Showing papers in "Taxon in 2004"
TL;DR: Recommendations are outlined on how to deal with the issue of plant invasions in standard floras with the aim of contributing to a better understanding between taxonomists and ecologists and allowing more detailed comparative analyses of alien floras of various regions of the world.
Abstract: The number of studies dealing with plant invasions is increasing rapidly, but the accumulating body of knowledge has unfortunately also spawned increasing confusion about terminology. Invasions are a global phenomenon and comparison of geographically distant regions and their introduced biota is a crucially important methodological approach for elucidation of the determinants of invasiveness and invasibility. Comparative studies of alien floras provide substantial new insights to our understanding of general patterns of plant invasions. Such studies, using information in previously published floras and checklists, are fundamentally dependent on the quality of the assessment of particular species with respect to their taxonomic identity, time of immigration and invasion status. Three crucial decisions should be made when defining the status of a plant species in a given region: (1) whether the taxon is native or alien to that region (origin status); (2) what is its position in the invasion process, i.e., when was it introduced (residence status); and (3) what is the degree of its naturalization and possible invasion (invasion status). Standard floras differ hugely in their treatment of non-native species and those with appropriate categorization of alien species according to their status are rather rare. The present paper suggests definitions of terms associated with plant invasions and places these into the context of floras. Recommendations are outlined on how to deal with the issue of plant invasions in standard floras with the aim of contributing to a better understanding between taxonomists and ecologists and allowing more detailed comparative analyses of alien floras of various regions of the world.
1,283 citations
TL;DR: It is argued that comparisons of size, phenomena, and processes will only be possible by comprehensive study of the lineages comprising these genera and their immediate historical relatives; uncritical lists or relatively limited samples are not enough.
Abstract: "Big" plant genera, those of 500 or more species, have not only occasioned interest among systematic botanists, but for geographical, ecological or horticultural reasons, have also become well-established popular concepts. Their size has rendered them difficult, if not impossible, to study in their entirety; there have been few full revisions since the nineteenth century. Despite their embodiment of significant taxonomic, biological and evolutionary questions, from the 1980s their importance has been more generally recognised, and recent technological and methodological developments have made it easier to come to grips with their study. This paper synthesizes growth impediments to our knowledge of these genera and possible approaches to studying them. Of the 57 genera currently thought to have 500 or more species, 22 of these were also considered in 1883 to be large (300 or more species). Others gained their prominence as a result of later exploration, some of it driven by enthusiasts. It is argued that comparisons of size, phenomena, and processes will only be possible by comprehensive study of the lineages comprising these genera and their immediate historical relatives; uncritical lists or relatively limited samples are not enough. Such studies will be of great scientific as well as cultural benefit.
515 citations
TL;DR: The authors' data support a New World origin of Grammitidaceae, with Old World taxa generally being more evolutionarily derived and several clades are either primarily Neotropical or primarily Paleotropical but also have a few members distributed in the opposite hemisphere.
Abstract: We conducted phylogenetic analyses of the fern family Grammitidaceae using sequences from two cpDNA genes and from morphological characters. Data were obtained for 73 species from most recognized genera in the family. Thegenera Adenophorus, Ceradenia, Calymmodon, Cochlidium, Enterosora, and Melpomene were each strongly supported as being monophyletic. Other recognized genera that were not supported as monophyletic included Ctenopteris, Grammitis, Lellingeria, Micropolypodium, Prosaptia, and Terpsichore. Several previously unrecognized clades were identified, some of which are characterized by distinctive morphological features. Analyses of the distribution of morphological character states on our inferred phylogeny showed extremely high levels of homoplastic evolution for many different characters. Homoplasy for morphological characters was considerably greater than for molecular characters. Many of the characters that exhibited high levels of convergent or parallel evolution across the phylogeny are features that have been commonly used to circumscribe genera in this group (e.g., leaf blade dissection, various rhizome scale characters, and glandular paraphyses). Conversely, some of the characters that exhibited relatively low levels of homoplasy have either not been regarded as having taxonomic value or have been ignored (e.g., root insertion, rhizome scale sheen). Our data support a New World origin of Grammitidaceae, with Old World taxa generally being more evolutionarily derived. Several clades are either primarily Neotropical or primarily Paleotropical but also have a few members distributed in the opposite hemisphere. Thus, we postulate multiple, independent dispersal and colonization events in several lineages.
198 citations
TL;DR: A revised outline of the sections of Nicotiana with lists of their component species is presented, along with a generalized distribution and a list of accepted species names.
Abstract: Recent studies using regions of the nuclear and plastid genomes have shown that T. H. Goodspeed's sectional groupings in Nicotiana are for the large part upheld. However, we have shown that in several cases sectional membership should be revised. Here we present a revised outline of the sections of Nicotiana with lists of their component species. Relationships of the sections as defined can be seen in accompanying figures. Two sectional names with priority over those in current use are introduced (N. sect. Polydicliae & sect. Petunioides) and one new section, N. sect. Sylvestres, is described here. Two species names are changed to those with priority over those adopted by Goodspeed in his monograph of the genus: N. obtusifolia for N. trigonophylla and N. quadrivalvis for N. bigelovii. Synonymies are provided for each of these names. A short morphological description is provided for each section, along with a generalized distribution and a list of accepted species names.
