343 research outputs found
An account of a preliminary mechanistic model of swimming behaviour in Daphnia: its use in understanding diel vertical migration
Functional Characterization of MAT1-1-Specific Mating-Type Genes in the Homothallic Ascomycete Sordaria Macrospora Provides New Insights into Essential and Nonessential Sexual Regulators
Mating-type genes in fungi encode regulators of mating and sexual development. Heterothallic ascomycete species require different sets of mating-type genes to control nonself-recognition and mating of compatible partners of different mating types. Homothallic (self-fertile) species also carry mating-type genes in their genome that are essential for sexual development. To analyze the molecular basis of homothallism and the role of mating-type genes during fruiting-body development, we deleted each of the three genes, SmtA-1 (MAT1-1-1), SmtA-2 (MAT1-1-2), and SmtA-3 (MAT1-1-3), contained in the MAT1-1 part of the mating-type locus of the homothallic ascomycete species Sordaria macrospora. Phenotypic analysis of deletion mutants revealed that the PPF domain protein-encoding gene SmtA-2 is essential for sexual reproduction, whereas the alpha domain protein-encoding genes SmtA-1 and SmtA-3 play no role in fruiting-body development. By means of cross-species microarray analysis using Neurospora crassa oligonucleotide microarrays hybridized with S. macrospora targets and quantitative real-time PCR, we identified genes expressed under the control of SmtA-1 and SmtA-2. Both genes are involved in the regulation of gene expression, including that of pheromone genes
Re-circumscription of the mimosoid genus Entada including new combinations for all species of the phylogenetically nested Elephantorrhiza (Leguminosae, Caesalpinioideae, mimosoid clade)
Recent phylogenomic analyses of 997 nuclear genes support the long-held view that the genus Entada is congeneric with Elephantorrhiza. Entada is resolved as monophyletic only if the genus Elephantorrhiza is subsumed within it. The two genera were distinguished solely by relatively minor differences in the mode of dehiscence of the fruits (a craspedium separating into one-seeded endocarp segments in Entada versus a craspedium with the whole fruit valve breaking away from the persistent replum in Elephantorrhiza) and the craspedial fruit type itself provides a shared synapomorphy for the re-circumscribed Entada. Here, we provide a synopsis of Entada, including 11 new combinations in total, for the eight species, one subspecies and one variety previously placed in Elephantorrhiza, as well as a new combination for a subspecies of Entada rheedei Spreng. not previously dealt with when Entada pursaetha DC. was placed in synonymy. These new combinations are: Entada burkei (Benth.) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada elephantina (Burch.) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada goetzei (Harms) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada goetzei subsp. lata (Brenan & Brummitt) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada obliqua (Burtt Davy) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada praetermissa (J.H. Ross) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada rangei (Harms) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada rheedei subsp. sinohimalensis (Grierson & D.G. Long) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada schinziana (Dinter) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada woodii (E. Phillips) S.A. O’Donnell & G.P. Lewis, comb. nov.; and Entada woodii var. pubescens (E. Phillips) S.A. O’Donnell & G.P. Lewis, comb. nov. We provide a revised circumscription of the genus Entada which now comprises 40 species distributed pantropically, with the greatest diversity of species in tropical Africa. We present a complete taxonomic synopsis, including a map showing the global distribution of the genus and photographs showing variation amongst species in habit, foliage, flowers and fruits. A short discussion about extrafloral nectaries, mainly observed in the Madagascan species, is presented
An investigation of some of the resistance aspects of the catamaran hull
This thesis document was issued under the authority of another institution, not NPS. At the time it was written, a copy was added to the NPS Library collection for reasons not now known. It has been included in the digital archive for its historical value to NPS. Not believed to be a CIVINS (Civilian Institutions) title.A symmetrical hull catamaran with dimensions 1n line with current proposed submarine rescue vessels was designed and tested at several hull spacings in order to determine the effect of separation on resistance. A single hull was tested to assess the relative increase in resistance or interference compared to the infinite separation represented by the single hull results. In general, it was found that the resistance decrease with increasing separations and for certain speeds and separations favorable interference was observed which made the overall resistance slightly less than twice the single hull results. A comparison with the submarine rescue vessels, a Taylor expansion and a comparable single hull ship is made where in the case of the latter the catamaran demonstrates its superiority at speed length ratios greater than 1.2. The effect of trim for the proposed design is also evaluated, resulting in decreased resistance with trim by the stern. A possible method employing the use of a single model to predict the resistance of a catamaran was tested with promising results.http://www.archive.org/details/investigationofs00braeLieutenant, United States Nav
