خيارات البحث
النتائج 1 - 10 من 3,033
Analysis of mitochondrial D-loop region casts new light on domestic water buffalo (Bubalus bubalis) phylogeny النص الكامل
2004
Kierstein, G. | Vallinoto, M. | Silva, A. | Schneider, M.P. | Iannuzzi, L. | Brenig, B.
The phylogeny of water buffaloes (Bubalus bubalis) is still a matter of discussion, especially if the two types of domestic water buffalo (swamp and river) derived from different domestication events or if they are products of human selection. To obtain more insight, we analyzed the entire mitochondrial D-loop region of 80 water buffaloes of four different breeds, i.e., 19 swamp buffaloes (Carabao) and 61 river buffaloes (Murrah, Jafarabadi, and Mediterranean), sampled in Brazil and Italy. We detected 36 mitochondrial haplotypes with 128 polymorphic sites. Pooled with published data of South-East Asian and Australian water buffaloes and based on comprehensive median-joining network and population demography analyses we show evidence that both river and swamp buffaloes decent from one domestication event, probably in the Indian subcontinent. However, the today swamp buffaloes have an unravelled mitochondrial history, which can be explained by introgression of wild water buffalo mtDNA into domestic stocks. We are also discussing indications for an independent domestication of buffaloes in China.
اظهر المزيد [+] اقل [-]Molecular and morphological phylogenetic analysis of Brachiaria and Urochloa (Poaceae) النص الكامل
2005
Torres González, Alba Marina | Morton, C.M.
Mitochondrial and nuclear multilocus phylogeny of Rhipicephalus ticks from Kenya النص الكامل
2019
Kanduma, Esther G. | Bishop, Richard P. | Githaka, Naftaly W. | Skilton, Robert A. | Heyne, H. | Mwacharo, J.M.
Mitochondrial and nuclear multilocus phylogeny of Rhipicephalus ticks from Kenya النص الكامل
2019
Kanduma, Esther G. | Bishop, Richard P. | Githaka, Naftaly W. | Skilton, Robert A. | Heyne, H. | Mwacharo, J.M.
The morphological diversity of African ticks of the genus Rhipicephalus and subgenus Boophilus have been studied in detail. However, their taxonomy remains poorly resolved with limited molecular studies performed to improve inter-species discrimination. Herein, ribosomal cytochrome c oxidase I (COI), 12S ribosomal DNA (12S rDNA) and nuclear ribosomal DNA internal transcriber spacer 2 (ITS2) were analyzed in Rhipicephalus tick populations in Kenya. While the morphological and molecular criteria separated R. e. evertsi, R. pulchellus and R. appendiculatus from other members of the genus, except the morphologically similar sibling species R. zambeziensis, this was not the case for other tick populations. COI sequences of Rhipicephalus ticks from Ruma National Park (RNP) in Southwestern Kenya, that were morphologically similar to R. praetextatus/R. simus, a formed distinct clade and barcode gap group. 12S rDNA haplotypes of this population were 99% identical to a GenBank accession of R. muhsamae which is thought to be endemic in West and Central Africa. However, the ITS2 locus indicated that the RNP samples were genetically closest to ticks identified morphologically as R. praetextatus. The COI and 12S rDNA haplotype sequences of R. praetextatus clustered closely with R. simus reference sequences though the two species occurred in distinct barcode gap groups. Our results suggest that the R. simus/R. praetextatus/R. muhsamae comprise a closely related tick species complex found across sub-Saharan Africa and includes the yet to be described RNP population. More studies on the biology, ecology and genomics of all life stages of tick species in the complex may clarify their taxonomic status. A continent-wide study that combines morphology, DNA marker sequencing and emerging methods, such as mass spectrometry and whole-genome resequencing may reveal the diversity and distribution of taxa within the genus Rhipicephalus in sub-Saharan Africa.