194 citations
TL;DR: The tribe Miconieae is not resolved as monophyletic, but rather composed of two distinct clades: one composed of the cauliflorous genera Henriettea, Henriettella, Loreya and Bellucia, and a second clade with all other taxa in MiconIEae, sister to a polytomy that includes representatives from tribes Merianieae and Blakeeae.
Abstract: Miconieae is the most diverse tribe of Melastomataceae, with 30 genera and over 2200 species. The tribe is characterized by fleshy fruits and partially to totally inferior ovaries. To test monophyly of the tribe and assess phylogenetic relationships within it, sequence data from nrITS were gathered and analyzed for 110 taxa in Miconieae and 32 putative outgroups. The tribe Miconieae is not resolved as monophyletic, but rather composed of two distinct clades: one composed of the cauliflorous genera Henriettea, Henriettella, Loreya and Bellucia, and a second clade with all other taxa in Miconieae, sister to a polytomy that includes representatives from tribes Merianieae and Blakeeae. Terminal inflorescences are optimized as basal within Miconieae, with lateral inflorescences evolving in at least four different instances. Cauliflory does not appear to be derived from truly axillary inflorescences; instead it seems to have evolved independently. The terminal-flowered genera Tococa, Conostegia, Tetrazygia, Anaectocalyx, Charianthus, Calycogonium, and Leandra pro parte seem to be derived from within the large genus Miconia, as is Clidemia, a genus with both axillary inflorescences and terminal inflorescences that are deflexed to a lateral position by an axillary branch. Maieta and Necranium, both with axillary inflorescences, are resolved as derived from within Clidemia.
150 citations
TL;DR: The ITS phylogenies reveal that extant Impatiens species are of Southeast Asian origin, from where dispersals to boreal Eurasia and North America, to central Asia and eastern Europe via the Himalayas, and to India and Africa have occurred.
Abstract: Sequences of the internal transcribed spacers (ITS) of nuclear ribosomal DNA were acquired for 112 species of Balsaminaceae worldwide and five species of its closest relatives Marcgraviaceae and Tetrameristaceae. Phylogenetic analyses applying parsimony and distance estimates confirmed the monophyly of Balsaminaceae and suggest the monophyly of Impatiens. Within Impatiens, a few clades are recognized with strong support. Two of the most important clades are the spurless Madagascan endemic group, and the one comprising species with broadly fusiform fruits and the basic chromosome number x = 8, that shows a Southeast Asia, southern India, Africa, and Madagascar connection. Despite recognition of several strongly supported small lineages, ITS data alone could.not resolve relationships among most of the lineages with confident support values. ITS phylogenies are therefore of limited taxonomic value for Impatiens. However, ITS phylogenies do reveal that extant Impatiens species are of Southeast Asian origin, from where dispersals to boreal Eurasia and North America, to central Asia and eastern Europe via the Himalayas, and to India and Africa have occurred. The Madagascan Impatiens show an African origin. Molecular phylogenies suggest the ancestral basic chromosome number to be x = 10, and the spurred flowers and elongated linear fruits to be plesiomorphic states in Impatiens. A predominantly descending dysploid chromosome evolution, following dispersal of the clade with broadly fusiform fruits from Southeast Asia to India, Africa, and Madagascar, is also suggested.
144 citations
TL;DR: The results indicate that the lichens containing Xanthoparmelia-type lichenan form a monophyletic group, however, the segregates proposed earlier do not form distinct clades within the group.
Abstract: Generic concepts in the parmelioid lichens have been discussed intensively over the past three decades without reaching a broad consensus. We have now employed molecular data from three genes to provide a basis for a revised generic concept of the parmelioid lichens containing Xanthoparmelia-type lichenan. The phylogeny of the parmelioid lichens containing Xanthoparmelia-type lichenan was reconstructed using a combined Bayesian analysis of nuclear ITS, LSU rDNA and mitochondrial SSU rDNA sequences, and a maximum parsimony analysis was also made for comparison. 179 new partial sequences of 58 taxa were generated and 12 sequences were downloaded from GenBank. Our results indicate that the lichens containing Xanthoparmelia-type lichenan form a monophyletic group. However, the segregates proposed earlier do not form distinct clades within the group. Alternative hypotheses of monophyletic Karoowia and Neofuscelia that are not nested within Xanthoparmelia were rejected with our dataset; Karoowia is polyphyletic, and Neofuscelia is reduced to synonymy under Xanthoparmelia. Xanthomaculina convoluta also belongs to Xanthoparmelia. Since we were unable to sequence the umbilicate type species ofXanthomaculina, we refrain from synonymizing that genus with Xanthoparmelia here. The synonymy of Chondropsis and Paraparmelia under Xanthoparmelia already proposed is supported. The revised and enlarged genus Xanthoparmelia includes species that have cell walls with Xanthoparmelia-type lichenan, a palisade plectenchyma with a pored epicortex, lack pseudocyphellae, with usually simple rhizines, generally bifusiform conidia, and medullary chemical diversity. Ten new names are proposed, and 129 new combinations are made into Xanthoparmelia.
138 citations
TL;DR: Study of Caribbean taxa with high levels of endemicity allows tracing the correspondence between taxa and geographic areas, and thus, permits application of a phylogeny for assessments of geographic relatedness under both dispersal and vicariant scenarios.
