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Leppänen J, Seppä P, Vepsäläinen K, Savolainen R. Genetic divergence between the sympatric queen morphs of the antMyrmica rubra. Mol Ecol 2015; 24:2463-76. [DOI: 10.1111/mec.13170] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 03/18/2015] [Accepted: 03/19/2015] [Indexed: 01/09/2023]
Affiliation(s)
- Jenni Leppänen
- Department of Biosciences; University of Helsinki; P.O. Box 65 Helsinki 00014 Finland
| | - Perttu Seppä
- Centre of Excellence in Biological Interactions; Department of Biosciences; University of Helsinki; P.O. Box 65 Helsinki 00014 Finland
| | - Kari Vepsäläinen
- Department of Biosciences; University of Helsinki; P.O. Box 65 Helsinki 00014 Finland
| | - Riitta Savolainen
- Department of Biosciences; University of Helsinki; P.O. Box 65 Helsinki 00014 Finland
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Wei W, Gießler S, Wolinska J, Ma X, Yang Z, Hu W, Yin M. Genetic structure of Daphnia galeata populations in Eastern China. PLoS One 2015; 10:e0120168. [PMID: 25768727 PMCID: PMC4358959 DOI: 10.1371/journal.pone.0120168] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 01/26/2015] [Indexed: 11/18/2022] Open
Abstract
This study presents the first examination of the genetic structure of Daphnia longispina complex populations in Eastern China. Only one species, D. galeata, was present across the eight investigated lakes; as identified by taxon assignment using allelic variation at 15 microsatellite loci. Three genetically differentiated D. galeata subgroups emerged independent of the type of statistical analysis applied. Thus, Bayesian clustering, discriminant analysis based on results from factorial correspondence analysis, and UPGMA clustering consistently showed that populations from two neighbouring lakes were genetically separated from a mixture of genotypes found in other lakes, which formed another two subgroups. Clonal diversity was high in all D. galeata populations, and most samples showed no deviation from Hardy-Weinberg equilibrium, indicating that clonal selection had little effect on the genetic diversity. Overall, populations did not cluster by geographical origin. Further studies will show if the observed pattern can be explained by natural colonization processes or by recent anthropogenic impact on predominantly artificial lakes.
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Affiliation(s)
- Wenzhi Wei
- Yangzhou University, College of Animal Science and Technology, Yangzhou, China
| | - Sabine Gießler
- Ludwig-Maximilians-Universität, Department Biologie II, Evolutionsökologie, Planegg-Martinsried, Germany
| | - Justyna Wolinska
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Department of Ecosystem Research, Berlin, Germany
| | - Xiaolin Ma
- Fudan University, School of Life Science, MOE Key Laboratory for Biodiversity Science and Ecological Engineering, Shanghai, China
| | - Zhong Yang
- Fudan University, School of Life Science, MOE Key Laboratory for Biodiversity Science and Ecological Engineering, Shanghai, China
| | - Wei Hu
- Fudan University, School of Life Science, MOE Key Laboratory for Biodiversity Science and Ecological Engineering, Shanghai, China
| | - Mingbo Yin
- Fudan University, School of Life Science, MOE Key Laboratory for Biodiversity Science and Ecological Engineering, Shanghai, China
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Matsuo A, Tomimatsu H, Suzuki JI, Saitoh T, Shibata S, Makita A, Suyama Y. Female and male fitness consequences of clonal growth in a dwarf bamboo population with a high degree of clonal intermingling. ANNALS OF BOTANY 2014; 114:1035-1041. [PMID: 25228034 PMCID: PMC4171080 DOI: 10.1093/aob/mcu176] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 07/08/2014] [Indexed: 06/03/2023]
Abstract
BACKGROUND AND AIMS Although many studies have reported that clonal growth interferes with sexual reproduction as a result of geitonogamous self-pollination and inbreeding depression, the mating costs of clonal growth are expected to be reduced when genets are spatially intermingled with others. This study examined how clonal growth affects both female and male reproductive success by studying a population of a mass-flowering plant, Sasa veitchii var. hirsuta, with a high degree of clonal intermingling. METHODS In a 10 × 10 m plot, genets were discriminated based on the multilocus genotypes of 11 nuclear microsatellite loci. The relationships between genet size and the components of reproductive success were then investigated. Male siring success and female and male selfing rates were assessed using paternity analysis. KEY RESULTS A total of 111 genets were spatially well intermingled with others. In contrast to previous studies with species forming distinct monoclonal patches, seed production linearly increased with genet size. While male siring success was a decelerating function of genet size, selfing rates were relatively low and not related to genet size. CONCLUSIONS The results, in conjunction with previous studies, emphasize the role of the spatial arrangement of genets on both the quantity and quality of offpsring, and suggest that an intermingled distribution of genets can reduce the mating costs of clonal growth and enhance overall fitness, particularly female fitness.
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Affiliation(s)
- Ayumi Matsuo
- Field Science Center, Graduate School of Agricultural Science, Tohoku University, Osaki, Miyagi 989-6711, Japan Faculty of Bioresource Sciences, Akita Prefectural University, Akita 010-0195, Japan
| | - Hiroshi Tomimatsu
- Department of Biology, Yamagata University, Yamagata 990-8560, Japan
| | - Jun-Ichirou Suzuki
- Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
| | - Tomoyuki Saitoh
- Tohoku Research Center, Forestry and Forest Products Research Institute, Morioka 020-0123, Japan
| | - Shozo Shibata
- Field Science Education and Research Center, Kyoto University, Kyoto 606-8502, Japan
| | - Akifumi Makita
- Faculty of Bioresource Sciences, Akita Prefectural University, Akita 010-0195, Japan
| | - Yoshihisa Suyama
- Field Science Center, Graduate School of Agricultural Science, Tohoku University, Osaki, Miyagi 989-6711, Japan
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Kati AN, Mandrioli M, Skouras PJ, Malloch GL, Voudouris CC, Venturelli M, Manicardi GC, Tsitsipis JA, Fenton B, Margaritopoulos JT. Recent changes in the distribution of carboxylesterase genes and associated chromosomal rearrangements in Greek populations of the tobacco aphidMyzus persicae nicotianae. Biol J Linn Soc Lond 2014. [DOI: 10.1111/bij.12357] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Amalia N. Kati
- Plant Pathology Laboratory; School of Agriculture; Aristotle University of Thessaloniki; 541 24 Thessaloniki Greece
| | - Mauro Mandrioli
- Department of Life Sciences; University of Modena and Reggio Emilia; Biology Building via Campi 213/D 411 25 Modena Italy
| | - Panagiotis J. Skouras
- Laboratory of Agricultural Entomology and Zoology; Department of Agricultural Technologies; Technological Educational Institute of Peloponnese; Kalamata Greece
| | | | - Costas Ch. Voudouris
- Department of Biochemistry and Biotechnology; University of Thessaly; 26 Ploutonos Str. 412 21 Larissa Greece
- Institute of Molecular Biology and Biotechnology; Foundation for Research and Technology; 100 Nikolaou Plastira Str. 700 13 Heraklion Crete Greece
| | - Mattia Venturelli
- Department of Life Sciences; University of Modena and Reggio Emilia; Biology Building via Campi 213/D 411 25 Modena Italy
| | - Gian Carlo Manicardi
- Department of Life Sciences; University of Modena and Reggio Emilia; Biology Building via Campi 213/D 411 25 Modena Italy
| | - John A. Tsitsipis
- Laboratory of Entomology and Agricultural Zoology; University of Thessaly; 384 46 Nea Ionia Greece
| | - Brian Fenton
- The James Hutton Institute; Invergowrie; Dundee DD2 5DA Scotland UK
| | - John T. Margaritopoulos
- Department of Biochemistry and Biotechnology; University of Thessaly; 26 Ploutonos Str. 412 21 Larissa Greece
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Ciampi-Guillardi M, Baldauf C, Souza AP, Silva-Junior GJ, Amorim L. Recent introduction and recombination in Colletotrichum acutatum populations associated with citrus postbloom fruit drop epidemics in São Paulo, Brazil. PHYTOPATHOLOGY 2014; 104:769-778. [PMID: 24423403 DOI: 10.1094/phyto-06-13-0165-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Citrus crops in São Paulo State, Brazil, have been severely affected by postbloom fruit drop disease (PFD), which is caused by Colletotrichum acutatum. This disease leads to the drop of up to 100% of young fruits. Previous studies have assumed that this pathogen exhibits a clonal reproductive mode, although no population genetic studies have been conducted so far. Thus, the genetic structure of six C. acutatum populations from sweet orange orchards showing PFD symptoms was determined using nine microsatellite markers, enabling inference on predominant mode of reproduction. C. acutatum populations exhibit a nearly panmictic genetic structure and a high degree of admixture, indicating either ongoing contemporary gene flow at a regional scale or a recent introduction from a common source, since this pathogen was introduced in Brazil only very recently. Sharing haplotypes among orchards separated by 400 km suggests the natural dispersal of fungal propagules, with the possible involvement of pollinators. A significant population expansion was detected, which was consistent with an increase in host density associated with crop expansion toward new areas across the state. Findings of moderate to high levels of haplotypic diversity and gametic equilibrium suggest that recombination might play an important role in these pathogen populations, possibly via parasexual reproduction or a cryptic sexual cycle. This study provides additional tools for epidemiological studies of C. acutatum to improve prevention and management strategies for this disease.