اظهر المزيد [+] اقل [-]Mitochondrial and nuclear multilocus phylogeny of Rhipicephalus ticks from Kenya النص الكامل
2019
Kanduma, Esther G. | Bishop, Richard P. | Githaka, Naftaly | Skilton, Robert | Heyne, Heloise | Mwacharo, Joram
The morphological diversity of African ticks of the genus Rhipicephalus and subgenus Boophilus have been studied in detail. However, their taxonomy remains poorly resolved with limited molecular studies performed to improve inter-species discrimination. Herein, ribosomal cytochrome c oxidase I (COI), 12S ribosomal DNA (12S rDNA) and nuclear ribosomal DNA internal transcriber spacer 2 (ITS2) were analyzed in Rhipicephalus tick populations in Kenya. While the morphological and molecular criteria separated R. e. evertsi, R. pulchellus and R. appendiculatus from other members of the genus, except the morphologically similar sibling species R. zambeziensis, this was not the case for other tick populations. COI sequences of Rhipicephalus ticks from Ruma National Park (RNP) in Southwestern Kenya, that were morphologically similar to R. praetextatus/R. simus, a formed distinct clade and barcode gap group. 12S rDNA haplotypes of this population were 99% identical to a GenBank accession of R. muhsamae which is thought to be endemic in West and Central Africa. However, the ITS2 locus indicated that the RNP samples were genetically closest to ticks identified morphologically as R. praetextatus. The COI and 12S rDNA haplotype sequences of R. praetextatus clustered closely with R. simus reference sequences though the two species occurred in distinct barcode gap groups. Our results suggest that the R. simus/R. praetextatus/R. muhsamae comprise a closely related tick species complex found across sub-Saharan Africa and includes the yet to be described RNP population. More studies on the biology, ecology and genomics of all life stages of tick species in the complex may clarify their taxonomic status. A continent-wide study that combines morphology, DNA marker sequencing and emerging methods, such as mass spectrometry and whole-genome resequencing may reveal the diversity and distribution of taxa within the genus Rhipicephalus in sub-Saharan Africa.
اظهر المزيد [+] اقل [-]Mitochondrial and nuclear multilocus phylogeny of Rhipicephalus ticks from Kenya النص الكامل
2019
Kanduma, Esther G. | Bishop, Richard P. | Githaka, Naftaly W. | Skilton, Robert A. | Heyne, H. | Mwacharo, J.M.
The morphological diversity of African ticks of the genus Rhipicephalus and subgenus Boophilus have been studied in detail. However, their taxonomy remains poorly resolved with limited molecular studies performed to improve inter-species discrimination. Herein, ribosomal cytochrome c oxidase I (COI), 12S ribosomal DNA (12S rDNA) and nuclear ribosomal DNA internal transcriber spacer 2 (ITS2) were analyzed in Rhipicephalus tick populations in Kenya. While the morphological and molecular criteria separated R. e. evertsi, R. pulchellus and R. appendiculatus from other members of the genus, except the morphologically similar sibling species R. zambeziensis, this was not the case for other tick populations. COI sequences of Rhipicephalus ticks from Ruma National Park (RNP) in Southwestern Kenya, that were morphologically similar to R. praetextatus/R. simus, a formed distinct clade and barcode gap group. 12S rDNA haplotypes of this population were 99% identical to a GenBank accession of R. muhsamae which is thought to be endemic in West and Central Africa. However, the ITS2 locus indicated that the RNP samples were genetically closest to ticks identified morphologically as R. praetextatus. The COI and 12S rDNA haplotype sequences of R. praetextatus clustered closely with R. simus reference sequences though the two species occurred in distinct barcode gap groups. Our results suggest that the R. simus/R. praetextatus/R. muhsamae comprise a closely related tick species complex found across sub-Saharan Africa and includes the yet to be described RNP population. More studies on the biology, ecology and genomics of all life stages of tick species in the complex may clarify their taxonomic status. A continent-wide study that combines morphology, DNA marker sequencing and emerging methods, such as mass spectrometry and whole-genome resequencing may reveal the diversity and distribution of taxa within the genus Rhipicephalus in sub-Saharan Africa.