Abstract: Knowledge of the evolution and biogeography of the Caribbean biota comes primarily from faunal studies, in spite of the tremendous richness of the Caribbean flora. The limited data to assess Caribbean phytogeography comes from fossils, floristic distributions, and phylogenetic studies. The geology in the Caribbean is extremely complex, but it is widely accepted that part of the Greater Antilles are old and precede the emergence of the Lesser Antilles and the Panamanian isthmus. Cuba and Hispaniola are each composed of a series of independent land blocks and Jamaica was mainly or entirely submerged during part of its history. Paleopalynological data, at present the only reliable source for reconstructing past plant communities, suggest warm-temperate to tropical conditions. Contemporary floristic data portray affinities with both Laurasian and Gondwanan derived plant groups. Shortcomings of traditional methodological approaches is a major criticism to studies assessing historical biogeography. Phylogenetics is an appropriate strategy to apply, because it: (1) elucidates the systematic relationships of taxa, (2) permits assessment of morphological and ecological evolution, and (3) illustrates the direction and sequence in which the distribution of a taxa originated. Study of Caribbean taxa with high levels of endemicity allows tracing the correspondence between taxa and geographic areas, and thus, permits application of a phylogeny for assessments of geographic relatedness under both dispersal and vicariant scenarios. Caribbean plant groups in several angiosperm families have now been studied phylogenetically. Some biogeographic patterns are starting to emerge from these studies, but more studies are needed for generalizations to be drawn.
106 citations
TL;DR: A new infratribal and infrageneric rearrangement for Veroniceae and Veronica is proposed and it is concluded that it is best to recognize a large genus Veronica with 13 subgenera, along with 8 other genera, including Scrofella, Veronicastrum and Paederota, in Veronicesae.
Abstract: Based on the most recent evidence from phylogenetic analyses of Veronica and its related genera, we propose a new infratribal and infrageneric rearrangement for Veroniceae and Veronica. These recent analyses have settled the long dispute about the relationship of the Northern Hemisphere Veronica and the Southern Hemisphere Hebe complex and have shown the derivation of the latter from within the former. Other currently recognized genera such as Synthyris and Pseudolysimachion are also derived from within Veronica. A classification based on monophyletic genera therefore needs to either lump some well recognized genera into a large genus Veronica or split Veronica into several genera that seem impossible to separate using morphological or structural characters. We discuss the advantages and disadvantages and conclude that it is best to recognize a large genus Veronica (including Hebe, Parahebe, Chionohebe, Heliohebe, Detzneria, Derwentia, Pseudolysimachion, Synthyris and Besseya) with 13 subgenera, along with 8 other genera, Scrofella, Veronicastrum (inclusive of Calorhabdos and Botryopleuron), Lagotis, Wulfenia, Kashmiria, Picrorhiza, Wulfeniopsis and Paederota, in Veroniceae.
102 citations
TL;DR: Here and in other groups of Achillea, various instances of conflicting evidence from nrITS, plastid trnL-F, and morphology point to hybridization and lineage sorting.
Abstract: The N Hemisphere genus Achillea includes about 130 perennial and allogamous species, is centered in SE Europe/SW Asia, and exhibits a complex phyletic structure due to excessive hybridization and polyploidy. About half ofthe species and five of the six traditional sections together with several outgroup genera were studied using nrITS and plastid trnL-F DNA sequences. In spite of some discordance, these markers were shown by Maximum Parsimony and Bayesian Inference to be suitable for revealing relationships with generic allies and for distinguishing the main lineages within Achillea. With the inclusion of Otanthus (and possibly Leucocyclus) Achillea s.1. becomes monophyletic and appears as sister to Anacyclus. A basal clade is formed by the xerophytes of Achillea sections Babounya and Santolinoideae in SW Asia together with the Mediterranean coastal Otanthus. Achillea sect. Ptarmica s.l. has to be divided into the meso- to hygrophytic herbs of A. sect. Ptarmica s.s. in the N Hemisphere and the mountain species of A. sect. Anthemoideae. The latter differentiated in the mountains from NW Anatolia to the Pyrenees, possibly originating from ancestors related to the extant A. ligustica. Finally, taxa of sect. Achillea s.l. (to be merged with A. sect. Filipendulinae) radiated from a center in SE Europe, occupied very different open habitats, and reached an extensive distribution with the very polymorphic polyploid and reticulate complex A. millefolium agg. Here and in other groups of Achillea, various instances of conflicting evidence from nrITS, plastid trnL-F, and morphology point to hybridization and lineage sorting. This means that reticulate evolution is not only involved in recent radiations but must have been active already in the early diversification of the genus.
92 citations
TL;DR: Pelargonium was found to consist of five main clades, some with contrasting evolutionary patterns with respect to biogeographic distributions, dispersal capacity, pollination biology and karyological diversification.
