摘要 :
A phylogenetic analysis of a combined data set for 560 angiosperms and seven outgroups based on three genes, 18S rDNA (1855bp), rbcL( 1428bp), and atpB(1450 bp) representing a total of 4733 bp is presented. Parsimony analysis was ...
展开
A phylogenetic analysis of a combined data set for 560 angiosperms and seven outgroups based on three genes, 18S rDNA (1855bp), rbcL( 1428bp), and atpB(1450 bp) representing a total of 4733 bp is presented. Parsimony analysis was expedited by use ofa new computer program, the RATCHET. Parsimony jackknifing was performed to assess the support of clades. The combination of three data sets for numerous species has resulted in the most highly resolved and strongly supported topology yet obtained for angiosperms. In contrast to previous analyses based on single genes, much of the spine of the tree and most of the larger clades receive jackknife support>=50%, Some of the noneudicots form a grade followed by a strongly supported eudicot clade. The early-branching angiosperms are Amborellaceae, Nymphaeaceae, and a clade of Austrobaileyaceae, Illiciaceae, and Schisandraceae. The remaining noneudicots, except Ceratophyllaceae, form a weakly supported core eumagnoliid clade comprising six well-supported subclades: Chloranthaceae, monocots, Winteraceae/Canellaceae, Piperales, Laurales, and Magnoliales.Ceratophyllaceae are sister to the eudicots. Within the well-supported eudicot clade, the early-diverging eudicots (e.g. Proteales, Ranunculales, Trochodendraceae, Sabiaceae) from a grade, followed by the core eudicots, the monophyly of which is slao strongly supported. The core eudicots comprise six well-supported subclades: (1) Berberidopsidaceae/Aextoxicaceae; (2) Myrothamnaceae/Gunneraceae; (3) Saxifragales, which are the sister to Vitaceae (including Leea) plus a strongly supported eurosid clade; (4) Santalales; (5) Caryophyllales, to which Dilleniaceae are sister; and (6)an asterid clade. The relationships among these six subclades of core eudicots donot receive strong support. This large data set has also helped place a number of enigmatic angiosperm families, including Podostemaceae, Aphloiaceae, and Ixerbaceae. This analysis further illustrates the tractability of large data sets and supports a recent, phylogenetically based, ordinal-level reclassification of the angiosperms based largely, but not exclusively, on molecular (DNA sequence) data.
收起
摘要 :
Following (1) the large-scale molecular phylogeny of seed plants based on plastid rbcL gene sequences (published in 1993 by Chase et al., Ann. Missouri Bot. Gard. 80:528-580) and (2) the 18S nuclear phylogeny of flowering plants (...
展开
Following (1) the large-scale molecular phylogeny of seed plants based on plastid rbcL gene sequences (published in 1993 by Chase et al., Ann. Missouri Bot. Gard. 80:528-580) and (2) the 18S nuclear phylogeny of flowering plants (published in 1997 by Soltis et al., Ann. Missouri Bot. Gard. 84:1-49), we present a phylogenetic analysis of flowering plants based on a second plastid gene, atpB, analyzed separately and in combination with rbcL sequences for 357 taxa. Despite some discrepancies, the atpB-based phylogenetic trees were highly congruent with those derived from the analysis of rbcL and 18S rDNA, and the combination of atpB and rbcL DNA sequences (comprising -3000 base pairs) produced increased bootstrap support for many major sets of taxa. The angiosperms are divided into two major groups: noneudicots with inaperturate or uniaperturate pollen (monocots plus Laurales, Magnoliales, Piperales, Ceratophyllales, and Amborellaceae Nymphaeaceae--Illiciaceae) and the eudicots with triaperturate pollen (particularly asterids and rosids). Based on rbcL alone and atpB/rbcL combined, the noneudicots (excluding Ceratophyllum) are monophyletic, whereas in the atpB trees they form a grade. Ceratophyllumis sister to the rest of angiosperms with rbcL alone and in the combined atpB/rbcL analysis, whereas with atpB alone, Amborellaceae, Nymphaeaceae, and Illiciaceae/Schisandraceae form a grade at the base of the angiosperms. The phylogenetic information at each codon position and the different types of substitutions (observed transitions and transversions in the trees vs. pairwise comparisons) were examined; taking into account their respective consistency and retention indices, we demonstrate that third-codon positions and transitions are the most useful characters in these phylogenetic reconstructions. This study further demonstrates that phylogenetic analysis of large matrices is feasible.