اظهر المزيد [+] اقل [-]Mitochondrial and nuclear multilocus phylogeny of Rhipicephalus ticks from Kenya النص الكامل
2019
Kanduma, Esther G. | Bishop, Richard P. | Githaka, Naftaly W. | Skilton, Robert A. | Heyne, Heloise | Mwacharo, Joram M.
The morphological diversity of African ticks of the genus Rhipicephalus and subgenus Boophilus have been studied in detail. However, their taxonomy remains poorly resolved with limited molecular studies performed to improve inter-species discrimination. Herein, ribosomal cytochrome c oxidase I (COI), 12S ribosomal DNA (12S rDNA) and nuclear ribosomal DNA internal transcriber spacer 2 (ITS2) were analyzed inRhipicephalus tick populations in Kenya. While the morphological and molecular criteria separated R. e. evertsi, R. pulchellus and R. appendiculatus from other members of the genus, except the morphologically similar sibling species R. zambeziensis, this was not the case for other tick populations. COI sequences of Rhipicephalusticks from Ruma National Park (RNP) in Southwestern Kenya, that were morphologically similar to R. praetextatus/R. simus, a formed distinct clade and barcode gap group. 12S rDNA haplotypes of this population were 99% identical to a GenBank accession of R. muhsamae which is thought to be endemic in West and Central Africa. However, the ITS2 locus indicated that the RNP samples were genetically closest to ticks identified morphologically as R. praetextatus. The COI and 12S rDNA haplotype sequences of R. praetextatus clustered closely with R. simus reference sequences though the two species occurred in distinct barcode gap groups. Our results suggest that the R. simus/R. praetextatus/R. muhsamae comprise a closely related tick species complex found across sub-Saharan Africa and includes the yet to be described RNP population. More studies on the biology, ecology and genomics of all life stages of tick species in the complex may clarify their taxonomic status. A continent-wide study that combines morphology, DNA marker sequencing and emerging methods, such as mass spectrometry and whole-genome resequencing may reveal the diversity and distribution of taxa within the genus Rhipicephalus in sub-Saharan Africa.
اظهر المزيد [+] اقل [-]Cryptic lineage diversity in the zoonotic pathogen #Angiostrongylus cantonensis# النص الكامل
2017
Dusitsittipon S. | Criscione C.D. | Morand S. | Komalamisra C. | Thaenkham U.
Cryptic lineage diversity in the zoonotic pathogen #Angiostrongylus cantonensis# النص الكامل
2017
Dusitsittipon S. | Criscione C.D. | Morand S. | Komalamisra C. | Thaenkham U.
Delimitation of species is still a necessity among parasitic pathogens especially where morphological characters provide limited discernibility. Identification of cryptic lineages (independently evolving lineages that are morphologically similar) is critical as there could be lineage-specific traits that are of epidemiological importance. Angiostrongylus cantonensis is a zoonotic pathogen that can cause eosinophilic meningitis in humans. Recent reports of single marker sequence divergence hint at the potential for cryptic diversity in this lungworm. However, to definitively address if single marker divergence corresponds to independent evolving lineages, a multilocus approach is necessary. Using multilocus data, our goal was to determine if there were cryptic lineages within Thailand, a country plagued by several outbreaks and isolated cases of A. cantonensis infection. We analyzed the genetic structure of A. cantonensis samples collected from snails, Achatina fulica, across provinces in Thailand. Multilocus data (mitochondrial sequence data and 12 nuclear microsatellites) and individual based analyses were used to test for cryptic lineages. We found strong linkage disequilibrium patterns between mitochondrial haplotypes and nuclear-identified genetic clusters. There were clearly two divergent and independent clades. Moreover, within each clade, the data suggested additional substructure where individual provinces were likely to harbor unique genetic clusters. The results indicate there are at minimum two and possibly up to eight cryptic lineages within the assumed single species of A. cantonensis. Importantly, the two main clades do not show geographic affiliation and can be found in sympatry. With recent studies highlighting A. cantonensis strain diversity in pathogenicity and infectivity, it will be important to determine if these critical epidemiological traits are associated with specific lineages. (Résumé d'auteur)