Abstract: Phylogenetic hypotheses for the largely South African genus Pelargonium L'Her. (Geraniaceae) were derived based on DNA sequence data from nuclear, chloroplast and mitochondrial encoded regions. The datasets were unequally represented and comprised cpDNA trnL-F sequences for 152 taxa, nrDNA ITS sequences for 55 taxa, and mtDNA nad1 b/c exons for 51 taxa. Phylogenetic hypotheses derived from the separate three datasets were overall congruent. A single hypothesis synthesising the information in the three datasets was constructed following a total evidence approach and implementing dataset specific stepmatrices in order to correct for substitution biases. Pelargonium was found to consist of five main clades, some with contrasting evolutionary patterns with respect to biogeographic distributions, dispersal capacity, pollination biology and karyological diversification. The five main clades are structured in two (subgeneric) clades that correlate with chromosome size. One of these clades includes a "winter rainfall clade" containing more than 70% of all currently described Pelargonium species, and all restricted to the South African Cape winter rainfall region. Apart from (woody) shrubs and small herbaceous rosette subshrubs, this clade comprises a large "xerophytic" clade including geophytes, stem and leaf succulents, harbouring in total almost half of the genus. This clade is considered to be the result of in situ proliferation, possibly in response to late-Miocene and Pliocene aridification events. Nested within it is a radiation comprising c. 80 species from the geophytic Pelargonium section Hoarea, all characterised by the possession of (a series of) tunicate tubers.
TL;DR: A recent survey revealed that during a five-year period over 65% of all molecular phylogenetic studies of plants at the generic level or lower included sequences of the internal transcribed spacer region of nuclear ribosomal DNA (ITS).
Abstract: A recent survey by Alvarez & Wendel (2003) revealed that during a five-year period over 65% of all molecular phylogenetic studies of plants at the generic level or lower included sequences of the internal transcribed spacer region of nuclear ribosomal DNA (ITS), and more than one third of the studies used this region exclusively for reconstructing phylogeny. Why the immense popularity of ITS among plant systematists? ITS sequences have achieved popularity for the same two reasons that any method or approach becomes popular in plant systematics: it is easy to generate data and the data seem to "work". There are universal primers (with rare exceptions) for the ITS region (Baldwin, 1992), and therefore, it is easy for systematists to generate data rapidly because they do not have to design primers. Also, because there are many copies of the ITS repeat per genome, it is relatively easy to amplify the region. The ITS region has "worked" in the sense that it has proven sufficiently variable to resolve relationships in many different plant groups at the generic level or lower, which are the levels at which many plant systematists conduct research. Several studies have also demonstrated the value of ITS sequences at higher taxonomic levels (Hershkovitz & Lewis, 1996; Hershkovitz & Zimmer, 1996; Goertzen & al., 2003). If the ITS region has served plant systematists so well, why even look for another region to sequence? It is beyond the scope of this column to discuss the potential limitations of the ITS region, and we refer readers to the insightful and comprehensive critique of these limitations provided by Alvarez & Wendel (2003). We hasten to add, however, that while there certainly are limitations in using ITS sequences for phylogenetic reconstruction, it remains a genomic region that has proven and likely will continue to prove immensely useful to plant systematists. After all, without the insights that sequences of the ITS region have provided, we would be limited in our ability to judge the utility of other nuclear sequences that we will discuss here. For example, Tank & Sang (2001) discuss the importance of having a well-established phylogeny for Paeonia (based on morphology and molecular data, including the ITS region) as a framework for judging the utility of their sequences of GPAT (Table 1). On the other hand, it is becoming increasingly clear that some of the advantages of the ITS region may also make this region problematic. For example, universal primers may facilitate PCR amplification of contaminants. Although most of the copies of ITS per genome are identical, there may be rare copies in an individual that are not amplified due to selective amplification of only one copy. Concerted evolution often homogenizes copy types, and together, selective amplification and concerted evolution could obscure processes (e.g., hybridization) in the history of an organism. Another compelling reason to search for alternative low-copy nuclear sequences is that, despite the utility of ITS sequences for resolving relationships within genera, there are many examples, too numerous to cite, where resolution is poor because of the relatively short sequence length of the ITS region and the lack of sufficient variation. Thus, including additional nuclear gene sequence data has the potential to provide a more robust estimate of phylogenetic relationships. Another motivation for seeking additional nuclear sequences is that any inferred organismal phylogeny becomes much more compelling when it is based on more than one region because it becomes more than just a single gene tree (Cronn & al., 2003). However, few nuclear genes exist as single copies in most plant species, which complicates generating DNA sequence data from the nuclear genome. Generating sequence data from multiple gene regions in the chloroplast is easily accomplished because many different regions have been well characterized (e.g., matK, trnL-trnF, psbA-trnH, atpB) and most of these regions have universal primers available for amplification and sequencing. Employing sequences of multiple cpDNA gene regions often helps to resolve relationships with more support, but since the chloroplast genome is generally inherited as a single unit and lacks recombination, phylogenies based on multiple cpDNA regions effectively represent a single gene tree (Doyle, 1992). Given that it is desirable to include low-copy nuclear
TL;DR: Monophyly and sister group relationship of Ceropegieae and Marsdenieae, the two Asclepiadoideae tribes possessing erect pollinia, are confirmed by molecular investigation of non-coding cpDNA markers.