Mezcala – a new segregate genus of mimosoid legume (Leguminosae, Caesalpinioideae, mimosoid clade) narrowly endemic to the Balsas Depression in Mexico
Recent results have demonstrated that the genus Desmanthus is non-monophyletic because the genus Kanaloa is nested within it, with a single species, Desmanthus balsensis placed as sister to the clade comprising Kanaloa plus the remaining species of Desmanthus. Here we transfer D. balsensis to a new segregate genus Mezcala, discuss the morphological features supporting this new genus, present a key to distinguish Mezcala from closely related genera in the Leucaena subclade, and provide a distribution map of M. balsensis
Disintegration of the genus Prosopis L. (Leguminosae, Caesalpinioideae, mimosoid clade)
Robust evidence from phylogenomic analyses of 997 nuclear genes has recently shown, beyond doubt, that the genus Prosopis is polyphyletic with three separate lineages, each with affinities to other genera of mimosoids: (i) Prosopis africana is an isolated lineage placed in the grade of Plathymenia, Newtonia and Fillaeopsis that subtends the core mimosoid clade; (ii) the remaining Old World species of Prosopis form a clade that is sister to the Indo-Nepalese monospecific genus Indopiptadenia and (iii) New World Prosopis has the Namibian / Namaqualand monospecific endemic genus Xerocladia nested within it. This means that it is now clear that maintaining the unity of the genus Prosopis sensu Burkart (1976) is no longer tenable. These three distinct lineages of Prosopis species correspond directly to Burkart’s (1976) sectional classification of the genus, to previously recognised genera and to the differences in types of armature that underpin Burkart’s sections. Here, we address this non-monophyly by resurrecting three segregate genera – Anonychium, Neltuma and Strombocarpa and provide 57 new name combinations where necessary, while maintaining the morphologically distinctive and geographically isolated genera Xerocladia and Indopiptadenia. The genus Prosopis itself is reduced to just three species and an emended description is presented. The impacts of these name changes for a genus of such high ecological and human use importance are discussed. These impacts are mitigated by clear differences in armature which facilitate identification and by potential benefits from the deeper biological understanding brought about by recognition of these divergent lineages at generic rank. We provide an identification key to genera and present a map showing the distributions of the segregate genera, as well as drawings and photos illustrating variation in armature and fruits
Phylogenomic assessment prompts recognition of the Serianthes clade and confirms the monophyly of Serianthes and its relationship with Falcataria and Wallaceodendron in the wider ingoid clade (Leguminosae, Caesalpinioideae)
The Indo-Pacific legume genus Serianthes was recently placed in the Archidendron clade (sensu Koenen et al. 2020), a subclade of the mimosoid clade in subfamily Caesalpinioideae, which also includes Acacia, Archidendron, Archidendropsis, Falcataria, Pararchidendron, Paraserianthes and Wallaceodendron. Serianthes comprises ca. 18 species, five subspecies and two varieties that are characterised by bipinnately compound leaves with alternate sessile leaflets, branched axillary corymbiform panicles and woody indehiscent pods. Generic relationships, as well as species relationships within genera in the Archidendron clade, remain uncertain. While the sister relationship between Serianthes and the genus Falcataria is strongly supported by molecular data, the distinction between Serianthes and the monotypic genus Wallaceodendron has been questioned, based on their similar flower and fruit morphologies. We combined three gene-enriched hybrid capture DNA sequence datasets (generated from the 964 mimobaits v1 probe set, the expanded 997 mimobaits v2 probe set and the GoFlag angiosperm 408 probe set) and used their overlapping markers (77 loci of the target exonic and flanking regions) to test the monophyly of Serianthes and to investigate generic relationships within the Archidendron clade using 55 ingoid plus two outgroup taxa. We show that Serianthes is monophyletic, confirm the Serianthes + Falcataria sister relationship to Wallaceodendron and recognise this combined clade as the Serianthes clade within the Archidendron clade. We also evaluated the use of overlapping loci across datasets in combination with concordance analyses to test generic relationships and further investigate previously unresolved relationships across the wider ingoid clade. Concordance analysis revealed limited gene tree conflicts near the tips of the Archidendron clade, but increased discordance at the base of the clade, which could be attributed to rapid lineage divergence (radiation) and/or incomplete lineage sorting
Dilemmas in generic delimitation of Senegalia and allies (Caesalpinioideae, mimosoid clade): how to reconcile phylogenomic evidence with morphology and taxonomy?
