Showing papers in "Taxon in 1988"
TL;DR: The Science as a Process (SAP) series as mentioned in this paper is a series of books about the process of science that Hull himself edited and published in the early 1970s, with the goal of providing a serious account of the social and intellectual dynamics of science.
Abstract: "Legend is overdue for replacement, and an adequate replacement must attend to the process of science as carefully as Hull has done. I share his vision of a serious account of the social and intellectual dynamics of science that will avoid both the rosy blur of Legend and the facile charms of relativism. . . . Because of [Hull's] deep concern with the ways in which research is actually done, "Science as a Process" begins an important project in the study of science. It is one of a distinguished series of books, which Hull himself edits".--Philip Kitcher, "Nature"
1,655 citations
TL;DR: In this paper, the nature, occurrence and composition of ultamafic rocks are discussed and the serpentine factor factor is discussed, and the distribution and phytochemistry of plants which hyperaccumulate nickel.
Abstract: Part I: Serpentine ecology. Introduction. The nature, occurrence and composition of ultamafic rocks. The formation and composition of serpentine soils. The serpentine factor. Serpentine and agriculture. Plant evolution and serpentine. Animals and serpentine. The distribution and phytochemistry of plants which hyperaccumulate nickel. Kimberlites, carbonatites and their vegetation. Part II: Serpentine vegetation of the world. Introduction to Serpentine vegetation of the world. North America. Tropical America. Northwest Europe Central and southern Europe. Continental Asia. Japan. Africa. The Malay Archipelago. New Caledonia. Australia. New Zealand.
585 citations
TL;DR: All flower-visiting insect groups had already existed at the time of early angiosperm differentiation; beetles, flies, thrips, and moths were available as potential pollinators and unspecific interactions are found in the Winteraceae, archaic Magnoliidae.
Abstract: Summary Virtually all flower-visiting insect groups had already existed at the time of early angiosperm differentiation; beetles, flies, thrips, and moths were available as potential pollinators. Unspecific interactions with these insect groups are found in the Winteraceae, archaic Magnoliidae. Winteraceae are often weedy species for which an open pollination system may be advantageous in view of the different insect faunas of newly invaded habitats. Winteraceous pollination modes and life strategies are here interpreted as close to the ancestral condition of the angiosperms. The Annonaceae provide examples of more economic and effective plant/pollinator interactions. Within this family a range exists of different adaptations for pollination by beetles. Flowers in several genera provide pollination chambers resulting from enfolding petals in which beetles stay for long periods of time. In the dark chambers the beetles are protected against environmental changes and predators. The permanently recurved microsporophylls of the flowers of the late bennettitalean genus Cycadeoidea, evolving during the early Cretaceous, may be a comparable adaptation to beetle pollination.
111 citations
TL;DR: Accumulation of nickel to levels exceeding 1000 gg/g of dry matter, already found in many species of Thlaspi L.A. from Europe and western U.S.A., is also characteristic of seven species of this genus growing on ultramafic soils in Cyprus, Turkey, northern Syria and Japan.
Abstract: Summary Accumulation of nickel to levels exceeding 1000 gg/g of dry matter, already found in many species of Thlaspi L. from Europe and western U.S.A., is also characteristic of seven species of this genus growing on ultramafic soils in Cyprus, Turkey, northern Syria and Japan. Two Turkish serpentineendemic species of Cochlearia behave in the same way, but many other members of the Brassicaceae from nickel-rich soils show only slightly elevated nickel levels. Zinc accumulation is known to occur in some European Thlaspi species, in Cochlearia pyrenaica and in Arabidopsis thaliana on zinc-rich soils. Some Thlaspi species, however, accumulate high levels of zinc even when they are not associated with known zinc mineralisation. Abnormal metal uptake by many species of Thlaspi and Cochlearia is a property of fundamental importance in considerations of the taxonomy and distribution in these genera.
92 citations
TL;DR: It is proposed that the Guayana highland and lowland biota have been and still are dynamically and genetically interdependent, not only within the Guyana region itself, but also with the adjacent complex of lowland and mountain biota.