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Rubiano-Rodríguez JA, Fuentes-Contreras E, Figueroa CC, Margaritopoulos JT, Briones LM, Ramírez CC. Genetic diversity and insecticide resistance during the growing season in the green peach aphid (Hemiptera: Aphididae) on primary and secondary hosts: a farm-scale study in Central Chile. BULLETIN OF ENTOMOLOGICAL RESEARCH 2014; 104:182-194. [PMID: 24484894 DOI: 10.1017/s000748531300062x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The seasonal dynamics of neutral genetic diversity and the insecticide resistance mechanisms of insect pests at the farm scale are still poorly documented. Here this was addressed in the green peach aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae) in Central Chile. Samples were collected from an insecticide sprayed peach (Prunus persica L.) orchard (primary host), and a sweet-pepper (Capsicum annum var. grossum L.) field (secondary host). In addition, aphids from weeds (secondary hosts) growing among these crops were also sampled. Many unique multilocus genotypes were found on peach trees, while secondary hosts were colonized mostly by the six most common genotypes, which were predominantly sensitive to insecticides. In both fields, a small but significant genetic differentiation was found between aphids on the crops vs. their weeds. Within-season comparisons showed genetic differentiation between early and late season samples from peach, as well as for weeds in the peach orchard. The knock-down resistance (kdr) mutation was detected mostly in the heterozygote state, often associated with modified acetylcholinesterase throughout the season for both crops. This mutation was found in high frequency, mainly in the peach orchard. The super-kdr mutation was found in very low frequencies in both crops. This study provides farm-scale evidence that the aphid M. persicae can be composed of slightly different genetic groups between contiguous populations of primary and secondary hosts exhibiting different dynamics of insecticide resistance through the growing season.
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Affiliation(s)
| | - E Fuentes-Contreras
- Facultad de Ciencias Agrarias, Universidad de Talca, Casilla 747, Talca, Chile
| | - C C Figueroa
- Instituto de Biología Vegetal y Biotecnología, Universidad de Talca, Casilla 747, Talca, Chile
| | - J T Margaritopoulos
- Department of Biochemistry and Biotechnology, University of Thessaly, Ploutonos 26 & Aiolou Street, 412 21 Larissa, Greece
| | - L M Briones
- Instituto de Biología Vegetal y Biotecnología, Universidad de Talca, Casilla 747, Talca, Chile
| | - C C Ramírez
- Instituto de Biología Vegetal y Biotecnología, Universidad de Talca, Casilla 747, Talca, Chile
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Saleh D, Milazzo J, Adreit H, Fournier E, Tharreau D. South-East Asia is the center of origin, diversity and dispersion of the rice blast fungus, Magnaporthe oryzae. THE NEW PHYTOLOGIST 2014; 201:1440-1456. [PMID: 24320224 PMCID: PMC4265293 DOI: 10.1111/nph.12627] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 10/23/2013] [Indexed: 05/11/2023]
Abstract
• Inferring invasion routes and identifying reservoirs of diversity of plant pathogens are essential in proposing new strategies for their control. Magnaporthe oryzae, the fungus responsible for rice blast disease, has invaded all rice growing areas. Virulent genotypes regularly (re)emerge, causing rapid resistance breakdowns. However, the world-wide genetic subdivision of M. oryzae populations on rice and its past history of invasion have never been elucidated. • In order to investigate the centers of diversity, origin and migration of M. oryzae on rice, we analyzed the genetic diversity of 55 populations from 15 countries. • Three genetic clusters were identified world-wide. Asia was the center of diversity and the origin of most migrations to other continents. In Asia, two centers of diversity were revealed in the Himalayan foothills: South China-Laos-North Thailand, and western Nepal. Sexual reproduction persisted only in the South China-Laos-North Thailand region, which was identified as the putative center of origin of all M. oryzae populations on rice. • Our results suggest a scenario of early evolution of M. oryzae on rice that matches the past history of rice domestication. This study confirms that crop domestication may have considerable influence on the pestification process of natural enemies.
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Affiliation(s)
- Dounia Saleh
- CIRAD, UMR BGPITA A54/K, F 34398, Montpellier, France
- INRA, UMR BGPITA A54/K, F 34398, Montpellier, France
| | | | - Henri Adreit
- CIRAD, UMR BGPITA A54/K, F 34398, Montpellier, France
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Ali S, Gladieux P, Rahman H, Saqib MS, Fiaz M, Ahmad H, Leconte M, Gautier A, Justesen AF, Hovmøller MS, Enjalbert J, de Vallavieille-Pope C. Inferring the contribution of sexual reproduction, migration and off-season survival to the temporal maintenance of microbial populations: a case study on the wheat fungal pathogenPuccinia striiformisf.sp.tritici. Mol Ecol 2014; 23:603-17. [DOI: 10.1111/mec.12629] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 11/30/2013] [Accepted: 12/04/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Sajid Ali
- INRA UR 1290 BIOGER-CPP; BP01 78850 Thiverval-Grignon France
- Institute of Biotechnology and Genetic Engineering; The University of Agriculture; Peshawar 25000 Pakistan
- Department of Agroecology; Aarhus University; Flakkebjerg; DK-4200 Slagelse Denmark
| | - Pierre Gladieux
- Department of Plant and Microbial Biology; University of California; Berkeley CA 94720-3102 USA
- Ecologie, Systématique et Evolution; UMR8079; Univ Paris-Sud; 91405 Orsay France
- Ecologie, Systématique et Evolution; UMR8079; CNRS; 91405 Orsay France
| | - Hidayatur Rahman
- Department of Plant Breeding and Genetics; The University of Agriculture; Peshawar 25000 Pakistan
| | - Muhammad S. Saqib
- Department of Plant Breeding and Genetics; The University of Agriculture; Peshawar 25000 Pakistan
| | | | | | - Marc Leconte
- INRA UR 1290 BIOGER-CPP; BP01 78850 Thiverval-Grignon France
| | | | | | - Mogens S. Hovmøller
- Department of Agroecology; Aarhus University; Flakkebjerg; DK-4200 Slagelse Denmark
| | - Jérôme Enjalbert
- INRA UMR 320 Génétique Végétale; Ferme du Moulon; 91190 Gif sur Yvette France
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Islam MS, Roush TL, Walker MA, Granett J, Lin H. Reproductive mode and fine-scale population genetic structure of grape phylloxera (Daktulosphaira vitifoliae) in a viticultural area in California. BMC Genet 2013; 14:123. [PMID: 24367928 PMCID: PMC3890642 DOI: 10.1186/1471-2156-14-123] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 12/11/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Grape phylloxera (Daktulosphaira vitifoliae) is one of the world's most important viticultural pests. However, the reproductive mode, genetic structure and host adaptation of phylloxera in various viticultural environments remains unclear. We examined reproductive mode and genetic structure of phylloxera by analyzing microsatellite makers across the samples from four vineyard-sites in California. RESULT The phylloxera populations in California are believed to have predominantly parthenogenetic reproduction. Therefore, genetic diversity of phylloxera is expected to be limited. However, this study showed relatively high levels of diversity in Napa and Yolo county populations with a large number of unique genotypes, average number of alleles (2.1 to 2.9) and observed heterozygosities (0.330 to 0.388) per vineyard-sites. Reproduction diversity index (G: N-unique genotypes versus number of samples) ranged from 0.500 to 0.656 among vineyard-sites. Both significant and non-significant Psex (probability of sexual reproduction) were observed among different repeated genotypes within each vineyard. Moreover, high variation of FIS was observed among different loci in each vineyard-site. Genetic structure analysis (UPGMA) and various measures of population differentiations (FST, PCA, and gene flow estimates) consistently separated AXR#1 (Vitis vinifera x V. rupestris-widely planted in California during the 1960s and 1970s) associated populations from the populations associated with other different rootstocks. CONCLUSION Genetic diversity, G: N ratio, Psex and FIS consistently suggested the occurrence of both parthenogenetic and sexual reproduction in California populations. This study clearly identified two major groups of phylloxera obtained from various rootstocks, with one group exclusively associated with only AXR#1 rootstock, defined as "biotype B", and another group associated with vinifera-based rootstocks, known as "biotype A".
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Affiliation(s)
| | | | | | | | - Hong Lin
- USDA, Agricultural Resarch Service, USDA-ARS, San Joaquin Valley Agricultural Sciences Center, 9611 South Riverbend Avenue, Parlier, CA 93648-9757, USA.
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Boulay JN, Hellberg ME, Cortés J, Baums IB. Unrecognized coral species diversity masks differences in functional ecology. Proc Biol Sci 2013; 281:20131580. [PMID: 24335977 DOI: 10.1098/rspb.2013.1580] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Porites corals are foundation species on Pacific reefs but a confused taxonomy hinders understanding of their ecosystem function and responses to climate change. Here, we show that what has been considered a single species in the eastern tropical Pacific, Porites lobata, includes a morphologically similar yet ecologically distinct species, Porites evermanni. While P. lobata reproduces mainly sexually, P. evermanni dominates in areas where triggerfish prey on bioeroding mussels living within the coral skeleton, thereby generating asexual coral fragments. These fragments proliferate in marginal habitat not colonized by P. lobata. The two Porites species also show a differential bleaching response despite hosting the same dominant symbiont subclade. Thus, hidden diversity within these reef-builders has until now obscured differences in trophic interactions, reproductive dynamics and bleaching susceptibility, indicative of differential responses when confronted with future climate change.