Abstract: Monophyly and sister group relationship of Ceropegieae and Marsdenieae, the two Asclepiadoideae tribes possessing erect pollinia, are confirmed by molecular investigation of non-coding cpDNA markers (trnT-L and trnL-F spacers, and the trnL intron). In Ceropegieae, the analyzed taxa fall in four subclades. The Heterostemma subclade is sister to other three subclades, of which the Conomitra-Leptadenia-Orthanthera subclade is sister to the Anisotoma-Neoschumannia-Riocreuxia-Sisyranthus subclade and to the large subclade comprising the stem-succulent stapeliads, Brachystelma and Ceropegia. Following these results, subdivision of Ceropegieae into four subtribes, Anisotominae, Heterostemminae, Leptadeniinae and Stapeliinae, is proposed.
TL;DR: This proposal, meant to bring a better comprehension of this group within the Eriocaulaceae, is supported by the phylogenetic analyses of Giulietti et al. (1995, 2000) that show the group to be monophyletic.
Abstract: Paepalanthus Mart, the largest genus of Eriocaulaceae, has been shown to be polyphyletic by all the phylogenetic analyses performed so far in the family After intensive and extensive field work and an analysis of various characters in a recent revision of Paepalanthus section Actinocephalus (Korn) Ruhland, I encountered consistent evidence that this group should be elevated to generic status This proposal, meant to bring a better comprehension of this group within the family, is supported by the phylogenetic analyses of Giulietti et al (1995, 2000) that show the group to be monophyletic Actinocephalus (Korn) Sano, as proposed here, contains 28 species The necessary nomenclatural changes are made for the new status, with 28 new combinations proposed, 17 new synonyms, eight lectotypifications, five stati novi and one new name Actinocephalus (Korn) Sano is characterized principally by inflorescences composed of capitula in umbels and in having a geographic range restricted to Brazil
TL;DR: A transitional-combinational theory suggests that angiosperms evolved slowly from seed ferns in the Jurassic beginning first with the carpel, followed later by double fertilization, and lastly by the appearance of flowers, which may have taken more than 100 million years to complete.
Abstract: The origin of the angiosperms has long remained problematical. Recent new discoveries of early angiosperm fossils and many new molecular phylogenies have helped to identify basal extant angiosperms and to infer their inter-relationships. Still unclear, however, are ties with gymnosperms, both living and fossil. In view of difficulty of finding ancestors for angiosperms, yet also considering their sudden appearance and explosive evolutionary success, a transitional-combinational theory is proposed. This theory suggests that angiosperms evolved slowly from seed ferns in the Jurassic beginning first with the carpel, followed later by double fertilization, and lastly by the appearance of flowers. These three fundamental transitions may have taken more than 100 million years to complete. The extant (or modern) angiosperms did not appear until Early Cretaceous, as attested by micro- and macrofossils, when the final combination of all three important angiosperm features occurred. This combination provided the opportunity for explosive evolutionary diversification, especially in response to selection from insect pollinators and predators, plus attendant modifications in compatibility and breeding systems. The transitional-combinational theory explains some of the discrepancy between fossil and molecular phylogenetic data, the latter of which suggests that angiosperms originated pre-Cretaceous. DNA (and protein) sequence data and oleananes reflect ancestry in an earlier transitional carpellate lineage (or lineages), much earlier than appearance of the final combination that includes floral and associated pollen modifications. The theory suggests viewing all gymnosperms, other than extinct seed ferns from which carpels arose, as having had no direct phylogenetic connections to modern angiosperms.
TL;DR: A phylogenetic analysis of sequences of the internal transcribed spacers of the nuclear ribosomal DNA to test the hypothesis that the Canary Island genus Vierea is closely related to Pulicaria sect.
Abstract: We undertook a phylogenetic analysis of sequences of the internal transcribed spacers (ITS) of the nuclear ribosomal DNA to test the hypothesis that the Canary Island genus Vierea is closely related to Pulicaria sect. Vieraeopsis, a taxon with four species restricted to Socotra and Southern Arabia. The ITS tree does not support this relationship, although many of the nodes were weakly supported (bootstrap value below 75%). Vierea is sister to the Mediterranean genus Perralderia (bootstrap support 74%). We suggest that morphological similarities between Vierea and Pulicaria sect. Vieraeopsis are due mostly to morphological convergence. It is thus concluded that these two taxa do not share a common history. A review of molecular phylogenetic studies of taxa considered to represent putative biogeographical links between Macaronesia and Southern Arabia and/or distant regions of Africa, is also presented. With a few exceptions most of these putative relationships are not supported by molecular phylogenies. Additional cladistic studies are needed for at least 15 genera or sections with a predominant disjunct phytogeographical distribution between Macaronesia, East/South Africa and Southern Arabia.
TL;DR: Chromosome numbers of 45 accessions representing 16 genera and 37 species of Araliaceae are reported, of which 30 species and seven genera (Apiopetalum, Arthrophyllum, Delarbrea, Merrilliopanax, Metapanax, Myodocarpus, and Pseudosciadium) are recorded for the first time.
