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1.
Zookeys ; 1160: 89-108, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37187461

RESUMO

A new species of freshwater crab, Potamonautesamatholesp. nov., is described from the Winterberg-Amathole mountain range in the Eastern Cape Province, South Africa. Morphologically, P.amathole Peer & Gouws, sp. nov. most closely resembles P.tuerkayi but can be distinguished by key morphological characters including the variation in the shape of the subterminal segment of gonopod 2 between both species. Genetically, P.amathole Peer & Gouws, sp. nov. is placed within the clade of small-bodied, mountain-dwelling crabs including P.parvispina, P.parvicorpus, P.brincki, P.tuerkayi, P.baziya, and P.depressus. The new species is found in slow-moving mountain streams and pools at high altitudes. The continued discovery and description of new freshwater crab species reinforces the need for ongoing research, especially in under-sampled regions.

2.
Plant J ; 113(2): 262-276, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36424853

RESUMO

The king protea (Protea cynaroides), an early-diverging eudicot, is the most iconic species from the Megadiverse Cape Floristic Region, and the national flower of South Africa. Perhaps best known for its iconic flower head, Protea is a key genus for the South African horticulture industry and cut-flower market. Ecologically, the genus and the family Proteaceae are important models for radiation and adaptation, particularly to soils with limited phosphorus bio-availability. Here, we present a high-quality chromosome-scale assembly of the P. cynaroides genome as the first representative of the fynbos biome. We reveal an ancestral whole-genome duplication event that occurred in the Proteaceae around the late Cretaceous that preceded the divergence of all crown groups within the family and its extant diversity in all Southern continents. The relatively stable genome structure of P. cynaroides is invaluable for comparative studies and for unveiling paleopolyploidy in other groups, such as the distantly related sister group Ranunculales. Comparative genomics in sequenced genomes of the Proteales shows loss of key arbuscular mycorrhizal symbiosis genes likely ancestral to the family, and possibly the order. The P. cynaroides genome empowers new research in plant diversification, horticulture and adaptation, particularly to nutrient-poor soils.


Assuntos
Proteaceae , Proteaceae/genética , Ecossistema , Genômica , África do Sul , Solo
3.
Plants (Basel) ; 11(22)2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36432855

RESUMO

Many dicotyledonous plants produce structures called leaf domatia. Approximately 28% of 290 families have species with leaf domatia. These structures are abundant within the Rubiaceae and Vitaceae. 26% and 16% out of 206 representative species cited in literature from 48 plant families belong to the Rubiaceae and Vitaceae respectively. Leaf domatia are usually associated with mites and often mediate mutualistic relationships with predacious mites. These structures are pockets found in the underside of the leaf, where the secondary vein axils meet the major vein. In the present study, we examine the anatomical structures of leaf domatia from three plant species (Gardenia thunbergia Thunb., Rothmannia capensis Thunb., Rothmannia globosa (Hochst.) Keay) from the Rubiaceae family in order to find out if their internal tissues differ. These plants were sectioned and viewed under a Light Microscope in order to document their internal anatomy. A Transmission Electron Microscope was used to search for the presence of cuticular folds in their epidermis, which are thought to assist plant to communicate with mites. Results from this study suggested that the main features of domatial anatomy are the presence of an extra layer of tissue in the lower epidermis, a cuticle, cuticular folds, trichomes and the presence of an invagination. Cuticular folds were present inside the domatia but were not restricted to the domatial lamina. Thus, we conclude that these structures do not assist plant in plant-mite communication. This study provides a better understating of the anatomy of leaf domatia of the Rubiaceae.