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Affiliation(s)
- Jennifer N Boulay
- Department of Biology, The Pennsylvania State University, , 208 Mueller Laboratory, University Park, PA 16802, USA, Department of Biological Sciences, Louisiana State University, , 202 Life Sciences Building, Baton Rouge, LA 70803, USA, Centro de Investigación en Ciencias del Mar y Limnología, Universidad de Costa Rica, , San Pedro, 11501-2060 San José, Costa Rica
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Werth S, Cheenacharoen S, Scheidegger C. Propagule size is not a good predictor for regional population subdivision or fine-scale spatial structure in lichenized fungi. Fungal Biol 2013; 118:126-38. [PMID: 24528636 DOI: 10.1016/j.funbio.2013.10.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Revised: 10/22/2013] [Accepted: 10/28/2013] [Indexed: 12/18/2022]
Abstract
Propagule size has important consequences on the genetic structure of wind-dispersed species, as species with small propagules have higher capability of long-distance dispersal. Here, we studied reproductive modes and compared local and regional population structures in three Macaronesian lichenized fungi differing in propagule size. First, we quantified size distribution of propagules in each species. Second, genotype simulations based on microsatellite data were used to infer the reproductive mode. Third, using spatial analysis and population genetic approaches, we quantified the local and regional scale genetic structures of the fungal species. The three species differed in size distributions of propagules. The majority of populations exhibited clonal reproductive mode. Identical reproductive modes occurred often across species in the same sites, implying a possible relationship between reproductive mode and local site conditions. Contrary to expectation, at the local scale, the species exhibited similar patterns of spatial autocorrelation in genotypes. However, in agreement with the expectation based on propagule size, the species with highest frequency of small vegetative propagules (L. pulmonaria) exhibited lowest regional genetic differentiation. Nevertheless, altogether, our results show that propagule size is not a good predictor of population subdivision in lichenized fungi, neither at local nor regional spatial scale.
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Affiliation(s)
- Silke Werth
- Biodiversity and Conservation Biology, Swiss Federal Research Institute WSL, Zürcherstrasse 111, CH-8903 Birmensdorf, Switzerland; Faculty of Life and Environmental Sciences, University of Iceland, Sturlugata 7, 101 Reykjavik, Iceland.
| | - Saran Cheenacharoen
- Biodiversity and Conservation Biology, Swiss Federal Research Institute WSL, Zürcherstrasse 111, CH-8903 Birmensdorf, Switzerland
| | - Christoph Scheidegger
- Biodiversity and Conservation Biology, Swiss Federal Research Institute WSL, Zürcherstrasse 111, CH-8903 Birmensdorf, Switzerland
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Graça RN, Ross-Davis AL, Klopfenstein NB, Kim MS, Peever TL, Cannon PG, Aun CP, Mizubuti ESG, Alfenas AC. Rust disease of eucalypts, caused by Puccinia psidii, did not originate via host jump from guava in Brazil. Mol Ecol 2013; 22:6033-47. [PMID: 24112757 DOI: 10.1111/mec.12545] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 09/24/2013] [Accepted: 09/25/2013] [Indexed: 11/27/2022]
Abstract
The rust fungus, Puccinia psidii, is a devastating pathogen of introduced eucalypts (Eucalyptus spp.) in Brazil where it was first observed in 1912. This pathogen is hypothesized to be endemic to South and Central America and to have first infected eucalypts via a host jump from native guava (Psidium guajava). Ten microsatellite markers were used to genotype 148 P. psidii samples from eucalypts and guava plus five additional myrtaceous hosts across a wide geographic range of south-eastern Brazil and Uruguay. Principal coordinates analysis, a Bayesian clustering analysis and a minimum-spanning network revealed two major genetic clusters among the sampled isolates, one associated with guava and another associated with eucalypts and three additional hosts. Multilocus genotypes infecting guava differed by multiple mutational steps at eight loci compared with those infecting eucalypts. Approximate Bayesian computation revealed that evolutionary scenarios involving a coalescence event between guava- and eucalypt-associated pathogen populations within the past 1000 years are highly unlikely. None of the analyses supported the hypothesis that eucalypt-infecting P. psidii in Brazil originated via host jump from guava following the introduction of eucalypts to Brazil approximately 185 years ago. The existence of host-associated biotypes of P. psidii in Brazil indicates that this diversity must be considered when assessing the invasive threat posed by this pathogen to myrtaceous hosts worldwide.
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Affiliation(s)
- Rodrigo N Graça
- Departamento de Fitopatologia, Universidade Federal de Viçosa, Viçosa, MG, 36570-000, Brazil
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Dagan Y, Liljeroos K, Jokela J, Ben-Ami F. Clonal diversity driven by parasitism in a freshwater snail. J Evol Biol 2013; 26:2509-19. [PMID: 24118641 DOI: 10.1111/jeb.12245] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Revised: 07/12/2013] [Accepted: 08/12/2013] [Indexed: 11/28/2022]
Abstract
One explanation for the widespread abundance of sexual reproduction is the advantage that genetically diverse sexual lineages have under strong pressure from virulent coevolving parasites. Such parasites are believed to track common asexual host genotypes, resulting in negative frequency-dependent selection that counterbalances the population growth-rate advantage of asexuals in comparison with sexuals. In the face of genetically diverse asexual lineages, this advantage of sexual reproduction might be eroded, and instead sexual populations would be replaced by diverse assemblages of clonal lineages. We investigated whether parasite-mediated selection promotes clonal diversity in 22 natural populations of the freshwater snail Melanoides tuberculata. We found that infection prevalence explains the observed variation in the clonal diversity of M. tuberculata populations, whereas no such relationship was found between infection prevalence and male frequency. Clonal diversity and male frequency were independent of snail population density. Incorporating ecological factors such as presence/absence of fish, habitat geography and habitat type did not improve the predictive power of regression models. Approximately 11% of the clonal snail genotypes were shared among 2-4 populations, creating a web of 17 interconnected populations. Taken together, our study suggests that parasite-mediated selection coupled with host dispersal ecology promotes clonal diversity. This, in return, may erode the advantage of sexual reproduction in M. tuberculata populations.
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Affiliation(s)
- Y Dagan
- Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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Ferrucho RL, Ceresini PC, Ramirez-Escobar UM, McDonald BA, Cubeta MA, García-Domínguez C. The population genetic structure of Rhizoctonia solani AG-3PT from potato in the Colombian Andes. PHYTOPATHOLOGY 2013; 103:862-869. [PMID: 23464900 DOI: 10.1094/phyto-11-12-0278-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The soilborne fungus Rhizoctonia solani anastomosis group 3 (AG-3PT) is a globally important potato pathogen. However, little is known about the population genetic processes affecting field populations of R. solani AG-3PT, especially in the South American Colombian Andes, which is near the center of diversity of the two most common groups of cultivated potato, Solanum tuberosum and S. phureja. We analyzed the genetic structure of 15 populations of R. solani AG-3PT infecting potato in Colombia using 11 simple-sequence repeat (SSR) markers. In total, 288 different multilocus genotypes were identified among 349 fungal isolates. Clonal fractions within field populations were 7 to 33%. RST statistics indicated a very low level of population differentiation overall, consistent with high contemporary gene flow, though moderate differentiation was found for the most distant southern populations. Genotype flow was also detected, with the most common genotype found widely distributed among field populations. All populations showed evidence of a mixed reproductive mode, including both asexual and sexual reproduction, but two populations displayed evidence of inbreeding.
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Lasso E. The importance of setting the right genetic distance threshold for identification of clones using amplified fragment length polymorphism: a case study with five species in the tropical plant genus Piper. Mol Ecol Resour 2013; 8:74-82. [PMID: 21585721 DOI: 10.1111/j.1471-8286.2007.01910.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amplified fragment length polymorphism (AFLP) has been widely used for clone identification, but numerous studies have shown that clonemates do not always present identical AFLP fingerprints. Pairwise AFLP distances that distinguish known clones from nonclones have been used to identify a threshold genetic dissimilarity distance below which samples are considered to represent a single clone. Most studies to date have reported threshold values between 2% and 4%. Here, I determine the consistency of the clonal threshold across five species in the tropical plant genus Piper, and evaluate the sensitivity of genetic diversity indices and estimates of frequency of clonal reproduction to the threshold value selected. I sampled multiple ramets per individual from widely distributed plants for each of the five Piper species to set a threshold at the point where the error rate of clonal assignments was lowest. I then sampled all individuals of each shade-tolerant species in a 1-ha plot, and of each light-demanding species in 25 × 35-m plot, to estimate the frequency of asexual recruitment in natural populations using a series of different thresholds including the threshold set with the preliminary sampling. Clonal threshold values for the different species ranged from 0% to 5% AFLP genetic dissimilarity distance. To determine the sensitivity of estimates of clonal reproduction, I calculated several clonal diversity indexes for the natural populations of each of the five species guided by the range in clonal threshold values observed across the five Piper species. I show that small changes in the value of the clonal threshold can lead to very different conclusions regarding the level of clonal reproduction in natural populations.
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Affiliation(s)
- E Lasso
- Smithsonian Tropical Research Institute, Unit 0948 APO AA 34002-0948, Panama, University of Illinois at Urbana-Champaign, 265 Morrill Hall, 505 Goodwin Ave, IL 61801, USA
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Capewell P, Cooper A, Duffy CW, Tait A, Turner CMR, Gibson W, Mehlitz D, MacLeod A. Human and animal Trypanosomes in Côte d'Ivoire form a single breeding population. PLoS One 2013; 8:e67852. [PMID: 23844111 PMCID: PMC3699513 DOI: 10.1371/journal.pone.0067852] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 05/22/2013] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Trypanosoma brucei is the causative agent of African Sleeping Sickness in humans and contributes to the related veterinary disease, Nagana. T. brucei is segregated into three subspecies based on host specificity, geography and pathology. T. b. brucei is limited to animals (excluding some primates) throughout sub-Saharan Africa and is non-infective to humans due to trypanolytic factors found in human serum. T. b. gambiense and T. b. rhodesiense are human infective sub-species. T. b. gambiense is the more prevalent human, causing over 97% of human cases. Study of T. b. gambiense is complicated in that there are two distinct groups delineated by genetics and phenotype. The relationships between the two groups and local T. b. brucei are unclear and may have a bearing on the evolution of the human infectivity traits. METHODOLOGY/PRINCIPAL FINDINGS A collection of sympatric T. brucei isolates from Côte d'Ivoire, consisting of T. b. brucei and both groups of T. b. gambiense have previously been categorized by isoenzymes, RFLPs and Blood Incubation Infectivity Tests. These samples were further characterized using the group 1 specific marker, TgSGP, and seven microsatellites. The relationships between the T. b. brucei and T. b. gambiense isolates were determined using principal components analysis, neighbor-joining phylogenetics, STRUCTURE, FST, Hardy-Weinberg equilibrium and linkage disequilibrium. CONCLUSIONS/SIGNIFICANCE Group 1 T. b. gambiense form a clonal genetic group, distinct from group 2 and T. b. brucei, whereas group 2 T. b. gambiense are genetically indistinguishable from local T. b. brucei. There is strong evidence for mating within and between group 2 T. b. gambiense and T. b. brucei. We found no evidence to support the hypothesis that group 2 T. b. gambiense are hybrids of group 1 and T. b. brucei, suggesting that human infectivity has evolved independently in groups 1 and 2 T. b. gambiense.