Abstract: Chromosome numbers of 45 accessions representing 16 genera and 37 species of Araliaceae are herein reported, of which 30 species and seven genera (Apiopetalum, Arthrophyllum, Delarbrea, Merrilliopanax, Metapanax, Myodocarpus, and Pseudosciadium) are recorded for the first time. The evolution of this character is also examined in light of recent hypotheses of phylogenetic relationships. Chromosome numbers in the family are relatively uniform, generally with 2n = 24 or 48. However, the genus Hedera exhibits extreme variability, with a polyploid series ranging from 2n = 48 to 192. The basic number of Araliaceae is inferred to be x = 12, although x = 6 cannot be ruled out. The "Asian palmate" clade, the largest of the three major clades of core Araliaceae, is primarily characterized by polyploidy, although several genera have sometimes been regarded as evolutionarily "primitive". By contrast, Aralia, Panax, and Polyscias (representing other major clades within the family) include species with both diploids and tetraploids. Four genera recently segregated from core Araliaceae (Apiopetalum, Delarbrea, Myodocarpus, and Pseudosciadium) are reported as n = 12. The formerly apiaceous Hydrocotyle (now placed in Araliaceae) is best interpreted as x = 12, although some aneuploid species may exist with x = 9. Hydrocotyle also exhibits extensive variation in ploidal level. Within Araliaceae, chromosomal variation is largely related to ploidal level, with relatively few cases of aneuploidy, such as those documented in Panax ginseng and Hydrocotyle. The available data are largely consistent with the hypothesis that the basic chromosome number of Apiales is x = 6.
TL;DR: This work presents an epithet-based form of species name that is fully compatible with the rank-free system of the Phylocode, in which the genus rank does not exist, and guarantees uniqueness in all situations.
Abstract: reasons mentioned above (i.e., distinction between names and classification, and the absence of a mandatory genus rank, and thus generic names), we reject the binomial-based methods that have been proposed for use with the PhyloCode. The potential for confusion is particularly striking in the case of the creation of new species names. Therefore, we argue that the solution is for species names to become epithet-based. A problem that must be solved in this context is how to guarantee the uniqueness of epithet-based species names, considering that many species share the same epithet. We present an epithet-based form of species name that is fully compatible with the rank-free system of the Phylocode, in which the genus rank does not exist. Also, it guarantees uniqueness in all situations. However, we do not intend to argue that species names under the PhyloCode must follow the method we describe, although we find it convenient. Instead, we wish to stimulate a needed debate on the form of species names in a rank-free system.
TL;DR: The results indicate that the recognition of a single polymorphic species is the best solution for the genus Dupontia and that no genetic subdivision exists within the genus.
Abstract: The grass family (Poaceae) is the largest family of vascular plants in the Arctic. The family includes several species complexes that show high ploidy levels, predominantly reproduce asexually, are poorly morphologically delimited, and have a possible origin within the Arctic area by reticulate evolution. Challenged by work on the Panarctic Flora project and apparent discrepancies in recent taxonomic treatments, we investigated the arctic grass genus Dupontia by molecular and cytogenetic methods. Identical plastid DNA (trnL-F) sequences and very similar AFLP profiles indicated that Dupontia and Arctophila are closely related and that the latter might have been involved in a possible intergeneric hybrid origin of Dupontia. Despite the presence of intra-individual rDNA (ITS) variation in Dupontia indicating an allopolyploid hybrid origin of the genus, it was not possible to predict the second parental species from sequence data or from fluorescent in situ hybridization (FISH) experiments using genomic probes. Due to lack of sequence divergence within Dupontia, AFLP fingerprinting was applied to investigate whether any genetic subdivision exists within the genus. The data sorted Dupontia first of all according to geography and not to ploidy or morphological characters that have previously been used to discriminate between proposed taxa. The results indicate that the recognition of a single polymorphic species is the best solution for the genus Dupontia.
TL;DR: The analyses showed robust support for two outgroup clades, Liabeae-Vernonieae and Gundelieae-Lactuceae and two main subtribes within Arctoteae and Gorteriinae, which shows that the unusual taxa are of critical importance, and they should be included in any molecular analysis.
Abstract: Compositae (Asteraceae) are the largest flowering plant family (23,000 to 30,000 species) and its members are found throughout the world in both temperate and tropical habitats. The subfamilies and tribes of Compositae remained relatively constant for many years; recent molecular studies, however, have identified new subfamilial groups and identified previously unknown relationships. Currently there are 35 tribes and 10 subfamilies (Baldwin & al., 2002; Panero & Funk, 2002). Some of the tribes and subfamilies have not been tested for monophyly and without a clear understanding of the major genera that form each tribe and subfamily, an accurate phylogeny for the family cannot be reconstructed. The tribe Arctoteae (African daisies) is a diverse and interesting group with a primarily southern African distribution (ca. 17 genera, 220 species). They are especially important in that most of the species are found in the Cape Floral Kingdom, the smallest floral kingdom and the subject of intense conservation interest. Arctoteae are part of the monophyletic subfamily Cichorioideae s.s. Other tribes in the subfamily include Eremothamneae, Gundelieae, Lactuceae, Liabeae, Moquineae, and Vernonieae, and these were all evaluated as potential outgroups. Ultimately 29 ingroup taxa and 16 outgroup taxa with a total of 130 sequences (125 newly reported), from three genetic regions, two from chloroplast DNA (trnL-F and ndhF) and one from the nuclear genome (ITS), were used to evaluate the tribe and its proposed outgroups. Each molecular region is examined separately, the chloroplast markers are examined together, and the data are combined. The data were analyzed with and without outgroups and problem taxa using parsimony and maximum likelihood methods. The analyses showed robust support for two outgroup clades, Liabeae-Vernonieae and Gundelieae-Lactuceae and two main subtribes within Arctoteae: Arctotineae and Gorteriinae. Support for monophyly of Arctoteae is weak. Within Arctoteae, some taxa of interest are easily placed: Didelta, Cuspidia and Heterorhachis are consistently part of subtribe Gorteriinae, Cymbonotus, the Australian genus, is nested within subtribe Arctotineae, and Haplocarpha is at the base of Arctotineae. Berkheya, Haplocarpha, and Hirpicium are probably paraphyletic. Furthermore, Platycarpha most likely does not belong in Arctoteae, and Heterolepis and the tribe Eremothamneae are within Arctoteae but not within either of the two main subtribes. After some rearrangements, the two main subtribes, Arctotineae and Gorteriinae, are monophyletic and the latter has three clades. The study shows that the unusual taxa are of critical importance, and they should be included in any molecular analysis. Adequate representation of the ingroup is also important as all previous studies of Arctoteae had involved only a few taxa from the core subtribes, and so did not reveal the problems. Multiple outgroups evaluated in an iterative manner had pronounced effects on the relationships within the ingroup, not only on the position of the root. Finally, unrooted consensus trees and unrooted phylograms were found to be very useful in analyzing the data, allowing for examination of placement of taxa without the bias of a rooted tree.