اظهر المزيد [+] اقل [-]Cryptic lineage diversity in the zoonotic pathogen Angiostrongylus cantonensis النص الكامل
2017
Dusitsittipon, Sirilak | Criscione, Charles D. | Morand, S. | Komalamisra, Chalit | Thaenkham, Urusa
Delimitation of species is still a necessity among parasitic pathogens especially where morphological characters provide limited discernibility. Identification of cryptic lineages (independently evolving lineages that are morphologically similar) is critical as there could be lineage-specific traits that are of epidemiological importance. Angiostrongylus cantonensis is a zoonotic pathogen that can cause eosinophilic meningitis in humans. Recent reports of single marker sequence divergence hint at the potential for cryptic diversity in this lungworm. However, to definitively address if single marker divergence corresponds to independent evolving lineages, a multilocus approach is necessary. Using multilocus data, our goal was to determine if there were cryptic lineages within Thailand, a country plagued by several outbreaks and isolated cases of A. cantonensis infection. We analyzed the genetic structure of A. cantonensis samples collected from snails, Achatina fulica, across provinces in Thailand. Multilocus data (mitochondrial sequence data and 12 nuclear microsatellites) and individual based analyses were used to test for cryptic lineages. We found strong linkage disequilibrium patterns between mitochondrial haplotypes and nuclear-identified genetic clusters. There were clearly two divergent and independent clades. Moreover, within each clade, the data suggested additional substructure where individual provinces were likely to harbor unique genetic clusters. The results indicate there are at minimum two and possibly up to eight cryptic lineages within the assumed single species of A. cantonensis. Importantly, the two main clades do not show geographic affiliation and can be found in sympatry. With recent studies highlighting A. cantonensis strain diversity in pathogenicity and infectivity, it will be important to determine if these critical epidemiological traits are associated with specific lineages.
اظهر المزيد [+] اقل [-]A first higher-level time-calibrated phylogeny of antlions (Neuroptera: Myrmeleontidae) النص الكامل
2017
Michel B. | Clamens A.L. | Béthoux O. | Kergoat G.J. | Condamine F.L.
A first higher-level time-calibrated phylogeny of antlions (Neuroptera: Myrmeleontidae) النص الكامل
2017
Michel B. | Clamens A.L. | Béthoux O. | Kergoat G.J. | Condamine F.L.
In this study, we reconstruct the first time-calibrated phylogeny of the iconic antlion family, the Myrmeleontidae (Neuroptera: Myrmeleontiformia). We use maximum likelihood and Bayesian inference to analyse a molecular dataset based on seven mitochondrial and nuclear gene markers. The dataset encompasses 106 species of Neuroptera, including 94 antlion species. The resulting phylogenetic framework provides support for a myrmeleontid classification distinguishing four subfamilies: Acanthaclisinae, Myrmeleontinae, Palparinae, and Stilbopteryginae. Within Myrmeleontinae, Myrmecaelurini and Nemoleontini are recovered as monophyletic clades; Gepini also appears as a valid tribe, distinct from Myrmecaelurini whereas Myrmecaelurini and Nesoleontini on one hand and Brachynemurini and Dendroleontini on the other hand, appear closely related. Some preliminary information related to generic and specific levels are also implied from our results, such as the paraphyly of several genera. Dating analyses based on thoroughly evaluated fossil calibrations indicate that the antlion family likely originated in the Cretaceous, between 135 and 138 million years ago (depending on the set of fossil calibrations), and that all higher-level lineages appeared during the Early Cretaceous. This first phylogenetic hypothesis will provide a valuable basis to further expand the taxonomic coverage and molecular sampling, and to lay the foundations of future systematic revisions. (Résumé d'auteur
