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PubMed | University of Xalapas, The Institute for Regional Conservation, Pulsar Group LLC, Volcan Toliman 6100 and 51 more.
Type: | Journal: Nature plants | Year: 2016

A high proportion of plant species is predicted to be threatened with extinction in the near future. However, the threat status of only a small number has been evaluated compared with key animal groups, rendering the magnitude and nature of the risks plants face unclear. Here we report the results of a global species assessment for the largest plant taxon evaluated to date under the International Union for Conservation of Nature (IUCN) Red List Categories and Criteria, the iconic Cactaceae (cacti). We show that cacti are among the most threatened taxonomic groups assessed to date, with 31% of the 1,478 evaluated species threatened, demonstrating the high anthropogenic pressures on biodiversity in arid lands. The distribution of threatened species and the predominant threatening processes and drivers are different to those described for other taxa. The most significant threat processes comprise land conversion to agriculture and aquaculture, collection as biological resources, and residential and commercial development. The dominant drivers of extinction risk are the unscrupulous collection of live plants and seeds for horticultural trade and private ornamental collections, smallholder livestock ranching and smallholder annual agriculture. Our findings demonstrate that global species assessments are readily achievable for major groups of plants with relatively moderate resources, and highlight different conservation priorities and actions to those derived from species assessments of key animal groups.

Garcia-Verdugo C.,500 N College Ave | Garcia-Verdugo C.,Complutense University of Madrid
Trees - Structure and Function | Year: 2011

Trees have the ability to respond to local environmental cues by expressing particular phenotypes across their canopy through a mechanism known as intracanopy plasticity. In this study, intracanopy plasticity of Olea europaea subsp. europaea was analyzed by sampling leeward and windward canopy exposures of individuals occurring in an area with sustained strong wind conditions. A suite of morphofunctional and reproductive traits was measured at these contrasting canopy positions and, for comparison, also in wind-protected trees. Furthermore, the pattern of intracanopy plasticity of these plants was compared to that previously documented in a closely related species, Olea europaea subsp. guanchica. Plants exposed to strong winds displayed substantial differences between leeward and windward exposures in most of the study traits. Leeward exposures experienced a mean reduction of 73% in wind speed as compared to windward ones, and displayed a modular phenotype matching that observed in wind-protected plants. Wind-exposed plants, however, were comparatively smaller and had fewer and smaller inflorescences, since inflorescence size was positively associated with crown size. The two closely related species showed similar crown and leaf sizes between populations exposed to strong winds, and intracanopy responses were comparable for most traits. These observations suggest that intracanopy plasticity resulted in the expression of contrasting phenotypes within individuals, which allowed trees to persist under sustained wind stress, although at the cost of a reduced reproductive fitness. In addition, this study gives support to the idea that intracanopy responses are conserved among closely related taxa evolving in different habitats, but experiencing a comparable limiting factor. © Springer-Verlag 2010.

McGlaughlin M.E.,500 N College Ave | McGlaughlin M.E.,University of Northern Colorado | Friar E.A.,500 N College Ave | Friar E.A.,National Science Foundation
Annals of Botany | Year: 2011

Background and AimsThe Hawaiian silversword alliance (Asteraceae) is one the best examples of a plant adaptive radiation, exhibiting extensive morphological and ecological diversity. No research within this group has addressed the role of geographical isolation, independent of ecological adaptation, in contributing to taxonomic diversity. The aims of this study were to examine genetic differentiation among subspecies of Dubautia laxa (Asteraceae) to determine if allopatric or sympatric populations and subspecies form distinct genetic clusters to understand better the role of geography in diversification within the alliance.MethodsDubautia laxa is a widespread member of the Hawaiian silversword alliance, occurring on four of the five major islands of the Hawaiian archipelago, with four subspecies recognized on the basis of morphological, ecological and geographical variation. Nuclear microsatellites and plastid DNA sequence data were examined. Data were analysed using maximum-likelihood and Bayesian phylogenetic methodologies to identify unique evolutionary lineages.Key ResultsPlastid DNA sequence data resolved two highly divergent lineages, recognized as the Laxa and Hirsuta groups, that are more similar to other members of the Hawaiian silversword alliance than they are to each other. The Laxa group is basal to the young island species of Dubautia, whereas the Hirsuta group forms a clade with the old island lineages of Dubautia and with Argyroxiphium. The divergence between the plastid groups is supported by Bayesian microsatellite clustering analyses, but the degree of nuclear differentiation is not as great. Clear genetic differentiation is only observed between allopatric populations, both within and among islands.ConclusionsThese results indicate that geographical separation has aided diversification in D. laxa, whereas ecologically associated morphological differences are not associated with neutral genetic differentiation. This suggests that, despite the stunning ecological adaptation observed, geography has also played an important role in the Hawaiian silversword alliance plant adaptive radiation. © The Author 2010. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved.