TL;DR: A phylogenetic analysis of subtribe Scorzonerinae using ITS sequence data reveals that most genera, including Tragopogon, Epilasia, Podospermum, Koelpinia, and Lasiospora, are monophyletic; however, traditionally important morphological and karyological characters have multiple origins in Scorzonera.
Abstract: Subtribe Scorzonerinae of tribe Lactuceae (Asteraceae: Cichorioideae) appears to be well supported as monophyletic; however, generic circumscription and relationships within the group have been problematic. To investigatethe monophyly and circumscription of the recognized genera and their intergeneric relationships, we conducted a phylogenetic analysis of subtribe Scorzonerinae using ITS sequence data. Our results reveal that most genera, including Tragopogon, Epilasia, Podospermum, Koelpinia, and Lasiospora, are monophyletic. The monotypic Pterachaenia and Tourneuxia are distinct lineages within Scorzonerinae. The monotypic Geropogon, which has often been included in Tragopogon, is phylogenetically removed from the highly supported Tragopogon clade. In contrast, Scorzonera is clearly not monophyletic, with species of the genus appearing in multiple clades with other genera. Scorzonera purpurea is weakly supported as the sister to Podospermum. Scorzonera austriaca is sister to Takhtajaniantha and may represent one ancestral parent of this monotypic polyploid genus. Species of Scorzonera sections Tuberosae, Vierhapperia, Nervosae, and Pulvinares form a clade with the genus Lasiospora. Scorzonera sections Pulvinares, Tuberosae, and Foliosae are clearly not monophyletic. Some non-DNA characters (e.g., achene morphology) generally agree with the clades recognized by ITS sequence data. However, our analyses also show that traditionally important morphological and karyological characters have multiple origins in Scorzonerinae.
TL;DR: This study tested the monophyly of the previously proposed genera Alaternus, Frangula, Oreoherzogia, and Rhamnus s.str.
Abstract: This study tested the monophyly of the previously proposed genera Alaternus, Frangula, Oreoherzogia, and Rhamnus s.str., and the phylogenetic relations suggested by Grubov (1949), within the Rhamnu ...
TL;DR: It is suggested, however, that Hemipteran insects do not feed on taxa of Anacardiaceae that produce alkylcatechols, suggesting that these substances are produced in unrelated groups of genera.
Abstract: Anacardiaceae are largely tropical trees, shrubs and lianas of the order Sapindales, characterized by production of three types of toxic phenols: biflavonoids, alkylcatechols and alkylresorcinols. Anatomical, morphological and rbcL sequence data were used to reconstruct the phylogeny of a group of Anacardiaceae and address questions about the origin and evolution of these toxic phenolic compounds. Their evolutionary patterns are discussed in relation to the group of Hemipteran insects that feed on Anacardiaceae. Our study included 22 taxa of Anacardiaceae and the results support previous phylogenetic studies in that two clades are detected: a basal clade, with Spondias and related genera that do not produce toxic phenolic compounds, and a second clade with the remaining genera, i.e., those that produce biflavonoids, as do species of Burseraceae. The evolutionary patterns of alkylcatechols and alkylresorcinols are not straightforward; these substances are produced in unrelated groups of genera. We suggest, however, that Hemipteran insects do not feed on taxa of Anacardiaceae that produce alkylcatechols.
TL;DR: This paper provides a practical taxonomic treatment of the polyphyletic genus Centaurium Hill and establishment of a new genus, Zeltnera, along with the reinstatement of Gyrandra Grise b.