Abstract: Summary During the last 40 years, an impressive amount of biological, especially botanical, information concerning the Venezuelan Guayana region has been accumulated. Both the lowlands, as well as the distinctive highland mountains ('tepuis'), evidence an outstandingly rich and diversified flora and vegetation. It has been postulated that this biological richness and the high degree of endemism are the result of long-term and highly effective isolation suffered by the flat summit areas during extremely long geologic epochs. This static view is being challenged presently by the results of recent intensive fieldwork made in the Venezuelan Guayana. A detailed analysis of two highly evolved Guayana taxa, Stegolepis (Rapateaceae) and Bonnetia (Theaceae s.l.) shows a rather uniform distribution not only in summit habitats, but also in intermediate and lowland habitats. As a whole, both genera and several related taxa prove to have occupied successfully not only the ancient summit regions of the tepuis, but also the surrounding lowlands of much more recent geomorphological origin. Palaeoecological research also supports the hypothesis that the entire Guayana Shield area has been affected by climatic oscillations during the recent past as have the nearby Andes. This implies significant past fluctuations of the altitudinal vegetation belts in the tepui area and could well explain the wide altitudinal gradient of most of the Guayana Highland taxa. Also, the presence of convergent 'paramoid' vegetation types on the summits of the Chimantf Massif, indicates active speciation not only at the systematic level, but especially at the ecologic level. Thus, it is proposed that the Guayana highland and lowland biota have been and still are dynamically and genetically interdependent, not only within the Guayana region itself, but also with the adjacent complex of lowland and mountain biota.
89 citations
70 citations
TL;DR: Platform is a volunteer effort to create and share e-books online, and books are available in ePub, Kindle, HTML and simple text formats.
Abstract: Most popular website for free PDF. Platform is a high quality resource for free Books books.It is known to be world's largest free eBooks resources. You can easily search by the title, author and subject.Platform is a volunteer effort to create and share e-books online. No registration or fee is required, and books are available in ePub, Kindle, HTML and simple text formats.If you're looking for a wide variety of books in various categories, check out this site. Resources dallaspinballproject.com is a volunteer effort to create and share e-books online.
58 citations
TL;DR: Ecuadorean flora is divided into three natural regions: the coastal plain, the Andes cordillera, and the eastern lowlands, which includes an estimated 20,000 species of vascular plants.
Abstract: Summary Ecuador covers some 300,000 km2 on the west coast of the South American continent. The country is divided into three natural regions: the coastal plain, the Andes cordillera, and the eastern lowlands. Twenty-six life zones, including deserts, rainforests, and high montane vegetation types, are represented in the country. The flora includes an estimated 20,000 species of vascular plants. In this study the distribution of a sample of 536 species is analyzed, and some conspicuous phytogeographic patterns are obvious. The lowland flora is rich in widespread species and many of them occur on both sides of the Andes. The coastal plain is rich and the eastern lowlands are poor in endemics. The midelevations between 900 m and 3000 m house about half of the species of the country although they constitute only 10% of the area. Endemism is high at mid-elevations: 39% of the mid-elevation species do not reach beyond Ecuador. Especially the western slopes of the Andes are rich in endemics with 10% of the total Ecuadorean flora being restricted to them. The Ecuadorean highlands above 3000 m house 10% of the total flora of the country. Endemism in the highlands is about the same as at midelevations.
56 citations
TL;DR: The discovery of new fossil plant remains, together with new interpretations of previously described forms, suggests that some ideas regarding the origin of land plants need to be modified and the current classification of early land plants be re-examined.
Abstract: Summary The discovery of new fossil plant remains, together with new interpretations of previously described forms, suggests that some ideas regarding the origin of land plants need to be modified. Some evidence suggests that perhaps plants with a bryophytic level of organization were on the land as early as the Ordovician. This suggestion is strengthened by a number of Devonian plants that lack tracheids despite possessing a suite of morphological features generally attributed to vascular plants. Such information necessitates that the current classification of early land plants be re-examined, together with ideas about the origin and subsequent evolution of vascular plants and bryophytes.
TL;DR: In this article, the main forest types occurring in the Guianas: upland moist forest, montane and lower montane forest, inundated forests, transition forests, and forests on white sand soils.