McDade L.A.,500 N College Ave | McDade L.A.,Claremont Graduate University | Daniel T.F.,California Academy of Sciences | Kiel C.A.,500 N College Ave | And 2 more authors.
Taxon | Year: 2012

We took a two-tiered approach to test monophyly of Nelsonioideae and place the group within Lamiales, and to determine relationships among taxa within the group. Phylogenetic analysis of a molecular dataset (ndhF + trnL-F) for a broad sample of Lamiales supports monophyly of Nelsonioideae and places the clade with strong support as sister to a lineage composed of all other plants treated as Acanthaceae (Avicennia, Thunbergioideae, Acanthoideae). We propose to treat this entire group as Acanthaceae s.l. and hypothesize that indurate, explosively dehiscent capsules are a synapomorphy for the family, albeit with autapomorphic fruit types in Avicennia and Mendoncia. These results further support monophyly of family-level groups that have emerged from recent studies of Lamiales but are largely unsuccessful in resolving relationships among these groups, as also encountered by other workers. Our results contradict some aspects of relationships that have seemed resolved by earlier studies, notably among Byblidaceae, Scrophulariaceae, Thomandersia, and other Lamiales. Among Nelsonioideae, analysis of sequence data from rapidly evolving genic regions (trnS-G, ndhF-rpl32 + rpl32-trnL(UAG), nrITS) and a larger sample of nelsonioids (i.e., all genera and multiple taxa to represent the diversity of species-rich genera) indicates that Nelsonia and Elytraria are monophyletic with strong support, but with only moderate support for Nelsonia as the first branching clade and Elytraria sister to the remaining nelsonioids. An African clade comprising monospecific Saintpauliopsis sister to Anisosepalum (two of three species sampled) is sister to a clade that includes all sampled members of pantropical Staurogyne plus New World Gynocraterium and Asian Ophiorrhiziphyllon. Gynocraterium is sister to all sampled members of New World Staurogyne; this last clade is sister to a clade comprising the other sampled Staurogyne plus Ophiorrhiziphyllon, which is nested among Asian Staurogyne. The taxonomic implications of these patterns of relationship are discussed. Our results suggest that Nelsonioideae have a complex history of inter-continental dispersals compared to other lineages of Acanthaceae of similar to much larger size in terms of number of species, making it an interesting group for biogeographic study.

Kempton E.A.,500 N College Ave | Kempton E.A.,Claremont Graduate University
Systematic Botany | Year: 2012

Eriogonoideae s. s. (buckwheats and spineflowers, Polygonaceae) comprises morphologically diverse plants (ca. 325 species, 20 genera) distributed amphitropically in the New World. The lineage is hypothesized to have recently diversified mostly in arid habitats of the western U. S. A., where species richness and endemism are highest. Generic classification of Eriogonoideae s. s. has been unstable, mostly due to different morphological interpretations of the involucre. In this study, phylogenetic relationships of Eriogonoideae s. s. were estimated using multiple genes (ITS, trnLF and psbDtrnT), optimality criteria (Bayesian, Garli ML and RAxML), and a large taxonomic sample (n = 160). Tribes Pterostegieae and Eriogoneae are monophyletic and subtribes Chorizanthineae and Eriogoneae are paraphyletic. The largest genera (Eriogonum and Chorizanthe) and most subgenera are paraphyletic. Most taxonomic groups shown to be non-monophyletic in phylogenies are also rejected for monophyly using the Shimodaira-Hasegawa test. With a primary goal of informing future taxonomic changes, major clades are identified that may be referrable to generic or infrageneric groups within Eriogonoideae s. s. Also, hypotheses regarding the variation of inflorescence features among Eriogonoideae s. s. are discussed. © Copyright 2012 by the American Society of Plant Taxonomists.

Darbyshire I.,Herbarium | Tripp E.A.,500 N College Ave | Dexter K.G.,Royal Botanic Garden Edinburgh
Kew Bulletin | Year: 2012

Summary: Barleria grootbergensis I. Darbysh. & E. Tripp is described from the Grootberg Pass in Kunene Region, Namibia. Its affinities within Barleria sect. Somalia are discussed. A second taxon, named as Barleria galpinii C. B. Clarke in the Prodromus einer Flora von SüdwestAfrika, is reassessed and found to be referable to B. pseudosomalia I. Darbysh., a species previously known only from central Tanzania. A revised checklist to the Barleria of Namibia is presented. © 2012 The Board of Trustees of the Royal Botanic Gardens, Kew.