收起
摘要 :
The utility of 18S and 26S in broad phylogenetic analyses has been much maligned due in large part to the low signal in both genes. However, few analyses have employed complete 26S rDNA sequences over a broad range of taxa, and mo...
展开
The utility of 18S and 26S in broad phylogenetic analyses has been much maligned due in large part to the low signal in both genes. However, few analyses have employed complete 26S rDNA sequences over a broad range of taxa, and most alignments of the two genes are done de novo, without taking into account the secondary structure of the two rRNA genes. Here we mine next-generation sequence data to compile large matrices (429 taxa) of complete 18S + 26S gene sequences, and we compare both de novo alignment methods with curated alignments done by eye that take into account secondary structure and hard-to-align regions (profile alignments). The combined 18S + 26S topology is overall very similar to recently published gene trees for the angiosperms based on three or more genes. Overall support for the backbone or framework of the combined tree is low (bootstrap support below 50％). Few major clades have bootstrap support above 50％. Most well-supported clades are tip clades (families and orders sensu APG Ⅲ 2009). Importantly, the 18S + 26S rDNA topology is consistent with current estimates of relationships: the basalmost angiosperms are recovered (Amborellaceae, Nymphaeales, Austrobaileyales), as are most major clades, including Mesangio-spermae, eudicots (Eudicotyledoneae sensu Cantino et al. 2007), core eudicots (Gunneridae sensu Cantino et al. 2007), rosids (Rosidae sensu Cantino et al. 2007), asterids (Asteridae sensu Cantino et al. 2007), and Caryophyllales. Most clades recognized at the ordinal level (sensu APG Ⅲ 2009) are also recovered. However, there are also some unusual placements in the 18S + 26S topology, but none of these receives bootstrap support above 50％. The profile and de novo alignments gave very similar topologies. 18S + 26S trees remain useful sources of data in large combined analyses. This is the first time a large data set of complete 26S gene sequences has been employed at this scale; this gene in particular proved to be useful phylogenetically. Targeted sequencing of 18S/26S rDNA is not advocated here, but given that these regions provide useful phylogenetic information and are abundant in next-generation sequencing runs, we suggest that the data be used rather than discarded.
收起
摘要 :
The order Poales comprises a substantial portion of plant life (7% oi all angiosperms and 33% ot monoeots) and includes taxa of enormous economic and ecological significance. Molecular and morphological studies over the past two d...
