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81.
Dubois recently suggested that Linnean taxa should be quoted with the year of publication only, rather than with the author ± year of publication. This would reduce the perceived artificial nomenclatural inflation produced by new synonyms. We do not consider this inflation a problem and recommend the maintenance of the current methodology. This has several advantages over that suggested by Dubois, including easy identification of taxa introduced by splitters, which are known by name, not year of publication; managers of systematic facilities expect to see their institute's papers cited; most systematists are dead, but recognition of their efforts is fitting; and a complete reference of author and year supports the best scholarship. Present and future systematists would be better served if Dubois' recommendation was not implemented. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96 , 709–711.  相似文献   
82.
The spruce bark beetle Ips typographus is one of the major insect pests of mature Norway spruce forests. In this study, a model describing the temperature-dependent thresholds for swarming activity and temperature requirement for development from egg to adult was driven by transient regional climate scenario data for Sweden, covering the period of 1961–2100 for three future climate change scenarios (SRES A2, A1B and B2). During the 20th century, the weather supported the production of one bark beetle generation per year, except in the north-western mountainous parts of Sweden where the climate conditions were too harsh. A warmer climate may sustain a viable population also in the mountainous part; however, the distributional range of I. typographus may be restricted by the migration speed of Norway spruce. Modelling suggests that an earlier timing of spring swarming and fulfilled development of the first generation will significantly increase the frequency of summer swarming. Model calculations suggest that the spruce bark beetle will be able to initiate a second generation in South Sweden during 50% of the years around the mid century. By the end of the century, when temperatures during the bark beetle activity period are projected to have increased by 2.4–3.8 °C, a second generation will be initiated in South Sweden in 63–81% of the years. The corresponding figures are 16–33% for Mid Sweden, and 1–6% for North Sweden. During the next decades, one to two generations per year are predicted in response to temperature, and the northern distribution limit for the second generation will vary. Our study addresses questions applicable to sustainable forest management, suggesting that adequate countermeasures require monitoring of regional differences in timing of swarming and development of I. typographus , and planning of control operations during summer periods with large populations of bark beetles.  相似文献   
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Popov, L.E., Bassett, M.G. & Holmer, L.E. 2012: Earliest ontogeny of Early Palaeozoic Craniiformea: compelling evidence for lecithotrophy. Lethaia, Vol. 45, pp. 566–573. The early ontogeny of Palaeozoic Craniiformea (Brachiopoda) remains controversial, with conflicting reports of evidence indicating lecithotrophic versus planktotrophic larval stages. Further compelling evidence for lecithotrophy in Palaeozoic craniiforms is described here. Newly obtained, well‐preserved Silurian specimens of craniiforms, including Craniops (Craniopsida), and Lepidocrania? and Orthisocrania (Craniida) from Gotland and the St. Petersburg region, form the basis for this study. The new material demonstrates that the characters of shell structure and shell formation provide evidence of early differentiation of an adult dorsal mantle, and the presence of a distinctive primary layer with a characteristic lath‐like pattern indicates that these craniiforms underwent a lecithotrophic larval stage, more or less identical to that of living. □Novocrania. Brachiopoda, Craniiformea, ontogeny, phylogeny, Early Palaeozoic.  相似文献   
85.
Kurtén, B. 1988: On Evolution and Fossil Mammals . XVII + 301 pp. Columbia University Press. ISBN 0–231–05868–3. Price: USD40.00 (bound).  相似文献   
86.
de Muizon, C. 1988: Les Vertébrés Fossiles de la Formation Pisco (Pérou) III. Les Odontocètes (Cetacea, Mammalia) du Miocène . 244 pp. Institut Fran¸ais d'études Andines et Institut de Paléon-tologie du Museum National d'Histoíre Naturelle. éditions Recherche sur les Civilisations, A.D.P.F., Paris. ISBN 2–86538–187–0, ISSN 0291–1655. Price: 289.00 FF (paper).  相似文献   
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Theoretical work on multivariate evolution predicts that genetic correlations can act to constrain the rate at which new adaptive peaks are reached, but there is very limited empirical information available on this issue so far. To evaluate the importance of genetic correlations for evolutionary change, we studied the morphological differences between two flycatcher species (Ficeduia albicollis and F. hypoleuca) using both univariate and multivariate quantitative genetic models. Comparison of the results obtained using these different models revealed that even relatively low genetic correlations between traits will considerably increase the net selection forces needed for evolutionary changes in morphology. In particular, the divergence in wing and tail length, which are positively genetically correlated, would require a considerable amount of antagonistic selection. Because of the genetic correlations, strong selection will be needed to retain certain traits unchanged while others are changing. Based on these results, we argue that it is unlikely that small morphological differences such as between these two species could have evolved during a short (200 years) time period, i.e. the period of sympatry of these species in Sweden. These findings support the hypothesis that even relatively low genetic correlations may constrain short-term adaptive evolution in natural populations.  相似文献   
89.
The influence of ice crystal formation in tissues of unhardened and hardened seedlings of Pinus silvestris L. and Picea abies (L.) Karst. was determined. An apparatus for this purpose was constructed. Unhardened seedlings of spruce collapsed completely as a result of ice crystal formation in their shoots, while unhardened seedlings of pine survived ice crystal formation with or without injury to the needles. After a hardening period of 4–5 weeks, seedlings of spruce and pine survived ice formation but injuries occurred in spruce. For pine, on the contrary, the temperature after ice formation had a decisive effect on the extent of the injuries. Observed injuries are discussed in terms of inter- and intracellular ice crystal formation.  相似文献   
90.
IMMOBILIZED proteins have been used successfully for the purification and isolation of specific natural products, particularly proteins such as antigens, antibodies, enzymes and enzyme inhibitors1–3. They have also been used for the commercial production of biochemicals4 and as models for imitating enzymes bound to cellular components in vivo.  相似文献   
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