اظهر المزيد [+] اقل [-]A first higher-level time-calibrated phylogeny of antlions (Neuroptera: Myrmeleontidae) النص الكامل
2017
Michel, Bruno | Clamens, Anne Laure | Bethoux, Olivier | Kergoat, Gael | Condamine, Fabien L. | Centre de Biologie pour la Gestion des Populations (UMR CBGP) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université de Montpellier (UM)-Institut de Recherche pour le Développement (IRD [Occitanie])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro) | Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad) | Centre de recherche sur la Paléobiodiversité et les Paléoenvironnements (CR2P) ; Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS) | Université Pierre et Marie Curie - Paris 6 (UPMC) | Centre National de la Recherche Scientifique (CNRS) | Sorbonne Université (SU) | Institut des Sciences de l'Evolution de Montpellier (UMR ISEM) ; Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE) ; Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS) | Université de Montpellier (UM) | Institut de Recherche pour le Développement (IRD [France-Ouest]) | École Pratique des Hautes Études (EPHE) ; Université Paris Sciences et Lettres (PSL)
In this study, we reconstruct the first time-calibrated phylogeny of the iconic antlion family, the Myrmeleontidae (Neuroptera: Myrmeleontiformia). We use maximum likelihood and Bayesian inference to analyse a molecular dataset based on seven mitochondrial and nuclear gene markers. The dataset encompasses 106 species of Neuroptera, including 94 antlion species. The resulting phylogenetic framework provides support for a myrmeleontid classification distinguishing four subfamilies: Acanthaclisinae, Myrmeleontinae, Palparinae, and Stilbopteryginae. Within Myrmeleontinae, Myrmecaelurini and Nemoleontini are recovered as monophyletic clades; Gepini also appears as a valid tribe, distinct from Myrmecaelurini whereas Myrmecaelurini and Nesoleontini on one hand and Brachynemurini and Dendroleontini on the other hand, appear closely related. Some preliminary information related to generic and specific levels are also implied from our results, such as the paraphyly of several genera. Dating analyses based on thoroughly evaluated fossil calibrations indicate that the antlion family likely originated in the Cretaceous, between 135 and 138 million years ago (depending on the set of fossil calibrations), and that all higher-level lineages appeared during the Early Cretaceous. This first phylogenetic hypothesis will provide a valuable basis to further expand the taxonomic coverage and molecular sampling, and to lay the foundations of future systematic revisions.
اظهر المزيد [+] اقل [-]A first higher-level time-calibrated phylogeny of antlions (Neuroptera: Myrmeleontidae) النص الكامل
2017
Michel, Bruno | Clamens, Anne-Laure | Béthoux, Olivier | Kergoat, Gael J. | Condamine, Fabien L.
In this study, we reconstruct the first time-calibrated phylogeny of the iconic antlion family, the Myrmeleontidae (Neuroptera: Myrmeleontiformia). We use maximum likelihood and Bayesian inference to analyse a molecular dataset based on seven mitochondrial and nuclear gene markers. The dataset encompasses 106 species of Neuroptera, including 94 antlion species. The resulting phylogenetic framework provides support for a myrmeleontid classification distinguishing four subfamilies: Acanthaclisinae, Myrmeleontinae, Palparinae, and Stilbopteryginae. Within Myrmeleontinae, Myrmecaelurini and Nemoleontini are recovered as monophyletic clades; Gepini also appears as a valid tribe, distinct from Myrmecaelurini whereas Myrmecaelurini and Nesoleontini on one hand and Brachynemurini and Dendroleontini on the other hand, appear closely related. Some preliminary information related to generic and specific levels are also implied from our results, such as the paraphyly of several genera. Dating analyses based on thoroughly evaluated fossil calibrations indicate that the antlion family likely originated in the Cretaceous, between 135 and 138 million years ago (depending on the set of fossil calibrations), and that all higher-level lineages appeared during the Early Cretaceous. This first phylogenetic hypothesis will provide a valuable basis to further expand the taxonomic coverage and molecular sampling, and to lay the foundations of future systematic revisions.