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Affiliation(s)
- Paul Capewell
- Wellcome Trust Centre for Molecular Parasitology, College of Medical, Veterinary and Biological Sciences, Glasgow, United Kingdom
| | - Anneli Cooper
- Wellcome Trust Centre for Molecular Parasitology, College of Medical, Veterinary and Biological Sciences, Glasgow, United Kingdom
| | - Craig W. Duffy
- Wellcome Trust Centre for Molecular Parasitology, College of Medical, Veterinary and Biological Sciences, Glasgow, United Kingdom
| | - Andy Tait
- Wellcome Trust Centre for Molecular Parasitology, College of Medical, Veterinary and Biological Sciences, Glasgow, United Kingdom
| | | | - Wendy Gibson
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - Dieter Mehlitz
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Annette MacLeod
- Wellcome Trust Centre for Molecular Parasitology, College of Medical, Veterinary and Biological Sciences, Glasgow, United Kingdom
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Murat C, Rubini A, Riccioni C, De la Varga H, Akroume E, Belfiori B, Guaragno M, Le Tacon F, Robin C, Halkett F, Martin F, Paolocci F. Fine-scale spatial genetic structure of the black truffle (Tuber melanosporum) investigated with neutral microsatellites and functional mating type genes. THE NEW PHYTOLOGIST 2013; 199:176-187. [PMID: 23574460 DOI: 10.1111/nph.12264] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 02/28/2013] [Indexed: 06/02/2023]
Abstract
The genetic structure of ectomycorrhizal (ECM) fungal populations results from both vegetative and sexual propagation. In this study, we have analysed the spatial genetic structure of Tuber melanosporum populations, a heterothallic ascomycete that produces edible fruit bodies. Ectomycorrhizas from oaks and hazels from two orchards were mapped and genotyped using simple sequence repeat markers and the mating type locus. The distribution of the two T. melanosporum mating types was also monitored in the soil. In one orchard, the genetic profiles of the ascocarps were compared with those of the underlying mycorrhizas. A pronounced spatial genetic structure was found. The maximum genet sizes were 2.35 and 4.70 m in the two orchards, with most manifesting a size < 1 m. Few genets persisted throughout two seasons. A nonrandom distribution pattern of the T. melanosporum was observed, resulting in field patches colonized by genets that shared the same mating types. Our findings suggest that competition occurs between genets and provide basic information on T. melanosporum propagation patterns that are relevant for the management of productive truffle orchards.
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Affiliation(s)
- Claude Murat
- INRA, UMR 1136 INRA Université de Lorraine 'Interactions Arbres-Microorganismes', Labex ARBRE, FR EFABA, 54280, Champenoux, France
| | - Andrea Rubini
- Plant Genetics Institute - Perugia Division, National Research Council, Via della Madonna Alta 130, 06128, Perugia, Italy
| | - Claudia Riccioni
- Plant Genetics Institute - Perugia Division, National Research Council, Via della Madonna Alta 130, 06128, Perugia, Italy
| | - Herminia De la Varga
- INRA, UMR 1136 INRA Université de Lorraine 'Interactions Arbres-Microorganismes', Labex ARBRE, FR EFABA, 54280, Champenoux, France
| | - Emila Akroume
- INRA, UMR 1136 INRA Université de Lorraine 'Interactions Arbres-Microorganismes', Labex ARBRE, FR EFABA, 54280, Champenoux, France
| | - Beatrice Belfiori
- Plant Genetics Institute - Perugia Division, National Research Council, Via della Madonna Alta 130, 06128, Perugia, Italy
| | - Marco Guaragno
- Plant Genetics Institute - Perugia Division, National Research Council, Via della Madonna Alta 130, 06128, Perugia, Italy
| | - François Le Tacon
- INRA, UMR 1136 INRA Université de Lorraine 'Interactions Arbres-Microorganismes', Labex ARBRE, FR EFABA, 54280, Champenoux, France
| | - Christophe Robin
- Université de Lorraine - INRA, UMR 1121 'Agronomie et Environnement Nancy-Colmar', BP 172, 54505, Vandoeuvre les Nancy Cedex, France
| | - Fabien Halkett
- INRA, UMR 1136 INRA Université de Lorraine 'Interactions Arbres-Microorganismes', Labex ARBRE, FR EFABA, 54280, Champenoux, France
| | - Francis Martin
- INRA, UMR 1136 INRA Université de Lorraine 'Interactions Arbres-Microorganismes', Labex ARBRE, FR EFABA, 54280, Champenoux, France
| | - Francesco Paolocci
- Plant Genetics Institute - Perugia Division, National Research Council, Via della Madonna Alta 130, 06128, Perugia, Italy
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Gorospe KD, Karl SA. Genetic relatedness does not retain spatial pattern across multiple spatial scales: dispersal and colonization in the coral,Pocillopora damicornis. Mol Ecol 2013; 22:3721-36. [DOI: 10.1111/mec.12335] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 03/27/2013] [Accepted: 03/29/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Kelvin D. Gorospe
- Hawai‘i Institute of Marine Biology; University of Hawai‘i, Mānoa; PO Box 1346 Kāne‘ohe HI 96744 USA
| | - Stephen A. Karl
- Hawai‘i Institute of Marine Biology; University of Hawai‘i, Mānoa; PO Box 1346 Kāne‘ohe HI 96744 USA
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Pietiläinen M, Korpelainen H. Population genetics of purple saxifrage (Saxifraga oppositifolia) in the high Arctic archipelago of Svalbard. AOB PLANTS 2013; 5:plt024. [PMID: 23700503 PMCID: PMC3660837 DOI: 10.1093/aobpla/plt024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 03/18/2013] [Indexed: 06/02/2023]
Abstract
We investigated patterns of genetic variability in Saxifraga oppositifolia in the isolated Arctic Svalbard archipelago. The genetic analysis included genotyping using nine polymorphic microsatellite markers and sequencing of the nuclear internal transcribed spacer region. Among populations, mean allele numbers per microsatellite locus ranged from 2.0 to 2.6, and 9 % of alleles were unique. Observed (H O) and expected (H E) heterozygosities averaged 0.522 and 0.445, respectively. Typically negative but non-significant F IS values (mean -0.173) were found in S. oppositifolia populations. F ST values were relatively low (mean 0.123). The Bayesian structure analysis provided additional information on population genetic structures. Seven out of 11 studied populations, including populations located both near each other and far apart (distances 5-210 km), showed relatively homogeneous clustering patterns, while one population located on a slope in the main settlement of Longyearbyen possessed a unique genetic structure. The Mantel test proved that there is no significant correlation between genetic and geographical distances. Different growth habits (compact, trailing and intermediate) did not possess distinct genetic compositions based on microsatellite variation. Internal transcribed spacer sequencing revealed 12 polymorphic sites. Among 24 sequenced Svalbard samples, eight haplotypes were detected, none shared by the mainland samples. Population genetic structures of S. oppositifolia in Svalbard show that both genetic variation and differentiation levels are modest, outcrossing is the main mating system, and dispersal and gene flow are important, probably attributable to strong winds and human and animal vectors.
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70
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Brewer MT, Frenkel O, Milgroom MG. Linkage disequilibrium and spatial aggregation of genotypes in sexually reproducing populations of Erysiphe necator. PHYTOPATHOLOGY 2012; 102:997-1005. [PMID: 22755546 DOI: 10.1094/phyto-11-11-0321] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Random mating and recombination in heterothallic ascomycetes should result in high genotypic diversity, 1:1 mating-type ratios, and random associations of alleles, or linkage equilibrium, at different loci. To test for random mating in populations of the grape powdery mildew fungus Erysiphe necator, we sampled isolates from vineyards of Vitis vinifera in Burdett, NY (NY09) and Winchester, VA (VA09) at the end of the epidemic in fall 2009. We also sampled isolates from the same Winchester, VA vineyard in spring 2010 at the onset of the next epidemic. Isolates were genotyped for mating type and 11 microsatellite markers. In the spring sample, which originated from ascospore infections, nearly every isolate had a unique genotype. In contrast, fall populations were less diverse. In all, 9 of 45 total genotypes in VA09 were represented by two or more isolates; 3 of 40 total genotypes in NY09 were represented by two or more isolates, with 1 genotype represented by 20 isolates. After clone correction, mating-type ratios in the three populations did not deviate from 1:1. However, even with clone correction, we detected significant linkage disequilibrium (LD) in all populations. Mantel tests detected positive correlations between genetic and physical distances within vineyards. Spatial autocorrelation showed aggregations up to 42 and 3 m in VA09 and NY09, respectively. Spatial autocorrelation most likely results from short dispersal distances. Overall, these results suggest that spatial genetic aggregation and clonal genotypes that arise during the asexual phase of the epidemic contribute to persistent LD even though populations undergo sexual reproduction annually.