4.
Mol Ecol ; 31(22): 5846-5860, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36089907

RESUMO

Ecotypes are distinct populations within a species that are adapted to specific environmental conditions. Understanding how these ecotypes become established, and how they interact when reunited, is fundamental to elucidating how ecological adaptations are maintained. This study focuses on Themeda triandra, a dominant grassland species across Asia, Africa and Australia. It is the most widespread plant in Australia, where it has distinct ecotypes that are usually restricted to either wetter and cooler coastal regions or the drier and hotter interior. We generate a reference genome for T. triandra and use whole genome sequencing for over 80 Themeda accessions to reconstruct the evolutionary history of T. triandra and related taxa. Organelle phylogenies confirm that Australia was colonized by T. triandra twice, with the division between ecotypes predating their arrival in Australia. The nuclear genome provides evidence of differences in the dominant ploidal level and gene-flow among the ecotypes. In northern Queensland there appears to be a hybrid zone between ecotypes with admixed nuclear genomes and shared chloroplast haplotypes. Conversely, in the cracking claypans of Western Australia, there is cytonuclear discordance with individuals possessing the coastal chloroplast and interior clade nuclear genome. This chloroplast capture is potentially a result of adaptive introgression, with selection detected in the rpoC2 gene which is associated with water use efficiency. The reason that T. triandra is the most widespread plant in Australia appears to be a result of distinct ecotypic genetic variation and genome duplication, with the importance of each depending on the geographic scale considered.


Assuntos
Cloroplastos , Hibridização Genética , Austrália , Cloroplastos/genética , Variação Genética/genética , Haplótipos/genética , Filogenia
5.
J Phycol ; 57(5): 1542-1553, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-33982309

RESUMO

Most intertidal algae have limited dispersal potential, and areas that lack hard substratum suitable for attachment are thus expected to isolate regional populations from each other. Here, we used nuclear and mitochondrial genetic data to compare genetic structure in two co-distributed intertidal red algae with different dispersal potential along the South African coastline. Gelidium pristoides is divided into a south-eastern and a south-western evolutionary lineage separated by extensive, continuous sandy shoreline habitat adjacent to coastal dunefields. In contrast, Hypnea spicifera is genetically homogeneous throughout its range. In G. pristoides, the genetic breaks are associated with contemporary coastal dunefields. The age of the divergence event suggests that this may reflect the effect of older dispersal barriers, and that genetic structure was subsequently maintained by the formation of contemporary coastal dunefields.


Assuntos
DNA Mitocondrial , Rodófitas , Ecossistema , Estruturas Genéticas , Filogeografia , Rodófitas/genética
6.
7.
F1000Res ; 9: 339, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32934803

RESUMO

Background: Mitochondrial DNA (mtDNA) has long been used to date historical demographic events. The idea that it is useful for molecular dating rests on the premise that its evolution is neutral. Even though this idea has long been challenged, the evidence against clock-like evolution of mtDNA is often ignored. Here, we present a particularly clear and simple example to illustrate the implications of violations of the assumption of selective neutrality. Methods: DNA sequences were generated for the mtDNA COI gene and the nuclear 28S rRNA of two closely related rocky shore snails, and species-level variation was compared. To our knowledge, this is the first study to use nuclear rRNA at this taxonomic level, presumably because this marker is assumed to evolve so slowly that it is only suitable for phylogenetics.   Results: Even though high inter-specific divergence reflected the faster evolutionary rate of COI, intraspecific genetic variation was similar for both markers. As a result, estimates of population expansion times based on mismatch distributions differed between the two markers by millions of years. Conclusions: Assuming that 28S evolves effectively clock-like, these findings can be explained by variation-reducing purifying selection in mtDNA at the species level, and an elevated divergence rate caused by diversifying selection between the two species. Although these two selective forces together make mtDNA suitable as a marker for species identifications by means of DNA barcoding because they create a 'barcoding gap', estimates of demographic change based on this marker can be expected to be highly unreliable. Our study contributes to the growing evidence that the utility of mtDNA sequence data beyond DNA barcoding is limited.


