| 1. |
- Monge, M., et al.
(författare)
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Nomenclatural novelties in Tessaria (Asteraceae, Inuleae): a new species from the Andes and uncovering the identity of T. boliviensis.
- 2018
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Ingår i: Systematic Botany. - 0363-6445 .- 1548-2324. ; 43:2, s. 591-594
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Tidskriftsartikel (refereegranskat)abstract
- During the study of Brazilian genera of the Inuleae-Plucheinae (Asteraceae), we have encountered a specimen representing an undescribed species, here described as Tessaria andina. The new species is characterized by having puberulous, tomentose, lanate, or glabrescent indumentum on its branches, a tomentose abaxial leaf surface, leaves with an apically serrate margin, corymbiform inflorescences, a cream to yellowish involucre, erect inner involucral bracts, and the corolla of male flowers with short-stalked glands and trichomes. So far, only one collection of this new species has been made, and that was more than forty years ago. The new species is described, illustrated, and its affinities are discussed. Furthermore, during this investigation we found out that the name Tessaria boliviensis is a nomen nudum, applied to material here shown tobelongto Tessaria fastigiata. An identification key to the species of Tessaria is also presented.
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| 2. |
- Morrison, David A.
(författare)
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Is Sequence Alignment an Art or a Science?
- 2015
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Ingår i: Systematic Botany. - 0363-6445 .- 1548-2324. ; 40:1, s. 14-26
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Tidskriftsartikel (refereegranskat)abstract
- Aligning multiple nucleotide sequences is a prerequisite for many if not most comparative sequence analyses in evolutionary biology. These alignments are often recognized as representing the homology relations of the aligned nucleotides, but this is a necessary requirement only for phylogenetic analyses. Unfortunately, existing computer programs for sequence alignment are not based explicitly on detecting the homology of nucleotides, and so there is a notable gap in the existing bioinformatics repertoire. If homology is the goal, then current alignment procedures may be more art than science. To resolve this issue, I present a simple conceptual scheme relating the traditional criteria for homology to the features of nucleotide sequences. These relations can then be used as optimization criteria for nucleotide sequence alignments. I point out the way in which current computer programs for multiple sequence alignment relate to these criteria, noting that each of them usually implements only one criterion. This explains the apparent dissatisfaction with computerized sequence alignment in phylogenetics, as any program that truly tried to produce alignments based on homology would need to simultaneously optimize all of the criteria.
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| 3. |
- Owusu, Sandra A., et al.
(författare)
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Taxonomic Relationships and Gene Flow in Four North American Quercus Species (Quercus section Lobatae)
- 2015
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Ingår i: Systematic Botany. - 0363-6445 .- 1548-2324. ; 40:2, s. 510-521
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Tidskriftsartikel (refereegranskat)abstract
- Taxonomic relationships between North American red oak species (Quercus section Lobatae) are not well resolved using genetic and morphological markers. Phenotypic plasticity, recent species divergence, and hybridization may all contribute to the unclear species boundaries in red oaks. We applied twenty-eight genomic and gene-basedmicrosatellites, including outlier loci with potential roles in reproductive isolation and adaptive divergence between species, to natural populations of four monophyletic interfertile oak species: Quercus ellipsoidalis, Q. coccinea, Q. rubra, and Q. velutina. To better resolve the taxonomic relationships in this difficult clade, we assigned individual samples to species, identified hybrids and introgressive forms, and reconstructed phylogenetic relationships among the four species after exclusion of genetically intermediate individuals. Genetic assignment analyses identified four distinct species clusters, with Q. rubra most differentiated from the three other species. However, especially between Q. ellipsoidalis and Q. velutina, a comparatively large number of misclassified individuals (7.14%), hybrids (7.14%), and introgressive forms (18.83%) were detected. After the exclusion of genetically intermediate individuals, Q. ellipsoidalis grouped as sister species to the largely parapatric Q. coccinea with high bootstrap support (91%). Genetically intermediate forms in a mixed species stand were located proximate to both potential parental species, which supports recent hybridization of Q. velutina with both Q. ellipsoidalis and Q. rubra. Analyses of genome-wide patterns of interspecific differentiation can provide a better understanding of speciation processes and taxonomic relationships in this taxonomically difficult group of red oak species.
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| 4. |
- Schwartz, Thomas, et al.