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Affiliation(s)
- Marin Talbot Brewer
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY, USA
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71
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Kronauer DJC, Pierce NE, Keller L. Asexual reproduction in introduced and native populations of the ant Cerapachys biroi. Mol Ecol 2012; 21:5221-35. [PMID: 23013522 DOI: 10.1111/mec.12041] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 07/19/2012] [Accepted: 08/08/2012] [Indexed: 12/11/2022]
Abstract
Asexual reproduction is particularly common among introduced species, probably because it helps to overcome the negative effects associated with low population densities during colonization. The ant Cerapachys biroi has been introduced to tropical and subtropical islands around the world since the beginning of the last century. In this species, workers can reproduce via thelytokous parthenogenesis. Here, we use genetic markers to reconstruct the history of anthropogenic introductions of C. biroi, and to address the prevalence of female parthenogenesis in introduced and native populations. We show that at least four genetically distinct lineages have been introduced from continental Asia and have led to the species' circumtropical establishment. Our analyses demonstrate that asexual reproduction dominates in the introduced range and is also common in the native range. Given that C. biroi is the only dorylomorph ant that has successfully become established outside of its native range, this unusual mode of reproduction probably facilitated the species' worldwide spread. On the other hand, the rare occurrence of haploid males and at least one clear case of sexual recombination in the introduced range show that C. biroi has not lost the potential for sex. Finally, we show that thelytoky in C. biroi probably has a genetic rather than an infectious origin, and that automixis with central fusion is the most likely underlying cytological mechanism. This is in accordance with what is known for other thelytokous eusocial Hymenoptera.
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Affiliation(s)
- Daniel J C Kronauer
- Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138, USA.
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72
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Barrès B, Dutech C, Andrieux A, Halkett F, Frey P. Exploring the role of asexual multiplication in poplar rust epidemics: impact on diversity and genetic structure. Mol Ecol 2012; 21:4996-5008. [DOI: 10.1111/mec.12008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 07/06/2012] [Accepted: 07/15/2012] [Indexed: 11/28/2022]
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Erler S, Popp M, Wolf S, Lattorff HMG. Sex, horizontal transmission, and multiple hosts prevent local adaptation of Crithidia bombi, a parasite of bumblebees (Bombus spp.). Ecol Evol 2012; 2:930-40. [PMID: 22837838 PMCID: PMC3399159 DOI: 10.1002/ece3.250] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 02/28/2012] [Accepted: 02/29/2012] [Indexed: 12/04/2022] Open
Abstract
Local adaptation within host-parasite systems can evolve by several non-exclusive drivers (e.g., host species-genetic adaptation; ecological conditions-ecological adaptation, and time-temporal adaptation). Social insects, especially bumblebees, with an annual colony life history not only provide an ideal system to test parasite transmission within and between different host colonies, but also parasite adaptation to specific host species and environments. Here, we study local adaptation in a multiple-host parasite characterized by high levels of horizontal transmission. Crithidia bombi occurs as a gut parasite in several bumblebee species. Parasites were sampled from five different host species in two subsequent years. Population genetic tools were used to test for the several types of adaptation. Although we found no evidence for local adaptation of the parasite toward host species, there was a slight temporal differentiation of the parasite populations, which might have resulted from severe bottlenecks during queen hibernation. Parasite populations were in Hardy-Weinberg equilibrium and showed no signs of linkage disequilibrium suggesting that sexual reproduction is an alternative strategy in this otherwise clonal parasite. Moreover, high levels of multiple infections were found, which might facilitate sexual genetic exchange. The detection of identical clones in different host species suggested that horizontal transmission occurs between host species and underpins the lack of host-specific adaptation.
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Affiliation(s)
- Silvio Erler
- Institut für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-WittenbergHoher Weg 4, 06099 Halle (Saale), Germany
- Present address: Departamentul de Tehnologii Apicole şi Sericicole, Universitatea de Ştiinţe Agricole şi Medicină VeterinarăCalea Mănăştur 3–5, 400372, Cluj-Napoca, Romania
| | - Mario Popp
- Institut für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-WittenbergHoher Weg 4, 06099 Halle (Saale), Germany
| | - Stephan Wolf
- Institut für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-WittenbergHoher Weg 4, 06099 Halle (Saale), Germany
- Present address: Department of Plant and Invertebrate Ecology, Rothamsted ResearchAL5 2JQ Harpenden, United Kingdom
| | - H Michael G Lattorff
- Institut für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-WittenbergHoher Weg 4, 06099 Halle (Saale), Germany
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Ivens ABF, Kronauer DJC, Pen I, Weissing FJ, Boomsma JJ. Reproduction and dispersal in an ant-associated root aphid community. Mol Ecol 2012; 21:4257-69. [PMID: 22804757 DOI: 10.1111/j.1365-294x.2012.05701.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Clonal organisms with occasional sex are important for our general understanding of the costs and benefits that maintain sexual reproduction. Cyclically parthenogenetic aphids are highly variable in their frequency of sexual reproduction. However, studies have mostly focused on free-living aphids above ground, whereas dispersal constraints and dependence on ant-tending may differentially affect the costs and benefits of sex in subterranean aphids. Here, we studied reproductive mode and dispersal in a community of root aphids that are obligately associated with the ant Lasius flavus. We assessed the genetic population structure of four species (Geoica utricularia, Tetraneura ulmi, Forda marginata and Forda formicaria) in a Dutch population and found that all species reproduce predominantly if not exclusively asexually, so that populations consist of multiple clonal lineages. We show that population viscosity is high and winged aphids rare, consistent with infrequent horizontal transmission between ant host colonies. The absence of the primary host shrub (Pistacia) may explain the absence of sex in three of the studied species, but elm trees (Ulmus) that are primary hosts of the fourth species (T. ulmi) occurred within a few km of the study population. We discuss the extent to which obligate ant-tending and absence of primary hosts may have affected selection for permanent parthenogenesis, and we highlight the need for further study of these aphids in Southern Europe where primary hosts may occur close to L. flavus populations, so that all four root aphid species would have realistic opportunities for completing their sexual life cycle.
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Affiliation(s)
- A B F Ivens
- Theoretical Biology, Centre for Ecological and Evolutionary Studies, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands.
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Ivens ABF, Kronauer DJC, Pen I, Weissing FJ, Boomsma JJ. Ants farm subterranean aphids mostly in single clone groups--an example of prudent husbandry for carbohydrates and proteins? BMC Evol Biol 2012; 12:106. [PMID: 22747564 PMCID: PMC3499235 DOI: 10.1186/1471-2148-12-106] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 05/16/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mutualistic interactions are wide-spread but the mechanisms underlying their evolutionary stability and ecological dynamics remain poorly understood. Cultivation mutualisms in which hosts consume symbionts occur in phylogenetically diverse groups, but often have symbiont monocultures for each host. This is consistent with the prediction that symbionts should avoid coexistence with other strains so that host services continue to benefit relatives, but it is less clear whether hosts should always favor monocultures and what mechanisms they might have to manipulate symbiont diversity. Few mutualisms have been studied in sufficient genetic detail to address these issues, so we decided to characterize symbiont diversity in the complex mutualism between multiple root aphid species and Lasius flavus ants. After showing elsewhere that three of these aphid species have low dispersal and mostly if not exclusively asexual reproduction, we here investigate aphid diversity within and between ant nest mounds. RESULTS The three focal species (Geoica utricularia, Forda marginata and Tetraneura ulmi) had considerable clonal diversity at the population level. Yet more than half of the ant mounds contained just a single aphid species, a significantly higher percentage than expected from a random distribution. Over 60% of these single-species mounds had a single aphid clone, and clones tended to persist across subsequent years. Whenever multiple species/clones co-occurred in the same mound, they were spatially separated with more than 95% of the aphid chambers containing individuals of a single clone. CONCLUSIONS L. flavus "husbandry" is characterized by low aphid "livestock" diversity per colony, especially at the nest-chamber level, but it lacks the exclusive monocultures known from other cultivation mutualisms. The ants appear to eat most of the early instar aphids, so that adult aphids are unlikely to face limited phloem resources and scramble competition with other aphids. We suggest that such culling of carbohydrate-providing symbionts for protein ingestion may maintain maximal host yield per aphid while also benefitting the domesticated aphids as long as their clone-mates reproduce successfully. The cost-benefit logic of this type of polyculture husbandry has striking analogies with human farming practices based on slaughtering young animals for meat to maximize milk-production by a carefully regulated adult livestock population.
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Affiliation(s)
- Aniek B F Ivens
- Theoretical Biology, Centre for Ecological and Evolutionary Studies, University of Groningen, Groningen, The Netherlands.