Assuntos
Evolução Molecular , Genes Mitocondriais , Variação Genética , RNA Ribossômico 28S/genética , Caramujos/genética , Animais , Filogenia , Seleção Genética , Análise de Sequência de DNA , Caramujos/classificação , Especificidade da Espécie
8.
Zookeys ; 936: 1-24, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32547291

RESUMO

This study investigates genetic diversity in three species of Ephemeroptera, one eurytopic and therefore widespread (Afroptilum sudafricanum) and two stenotopic and thus endemic (Demoreptus natalensis and Demoreptus capensis) species, all of which co-occur in the southern Great Escarpment, South Africa. Mitochondrial DNA was analysed to compare the genetic diversity between the habitat generalist and the two habitat specialists. Afroptilum sudafricanum showed no indication of population genetic structure due to geographic location, while both Demoreptus species revealed clear genetic differentiation between geographic localities and catchments, evident from phylogenetic analyses and high FST values from AMOVA. In addition, the phylogenetic analyses indicate some deeper haplotype divergences within A. sudafricanum and Demoreptus that merit taxonomic attention. These results give important insight into evolutionary processes occurring through habitat specialisation and population isolation. Further research and sampling across a wider geographic setting that includes both major mountain blocks of the Escarpment and lowland non-Escarpment sites will allow for refined understanding of biodiversity and associated habitat preferences, and illuminate comparative inferences into gene flow and cryptic speciation.

9.
PhytoKeys ; (113): 1-31, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30524187

RESUMO

This paper aims to provide a baseline for conservation planning by documenting patterns of plant diversity and vegetation in the upper catchment of the Cuito River. 417 species are recorded from this region. Nine of these are species potentially new to science. Ten species are newly recorded from Angola, with an additional species only recorded previously within Angola from the northern enclave of Cabinda. The 108 new provincial records for Moxico clearly indicate the lack of collections from Angola's largest province. We note the existence of extensive peat deposits in the Cuito river system for the first time and suggest that one of Barbosa's vegetation types in the area needs to be reassessed.

10.
Front Plant Sci ; 9: 1199, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30158948

RESUMO

Plants have developed morphological, physiological, biochemical, cellular, and molecular mechanisms to survive in drought-stricken environments with little or no water caused by below-average precipitation. In this mini-review, we highlight the characteristics that allows marama bean [Tylosema esculentum (Burchell) Schreiber], an example of an orphan legume native to arid regions of southwestern Southern Africa, to flourish under an inhospitable climate and dry soil conditions where no other agricultural crop competes in this agro-ecological zone. Orphan legumes are often better suited to withstand such harsh growth environments due to development of survival strategies using a combination of different traits and responses. Recent findings on questions on marama bean speciation, hybridization, population dynamics, and the evolutionary history of the bean and mechanisms by which the bean is able to extract and conserve water and nutrients from its environment as well as aspects of morphological and physiological adaptation will be reviewed. The importance of the soil microbiome and the genetic diversity in this species, and their interplay, as a reservoir for improvement will also be considered. In particular, the application of the newly established marama bean genome sequence will facilitate both the identification of important genes involved in the interaction with the soil microbiome and the identification of the diversity within the wild germplasm for genes involved drought tolerance. Since predicted future changes in climatic conditions, with less water availability for plant growth, will severely affect agricultural productivity, an understanding of the mechanisms of unique adaptations in marama bean to such conditions may also provide insights as to how to improve the performance of the major crops.

11.
Mol Phylogenet Evol ; 117: 95-101, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28559212

RESUMO

Southern Africa is a biodiversity hotspot of patellid limpets, with three genera (Helcion, Cymbula and Scutellastra) identified and described in the region. Scutellastra is the most diverse and most frequently studied of these and, along with Cymbula, includes species with territorial and non-territorial foraging behaviours. We used three mitochondrial markers (12S rRNA, 16S rRNA and COI) and one nuclear marker (ATPSß intron) to assess evolutionary relationships among species of Cymbula and Scutellastra with these two foraging behaviours and to identify which foraging mode is the more ancient. Maximum Likelihood and Bayesian Inference phylogenetic analyses revealed that the species sharing a foraging type are monophyletic in both genera. Territoriality is a derived character, as the clades with this foraging type are nested within a tree that otherwise comprises non-territorial taxa. These include Helcion, which was recovered as sister to the Cymbula/Scutellastra clade, and the next basal genus, Patella, which is ancestral to all southern African patellogastropods. Deep genetic divergence between the two foraging traits reflects strong adaptive effects of resource partitioning in the evolution of southern African patellid limpets.