(författare)
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The origin of oranges: a multi-locus phylogeny of Rutaceae subfamily Aurantioideae
- 2015
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Ingår i: Systematic Botany. - 0363-6445 .- 1548-2324. ; 40:4
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Tidskriftsartikel (refereegranskat)abstract
- The phylogeny of Rutaceae subfamily Aurantioideae has previously been estimated only using plastid and repetitive nuclear sequences. We added sequences of two low copy nuclear loci to allow further diagnosis of phenomena that may mislead phylogenetic inference. After testing for patterns expected under recombination, positive selection, and hybridization, we excluded data sets or sequences accordingly and then inferred the species tree using the multispecies coalescent. We then reconstructed the ancestral area using parsimony and the dispersal-extinction-cladogenesis model to test the hypothesis that Citrus s. l. may have originated in Australasia and migrated or rafted to Eastern Asia. The ancestral area of Citrus s. l. inferred under either method and several models was west of Wallace’s line. Therefore, Citrus s. l. did not appear to have rafted west on what became the Halmahera Islands (Indonesia). Our findings are also consistent with previously reported ages for the origin of this group that may be too young to have allowed this rafting. The species tree is well resolved and largely consistent with previous molecular phylogenies, especially those using chloroplast sequences.
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| 5. |
- Terra-Araujo, Mário H., et al.
(författare)
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A taxonomic update of Neotropical Pradosia (Sapotaceae, Chrysophylloideae)
- 2016
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Ingår i: Systematic Botany. - 0363-6445 .- 1548-2324. ; 41, s. 634-650
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Tidskriftsartikel (refereegranskat)abstract
- We provide a systematic update of Pradosia (Sapotaceae, Chrysophylloideae), including overall morphology, a key to all species, comprehensive morphological descriptions, geographic distributions, and important characteristics for each species. Phyloge- netic analyses based on molecular data demonstrated that the genus is monophyletic and includes three main clades. Twenty-three species of Pradosia are accepted, which are mostly distributed in lowland rainforests on either white-sand or clayish soils in tropical South America. A rotate corolla with a short tube, lack of staminodes, a drupaceous fruit with plano-convex cotyledons, an exserted radicle below the cotyledons, and the absence of endosperm are diagnostic for the genus. Two names are reduced into synonymy, viz. Pradosia atroviolacea Ducke, syn. of P. grisebachii (Pierre) T. D. Penn., and Pradosia verrucosa Ducke, syn. of P. glaziovii (Pierre) T. D. Penn. The affinity of P. argentea (Kunth) T. D. Penn., a species known only from the type collection, remains uncertain and for now excluded from the genus.
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| 6. |
- Thulin, Mats, 1948-, et al.
(författare)
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Phylogeny and Systematics of Kewa (Kewaceae)
- 2018
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Ingår i: Systematic Botany. - 0363-6445 .- 1548-2324. ; 43:3, s. 689-700
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Tidskriftsartikel (refereegranskat)abstract
- The genus Kewa in the monogeneric family Kewaceae (Caryophyllales) is revised. Six species are recognized, K. acida on St. Helena, K. angrae-pequenae in Namibia and South Africa, K. arenicola (incl. K. trachysperma) in South Africa, K. bowkeriana (incl. K. suffruticosa) widespread in eastern and southern Africa and in Madagascar, K. caespitosa in Angola and Namibia, and K. salsoloides in Namibia, Botswana, and South Africa. Kewa is morphologically distinctive, notably by its simple perianth where the two outer perianth-segments are more or less sepaloid and the three inner ones more or less petaloid, and by its indumentum of short glandular hairs, often with prominent, persistent, wart-like bases. All species have an acid taste, apparently due to the presence of oxalic acid. All names are typified, including one lectotype designated here. An identification key and distribution maps for all species are provided. The phylogeny of Kewa is reconstructed based on plastid trnK-matK and rbcL and nuclear ITS sequences. Kewa is strongly supported and the included species have strong to no support, whereas the relationships between the species are mostly unsupported. The phylogeny is dated and the estimated age of the Kewa stem clade is (37.5-)45.0(-57.0) million years and of the crown lade (3.0-)3.9(-7.4) million years. The age of the crown lade would also be the estimated date when K. acida on the approximately 14 million years old St. Helena diverged from its potential sister group on the African continent, and would coincide with the earliest possible date for the introduction of the ancestor of K. acida to St. Helena.
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| 7. |
- Thulin, Mats, 1948-, et al.
(författare)
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Resurrection of the Genus Rorida (Cleomaceae), a Distinctive Old World Segregate of Cleome
- 2017
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Ingår i: Systematic Botany. - : AMER SOC PLANT TAXONOMISTS. - 0363-6445 .- 1548-2324. ; 42:3, s. 569-577
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Tidskriftsartikel (refereegranskat)abstract
- The genus Rorida J.F. Gmel. is resurrected for Cleome L. sect. Thylacophora Franch. within the non-monophyletic Cleome. Rorida is strongly supported as monophyletic by molecular data and is also morphologically very distinctive, with simple leaves, four stamens, and triangular, very shortly clawed, dimorphic petals, appendaged at the base. Twelve species are recognized in desert and semidesert regions from northeastern Africa through the Arabian Peninsula to Afghanistan, Tajikistan, and Pakistan. Rorida cornus-africani is described as new from Somalia and new combinations are made for the other eleven species. All names are typified, including 10 lectotypes designated here. An identification key and distribution maps for all species are provided.
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