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76
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XHAARD CONSTANCE, BARRÈS BENOÎT, ANDRIEUX AXELLE, BOUSSET LYDIA, HALKETT FABIEN, FREY PASCAL. Disentangling the genetic origins of a plant pathogen during disease spread using an original molecular epidemiology approach. Mol Ecol 2012; 21:2383-98. [DOI: 10.1111/j.1365-294x.2012.05556.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Minimal genetic diversity in the facultatively outcrossing perennial pepperweed (Lepidium latifolium) invasion. Biol Invasions 2012. [DOI: 10.1007/s10530-012-0190-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Fine-scale temporal and spatial variation of taxon and clonal structure in the Daphnia longispina hybrid complex in heterogeneous environments. BMC Evol Biol 2012; 12:12. [PMID: 22280487 PMCID: PMC3305588 DOI: 10.1186/1471-2148-12-12] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 01/27/2012] [Indexed: 11/16/2022] Open
Abstract
Background Cyclical parthenogenetic water fleas of the genus Daphnia have become a prominent model organism in ecology and evolution. In the past, analyses of their population structure have been limited by the prevailing use of allozyme markers, which in general do not allow for the distinction of individual clones. In this study, we used 10 microsatellite markers to track changes in the taxonomic and clonal composition of Daphnia populations, and traced the abundance of the most common clones in two European reservoirs. One of the localities was inhabited by a single species of the Daphnia longispina complex (D. galeata), the other by two parental species (D. galeata and D. longispina) and their interspecific hybrids. The study took place during the transition from summer stratification to autumn mixing, representing a period of major environmental change within lake habitats. Results In both reservoirs, we observed temporal (generation-to-generation) and spatial (along the heterogeneous reservoir environment) changes in Daphnia community structure. In the single-species reservoir, the clonal diversity of D. galeata increased with time, as a few dominant clones were replaced by a higher number of less common clones. A loss in selective advantage for the dominant clones may have been due to gradual changes in the environment, or due to selection acting in a negative frequency-dependent manner. In the multispecies reservoir, there were no apparent temporal trends in clonal diversity but we observed significantly lower clonal diversity in the interspecific hybrids than in the coexisting parental species, supporting the existence of reproductive barriers between the parental genomes. Conclusions Our study, tracing clonal lineages of Daphnia in time and space by the fine-resolution markers, contributes to the understanding of how clonal reproduction impacts community structure in cyclically parthenogenetic organisms.
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Abstract
Knowledge of the functioning, health state, and capacity for recovery of marine benthic organisms and assemblages has become essential to adequately manage and preserve marine biodiversity. Molecular tools have allowed an entirely new way to tackle old and new questions in conservation biology and ecology, and sponge science is following this lead. In this review, we discuss the biological and ecological studies of sponges that have used molecular markers during the past 20 years and present an outlook for expected trends in the molecular ecology of sponges in the near future. We go from (1) the interface between inter- and intraspecies studies, to (2) phylogeography and population level analyses, (3) intra-population features such as clonality and chimerism, and (4) environmentally modulated gene expression. A range of molecular markers has been assayed with contrasting success to reveal cryptic species and to assess the genetic diversity and connectivity of sponge populations, as well as their capacity to respond to environmental changes. We discuss the pros and cons of the molecular gene partitions used to date and the prospects of a plentiful supply of new markers for sponge ecological studies in the near future, in light of recently available molecular technologies. We predict that molecular ecology studies of sponges will move from genetics (the use of one or some genes) to genomics (extensive genome or transcriptome sequencing) in the forthcoming years and that sponge ecologists will take advantage of this research trend to answer ecological and biological questions that would have been impossible to address a few years ago.
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Affiliation(s)
- Maria J Uriz
- Department of Marine Ecology, Centre d'Estudis Avançats de Blanes (CEAB-CSIC), Blanes, Girona, Spain.
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80
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Kreivi M, Aspi J, Leskinen E. Regional and local spatial genetic structure of Siberian primrose populations in Northern Europe. CONSERV GENET 2011. [DOI: 10.1007/s10592-011-0252-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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XHAARD C, FABRE B, ANDRIEUX A, GLADIEUX P, BARRÈS B, FREY P, HALKETT F. The genetic structure of the plant pathogenic fungus Melampsora larici-populina on its wild host is extensively impacted by host domestication. Mol Ecol 2011; 20:2739-55. [DOI: 10.1111/j.1365-294x.2011.05138.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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82
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CARLON DAVIDB, LIPPÉ CATHERINE. Estimation of mating systems in Short and Tall ecomorphs of the coral Favia fragum. Mol Ecol 2011; 20:812-28. [DOI: 10.1111/j.1365-294x.2010.04983.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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83
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YIN MINGBO, WOLINSKA JUSTYNA, GIEßLER SABINE. Clonal diversity, clonal persistence and rapid taxon replacement in natural populations of species and hybrids of the Daphnia longispina complex. Mol Ecol 2010; 19:4168-78. [DOI: 10.1111/j.1365-294x.2010.04807.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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84
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Parra F, Casas A, Peñaloza-Ramírez JM, Cortés-Palomec AC, Rocha-Ramírez V, González-Rodríguez A. Evolution under domestication: ongoing artificial selection and divergence of wild and managed Stenocereus pruinosus (Cactaceae) populations in the Tehuacan Valley, Mexico. ANNALS OF BOTANY 2010; 106:483-96. [PMID: 20729372 PMCID: PMC2924835 DOI: 10.1093/aob/mcq143] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Revised: 05/27/2010] [Accepted: 06/04/2010] [Indexed: 05/10/2023]
Abstract
BACKGROUND AND AIMS The Tehuacán Valley in Mexico is a principal area of plant domestication in Mesoamerica. There, artificial selection is currently practised on nearly 120 native plant species with coexisting wild, silvicultural and cultivated populations, providing an excellent setting for studying ongoing mechanisms of evolution under domestication. One of these species is the columnar cactus Stenocereus pruinosus, in which we studied how artificial selection is operating through traditional management and whether it has determined morphological and genetic divergence between wild and managed populations. METHODS Semi-structured interviews were conducted with 83 households of three villages to investigate motives and mechanisms of artificial selection. Management effects were studied by comparing variation patterns of 14 morphological characters and population genetics (four microsatellite loci) of 264 plants from nine wild, silvicultural and cultivated populations. KEY RESULTS Variation in fruit characters was recognized by most people, and was the principal target of artificial selection directed to favour larger and sweeter fruits with thinner or thicker peel, fewer spines and pulp colours other than red. Artificial selection operates in agroforestry systems favouring abundance (through not felling plants and planting branches) of the preferred phenotypes, and acts more intensely in household gardens. Significant morphological divergence between wild and managed populations was observed in fruit characters and plant vigour. On average, genetic diversity in silvicultural populations (H(E) = 0.743) was higher than in wild (H(E) = 0.726) and cultivated (H(E) = 0.700) populations. Most of the genetic variation (90.58 %) occurred within populations. High gene flow (Nm(FST) > 2) was identified among almost all populations studied, but was slightly limited by mountains among wild populations, and by artificial selection among wild and managed populations. CONCLUSIONS Traditional management of S. pruinosus involves artificial selection, which, despite the high levels of gene flow, has promoted morphological divergence and moderate genetic structure between wild and managed populations, while conserving genetic diversity.
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Affiliation(s)
| | - Alejandro Casas
- Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México, campus Morelia, Apartado Postal 27-3 (Santa María de Guido), Morelia, Michoacán, 58190, México
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85
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Steinauer ML, Blouin MS, Criscione CD. Applying evolutionary genetics to schistosome epidemiology. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2010; 10:433-43. [PMID: 20176142 PMCID: PMC2861999 DOI: 10.1016/j.meegid.2010.02.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 02/09/2010] [Accepted: 02/15/2010] [Indexed: 10/19/2022]
Abstract
We review how molecular markers and evolutionary analysis have been applied to the study of schistosome parasites, important pathogens that infect over 200 million people worldwide. Topics reviewed include phylogenetics and biogeography, hybridization, infection within snails, mating systems, and genetic structure. Some interesting generalizations include that schistosome species hybridize frequently and have switched definitive hosts repeatedly in evolutionary time. We show that molecular markers can be used to infer epidemiologically relevant processes such as spatial variation in transmission, or to reveal complex patterns of mate choice. Analysis of genetic structure data shows that transmission foci can be structured by watershed boundaries, habitat types, and host species. We also discuss sampling and analytical problems that arise when using larvae to estimate genetic parameters of adult schistosome populations. Finally, we review pitfalls in methodologies such as genotyping very small individuals, statistical methods for identifying clonemates or for identifying sibling groups, and estimating allele frequencies from pooled egg samples.
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Affiliation(s)
- Michelle L Steinauer
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, 105 Magruder Hall, Corvallis, OR 97331, United States.
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86
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Duffy CW, Morrison LJ, Black A, Pinchbeck GL, Christley RM, Schoenefeld A, Tait A, Turner CMR, MacLeod A. Trypanosoma vivax displays a clonal population structure. Int J Parasitol 2009; 39:1475-83. [PMID: 19520081 DOI: 10.1016/j.ijpara.2009.05.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2009] [Revised: 05/21/2009] [Accepted: 05/22/2009] [Indexed: 10/20/2022]
Abstract
African animal trypanosomiasis, or Nagana, is a debilitating and economically costly disease with a major impact on animal health in sub-Saharan Africa. Trypanosoma vivax, one of the principal trypanosome species responsible for the disease, infects a wide host range including cattle, goats, horses and donkeys and is transmitted both cyclically by tsetse flies and mechanically by other biting flies, resulting in a distribution covering large swathes of South America and much of sub-Saharan Africa. While there is evidence for mating in some of the related trypanosome species, Trypanosoma brucei, Trypanosoma congolense and Trypanosoma cruzi, very little work has been carried out to examine this question in T. vivax. Understanding whether mating occurs in T. vivax will provide insight into the dynamics of trait inheritance, for example the spread of drug resistance, as well as examining the origins of meiosis in the order Kinetoplastida. With this in mind we have identified orthologues of eight core meiotic genes within the genome, the presence of which imply that the potential for mating exists in this species. In order to address whether mating occurs, we have investigated a sympatric field population of T. vivax collected from livestock in The Gambia, using microsatellite markers developed for this species. Our analysis has identified a clonal population structure showing significant linkage disequilibrium, homozygote deficits and disagreement with Hardy-Weinberg predictions at six microsatellite loci, indicative of a lack of mating in this population of T. vivax.