Assuntos
Evolução Molecular , Gastrópodes/genética , Gastrópodes/fisiologia , Deriva Genética , Filogenia , África Austral , Animais , Teorema de Bayes , DNA Mitocondrial/genética , Íntrons/genética , RNA Ribossômico/genética , RNA Ribossômico 16S/genética
12.
PhytoKeys ; (62): 113-24, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27212887

RESUMO

South Africa's 800 km-long southern Great Escarpment hosts numerous endemic plant species only known from their type specimens or from very few records. This is a legacy of a 100-150 year lag between the pioneer work of 19(th) century botanists and repeat fieldwork in the 21(st) century. As a result, population and ecological data are lacking for many local endemic species. Here we report on the rediscovery of Lotononis harveyi B.-E.van Wyk 147 years after its original description, and provide the first detailed ecological notes on the poorly known shrub Macowania revoluta Oliv. Both species are locally endemic to the Great Winterberg-Amatholes (Eastern Cape Province). With only six known individuals, Lotononis harveyi is recommended the conservation status of Critically Endangered, with fire (and potentially grazing) being the main population constraints. Macowania revoluta is locally abundant, and it is surprising that it has been so poorly collected in recent decades. It occupies an important local niche as a keystone montane wetland species, and its narrow distribution range - combined with pressure from woody alien invasive species - suggests that its conservation status should be Rare. The research further highlights the need for continued biodiversity field research along South Africa's poorly explored Great Escarpment.

13.
Cornea ; 35(5): 679-82, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26938327

RESUMO

PURPOSE: To present the first reported cases of keratitis caused by Rhizobium radiobacter. METHODS: A retrospective review of an observational case series from 2 institutions. RESULTS: There were 4 cases of microbiologically proven R. radiobacter. Three of these patients were contact lens wearers. The patient in case 4 defaulted from follow-up after receipt of the culture result. Keratitis in the other cases resolved with variable clinical courses once culture-directed therapy was instituted. CONCLUSIONS: R. radiobacter is a member of the genus Rhizobium. It is a gram-negative bacillus and was previously identified as an opportunistic pathogen in nonophthalmic infections and in a few cases of endophthalmitis. To our knowledge, we have described the clinical presentation, management, and treatment outcomes of the first reported cases of keratitis caused by R. radiobacter.


Assuntos
Agrobacterium tumefaciens/isolamento & purificação , Úlcera da Córnea/microbiologia , Infecções Oculares Bacterianas/microbiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Adulto , Antibacterianos/uso terapêutico , Úlcera da Córnea/diagnóstico , Úlcera da Córnea/tratamento farmacológico , Infecções Oculares Bacterianas/diagnóstico , Infecções Oculares Bacterianas/tratamento farmacológico , Feminino , Infecções por Bactérias Gram-Negativas/diagnóstico , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Humanos , Masculino , Testes de Sensibilidade Microbiana , Estudos Retrospectivos , Acuidade Visual , Adulto Jovem
14.
PhytoKeys ; (48): 29-41, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25941448

RESUMO

Two new species of Indigofera L. (Leguminosae) are described from the Sneeuberg Centre of Floristic Endemism on the southern Great Escarpment, Eastern and Western Cape Provinces, South Africa. Both species are localised high-altitude endemics. Indigoferamagnifica Schrire & V.R. Clark is confined to the summit plateau of the Toorberg-Koudeveldberg-Meelberg west of Graaff-Reinet, and complements other western Sneeuberg endemics such as Ericapasserinoides (Bolus) E.G.H. Oliv. and Faurearecondita Rourke & V.R. Clark. Indigoferaasantasanensis Schrire & V.R. Clark is confined to a small area east of Graaff-Reinet, and complements several other eastern Sneeuberg endemics such as Euryopsexsudans B. Nord & V.R. Clark and Euryopsproteoides B. Nord. & V.R. Clark. Based on morphology, both new species belong to the Cape Clade of Indigofera, supporting a biogeographical link between the Cape Floristic Region and the Sneeuberg, as well as with the rest of the eastern Great Escarpment.

