498 research outputs found
FIGURE 1. Monanthotaxis paniculata. A. Flowering branch. B. Flower bud. C. Flower bud with 3 petals removed. D. Petal from outside. E. Petal from inside. F. Stamen from inside. G. Stamen lateral view. H. Stamen from outside. I. Stamen from top. J. Staminode. K. Ovary. L. Leaf uppserside. A–K from McPherson 16123 in A new species of Monanthotaxis from Gabon with a unique inflorescence type for Annonaceae
No full textFIGURE 1. Monanthotaxis paniculata. A. Flowering branch. B. Flower bud. C. Flower bud with 3 petals removed. D. Petal from outside. E. Petal from inside. F. Stamen from inside. G. Stamen lateral view. H. Stamen from outside. I. Stamen from top. J. Staminode. K. Ovary. L. Leaf uppserside. A–K from McPherson 16123; L from Reitsma 2870. Illustrator: Esmée Winkel.Published as part of Hoekstra, Paul H., Chatrou, Lars W. & Wieringa, Jan J., 2014, A new species of Monanthotaxis from Gabon with a unique inflorescence type for Annonaceae, pp. 106-112 in Phytotaxa 186 (2) on page 107, DOI: 10.11646/phytotaxa.186.2.5, http://zenodo.org/record/514698
Two new rarely collected species of Annonaceae from the Peruvian Amazon
No full textWhile preparing a taxonomic revision of the Neotropical genus Klarobelia Chatrou (Annonaceae), two species new to science – Klarobelia icoja S.Lara & Chatrou, sp. nov., and Malmea abscondita Chatrou & Gees, sp. nov. – were discovered. Both species are known from only two collections, made in Amazonian Peru. We clarify their generic placement and taxonomic identity based on a comparison of morphological characters with previously described species and on molecular phylogenetic analysis of four plastid markers. The conservation status of both species is assessed following IUCN criteria, and line drawings and distribution map are provided
Little ecological divergence associated with speciation in two African rain forest tree genera
No full textAbstract Background The tropical rain forests (TRF) of Africa are the second largest block of this biome after the Amazon and exhibit high levels of plant endemism and diversity. Two main hypotheses have been advanced to explain speciation processes that have led to this high level of biodiversity: allopatric speciation linked to geographic isolation and ecological speciation linked to ecological gradients. Both these hypotheses rely on ecology: in the former conservation of ecological niches through time is implied, while in the latter adaptation via selection to alternative ecological niches would be a prerequisite. Here, we investigate the role of ecology in explaining present day species diversity in African TRF using a species level phylogeny and ecological niche modeling of two predominantly restricted TRF tree genera, Isolona and Monodora (Annonaceae). Both these genera, with 20 and 14 species, respectively, are widely distributed in African TRFs, with a few species occurring in slightly less humid regions such as in East Africa. Results A total of 11 sister species pairs were identified most of them occurring in allopatry or with little geographical overlap. Our results provide a mixed answer on the role of ecology in speciation. Although no sister species have identical niches, just under half of the tests suggest that sister species do have more similar niches than expected by chance. PCA analyses also support little ecological differences between sister species. Most speciation events within both genera predate the Pleistocene, occurring during the Late Miocene and Pliocene periods. Conclusions Ecology is almost always involved in speciation, however, it would seem to have had a little role in species generation within Isolona and Monodora at the scale analyzed here. This is consistent with the geographical speciation model for TRF diversification. These results contrast to other studies for non-TRF plant species where ecological speciation was found to be an important factor of diversification. The Pliocene period appears to be a vital time in the generation of African TRF diversity, whereas Pleistocene climatic fluctuations have had a smaller role on speciation than previously thought. Ecological niche modeling, species level phylogeny, ecological speciation, African tropics, Isolona, Monodora, Annonaceae</p
Insights into the influence of priors in posterior mapping of discrete morphological characters: a case study in Annonaceae