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Affiliation(s)
- Craig W Duffy
- Wellcome Centre for Molecular Parasitology, Glasgow Biomedical Research Centre, Faculty of Veterinary Medicine, University of Glasgow, Glasgow G12 8TA, United Kingdom
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87
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Discovery of mating in the major African livestock pathogen Trypanosoma congolense. PLoS One 2009; 4:e5564. [PMID: 19440370 PMCID: PMC2679202 DOI: 10.1371/journal.pone.0005564] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Accepted: 04/12/2009] [Indexed: 12/04/2022] Open
Abstract
The protozoan parasite, Trypanosoma congolense, is one of the most economically important pathogens of livestock in Africa and, through its impact on cattle health and productivity, has a significant effect on human health and well being. Despite the importance of this parasite our knowledge of some of the fundamental biological processes is limited. For example, it is unknown whether mating takes place. In this paper we have taken a population genetics based approach to address this question. The availability of genome sequence of the parasite allowed us to identify polymorphic microsatellite markers, which were used to genotype T. congolense isolates from livestock in a discrete geographical area of The Gambia. The data showed a high level of diversity with a large number of distinct genotypes, but a deficit in heterozygotes. Further analysis identified cryptic genetic subdivision into four sub-populations. In one of these, parasite genotypic diversity could only be explained by the occurrence of frequent mating in T. congolense. These data are completely inconsistent with previous suggestions that the parasite expands asexually in the absence of mating. The discovery of mating in this species of trypanosome has significant consequences for the spread of critical traits, such as drug resistance, as well as for fundamental aspects of the biology and epidemiology of this neglected but economically important pathogen.
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88
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Kanbe T, Akimoto SI. Allelic and genotypic diversity in long-term asexual populations of the pea aphid, Acyrthosiphon pisum in comparison with sexual populations. Mol Ecol 2009; 18:801-16. [PMID: 19207245 DOI: 10.1111/j.1365-294x.2008.04077.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Many aphid species exhibit geographical variation in the mode of reproduction that ranges from cyclical parthenogenesis with a sexual phase to obligate parthenogenesis (asexual reproduction). Theoretical studies predict that organisms reproducing asexually should maintain higher allelic diversity per locus but lower genotypic diversity than organisms reproducing sexually. To corroborate this hypothesis, we evaluated genotypic and allelic diversities in the sexual and asexual populations of the pea aphid, Acyrthosiphon pisum (Harris). Microsatellite analysis revealed that populations in central Japan are asexual, whereas populations in northern Japan are obligatorily sexual. No mixed populations were detected in our study sites. Phylogenetic analysis using microsatellite data and mitochondrial cytochrome oxidase subunit I (COI) gene sequences revealed a long history of asexuality in central Japan and negated the possibility of the recent origin of the asexual populations from the sexual populations. Asexual populations exhibited much lower genotypic diversity but higher allelic richness per locus than did sexual populations. Asexual populations consisted of a few predominant clones that were considerably differentiated from one another. Sexual populations on alfalfa, an exotic plant in Japan, were most closely related to asexual populations associated with Vicia sativa L. The alfalfa-associated sexual populations harboured one COI haplotype that was included in the haplotype clade of the asexual populations. Available evidence suggests that the sexuality of the alfalfa-associated populations has recently been restored through the northward migration and colonization of alfalfa by V. sativa-associated lineages. Therefore, our results support the theoretical predictions and provide a new perspective on the origin of sexual populations.
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Affiliation(s)
- Takashi Kanbe
- Systematic Entomology, Department of Ecology and Systematics, Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan.
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89
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Trypanosoma brucei gambiense Type 1 populations from human patients are clonal and display geographical genetic differentiation. INFECTION GENETICS AND EVOLUTION 2008; 8:847-54. [DOI: 10.1016/j.meegid.2008.08.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2008] [Revised: 08/11/2008] [Accepted: 08/15/2008] [Indexed: 11/19/2022]
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90
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Abstract
Worldwide degradation of coral reef communities has prompted a surge in restoration efforts. They proceed largely without considering genetic factors because traditionally, coral populations have been regarded as open over large areas with little potential for local adaptation. Since, biophysical and molecular studies indicated that most populations are closed over shorter time and smaller spatial scales. Thus, it is justified to re-examine the potential for site adaptation in corals. There is ample evidence for differentiated populations, inbreeding, asexual reproduction and the occurrence of ecotypes, factors that may facilitate local adaptation. Discovery of widespread local adaptation would influence coral restoration projects mainly with regard to the physical and evolutionary distance from the source wild and/or captive bred propagules may be moved without causing a loss of fitness in the restored population. Proposed causes for loss of fitness as a result of (plant) restoration efforts include founder effects, genetic swamping, inbreeding and/or outbreeding depression. Direct evidence for any of these processes is scarce in reef corals due to a lack of model species that allow for testing over multiple generations and the separation of the relative contributions of algal symbionts and their coral hosts to the overall performance of the coral colony. This gap in our knowledge may be closed by employing novel population genetic and genomics approaches. The use of molecular tools may aid managers in the selection of appropriate propagule sources, guide spatial arrangement of transplants, and help in assessing the success of coral restoration projects by tracking the performance of transplants, thereby generating important data for future coral reef conservation and restoration projects.
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Affiliation(s)
- Iliana B Baums
- Department of Biology, The Pennsylvania State University, 208 Mueller Laboratory, University Park, PA, USA.
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91
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Muller F, Voccia M, Bâ A, Bouvet JM. Genetic diversity and gene flow in a Caribbean tree Pterocarpus officinalis Jacq.: a study based on chloroplast and nuclear microsatellites. Genetica 2008; 135:185-98. [DOI: 10.1007/s10709-008-9268-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Accepted: 04/13/2008] [Indexed: 11/30/2022]
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92
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Genetic structure of the poplar rust fungus Melampsora larici-populina: evidence for isolation by distance in Europe and recent founder effects overseas. INFECTION GENETICS AND EVOLUTION 2008; 8:577-87. [PMID: 18499532 DOI: 10.1016/j.meegid.2008.04.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Revised: 04/09/2008] [Accepted: 04/11/2008] [Indexed: 11/21/2022]
Abstract
Dispersal has a great impact on the genetic structure of populations, but remains difficult to estimate by direct measures. In particular, gradual and stochastic dispersal are often difficult to assess and to distinguish, although they have different evolutionary consequences. Plant pathogens, especially rust fungi, are suspected to display both dispersal modes, though on different spatial scales. In this study, we inferred dispersal capacities of the poplar rust fungus Melampsora larici-populina by examining the genetic diversity and structure of 13 populations from eight European and two overseas countries in the Northern hemisphere. M. larici-populina was sampled from both cultivated hybrid poplars and on the wild host, Populus nigra. The populations were analyzed with 11 microsatellite and 8 virulence markers. Although isolates displayed different virulence profiles according to the host plant, neutral markers revealed little population differentiation with respect to the type of host. This suggests an absence of reproductive isolation between populations sampled from cultivated and wild poplars. Conversely, studying the relationship between geographic and genetic structure allowed us to distinguish between isolation by distance (IBD) patterns and long distance dispersal (LDD) events. The European populations exhibited a significant IBD pattern, suggesting a regular and gradual dispersal of the pathogen over this spatial scale. Nonetheless, the genetic differentiation between these populations was low, suggesting an important gene flow on a continental scale. The two overseas populations from Iceland and Canada were shown to result from rare LDD events, and exhibited signatures of strong founder effects. Furthermore, the high genetic differentiation between both populations suggested that these two recent introductions were independent. This study illustrated how the proper use of population genetics methods can enable contrasted dispersal modes to be revealed.
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93
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Nassar NMA, Kalkmann DC, Collevatti R. A further study of microsatellite on apomixis in cassava. Hereditas 2007; 144:181-4. [PMID: 18031351 DOI: 10.1111/j.2007.0018-0661.01961.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Cassava is the main staple crop in the tropics. It is vegetatively propagated by stem cuttings that maintain superior genotypes, but favors disease accumulation. In this report we present the results of the screening of the progeny and the second generation of the clone UnB 307 for apomixis using microsatellites. A total of 29 plants were screened, representing the maternal plant, its first and second generations, that were left to open pollination. About 20% of the offspring were rated as genetically identical plants. This result confirms the facultative apomictic nature of cassava, with high environment effect.
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Affiliation(s)
- Nagib M A Nassar
- Departamento de Genética e Morfologia, Universidade de Brasília, Brasília, Brasil.
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94
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Calderón I, Ortega N, Duran S, Becerro M, Pascual M, Turon X. Finding the relevant scale: clonality and genetic structure in a marine invertebrate (Crambe crambe, Porifera). Mol Ecol 2007; 16:1799-810. [PMID: 17444893 DOI: 10.1111/j.1365-294x.2007.03276.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Important changes in genetic relatedness may occur at extremely small scales in benthic invertebrates, providing key information about structuring processes in populations of these organisms. We performed a small-scale study of the population structure of the sponge Crambe crambe, in which 177 individuals from the same rocky wall (interindividual distances from 0 to 7 m) were genotyped using six microsatellite markers. 101 sponges had unique genotypes and the remaining 76 individuals formed 24 groups of sponges sharing genotypes (clones). Mean intraclone distances were found to be c. 20 cm. Spatial autocorrelation analyses showed a drastic decrease in genetic relatedness over the first 100 cm of distance. If the contribution of clonality to this pattern was eliminated, the trend was attenuated, but remained a marked one and was still significant within the first distance classes (30-40 cm). Estimated mean dispersal distances per generation were c. 35 cm, and neighbourhood sizes were estimated at c. 33 sponges. Genetic similarities with sponges of the same locality, or from other Mediterranean localities, were within the same range as those found in sponges 2-7 m apart. It is concluded that asexual reproduction plays an important role in structuring populations in this species. However, over and above the effects of clonality, a strong fine-scale genetic structure was present at distances in the range of tens of centimetres, probably as a result of short dispersal of larvae. This fine-scale genetic structure may be common in invertebrates with lecitotrophic larvae.