15.
Surv Ophthalmol ; 60(5): 481-5, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26002588

RESUMO

Balloon cell nevi are rare, benign melanocytic tumors that may involve the conjunctiva, choroid, and skin. In the ocular adnexa they typically present as raised and mobile hyperpigmented masses. Histologically, balloon cell nevi consist of large cells forming nests that usually lack melanin pigment. The balloon cells have a clear or vacuolated cytoplasm with centrally located nuclei. The vacuolated cytoplasm may be the result of defective melanin synthesis, with the accumulation of melanin precursors in premelanosomes. Balloon cells can resemble xanthoma cells, adipocytes, macrophages, sebaceous adenomas, melanoma with balloon cell changes, and metastatic renal cell carcinoma. Differentiating between these various entities via morphology and immunohistochemistry thus remains clinically significant. We report three cases of conjunctival balloon cell nevi and review the literature.


Assuntos
Neoplasias da Túnica Conjuntiva/patologia , Nevo Pigmentado/patologia , Adolescente , Adulto , Biomarcadores Tumorais/metabolismo , Criança , Neoplasias da Túnica Conjuntiva/metabolismo , Neoplasias da Túnica Conjuntiva/cirurgia , Feminino , Humanos , Técnicas Imunoenzimáticas , Antígeno MART-1/metabolismo , Masculino , Nevo Pigmentado/metabolismo , Nevo Pigmentado/cirurgia , Proteínas S100/metabolismo
16.
Ann Bot ; 113(7): 1175-83, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24694830

RESUMO

BACKGROUND AND AIMS: The ability of plant lineages to reach all continents contributes substantially to their evolutionary success. This is exemplified by the Poaceae, one of the most successful angiosperm families, in which most higher taxa (tribes, subfamilies) have global distributions. Due to the old age of the ocean basins relative to the major angiosperm radiations, this is only possible by means of long-distance dispersal (LDD), yet the attributes of lineages with successful LDD remain obscure. Polyploid species are over-represented in invasive floras and in the previously glaciated Arctic regions, and often have wider ecological tolerances than diploids; thus polyploidy is a candidate attribute of successful LDD. METHODS: The link between polyploidy and LDD was explored in the globally distributed grass subfamily Danthonioideae. An almost completely sampled and well-resolved species-level phylogeny of the danthonioids was used, and the available cytological information was assembled. The cytological evolution in the clade was inferred using maximum likelihood (ML) as implemented in ChromEvol. The biogeographical evolution in the clade was reconstructed using ML and Bayesian approaches. KEY RESULTS: Numerous increases in ploidy level are demonstrated. A Late Miocene-Pliocene cycle of polyploidy is associated with LDD, and in two cases (the Australian Rytidosperma and the American Danthonia) led to secondary polyploidy. While it is demonstrated that successful LDD is more likely in polyploid than in diploid lineages, a link between polyploidization events and LDD is not demonstrated. CONCLUSIONS: The results suggest that polyploids are more successful at LDD than diploids, and that the frequent polyploidy in the grasses might have facilitated the extensive dispersal among continents in the family, thus contributing to their evolutionary success.


Assuntos
Dispersão Vegetal , Poaceae/fisiologia , Poliploidia , Teorema de Bayes , Evolução Biológica , Genoma de Planta , Funções Verossimilhança , Filogenia , Poaceae/genética , Análise de Sequência de DNA
17.
Cochrane Database Syst Rev ; (9): CD001861, 2012 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-22972054