No full textBackground - Posterior mapping is an increasingly popular hierarchical Bayesian based method used to infer character histories and reconstruct ancestral states at nodes of molecular phylogenies, notably of morphological characters. As for all Bayesian analyses specification of prior values is an integrative and important part of the analysis. He we provide an example of how alternative prior choices can seriously influence results and mislead interpretations. Methods/Principal Findings - For two contrasting discrete morphological characters, namely a slow and a fast evolving character found in the plant family Annonaceae, we specified a total of eight different prior distributions per character. We investigated how these prior settings affected important summary statistics. Our analyses showed that the different prior distributions had marked effects on the results in terms of average number of character state changes. These differences arise because priors play a crucial role in determining which areas of parameter space the values of the simulation will be drawn from, independent of the data at hand. However, priors seemed to fit the data better if they would result in a more even sampling of parameter space (normal posterior distribution), in which case alternative standard deviation values had little effect on the results. The most probable character history for each character was affected differently by the prior. For the slower evolving character, the same character history always had the highest posterior probability independent of the priors used. In contrast, the faster evolving character showed different most probable character histories depending on the prior. These differences could be related to the level of homoplasy exhibited by each character. Conclusions - Although our analyses were restricted to two morphological characters within a single family, our results underline the importance of carefully choosing prior values for posterior mapping. Prior specification will be of crucial importance when interpreting the results in a meaningful way. It is hard to suggest a statistically sound method for prior specification without more detailed studies. Meanwhile, we propose that the data could be used to estimate the prior value of the gamma distribution placed on the transformation rate in posterior mappin
A taxonomic revision of the Neotropical genus Cremastosperma (Annonaceae), including five new species
No full textWe present a taxonomic revision of Cremastosperma, a genus of Neotropical Annonaceae occurring in lowland to premontane wet forest, mostly in areas surrounding the Andean mountain chain. We recognise 34 species, describing five as new here: from east of the Andes, C. brachypodum Pirie & Chatrou, sp. nov. and C. dolichopodum Pirie & Maas, sp. nov., endemic to Peru; C. confusum Pirie, sp. nov., from southern Peru and adjacent Bolivia and Brazil; and C. alticola Pirie & Chatrou, sp. nov., at higher elevations in northern Peru and Ecuador; and from west of the Andes, C. osicola Pirie & Chatrou, sp. nov. endemic to Costa Rica, the most northerly distributed species of the genus. We provide an identification key, document diagnostic characters and distributions and provide illustrations and extensive lists of specimens, also presenting the latter in the form of mapping data with embedded links to images available online. Of the 34 species, 22 are regional endemics. On the basis of the extent of occurrence and area of occupancy of species estimated from the distribution data, we designate IUCN threat categries for all species. Fourteen species proved to be endangered (EN) and a further one critically endangered (CR), reflecting their rarity and narrow known distributions
Lars Q. English, There Is No Theory of Everything. A Physics Perspective on Emergence, Springer 2017, rec.
No full textLars Q. English’s book consists of an introduction, eight chapters and a short ending. The author shows how the latest discoveries of physics are changing thinking about the world, approving the occurrence of emergence. As a physicist himself, he combined the results obtained in physics with philosophical reflection, hence this book is worth recommending to students and graduates of science with philosophical tendencies.Książka Larsa Q. Englisha składa się ze wstępu, ośmiu rozdziałów i krótkiego zakończenia. Autor ukazuje w niej jak najnowsze odkrycia fizyki zmieniają myślenie o świecie, aprobując zachodzenie emergencji. Sam będąc fizykiem, połączył wyniki otrzymywane w ramach fizyki z refleksją filozoficzną, stąd książkę tę warto polecić studentom i absolwentom kierunków ścisłych posiadających zapędy filozoficzne
Annonaceae Supermatrix Alignment