展开
The order Poales comprises a substantial portion of plant life (7% oi all angiosperms and 33% ot monoeots) and includes taxa of enormous economic and ecological significance. Molecular and morphological studies over the past two decades, however, leave uncertain many relationships within Poales and among allied commelinid orders. Here we present the results of an initial project by the Monocot A ToL (Angiosperm Tree of Life) team on phylogeny and evolution in Poales, using sequence data for 81 plastid genes (exceeding 101 aligned kb) from 83 species of angiosperms. We recovered highly concordant relationships using maximum likelihood (ML) and maximum parsimony (MP), with 98.2% mean ML bootstrap support across monoeots. For the first time, ML resolves ties among Poales and other commelinid orders with moderate to strong support. Analyses provide strong support for Bromeliaceae being sister to the rest of Poales; Typhaceae, Kapateaceae, and cyperids (sedges, rushes, and their allies) emerge next along the phylogenetic spine. Graminids (grasses and their allies) and restiids (Restionaceae and its allies) are well supported as sister taxa. MP identifies a xyrid clade (Erioeaulaceae, Mayaoaeeae, Xyridaceae) sister to eyperids, but ML (with much stronger support) places them as a grade with respect to restiids + graminids. The conflict in resolution between these analyses likely reflects long-branch attraction and highly elevated substitution rates in some Poales. All other familial relationships within the order are strongly supported by both MP and ML analyses. Character-state mapping implies that ancestral Poales lived in sunny, fire-prone, at least seasonally damp/wet, and possibly nutrient-poor sites, and were animal pollinated. Five subsequent shifts to wind pollination-in Typhaceae, cyperids, restiids, Ecdeiocoleaceae, and the vast PACCMAD-BEP clade of grasses-are significantly correlated with shifts to open habitats and small, inconspicuous, unisexual, and nectar-free flowers. Prime ecological movers driving the repeated evolution of wind pollination in Poales appear to include open habitats combined with the high local dominance of conspecific taxa, with the latter resulting from large-scale disturbances, combined with tall plant stature, vigorous vegetative spread, and positive ecologieal feedback. Reproductive assurance in the absence of reliable animal visitation probably favored wind pollination in annuals and short-statured perennials of Centrolepidaeeae in ephemerally wet depressions and windswept alpine sites.
收起
摘要 :
Broad-scale, quantitative assessments of insect biodiversity and the factors shaping it remain particularly poorly explored. Here we undertook a spatial phylogenetic analysis of North American butterflies to test whether climate s...
展开
Broad-scale, quantitative assessments of insect biodiversity and the factors shaping it remain particularly poorly explored. Here we undertook a spatial phylogenetic analysis of North American butterflies to test whether climate stability and temperature gradients have shaped their diversity and endemism. We also performed the first quantitative comparisons of spatial phylogenetic patterns between butterflies and flowering plants. We expected concordance between the two groups based on shared historical environmental drivers and presumed strong butterfly-host plant specializations. We instead found that biodiversity patterns in butterflies are strikingly different from flowering plants, especially warm deserts. In particular, butterflies show different patterns of phylogenetic clustering compared with flowering plants, suggesting differences in habitat conservation between the two groups. These results suggest that shared biogeographic histories and trophic associations do not necessarily assure similar diversity outcomes. The work has applied value in conservation planning, documenting warm deserts as a North American butterfly biodiversity hotspot.
收起
摘要 :
Abstract Premise A major goal of systematic biology is to uncover the evolutionary history of organisms and translate that knowledge into stable classification systems. Here, we integrate three sets of genome‐wide data to resolve...
展开
Abstract Premise A major goal of systematic biology is to uncover the evolutionary history of organisms and translate that knowledge into stable classification systems. Here, we integrate three sets of genome‐wide data to resolve phylogenetic relationships in Cornaceae (containing only Cornus s.l.), reconstruct the biogeographic history of the clade, and provide a revised classification using the PhyloCode to stabilize names for this taxonomically controversial group. Methods We conducted phylogenetic analyses using 312 single‐copy nuclear genes and 70 plastid genes from Angiosperms353 Hyb‐Seq, plus numerous loci from RAD‐Seq. We integrated fossils using morphological data and produced a dated phylogeny for biogeographical analysis. Results A well‐resolved, strongly supported, comprehensive phylogeny was obtained. Biogeographic analyses support an origin and rapid diversification of Cornus into four morphologically distinct major clades in the Northern Hemisphere (with an eastern Asian ancestor) during the late Cretaceous. Dispersal into Africa from eastern Asia likely occurred along the Tethys Seaway during the Paleogene, whereas dispersal into South America likely occurred during the Neogene. Diversification within the northern hemisphere likely involved repeated independent colonization of new areas during the Paleogene and Neogene along the Bering Land Bridge, the North Atlantic Land Bridge, and the Tethys Seaway. Thirteen strongly supported clades were named following rules of the PhyloCode. Conclusions Our study provides an example of integrating genomic and morphological data to produce a robust, explicit species phylogeny that includes fossil taxa, which we translate into an updated classification scheme using the PhyloCode to stabilize names.