اظهر المزيد [+] اقل [-]Mitochondrial DNA reveals multiple introductions of domestic chicken in East Africa النص الكامل
2011
Mwacharo, Joram M. | Bjornstad, G. | Mobegi, V.A. | Nomura, K. | Hanada, H. | Amano, T. | Hanotte, Olivier H. | Han Jianlin
Mitochondrial DNA reveals multiple introductions of domestic chicken in East Africa النص الكامل
2011
Mwacharo, Joram M. | Bjornstad, G. | Mobegi, V.A. | Nomura, K. | Hanada, H. | Amano, T. | Hanotte, Olivier H. | Han Jianlin
Chicken were possibly domesticated in South and Southeast Asia. They occur ubiquitously in East Africa where they show extensive phenotypic diversity. They appeared in the region relatively late, with the first undisputed evidence of domestic chicken in Sudan, around not, vert, similar 700 BC. We reveal through a detailed analysis of mitochondrial DNA D-loop sequence diversity of 512 domestic village chickens, from four East African countries (Kenya, Ethiopia, Sudan, Uganda), the presence of at least five distinct mitochondrial DNA haplogroups. Phylogeographic analyses and inclusion of reference sequences from Asia allow us to address the origin, ways of introduction and dispersion of each haplogroup. The results indicate a likely Indian subcontinent origin for the commonest haplogroup (D) and a maritime introduction for the next commonest one (A) from Southeast and/or East Asia. Recent introgression of commercial haplotypes into the gene pool of village chickens might explain the rare presence of two haplogroups (B and C) while the origin of the last haplogroup (E) remains unclear being currently observed only outside the African continent in the inland Yunnan Province of China. Our findings not only support ancient historical maritime and terrestrial contacts between Asia and East Africa, but also indicate the presence of large maternal genetic diversity in the region which could potentially support genetic improvement programmes.
اظهر المزيد [+] اقل [-]Mitochondrial DNA reveals multiple introductions of domestic chicken in East Africa. النص الكامل
2011
Mwacharo, JM | Bjørnstad, G | Mobegi, V | Nomura, K | Hanada, H | Amano, T | Jianlin, H | Hanotte, O
Chicken were possibly domesticated in South and Southeast Asia. They occur ubiquitously in East Africa where they show extensive phenotypic diversity. They appeared in the region relatively late, with the first undisputed evidence of domestic chicken in Sudan, around ~ 700 BC. We reveal through a detailed analysis of mitochondrial DNA D-loop sequence diversity of 512 domestic village chickens, from four East African countries (Kenya, Ethiopia, Sudan, Uganda), the presence of at least five distinct mitochondrial DNA haplogroups. Phylogeographic analyses and inclusion of reference sequences from Asia allow us to address the origin, ways of introduction and dispersion of each haplogroup. The results indicate a likely Indian subcontinent origin for the commonest haplogroup (D) and a maritime introduction for the next commonest one (A) from Southeast and/or East Asia. Recent introgression of commercial haplotypes into the gene pool of village chickens might explain the rare presence of two haplogroups (B and C) while the origin of the last haplogroup (E) remains unclear being currently observed only outside the African continent in the inland Yunnan Province of China. Our findings not only support ancient historical maritime and terrestrial contacts between Asia and East Africa, but also indicate the presence of large maternal genetic diversity in the region which could potentially support genetic improvement programmes.
اظهر المزيد [+] اقل [-]Phylogenetic patterns in the genus Manihot (Euphorbiaceae) inferred from analyses of nuclear and chlorplast DNA regions النص الكامل
2008
Chacón Pinilla, Juliana | Madriñán, Santiago | Debouck, Daniel G. | Rodríguez Zapata, Fausto | Tohme, Joseph M.
Evidence of transoceanic dispersion of the genus Vanilla based on plastid DNA phylogenetic analysis النص الكامل
2010
Bouétard A. | Lefeuvre P. | Gigant R. | Bory S. | Pignal | Besse P. | Grisoni M.