RESUMO

BACKGROUND: Recurrent corneal erosion is a common cause of disabling ocular symptoms and predisposes the cornea to infection. It may follow corneal trauma. Measures to prevent the development of recurrent corneal erosion following corneal trauma have not been firmly established. Once recurrent corneal erosion develops simple medical therapy (standard treatment) may lead to resolution of the episode. However, some patients continue to suffer when such therapy fails and once resolved further episodes of recurrent erosion may occur. A number of treatment and prophylactic options are then available but there is no agreement as to the best option. OBJECTIVES: To assess the effectiveness and safety of prophylactic and treatment regimens for recurrent corneal erosion. SEARCH METHODS: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 6), MEDLINE (January 1946 to June 2012), EMBASE (January 1980 to June 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to June 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 13 June 2012. We also contacted researchers in the field. SELECTION CRITERIA: We included randomised and quasi-randomised trials that compared a prophylactic or treatment regimen with another prophylaxis/treatment or no prophylaxis/treatment for patients with recurrent corneal erosion. DATA COLLECTION AND ANALYSIS: Two authors independently extracted data and assessed trial quality. We contacted study authors for additional information. MAIN RESULTS: Seven randomised and one quasi-randomised controlled trial were included in the review. The trials were heterogenous and of poor quality. Safety data presented were incomplete. For the treatment of recurrent corneal erosion, a single-centre trial in the UK with 30 participants showed that oral tetracycline 250 mg twice daily for 12 weeks or topical prednisolone 0.5% four times daily for one week, or both, in addition to standard treatment, accelerated healing rates and improved symptoms. A single-centre trial in Sweden with 56 participants showed that excimer laser ablation in addition to mechanical debridement may reduce the number of erosions and improve symptoms. Furthermore, in a single-centre trial in Germany with 100 participants, transepithelial technique for excimer laser ablation had the same efficacy as the traditional subepithelial excimer laser technique but caused less pain. In a small study of 24 participants in UK, therapeutic contact lens wear was inferior to lubricant drops and ointment in abolishing the symptoms of recurrent corneal erosion and had a high complication rate, although the contact lenses used were the older generation with low oxygen permeability. A recent study in Hong Kong with 48 participants found diamond burr polishing to reduce episodes of recurrent corneal erosion. For prophylaxis of further episodes of recurrent corneal erosion, there was no difference in the occurrence of objective signs of recurrent erosion between hypertonic saline ointment versus tetracycline ointment or lubricating ointment in a small Japanese study with 26 participants. Also, in a single-centre study in the UK with 117 participants, there was no difference in symptom improvement between hypertonic saline versus paraffin ointment when used for prophylaxis. In a UK study with 42 participants, lubricating ointment at night in addition to standard treatment to prevent recurrence following traumatic corneal abrasion (erosion) caused by fingernail injury led to increased symptoms of recurrent corneal erosion compared to standard therapy alone. AUTHORS' CONCLUSIONS: Well-designed, masked, randomised controlled trials using standardised methods are needed to establish the benefits of new and existing prophylactic and treatment regimes for recurrent corneal erosion. International consensus is also needed to progress research efforts towards evaluation of the major effective treatments for recurrent corneal erosions.


Assuntos
Doenças da Córnea/prevenção & controle , Lesões da Córnea , Infecções Oculares/prevenção & controle , Antibacterianos/uso terapêutico , Lentes de Contato , Doenças da Córnea/terapia , Desbridamento/métodos , Infecções Oculares/etiologia , Glucocorticoides/uso terapêutico , Humanos , Prednisolona/uso terapêutico , Ensaios Clínicos Controlados Aleatórios como Assunto , Prevenção Secundária , Tetraciclina/uso terapêutico
18.
BMC Genet ; 13: 45, 2012 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-22694765

RESUMO

BACKGROUND: When genetic structure is identified using mitochondrial DNA (mtDNA), but no structure is identified using biparentally-inherited nuclear DNA, the discordance is often attributed to differences in dispersal potential between the sexes. RESULTS: We sampled the intertidal rocky shore mussel Perna perna in a South African bay and along the nearby open coast, and sequenced maternally-inherited mtDNA (there is no evidence for paternally-inherited mtDNA in this species) and a biparentally-inherited marker. By treating males and females as different populations, we identified significant genetic structure on the basis of mtDNA data in the females only. CONCLUSIONS: This is the first study to report sex-specific differences in genetic structure based on matrilineally-inherited mtDNA in a passively dispersing species that lacks social structure or sexual dimorphism. The observed pattern most likely stems from females being more vulnerable to selection in habitats from which they did not originate, which also manifests itself in a male-biased sex ratio. Our results have three important implications for the interpretation of population genetic data. First, even when mtDNA is inherited exclusively in the female line, it also contains information about males. For that reason, using it to identify sex-specific differences in genetic structure by contrasting it with biparentally-inherited markers is problematic. Second, the fact that sex-specific differences were found in a passively dispersing species in which sex-biased dispersal is unlikely highlights the fact that significant genetic structure is not necessarily a function of low dispersal potential or physical barriers. Third, even though mtDNA is typically used to study historical demographic processes, it also contains information about contemporary processes. Higher survival rates of males in non-native habitats can erase the genetic structure present in their mothers within a single generation.


