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Poecilogony, defined as more than one mode of reproduction within a single species, has been reported in various invertebrates, including mollusks and polychaetes. Many cases that have been described involve planktotrophic and non-planktotrophic development in allopatric populations, or instances of planktonic larval stages and benthic juveniles being found together, but not associated with adults. There is always the possibility of mis-assignment of larvae to adults of the wrong species. Most cases that offer these kinds of evidence are now known to involve cryptic species, not poecilogony. There are a few species in which release of young occurs both at metamorphosis and a day or so before. There may be cases in which extracellular yolk or nurse-egg production is variable and allows the release of larvae at different stages, but no actual instance is known. A few instances are known of allopatric populations with different modes of development and other differences in reproductive characters that lack reproductive isolation when brought into the laboratory. The polychaetes Streblospio benedicti, Cirriformia tentaculata, Boccardia proboscidea, and the opisthobranch Elysia chlorotica are in this category. All examples of poecilogony require further genetic substantiation. Despite the scarcity of proven examples of poecilogony, the presence of more than one mode of reproduction within a genus is the rule in most invertebrate phyla. The evolutionary and ecological significance of these patterns is discussed. 17 pp., 4.…

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Taschenbuch. Zustand: Neu. Allelopathy in Ecological Agriculture and Forestry | Proceedings of the III International Congress on Allelopathy in Ecological Agriculture and Forestry, Dharwad, India, 18-21 August 1998 | S. S. Narwal (u. a.) | Taschenbuch | xi | Englisch | 2012 | Springer Netherlands | EAN 9789401058179 | Verantwortliche Person für die EU: Springer Verlag GmbH, Tiergartenstr. 17, 69121 Heidelberg, juergen[dot]hartmann[at]springer[dot]com | Anbieter: preigu.…

Taschenbuch. Zustand: Neu. Druck auf Anfrage Neuware - Printed after ordering - The rapidly growing human population has increased the dependence on fossil fuel based agrochemicals such as fertilizers and pesticides to produce the required agricultural and forestry products. This has exerted a great pressure on the non renewable fossil fuel resources, which cannot last indefinitely. Besides, indiscriminate use ofpesticides for pests (weeds, insects, nematodes, pathogens) control has resulted in serious ecological and environmental problems viz. , (A) Increasing incidence of resistance in pest organisms to important pesticides. (B) Shift in pests population, particulary in weeds and insects. In weeds, species that are more closely related to the crops they infest have developed. In insects, scenario is most grim, the predators have been killed and minor insect pests have become major pests and require very heavy doses ofhighly toxic insecticides for their control. (C) Greater environmental pollution and health hazards (a) particularly from contamination of surface and underground drinking water resources and (b) from their inhalation during handling and application. (D) Toxic residues of pesticides pollute the environment and may prove hazardous to even our future generations. (E) Some agricultural commodities may contain minute quantities ofpesticides residues, with long tenn adverse effects on human and livestock health. Therefore, serious ecological questions about the reliance on pesticides for pests control has been raised. The use of fertilizers, besides causing environmental problems has also impoverished the soil health and decreased the beneficial soil fauna. For example, in some major crop rotations viz.…

Buch. Zustand: Neu. Druck auf Anfrage Neuware - Printed after ordering - The rapidly growing human population has increased the dependence on fossil fuel based agrochemicals such as fertilizers and pesticides to produce the required agricultural and forestry products. This has exerted a great pressure on the non renewable fossil fuel resources, which cannot last indefinitely. Besides, indiscriminate use ofpesticides for pests (weeds, insects, nematodes, pathogens) control has resulted in serious ecological and environmental problems viz. , (A) Increasing incidence of resistance in pest organisms to important pesticides. (B) Shift in pests population, particulary in weeds and insects. In weeds, species that are more closely related to the crops they infest have developed. In insects, scenario is most grim, the predators have been killed and minor insect pests have become major pests and require very heavy doses ofhighly toxic insecticides for their control. (C) Greater environmental pollution and health hazards (a) particularly from contamination of surface and underground drinking water resources and (b) from their inhalation during handling and application. (D) Toxic residues of pesticides pollute the environment and may prove hazardous to even our future generations. (E) Some agricultural commodities may contain minute quantities ofpesticides residues, with long tenn adverse effects on human and livestock health. Therefore, serious ecological questions about the reliance on pesticides for pests control has been raised. The use of fertilizers, besides causing environmental problems has also impoverished the soil health and decreased the beneficial soil fauna. For example, in some major crop rotations viz.…

Printed Wrappers. Zustand: Very Good. First Separate Edition. 294 pp. Offprint from the Journal, here first separately published. Some foxing to covers, otherwise lightly used, previous owner's name on top of front cover.

Paperback. Zustand: Brand New. 267 pages. 9.50x6.25x0.75 inches. In Stock.

Hardcover. Zustand: Brand New. 267 pages. 9.75x6.50x0.75 inches. In Stock.

Zustand: New. Proceedings of the III International Congress on Allelopathy in Ecological Agriculture and Forestry, Dharwad, India, 18-21 August 1998 Editor(s): Narwal, Shamsher S.; Hoagland, R. E.; Dilday, R. H. Num Pages: 267 pages, biography. BIC Classification: PST; TVK. Category: (P) Professional & Vocational; (UP) Postgraduate, Research & Scholarly; (UU) Undergraduate. Dimension: 235 x 155 x 17. Weight in Grams: 579. . 2000. Hardback. . . . . Books ship from the US and Ireland. …

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XII, 838 S. OLwd. Einbd. teils verblichen u. angeschmutzt. M. Rsign. Klebestelle a. Vorsatz. St. a. Vorsatz, Tit. u. einigen Seitenrändern. Sprache: Englisch 0 gr.