The phylogeny and the biogeographical history of the genus Vanilla was investigated using four chloroplastic genes (psbB, psbC; psaB and rbcL), on 47 accessions of Vanilla chosen from the ex situ CIRAD collection maintained in Reunion Island and additional sequences from GenBank. Bayesian methods provided a fairly well supported reconstruction of the phylogeny of the Vanilloideae sub-family and more particularly of the genus Vanilla. Three major phylogenetic groups in the genus Vanilla were differentiated, which is in disagreement with the actual classification in two sections (Foliosae and Aphyllae) based on morphological traits. Recent Bayesian relaxed molecular clock methods allowed to test the two main hypotheses of the phylogeography of the genus Vanilla. Early radiation of the Vanilla genus and diversification by vicariance consecutive to the break-up of Gondwana, 95 million years ago (Mya), was incompatible with the admitted age of origin of Angiosperm. Based on the Vanilloideae age recently estimated to 71 million years ago (Mya), we conclude that the genus Vanilla would have appeared (circa) 34 Mya in South America, when continents were already separated. Nevertheless, whatever the two extreme scenarios tested, at least three long distance migration events are needed to explain the present distribution of Vanilla species in tropical areas. These transoceanic dispersions could have occurred via transoceanic passageway such as the Rio Grande Ridge and the involvement of floating vegetation mats and migratory birds. (Résumé d'auteur)
اظهر المزيد [+] اقل [-]Evolution in African tropical trees displaying ploidy-habitat association: the genus Afzelia النص الكامل
2017
Donkpegan, A.S.L. | Doucet, J.L. | Migliore, J. | Duminil, J. | Dainou, K. | Piñeiro, R. | Wieringa, J.J. | Champluvier, D. | Hardy, Olivier J.
Evolution in African tropical trees displaying ploidy-habitat association: the genus Afzelia النص الكامل
2017
Donkpegan, A.S.L. | Doucet, J.L. | Migliore, J. | Duminil, J. | Dainou, K. | Piñeiro, R. | Wieringa, J.J. | Champluvier, D. | Hardy, Olivier J.
Evolution in African tropical trees displaying ploidy-habitat association: The genus Afzelia (Leguminosae) النص الكامل
2017
Donkpegan, Armel S.L. | Doucet, Jean-Louis | Migliore, Jérémy | Duminil, Jérôme | Dainou, Kasso | Piñeiro, Rosalía | Wieringa, Jan J. | Champluvier, Dominique | Hardy, Olivier J.
Polyploidy has rarely been documented in rain forest trees but it has recently been found in African species of the genus Afzelia (Leguminosae), which is composed of four tetraploid rain forest species and two diploid dry forest species. The genus Afzelia thus provides an opportunity to examine how and when polyploidy and habitat shift occurred in Africa, and whether they are associated. In this study, we combined three plastid markers (psbA, trnL, ndhF), two nuclear markers (ribosomal ITS and the single-copy PEPC E7 gene), plastomes (obtained by High Throughput Sequencing) and morphological traits, with an extensive taxonomic and geographic sampling to explore the evolutionary history of Afzelia. Both nuclear DNA and morphological vegetative characters separated diploid from tetraploid lineages. Although the two African diploid species were well differentiated genetically and morphologically, the relationships among the tetraploid species were not resolved. In contrast to the nuclear markers, plastid markers revealed that one of the diploid species forms a well-supported clade with the tetraploids, suggesting historical hybridisation, possibly in relation with genome duplication (polyploidization) and habitat shift from dry to rain forests. Molecular dating based on fossil-anchored gene phylogenies indicates that extant Afzelia started diverging c. 14.5 or 20Ma while extant tetraploid species started diverging c. 7.0 or 9.4Ma according to plastid and nuclear DNA, respectively. Additional studies of tropical polyploid plants are needed to assess whether the ploidy-habitat association observed in African Afzelia would reflect a role of polyploidization in niche divergence in the tropics.
اظهر المزيد [+] اقل [-]