No full textWe sampled 234 Annonaceae species (c. 10% of total) representing 105 (c. 97% of total) genera and all four subfamilies, and seven outgroup taxa from related families. For these species, we generated a molecular supermatrix of eight plastid markers as assembled by Chatrou et al. (2012) supplemented with 157 additional sequences for 37 species. For details on the methods, see Chatrou et al. (2012), GenBank numbers for the new sequences are provided in Appendix S1 (= Dryad file "Functional trait data and GenBank sequences in Annonaceae"). Please note that in the meantime some of the taxonomic names have changed (can also be found in Appendix S1) and should be updated in future use of this datafile
A new species of Monanthotaxis from Gabon with a unique inflorenscence type for Annonaceae
No full textMonanthotaxis Baillon (1890: 878) currently consists of 56 species (Rainer & Chatrou 2006) confined to tropical Africa and Madagascar and is the second most species-rich genus of Annonaceae in Africa after Uvaria Linnaeus (1753: 536). Both genera belong to the tribe Uvarieae Hooker & Thomson (1855: 91, 92). Circumscription of this tribe has recently been modified to comply with the principle of monophyly, and it now almost exclusively consists of climbing species, all from the Old World tropics (Chatrou et al. 2012). Generic circumscription within Uvarieae has been in disarray for considerable time. Delimitation of Uvaria and related genera has recently been modified based on phylogenetic relationships (Zhou et al. 2010, Zhou et al. 2009). Monanthotaxis was monophyletic in Wang et al. (2012), based on a limited sampling of seven species. Subsequent study with increased sampling (Hoekstra, unpub.) has revealed that the African species of Friesodielsia van Steenis (1948: 458) and Exellia Boutique (1951b: 117) are nested in Monanthotaxis. Whatever the solution and taxonomic consequences, the name Monanthotaxis with the type Monanthotaxis congoensis Baillon (1890: 879) will be retained as it is the oldest valid generic name. Along with phylogenetic analysis, we are conducting a taxonomic revision. The last revision of Monanthotaxis and allied genera was published over a century ago by Engler & Diels (1901). Since then, only contributions to local floras have been published (e.g. Boutique 1951a, Le Thomas 1969, Robson 1960, Verdcourt 1971a). While studying the material of Monanthotaxis, we encountered a remarkable new species, which differs from all other species of Annonaceae in its large and lax panicle-like inflorescence. Panicle-like inflorescences are rare in Annonaceae, and those that have been recorded are either congested, as in e.g. Unonopsis and Guatteria (Erkens et al. 2008, Maas et al. 2007), or with only a few flowers, as in Monanthotaxis le-testui Pellegrin (1950: 75). This new species is probably closely related to M. congoensis since they share several characters. Verdcourt (1971b) divided the genus in three subgenera and five sections. In his classification, this new species would join M. congoensis in the typical section Monanthotaxis, which is easily distinguished by having flowers with the four to six petals in a single whorl and less than 17 stamens. Because it is so similar to M. congoensis, our new species will almost certainly be classified within Monanthotaxis, and we decided to publish it before a new generic classification has been completed
Monanthotaxis paniculata P. H. Hoekstra 2014, spec. nov.
No full textMonanthotaxis paniculata P.H.Hoekstra, spec. nov. (Fig. 1) Type:— GABON. Ogooué-Ivindo: north of Koumameyong along SHM lumber roads, 0˚ 25’ N, 11˚ 55’ E, 31 January 1993, McPherson 16123 (holotype: WAG!, isotypes: MO!, P!). Additional specimen examined: GABON, Estuaire: ca 20 km N of Libreville, 29 January 1987, Reitsma 2870 (NY!, WAG!). Monanthotaxis paniculata resembles Monanthotaxis congoensis, but differs in the panicle-like inflorescence, instead of a raceme. Liana to 20 m long; old branches dark, blackish, glabrescent with lenticels, young branches densely pubescent with appressed, ferrugineous-brown hairs 0.5 mm long. Petioles 4–8 mm long, 1.0– 1.5 mm wide, grooved adaxially, densely pubescent around. Leaf lamina 8.5–23.5 × 3.3–6.6 cm, length: width ratio 2.0–4.2, ovate to oblong-lanceolate, base cuneate to almost rounded with small linear black swollen base (see notes), apex acute to acuminate, acumen to 2.7 cm long, chartaceous, discolorous, young leaves adaxially with scattered appressed white hairs 1 mm long, glabrescent, abaxially glaucous or green, densely pubescent with appressed yellowish hairs 2 mm long, less densely in older leaves, secondary veins 9–16 on each side of primary vein, oblique, curving upwards, impressed adaxially, tertiary venation scalariform to somewhat reticulate, finely raised adaxially, abaxially only visible in older leaves. Inflorescence axillary or terminal, a 5.5–27.0 cm long panicle-like rhipidium with many