Abstract: Summary In a brief introduction to the Guianan area (location, geomorphology and climate), the author gives a short description of the main forest types occurring in the Guianas: upland moist forest, montane and lower montane forest, inundated forests, transition forests, and forests on white sand soils. Then, the distribution patterns of selected plant groups represented in the Guianan lowland forest region (Meliaceae, Caryocaraceae, Tabemaemontanoideae, Musaceae, Zingiberaceae, Arecaceae, Passifloraceae, Lindsaea, Ochnaceae) are analyzed. The endemism and floristic affinities of the Guianan forests are briefly discussed in relation to the theory of the South American forest refugia.
TL;DR: A new procedure for coding quantitative measurements and ranges of measurements onto discrete characters suitable for input into existing cladistic analyses programs and the rationale for coding ranges is presented and justified from the taxonomist's point of view.
Abstract: A new procedure for coding quantitative measurements and ranges of measurements onto discrete characters suitable for input into existing cladistic analyses programs is presented. The procedure consists of rank ordering the ranges by their minimum values first, then by their midrange values. The rationale for coding ranges is presented and justified from the taxonomist's point of view. A detailed example is given and tested on a data set consisting of nine species of the genus Hordeum. Cladistic programs that deal directly with intra-OTU variability are needed.
TL;DR: Two hundred sixty-three species of the Magnoliidae distributed over the main genera of all its families were investigated with the TEM for ultrastructural characters from their sieve elements to provide a putative phylogenetic arrangement of the families of Magnoliiflorae.
Abstract: Two hundred sixty-three species of the Magnoliidae distributed over the main genera of all its families were investigated with the TEM for ultrastructural characters from their sieve elements. Details from sieve-element plastids (overall diameter, as well as qualitative and quantitative measurements of their starch and protein contents) provided the main data set for a putative phylogenetic arrangement of the families of Magnoliiflorae. The recording of the presence or absence of nondispersive protein bodies and nacreous wall thickenings yielded additional information. Within the Magnoliiflorae sieve-element plastids are proposed to have evolved from large-sized S-type plastids with high amount of starch to small-sized, starch-deficient P-type or, at the other extreme, to So-plastids. Along this line a basic group containing Austrobaileyaceae, Illiciaceae, Schisandraceae, Chloranthaceae, Myristicaceae, and Winteraceae is distinguished from four parallel and slightly advanced groups, the Annona-, Aristolochia-, Magnolia-, and Monimia-groups. The Aristolochia-group is held to represent one of the core groups of the Magnoliiflorae, incorporating the whole range of the different plastid forms from S-type to So-plastids or by several steps to formPc and the monocotyledon form-P2c plastids. Among the remaining five the Monimia-group, only, shows a comparably broad range, while all other taxa are confined to one or two plastid forms (i.e., S-type and/or form-Psc resp. -Pcs plastids).
TL;DR: Systematic botanists need urgently to devise comprehensive plans to inventory plant diversity, especially in the tropics, and play a major role in making possible the utilization of this diversity for human benefit, and in conserving as extensive a sample as possible.
Abstract: Summary Of the roughly 265,000 species of plants in the world, about a third occur in temperate regions, a third in Latin America, and a third in the tropics and subtropics of Africa and Asia. Tropical forests are being destroyed very rapidly, as a result of the explosive growth of a record human population, extensive poverty, and an unwillingness to learn about and practice sustainable land use in the tropics. As a consequence, at least a fifth of the total plant species in the world, something on the order of 60,000 species, are threatened with extinction over the next several decades. Systematic botanists need urgently to devise comprehensive plans to inventory plant diversity, especially in the tropics. They should play a major role in making possible the utilization of this diversity for human benefit, and in conserving as extensive a sample as possible.
TL;DR: Pairs of angiosperm species putatively separated by continental drift following the break-up of Gondwanaland have been used to derive linear regressions relating macromolecular differences to time and suggestions about which species disjunctions are likely to have originated more recently than the continental separations are allowed.
Abstract: Summary Pairs of angiosperm species putatively separated by continental drift following the break-up of Gondwanaland have been used to derive linear regressions relating macromolecular differences to time. Differences have been derived from N-terminal amino acid sequences of the small subunit of rubisco from members of Proteaceae, Winteraceae, Nothofagus and Solanum. Alternative sets of times have been taken from the literature on plate tectonics and biogeography. Botanical criteria have been used to discriminate tentatively between the two regression lines. The rate of evolution corresponding to the preferred regression is one inferred nucleotide difference between two evolutionary lineages in seven million years. An estimate of the variance about the regression lines has been obtained and has allowed suggestions about which species disjunctions are likely to have originated more recently than the continental separations.