Tripp E.A.,500 N College Ave | Lendemer J.C.,New York Botanical Garden | Harris R.C.,New York Botanical Garden
Lichenologist | Year: 2010

As part of our ongoing studies of the Graphidaceae in North America, we resolve the status of all taxa traditionally assigned to the genus Graphina that have been reported from the continent north of Mexico. Treatments for the North American members of Acanthothecis, Carbacanthographis, and Diorygma are presented because several species of Graphina have been reassigned to these genera, and our studies of accumulated herbarium materials revealed the existence of several previously unreported and unrecognized species. The following new combinations are made: Acanthothecis leucopepla, A. mosquitensis, A. peplophora, and A. poitaeoides. Carbacanthographis muriformis is described as new to science based on material from Florida. The following taxa are reported from North America for the first time: Acanthothecis poitaeoides, Diorygma junghuhnii, D. reniforme. © 2009 British Lichen Society.

Kuijt J.,649 Lost Lake Road | Steinmann V.W.,500 N College Ave
Phytotaxa | Year: 2016

Phoradendron longicaule (Viscaceae), a new, nearly leafless species of mistletoe from the Infiernillo-Zicuirán Biosphere Reserve of southern Michoacán, Mexico, is described and illustrated. It occurs in a tropical deciduous forest at elevations of 400 to 500 m, and all known hosts belong to Fabaceae. The long, straight, pendulous stems and elongated vegetative internodes are distinctive features. It is most similar to P. nudum but differs by having 3 or 4 pistillate flowers per fertile bract, expanded albeit highly reduced leaves, and longer vegetative internodes. It is also similar to P. teretifolium from which it differs by having a pendulous habit, longer vegetative internodes, 3 or 4 pistillate flowers per fertile bract, and fruits on short internodes. © 2016 Magnolia Press.

Garcia-Verdugo C.,500 N College Ave | Forrest A.D.,Real Jardin Botanico de Madrid | Fay M.F.,Jodrell Laboratory | Vargas P.,Real Jardin Botanico de Madrid
Evolution | Year: 2010

Theoretical and empirical studies suggest that geographical isolation and extinction-recolonization dynamics are two factors causing strong genetic structure in metapopulations, but their consequences in species with high dispersal abilities have not been tested at large scales. Here, we investigated the effect of population age structure and isolation by distance in the patterns of genetic diversity in a wind-pollinated, zoochorous tree (Olea europaea subsp. guanchica) sporadically affected by volcanic events across the Canarian archipelago. Genetic variation was assessed at six nuclear microsatellites (nDNA) and six chloroplast fragments (cpDNA) in nine subpopulations sampled on four oceanic islands. Subpopulations occurring on more recent substrates were more differentiated than those on older substrates, but within-subpopulation genetic diversity was not significantly different between age groups for any type of marker. Isolation-by-distance differentiation was observed for nDNA but not for cpDNA, in agreement with other metapopulation studies. Contrary to the general trend for island systems, between-island differentiation was extremely low, and lower than differentiation between subpopulations on the same island. The pollen-to-seed ratio was close to one, two orders of magnitude lower than the average estimated for other wind-pollinated, animal-dispersed plants. Our results showed that population turnover and geographical isolation increased genetic differentiation relative to an island model at equilibrium, but overall genetic structure was unexpectedly weak for a species distributed among islands. This empirical study shows that extensive gene flow, particularly mediated by seeds, can ameliorate population subdivision resulting from extinction-recolonization dynamics and isolation by distance. © 2010 The Author(s). Evolution © 2010 The Society for the Study of Evolution.

Tripp E.A.,Duke University | Tripp E.A.,500 N College Ave
Systematic Botany | Year: 2010

Ruellia section Chiropterophila as here recognized contains 11 species endemic to areas in and around the transnational Volcanic Belt of Mxico: the Sierra Madre del Sur, the Balsas Depression, and the Altiplano. Most of these species are rare, and nearly half are known only from one or two collections. Of the remaining six, two are restricted to single states. One species described as new to science, Ruellia laslobasensis, is distinguished from a close relative by its smaller corollas, calyces, and fruits. Ruellia chilpancingana is placed into synonymy with R. sororia. Ruellia section Urceolata is synonymized with sect. Chiropterophila. Two species previously treated in sect. Chiropterophila, Ruellia petiolaris (as R. palmeri) and R. carmenaemiliae, are excluded from the section. Phylogenetic analyses using three chloroplast markers (trnC-trnR, trnG-trnS, psbA-trnH) and one nuclear marker (ITS + 5.8S) were conducted to test the monophyly of sect. Chiropterophila and to reconstruct relationships among species. Sequences were successfully generated for all species in sect. Chiropterophila; some are known only from old herbarium material. One of these, collected in 1894, is among the oldest known plant herbarium specimens to be successfully sequenced. Analyses reveal that section Chiropterophila is monophyletic but not well supported; an alternative hypothesis of nonmonophyly of the section could not be rejected. Species descriptions, botanical illustrations, and a dichotomous key to distinguish the 11 taxa in Ruellia sect. Chiropterophila are provided. © 2010 by the American Society of Plant Taxonomists.

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