flowers, peduncle 15–40 mm, rachis often multiple times bi- or trifurcate, densely pubescent with short ferrugineous hairs, 1–3 flowers in the axil of each bract; bracts lanceolate 1.0–8.0 × 0.5–1.5 mm, same indumentum as rachis; flower buds depressed-globose. Flowers bisexual; pedicels 5–29 × 0.4–0.8 mm, indumentum as rachis; sepals 3, 0.6–1.3 ×1.0– 1.5 mm, broadly ovate, outside densely pubescent with ferrugineous hairs, inside glabrous, apex acute; petals 6 in one whorl, yellowish or dull yellow, 2.7–3.0 × 1.5–2.0 mm, ovate, both inside and outside with short, appressed yellowish hairs; receptacle 2.0– 3.5 mm in diameter; stamens 12, in one whorl, inserted on a black hexagonal disc, 6 fertile stamens opposite to the petals, free at the base, obconic, 0.6 mm long, filaments 0.2 mm long, theca introrse/latrorse, connective appendage glabrous, truncate, kidney-shaped from above, 1.0 mm wide, not hiding anther cells, 6 sterile stamens alternating with inner stamens, 0.4 mm long, 0.5 mm wide, reduced theca-like structures 2, dorsal; carpels 14–24, 0.9 × 0.4 mm, ellipsoid, densely ferrugineous pubescent with 1 ovule, stigma bifurcate, 0.2 mm long, glabrous. Fruits unknown. Etymology:— The specific epithet refers to the lax, many-flowered panicle-like inflorescence, which is unique within the family of Annonaceae. Distribution:— Gabon, provinces Estuaire and Ogooué-Ivindo (Fig. 2). Ecology:— In forest fringe of a marshy savannah and along lumber roads, elev. 0– 500 m. Phenology:— Flowers collected in the last week of January. IUCN-conservation status:— A first assessment results in “Data Deficient”, since the extent of occurrence cannot be calculated with only two data points. However, in the last decades many collections have been made in Gabon, and for the revision we have seen almost all collections of Monanthotaxis in Gabon and surrounding countries. No other material has thus far been found. Therefore, the species seems to be genuinely rare (see also the discussion). Furthermore, both collections have been made in unprotected areas, one of which is in danger because of the expanding city of Libreville. The other collection has been made in a logging area, and therefore we suggest the status endangered: B2 ab(iii) for this species. Notes:— A black swollen leaf margin at the base of the leaf is a common feature in many species of Monanthotaxis. In most literature, it is referred to as glands (e.g. Le Thomas 1969, Verdcourt 1971a). We are not sure if it is glandular tissue and until this is examined in more detail do not refer to it as such.Published as part of Hoekstra, Paul H., Chatrou, Lars W. & Wieringa, Jan J., 2014, A new species of Monanthotaxis from Gabon with a unique inflorescence type for Annonaceae, pp. 106-112 in Phytotaxa 186 (2) on pages 106-109, DOI: 10.11646/phytotaxa.186.2.5, http://zenodo.org/record/514698
Diversification of myco-heterotrophic angiosperms: evidence from Burmanniaceae.
No full textBackground - Myco-heterotrophy evolved independently several times during angiosperm evolution. Although many species of myco-heterotrophic plants are highly endemic and long-distance dispersal seems unlikely, some genera are widely dispersed and have pantropical distributions, often with large disjunctions. Traditionally this has been interpreted as evidence for an old age of these taxa. However, due to their scarcity and highly reduced plastid genomes our understanding about the evolutionary histories of the angiosperm myco-heterotrophic groups is poor. Results - We provide a hypothesis for the diversification of the myco-heterotrophic family Burmanniaceae. Phylogenetic inference, combined with biogeographical analyses, molecular divergence time estimates, and diversification analyses suggest that Burmanniaceae originated in West Gondwana and started to diversify during the Late Cretaceous. Diversification and migration of the species-rich pantropical genera Burmannia and Gymnosiphon display congruent patterns. Diversification began during the Eocene, when global temperatures peaked and tropical forests occurred at low latitudes. Simultaneous migration from the New to the Old World in Burmannia and Gymnosiphon occurred via boreotropical migration routes. Subsequent Oligocene cooling and breakup of boreotropical flora ended New-Old World migration and caused a gradual decrease in diversification rate in Burmanniaceae. Conclusion - Our results indicate that extant diversity and pantropical distribution of myco-heterotrophic Burmanniaceae is the result of diversification and boreotropical migration during the Eocene when tropical rain forest expanded dramaticall
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