TL;DR: The plantbook as mentioned in this paper is a portable dictionary of the higher plants using Cronquist's An integrated system of classification of flowering plants (1981) and current botanical literature arranged largely on the principles of editions 1-6 (1896/97-1931) of Willis's A Dictionary of the flowering plants and ferns.
Abstract: The plant-book: a portable dictionary of the higher plants utilising Cronquist's An integrated system of classification of flowering plants (1981) and current botanical literature arranged largely on the principles of editions 1-6 (1896/97-1931) of Willis's A dictionary of the flowering plants and ferns , The plant-book: a portable dictionary of the higher plants utilising Cronquist's An integrated syste... , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
TL;DR: In a phylogenetic context, the large and sometimes foliose pales of the Heliantheae seem best interpreted as adaptations for protection of large achenes and not necessarily as reflections of a primitive condition within the family.
Abstract: Many morphological features of the heads of Compositae are systematically useful. Receptacular bracts (pales or paleae) are of particular significance taxonomically. These structures occur in nine of the 13 recognized tribes (absent in Arctoteae, Calenduleae, Senecioneae and Tageteae), with the greatest concentration in the Anthemideae, Heliantheae, and Inuleae. Because the Heliantheae contain the broadest diversity of pale types, the adaptive significance of these features within this tribe deserves special emphasis. Certain subtribes of the Heliantheae are characterized by distinctive types of pales, such as flattened with orange-brown lines in the Coreopsidinae, pales subtending only the outer series of disc florets in the Madiinae, or their complete absence in the Bahiinae. Of the five principal factors affecting the evolution of features of heads in the family, viz., protection, dispersal, pollination, breeding systems, and seed germination, the former two are most likely the most important selective forces in the evolution of pales. Dispersal functions of pales include attachment or close envelopment of the achene by the pales with removal of the entire unit by wind from the head, conduplicate pales serving as chutes for release of unattached achenes, and brightly colored, fleshy pales being attractive to animals. Protective functions occur against predators and environmental extremes, and occur in bud, anthesis, and mature fruiting stages. Pales function during anthesis to protect ovaries and achenes from apical and lateral insect attack. The particular variations of the pales depend on the associated structures of the heads and breeding systems. In a phylogenetic context, the large and sometimes foliose pales of the Heliantheae seem best interpreted as adaptations for protection of large achenes and not necessarily as reflections of a primitive condition within the family.
TL;DR: It is made that ecological characteristics can provide valuable evidence for species delimitation in complex floras such as those of tropical rain forests, and ecological evidence should never be used as an integral part of taxonomic diagnosis.
Abstract: Summary The case is made that ecological characteristics can provide valuable evidence for species delimitation in complex floras such as those of tropical rain forests. Differences between sympatric populations of morphologically similar entities in such aspects as edaphic range, reproductive phenology, pollination biology, combined with evidence for outbreeding, and for interspecific hybridization in nature assist in evaluating whether such entities behave as biological species. Current evidence on the biological nature of rain forest tree species is discussed. Though ecology, as the study of spatial and temporal distribution patterns within and between species populations and their relationship with habitat, can illuminate biogeographic studies of taxa at all systematic levels, it is at or below the species level that ecology is most useful as a tool in systematics. This tool must, of course, be used with great discretion. Ecological characteristics of species in nature result from competition as well as interaction with the physical habitat, which makes generalization from limited studies hazardous. Though ecological evidence may provide valuable supporting evidence for species delineation therefore, it should never be used as an integral part of taxonomic diagnosis. Taxonomists working on tropical floras, however, face immense difficulties in their search for nomenclatural stability. Obviously, with such limited knowledge available now (and certainly in the future too), for the vast majority of taxa the concept of the biological species cannot be applied. Species must be based primarily on discontinuities in patterns of morphological variation. There are still severe difficulties in achieving this: taxonomy proceeds on the level of information available at the time. Contemporary workers are inevitably encumbered by decisions made by their predecessors on the basis of even less adequate information than is available to them. At best herbarium specimens can suggest only patterns of variation within the commonest taxa in tropical floras. How then can we be confident which discontinuities in morphological patterns observed in the herbarium are real in nature?