Senegalia comprises 219 species distributed in tropical and subtropical regions of North and South America, Africa, Asia and Australia. Two sections are currently recognised within Senegalia and these are most readily distinguished by the differences in disposition of their cauline prickles, i.e. sect. Senegalia with prickles at or near leaf nodes and sect. Monacanthea with mostly internodal prickles. Previous phylogenetic studies, based primarily on small numbers of plastid DNA loci, found Senegalia to be monophyletic with two large subclades corresponding to the sections. Here, we present new phylogenomic evidence from 997 single-copy nuclear gene sequences for a small, but representative set of species. These new analyses show that Senegalia is non-monophyletic, but instead, forms a grade that is paraphyletic with respect to the remainder of the ingoid clade (i.e. Ingeae + Acacia s.s. + Acaciella), comprising two well-supported subclades most likely representing the same clades as found in previous phylogenetic studies of the genus and, interspersed between these, a third, moderately supported clade, comprising the genera Mariosousa, Pseudosenegalia and Parasenegalia. In marked contrast to the nuclear phylogeny, the two Senegalia clades are sister groups in the plastid phylogeny, based on analyses of 72 chloroplast genes, rendering the genus monophyletic, based on plastid data alone. We discuss this new evidence that Senegalia is non-monophyletic in relation to the marked cytonuclear discordance, high gene tree conflict and lack of resolution across this senegalioid grade and review the consistency of the key morphological characters distinguishing the two sections of Senegalia. We conclude that it is likely that Senegalia will need to be split into two (or possibly more) genera: a re-circumscribed Senegalia s.s. that corresponds to the existing Senegalia sect. Senegalia plus the S. ataxacantha group (Senegalia sect. Monacanthea s.s.; future studies may show that this group warrants generic status) and a new genus corresponding to the remainder of sect. Monacanthea (here designated as Senegalia sect. Monacanthea p.p.). However, re-delimiting Senegalia now would be premature given that the key morphological characters are not fully congruent with the two sections and pending denser phylogenetic sampling of taxa. A judiciously selected list of critical taxa is presented to facilitate future phylogenomic studies. Finally, we discuss the identity of Albizia leonardii, which is also placed in this senegalioid grade in these new phylogenomic analyses and place it in synonymy with Parasenegalia vogeliana
Re-circumscription of the mimosoid genus Entada including new combinations for all species of the phylogenetically nested Elephantorrhiza (Leguminosae, Caesalpinioideae, mimosoid clade)
Recent phylogenomic analyses of 997 nuclear genes support the long-held view that the genus Entada is congeneric with Elephantorrhiza. Entada is resolved as monophyletic only if the genus Elephantorrhiza is subsumed within it. The two genera were distinguished solely by relatively minor differences in the mode of dehiscence of the fruits (a craspedium separating into one-seeded endocarp segments in Entada versus a craspedium with the whole fruit valve breaking away from the persistent replum in Elephantorrhiza) and the craspedial fruit type itself provides a shared synapomorphy for the re-circumscribed Entada. Here, we provide a synopsis of Entada, including 11 new combinations in total, for the eight species, one subspecies and one variety previously placed in Elephantorrhiza, as well as a new combination for a subspecies of Entada rheedei Spreng. not previously dealt with when Entada pursaetha DC. was placed in synonymy. These new combinations are: Entada burkei (Benth.) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada elephantina (Burch.) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada goetzei (Harms) S.A. O’Donnell and G.P. Lewis, comb. nov.; Entada goetzei subsp. lata (Brenan & Brummitt) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada obliqua (Burtt Davy) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada praetermissa (J.H. Ross) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada rangei (Harms) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada rheedei subsp. sinohimalensis (Grierson & D.G. Long) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada schinziana (Dinter) S.A. O’Donnell & G.P. Lewis, comb. nov.; Entada woodii (E. Phillips) S.A. O’Donnell & G.P. Lewis, comb. nov.; and Entada woodii var. pubescens (E. Phillips) S.A. O’Donnell & G.P. Lewis, comb. nov. We provide a revised circumscription of the genus Entada which now comprises 40 species distributed pantropically, with the greatest diversity of species in tropical Africa. We present a complete taxonomic synopsis, including a map showing the global distribution of the genus and photographs showing variation amongst species in habit, foliage, flowers and fruits. A short discussion about extrafloral nectaries, mainly observed in the Madagascan species, is presented
Extrafloral nectaries in Leguminosae: phylogenetic distribution, morphological diversity and evolution
Extrafloral nectaries (EFNs) mediating ecologically important ant-plant protection mutualisms are especially common and unusually diverse in the Leguminosae. We present the first comprehensively curated list of legume genera with EFNs, detailing and illustrating their systematic and phylogenetic distributions, locations on the plant, morphology and anatomy, based on a unified classification of EFN categories and a time-calibrated phylogeny incorporating 710 of the 768 genera. This new synthesis, the first since McKey (1989)?s seminal paper, increases the number of genera with EFNs to 152 (20% of legumes), distributed across subfamilies Cercidoideae (1), Detarioideae (19), Caesalpinioideae (87) and Papilionoideae (45). EFNs occur at nine locations, and are most prevalent on vegetative plant parts, especially leaves (74%) and inflorescence axes (26%). Four main categories (with eight subcategories) are recognized: formless, trichomatic (exposed, hollow), parenchymatic (embedded, pit, flat, elevated) and abscission zone EFNs (non-differentiated, swollen scars). Phylogenetic reconstruction of EFNs suggests independent evolutionary trajectories of different EFN types, with elevated EFNs restricted almost exclusively to Caesalpinioideae (where they underwent spectacular morphological disparification), flat EFNs in Detarioideae, swollen scar EFNs in Papilionoideae, and Cercidoideae is the only subfamily bearing intrastipular EFNs. We discuss the complex evolutionary history of EFNs and highlight future research directions.Fil: Marazzi, Brigitte. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentina. Natural History Museum Of Canton Ticino; SuizaFil: González, Ana MarÃa. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Delgado Salinas, Alfonso. Universidad Nacional Autónoma de México; MéxicoFil: Luckow, Melissa A.. Cornell University; Estados UnidosFil: Ringelberg, Jens J.. Universitat Zurich; SuizaFil: Hughes, Colin E.. Universitat Zurich; Suiz
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