收起
摘要 :
The importance of hybridization in plant speciation and evolution has been debated for decades, with opposing views of hybridization as either a creative evolutionary force or evolutionary noise. Hybrid speciation may occur at eit...
展开
The importance of hybridization in plant speciation and evolution has been debated for decades, with opposing views of hybridization as either a creative evolutionary force or evolutionary noise. Hybrid speciation may occur at either the homoploid (i.e., between two species of the same ploidy) or the polyploid level, each with its attendant genetic and evolutionary consequences. Whereas allopolyploidy (i.e., resulting from hybridization and genome doubling) has long been recognized as an important mode of plant speciation, the implications of genome duplication have typically not been taken into account in most fields of plant biology. Recent developments in genomics are revolutionizing our views of angiosperm genomes, demonstrating that perhaps all angiosperms have likely undergone at least one round of polyploidization and that hybridization has been an important force in generating angiosperm species diversity. Hybridization and polyploid formation continue to generate species diversity, with several new allopolyploids having originated just within the past century or so. The origins of polyploid species-whether via hybridization between species or be_tween genetically differentiated populations of a single species-and the immediate genetic consequences of polyploid formation are there_fore receiving enthusiastic attention. The time is therefore right for a review of the role of hybridization in plant speciation.
收起
摘要 :
Tragopogon is a large Eurasian genus of approximately 150 species. Despite the use of 6910 aligned bp of sequence data representing seven loci, relationships within the genus remain largely unresolved. The young age of the genus i...
展开
Tragopogon is a large Eurasian genus of approximately 150 species. Despite the use of 6910 aligned bp of sequence data representing seven loci, relationships within the genus remain largely unresolved. The young age of the genus in combination with rapid diversification may be the best explanation for this poor resolution. Our studies have revealed that Geropogon is well supported as the immediate sister to Tragopogon. Sections Tragopogon, Brevirostris, Chro-mopappus, and Hebecarpus of traditional taxonomic treatments are largely monophyletic; sections Angustissimi, Majores, Collini, and Profundisulcati are non-monophyletic. The monotypic sections Macropogon, Dasypogon, and Dybjanskya appear within other sections and no longer merit recognition. Ourmolecular investigations of geographically widespread species in Europe, including 77 crocifolius, T. pratensis, T. porrifolius, and T orientalis, indicate that each may be non-monophyletic, comprising several cryptic species. These widespread diploidsare the proposed parents of some of the Eurasian allopolyploids, as well as the parents of the recently formed 77 minis and 77 miscellus from North America.
收起
摘要 :
The convergence of distinct lineages upon interspecific hybridisation, including when accompanied by increases in ploidy (allopolyploidy), is a driving force in the origin of many plant species. In plant breeding too, both intersp...
展开
The convergence of distinct lineages upon interspecific hybridisation, including when accompanied by increases in ploidy (allopolyploidy), is a driving force in the origin of many plant species. In plant breeding too, both interspecific hybridisation and allopolyploidy are important because they facilitate introgression of alien DNA into breeding lines enabling the introduction of novel characters. Here we review how fluorescence in situ hybridisation (FISH) and genomic in situ hybridisation (GISH) have been applied to: 1) studies of interspecific hybridisation and polyploidy in nature, 2) analyses of phylogenetic relationships between species, 3) genetic mapping and 4) analysis of plant breeding materials. We also review how FISH is poised to take advantage of next-generation sequencing (NGS) technologies, helping the rapid characterisation of the repetitive fractions of a genome in natural populations and agricultural plants.
收起
原文获取