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Affiliation(s)
- Isabel Calderón
- Department of Animal Biology, Faculty of Biology, University of Barcelona, 645, Diagonal Ave, 08028 Barcelona, Spain
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95
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Arnaud-Haond S, Duarte CM, Alberto F, Serrão EA. Standardizing methods to address clonality in population studies. Mol Ecol 2007; 16:5115-39. [PMID: 17944846 DOI: 10.1111/j.1365-294x.2007.03535.x] [Citation(s) in RCA: 326] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Although clonal species are dominant in many habitats, from unicellular organisms to plants and animals, ecological and particularly evolutionary studies on clonal species have been strongly limited by the difficulty in assessing the number, size and longevity of genetic individuals within a population. The development of molecular markers has allowed progress in this area, and although allozymes remain of limited use due to their typically low level of polymorphism, more polymorphic markers have been discovered during the last decades, supplying powerful tools to overcome the problem of clonality assessment. However, population genetics studies on clonal organisms lack a standardized framework to assess clonality, and to adapt conventional data analyses to account for the potential bias due to the possible replication of the same individuals in the sampling. Moreover, existing studies used a variety of indices to describe clonal diversity and structure such that comparison among studies is difficult at best. We emphasize the need for standardizing studies on clonal organisms, and particularly on clonal plants, in order to clarify the way clonality is taken into account in sampling designs and data analysis, and to allow further comparison of results reported in distinct studies. In order to provide a first step towards a standardized framework to address clonality in population studies, we review, on the basis of a thorough revision of the literature on population structure of clonal plants and of a complementary revision on other clonal organisms, the indices and statistics used so far to estimate genotypic or clonal diversity and to describe clonal structure in plants. We examine their advantages and weaknesses as well as various conceptual issues associated with statistical analyses of population genetics data on clonal organisms. We do so by testing them on results from simulations, as well as on two empirical data sets of microsatellites of the seagrasses Posidonia oceanica and Cymodocea nodosa. Finally, we also propose a selection of new indices and methods to estimate clonal diversity and describe clonal structure in a way that should facilitate comparison between future studies on clonal plants, most of which may be of interest for clonal organisms in general.
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Affiliation(s)
- S Arnaud-Haond
- CCMAR - CIMAR Laboratório Associado, Univ. Algarve, Gambelas, 8005-139, Faro, Portugal.
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96
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Thiele EA, Sorensen RE, Gazzinelli A, Minchella DJ. Genetic diversity and population structuring of Schistosoma mansoni in a Brazilian village. Int J Parasitol 2007; 38:389-99. [PMID: 17825305 PMCID: PMC2476926 DOI: 10.1016/j.ijpara.2007.07.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2007] [Revised: 07/07/2007] [Accepted: 07/10/2007] [Indexed: 11/20/2022]
Abstract
The digenean trematode Schistosoma mansoni is responsible for chronic schistosomiasis worldwide, and in Brazil alone an estimated 35 million people are at risk. To evaluate epidemiological patterns among human definitive hosts, we assessed genetic diversity and population subdivision of S. mansoni infrapopulations in human hosts from the highly endemic village of Virgem das Graças in the state of Minas Gerais, Brazil. We believe this is the largest such survey to date. Genetic diversity of parasites, measured over eight polymorphic microsatellite loci, was relatively high and standard measures of inbreeding indicated that the population was panmictic. Furthermore, there was no significant isolation-by-distance of parasite infrapopulations, and measures of population subdivision indicated significant but low to moderate levels of population differentiation. We conclude that patients within this village sample from a broad range of schistosome genetic diversity and effectively act as "genetic mixing bowls" for the parasites. These results contrast with those previously observed in the Brazilian village of Melqui ades and thus provide the opportunity for comparisons of environmental and epidemiological differences that are likely to influence host-parasite coevolution and parasite transmission.
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Affiliation(s)
- E A Thiele
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.
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97
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Criscione CD, Blouin MS. MINIMAL SELFING, FEW CLONES, AND NO AMONG‐HOST GENETIC STRUCTURE IN A HERMAPHRODITIC PARASITE WITH ASEXUAL LARVAL PROPAGATION. Evolution 2007. [DOI: 10.1111/j.0014-3820.2006.tb01136.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
| | - Michael S. Blouin
- Department of Zoology, Oregon State University, Corvallis, Oregon 97331
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98
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Keeney DB, Waters JM, Poulin R. Clonal diversity of the marine trematode Maritrema novaezealandensis within intermediate hosts: the molecular ecology of parasite life cycles. Mol Ecol 2007; 16:431-9. [PMID: 17217355 DOI: 10.1111/j.1365-294x.2006.03143.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We quantified the clonal diversity of the New Zealand marine trematode Maritrema novaezealandensis (n = 1250) within Zeacumantus subcarinatus snail (n = 25) and Macrophthalmus hirtipes crab (n = 25) intermediate hosts using four to six microsatellite loci, and investigated the potential biological and physical factors responsible for the observed genetic patterns. Individual snails harboured one to five trematode genotypes and 48% of snails were infected by multiple parasite genotypes. Overall, the number of parasite genotypes did not increase with snail size, but was highest in intermediate-sized snails. Significantly larger numbers of parasite genotypes were detected in crabs (relative to snails; P < 0.001), with 16-25 genotypes recovered from individual crabs. Although crabs are typically infected by small numbers of cercariae sourced from many snails, they are occasionally infected by large numbers of cercariae sourced from single snails. The latter cases explain the significant genetic differentiation of trematode populations detected among their crab hosts (F(ST) = 0.009, P < 0.001). Our results suggest that the timing of infection and/or intraspecific competition among parasite clones within snails determine(s) the diversity of parasite clones that snails harbour. The presence of a large number of infected snails and tidal mixing of cercariae prior to infection results in crabs potentially harbouring hundreds of parasite genotypes despite the crabs' territorial behaviour.
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Affiliation(s)
- Devon B Keeney
- Department of Zoology, University of Otago, Dunedin, New Zealand.
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99
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Keeney DB, Waters JM, Poulin R. Diversity of trematode genetic clones within amphipods and the timing of same-clone infections. Int J Parasitol 2007; 37:351-7. [PMID: 17188274 DOI: 10.1016/j.ijpara.2006.11.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2006] [Revised: 11/02/2006] [Accepted: 11/06/2006] [Indexed: 10/23/2022]
Abstract
The genetic diversity of trematodes within second intermediate hosts has important implications for the evolution of trematode populations as these hosts are utilized after the parasites reproduce asexually within first intermediate hosts and before sexual reproduction within definitive hosts. We characterised the genetic clonal diversity of the marine trematode Maritrema novaezealandensis within amphipod (Paracalliope novizealandiae) second intermediate hosts using four to six microsatellite loci to determine if multiple copies of identical trematode clones existed within naturally infected amphipods. To determine the relative timing of infections by identical clones within hosts, trematode metacercariae were assigned to six developmental stages and the stages of identical clones were compared. The genotypes of 306 trematodes were determined from 44 amphipods each containing more than one trematode. Six pairs of identical trematode clones were recovered in total (representing five amphipods: 11% of amphipods with greater than one trematode) and all pairs of clones belonged to the same developmental stage. This suggests that identical clone infections are effectively synchronous. A general decrease in the number of metacercariae recovered, prevalence, and mean intensity of infection for each subsequent developmental stage coupled with large numbers of metacercariae (>9) only being recovered from recent infections, supports the occurrence of post-infection amphipod mortality and/or within-host trematode mortality. Taken together, our results indicate that natural infections are characterised by high genetic diversity, but that amphipods also periodically encounter "batches" of genetically identical clones, potentially setting the stage for interactions within and between clonal groups inside the host.
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Affiliation(s)
- Devon B Keeney
- Department of Zoology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
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100
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Vorwerk S, Forneck A. Reproductive mode of grape phylloxera (Daktulosphaira vitifoliae, Homoptera: Phylloxeridae) in Europe: molecular evidence for predominantly asexual populations and a lack of gene flow between them. Genome 2006; 49:678-87. [PMID: 16936847 DOI: 10.1139/g06-028] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The genetic structure of European grape phylloxera populations, Daktulosphaira vitifoliae (Homoptera: Phylloxeridae), was analyzed using 6 polymorphic microsatellite markers. Genetic diversity data of 6 populations originating from northern and southern European viticultural regions was assessed for geographic differences, and the structure of 2 additional populations was examined in more detail, focusing on specific host plant and habitat characteristics. To test for "signatures" of clonal reproduction, different population genetic measures were applied to the data obtained from these populations. A total of 195 multilocus genotypes were detected in 360 individuals tested. Significant deviations from Hardy-Weinberg equilibrium, negative FIS values (from -0.148 to -0.658 per population), and the presence of multicopy genotypes revealed that the current major reproductive mode at each of the locations tested was asexual. The high genotypic diversity detected within and among populations, however, together with the occurrence of unique D. vitifoliae genotypes, indicates sexual recombination events took place, probably prior to the multiple introductions into Europe. The absence of overlapping genotypes between the sampling sites suggests low migration rates among the populations studied and implies that the main mode of insect dispersal is through infested plant material carried by human agency. The specific features of European D. vitifoliae habitats are illustrated to discuss the role of habitat and life cycle in the genetic structure of this globally important pest aphid species.
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Affiliation(s)
- Sonja Vorwerk
- Department of Special Crop Cultivation and Crop Physiology, Section of Viticulture, 370a, University of Hohenheim, D-70593 Stuttgart, Germany
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