Assuntos
Bivalves/citologia , Bivalves/genética , Animais , Bivalves/fisiologia , Núcleo Celular/genética , DNA Mitocondrial/genética , Feminino , Masculino , Dados de Sequência Molecular , Caracteres Sexuais , África do Sul
19.
BMC Evol Biol ; 12: 26, 2012 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-22373076

RESUMO

BACKGROUND: Baetis harrisoni Barnard is a mayfly frequently encountered in river studies across Africa, but the external morphological features used for identifying nymphs have been observed to vary subtly between different geographic locations. It has been associated with a wide range of ecological conditions, including pH extremes of pH 2.9-10.0 in polluted waters. We present a molecular study of the genetic variation within B. harrisoni across 21 rivers in its distribution range in southern Africa. RESULTS: Four gene regions were examined, two mitochondrial (cytochrome c oxidase subunit I [COI] and small subunit ribosomal 16S rDNA [16S]) and two nuclear (elongation factor 1 alpha [EF1α] and phosphoenolpyruvate carboxykinase [PEPCK]). Bayesian and parsimony approaches to phylogeny reconstruction resulted in five well-supported major lineages, which were confirmed using a general mixed Yule-coalescent (GMYC) model. Results from the EF1α gene were significantly incongruent with both mitochondrial and nuclear (PEPCK) results, possibly due to incomplete lineage sorting of the EF1α gene. Mean between-clade distance estimated using the COI and PEPCK data was found to be an order of magnitude greater than the within-clade distance and comparable to that previously reported for other recognised Baetis species. Analysis of the Isolation by Distance (IBD) between all samples showed a small but significant effect of IBD. Within each lineage the contribution of IBD was minimal. Tentative dating analyses using an uncorrelated log-normal relaxed clock and two published estimates of COI mutation rates suggest that diversification within the group occurred throughout the Pliocene and mid-Miocene (~2.4-11.5 mya). CONCLUSIONS: The distinct lineages of B. harrisoni correspond to categorical environmental variation, with two lineages comprising samples from streams that flow through acidic Table Mountain Sandstone and three lineages with samples from neutral-to-alkaline streams found within eastern South Africa, Malawi and Zambia. The results of this study suggest that B. harrisoni as it is currently recognised is not a single species with a wide geographic range and pH-tolerance, but may comprise up to five species under the phylogenetic species concept, each with limited pH-tolerances, and that the B. harrisoni species group is thus in need of taxonomic review.


Assuntos
Variação Genética , Insetos/classificação , Insetos/genética , Animais , Núcleo Celular/genética , Insetos/citologia , Mitocôndrias/genética , Filogenia , África do Sul
20.
Springerplus ; 1(1): 56, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23316449

RESUMO

UNLABELLED: Botanical work since 2008 on the Sleeping Giant section of the Kamdebooberge (Sneeuberg mountain complex, Eastern Cape, South Africa) has indicated that these mountains may be of significant conservation value. Accordingly, a precursory, rapid multi-disciplinary biodiversity assessment was undertaken in January 2011, focusing on plants, tetrapod vertebrates and leafhoppers. The botanical results confirm the Kamdebooberge as being of high botanical conservation value, hosting three strict endemics, healthy populations of five other Sneeuberg endemics, and fynbos communities comprising species not found elsewhere in the Sneeuberg. The Kamdebooberge are important for herpetofauna (excluding serpentoids) and mammals, hosting several range-restricted and regional endemics. The expedition uncovered three new leafhopper species, together with several species previously only known from the Cape Floristic Region. Further detailed faunal work may provide further interesting results from these mountains, which show a high conservation value unique to the southern Escarpment. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/2193-1801-1-56) contains supplementary material, which is available to authorized users.

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