the P. costatus populations in the recent past (1960-80) was likely driven by environment fragmentation promoted by the construction of the Três Marias hydropower dam. The low allelic diversity that resulted from this event is still detected today; thus, active stocking programs are not effective at expanding the genetic diversity of this species in the river basin. Finally, this study highlights the importance of using mixed methods to understand spatial and temporal variation in genetic structure for effective mitigation and conservation programs for threatened species that are directly affected by human actions.

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