Abstract: This paper provides a practical taxonomic treatment of the polyphyletic genus Centaurium Hill. This new classification defines monophyletic groups and thus reflects the phylogenetic relationships within the subtribe Chironiinae (Gentianaceae). For this purpose, the establishment of a new genus, Zeltnera, along with the reinstatement of Gyrandra Griseb. and Schenkia Griseb., results in numerous new species combinations, a more restrictive circumscription of Centaurium Hill, and novel generic delimitations within Chironiinae. Fifteen genera are recognized, encompassing ca. 108 species. The new genus Zeltnera comprises 25 species mainly confined to California, Mexico, and Texas. Gyrandra is a small genus with three species restricted to some areas of Mexico (G. chironioides, G. pterocaulis and G. tenuifolia) and two species widespread in Central America (G. brachycalyx and G. pauciflora). Schenkia comprises five species: S. spicata is broadly distributed in Eurasia and north Africa, S. australis, S. clementii, and S. japonica are confined to Australia and the Pacific region, while S. sebaeoides is a rare and endangered Hawaiian endemic. Finally, the genus Centaurium s.s. consists of ca. 20 species of primarily Mediterranean distribution.
TL;DR: Personal thoughts on the history and possible future of biogeography are offered, with special reference to the role of molecular phylogeographic analyses in forging helpful connections between microevolutionary and macroevolutionaries perspectives on biogeographic phenomena.
Abstract: Biogeography can be both an eclectic and a unifying discipline-eclectic by virtue of the diversity of technical and conceptual approaches from which it borrows; and unifying by virtue of drawing together inputs from diverse fields (ranging from molecular biology to ecology to historical geology) in its attempts to understand the spatial and temporal dynamics of organismal distributions. Here I offer several personal thoughts on the history and possible future of biogeography, with special reference to the role of molecular phylogeographic analyses in forging helpful connections between microevolutionary and macroevolutionary perspectives on biogeographic phenomena.
TL;DR: A critical article-by-article examination of the current edition of the International Code of Botanical Nomenclature found that only 14 of the total 62 articles are relevant to whether or not classification is phylogenetic.
Abstract: As a follow-up to the 2001 Smithsonian Botanical Symposium, in late June of 2002 a group of 15 taxonomists took part in a Workshop entitled "Linnaean Nomenclature in the 21 s t Century" at the Hunt Institute for BotanicalDocumentation in Pittsburgh to discuss integrating phylogenetic information into the current systems of naming plants, animals, and microorganisms. The Hunt Group included a diversity of taxonomists, including traditional and phylogenetic practitioners as well as authorities on the current codes and end-users of nomenclatural rules. The discussion ranged from identifying problems and possible solutions to devising strategies for implementing change. It was concluded that the central problems revolve around the concepts of (1) circumscribing taxa, (2) hierarchical ranking, and (3) the use of binomials. In a critical article-by-article examination of the current edition of the International Code of Botanical Nomenclature it was found that only 14 of the total 62 articles (plus appendices) are relevant to whether or not classification is phylogenetic. Furthermore, each of these potentially problematic articles is either amenable to conveying phylogenetic information or neutral to phylogenetic considerations. There is nothing in the current Linnaean nomenclature that prevents cladistic information from being incorporated into the naming procedure. We suggest that a major effort is needed to educate the botanical community as well as lay persons on the implications and use of these pertinent articles in phylogenetic nomenclature.
TL;DR: The phylogenetic relationships of the genus Saussurea DC.
Abstract: The phylogenetic relationships of the genus Saussurea DC. and Hemistepta lyrata Bunge were analyzed using the nuclear ribosomal ITS and chloroplast matK gene. Phylogenetic analyses revealed that Saussurea ceratocarpa Decne. of subg. Jurinocera (Baill.) Lipsch. and the species assigned to sect. Elatae Hook.f. of subg. Saussurea were separated from all other members of the genus Saussurea. The species of subgen. Jurinocera and subgen. Saussurea sect. Elatae form a monophyletic unit along with a group including genus Jurinea Cass. The species of subg. Jurinocera and sect. Elatae share 4-5-gonal cypselas and apical pericarpal crowns bearing sharp horns or sharp teeth. The Saussurea s.s. group is comprised of representatives of six sections of the subg. Saussurea and morphologically distinctive subgenera [Amphilaena (Stschegl.) Lipsch., Eriocoryne (DC.) Hook.f., and Theodorea (Cass.) Lipsch.]. Two frigid-adapted forms, the "snowball plants" of subg. Eriocoryne and the "glasshouse plants" of subg. Amphilaena, were confirmed as members of Saussurea s.s. Hemistepta lyrata and Saussurea s.s. show a close sister relationship, which is supported by the pappus dimorphism involving free, short, scabrid outer bristles or tiny outer scales and basally connate in a ring, with much longer, plumose inner bristles.
TL;DR: The low level of divergence of ITS sequences among taxa to the north of the Trans-Mexican Neovolcanic mountain range suggests a pattern of recent, and perhaps rapid, speciation.
Abstract: The genus Ceratozamia contains more than 20 species distributed in eastern and southern Mexico, with extensions into Central America. Morphology, anatomy, and molecular (ITS) data allow resolution of some aspects of species relationships, provide correlations with ecology, and suggest phytogeographic hypotheses. Some species complexes, such as those centered around C. norstogii and C. miqueliana, are restricted to southernwest Mexico, in what are regarded as Pleistocene floristic refugia. The low level of divergence of ITS sequences among taxa to the north of the Trans-Mexican Neovolcanic mountain range suggests a pattern of recent, and perhaps rapid, speciation.