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排序方式: 共有1049条查询结果,搜索用时 109 毫秒
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Francesca R. Grati Francesca Malvestiti Beatrice Grimi Elisa Gaetani Anna Maria Di Meco Anna Trotta Rosaria Liuti Sara Chinetti Francesca Dulcetti Anna Maria Ruggeri Cristina Agrati Giuditta Frascoli Silvia Milani Simona De Toffol Lorenza Martinoni Silvia Paganini Livia Marcato Federico Maggi Giuseppe Simoni 《黑龙江环境通报》2013,33(5):502-508
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Effects of Population Size and Food Stress on Fitness-Related Characters in the Scarce Heath, a Rare Butterfly in Western Europe 总被引:6,自引:0,他引:6
Abstract: Knowledge about the effects of inbreeding in natural populations is scarce, especially in invertebrates. We analyzed to what extent fitness-related traits in the scarce heath ( Coenonympha hero ), a butterfly, are affected by population size and isolation and whether differences in food quality influence these effects. We categorized nine populations as either large or small and isolated. Full-sib groups of offspring from 27 females were followed under seminatural conditions. Because of increased zygote mortality, egg hatchability was significantly lower in the small and isolated populations than in the large ones. Population category had no effect on larval weight under optimal conditions, but weight was significantly lower in the small-isolated category with low food quality. The effects of inbreeding can thus be hidden when conditions are benign but can appear under stress. Survival also differed significantly between population categories, and larval developmental time tended to be longer in the small-isolated category, irrespective of food conditions. We suggest that the differences in fitness between offspring from large and small isolated populations are at least partly due to inbreeding. This adds a further threat to a species that is already suffering from decreasing population sizes and increasing isolation among populations. 相似文献
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Richard T. T. Forman Bjorn Reineking Anna M. Hersperger 《Environmental management》2001,29(6):782-800
An extensive road system with rapidly increasing traffic produces diverse ecological effects that cover a large land area. Our objective was to evaluate the effect of roads with different traffic volumes on surrounding avian distributions, and its importance relative to other variables. Grassland bird data (5 years) for 84 open patches in an outer suburban/rural landscape near Boston were analyzed relative to: distance from roads with 3000–8000 to >30,000 vehicles/day; open-habitat patch size; area of quality microhabitat within a patch; adjacent land use; and distance to other open patches. Grassland bird presence and regular breeding correlated significantly with both distance from road and habitat patch size. Distance to nearest other open patch, irrespective of size, was not significant. Similarly, except for one species, adjacent land use, in this case built area, was not significant. A light traffic volume of 3000–8000 vehicles/day (local collector street here) had no significant effect on grassland bird distribution. For moderate traffic of 8000–15,000 (through street), there was no effect on bird presence although regular breeding was reduced for 400 m from a road. For heavier traffic of 15,000–30,000 (two-lane highway), both bird presence and breeding were decreased for 700 m. For a heavy traffic volume of ≥30,000 vehicles/day (multilane highway), bird presence and breeding were reduced for 1200 m from a road. The results suggest that avian studies and long-term surveys near busy roads may be strongly affected by traffic volume or changes in volume. We conclude that road ecology, especially the effects extending outward >100 m from roads with traffic, is a sine qua non for effective land-use and transportation policy. 相似文献
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Rosalind Pratt Jan Deprest Tom Vercauteren Sebastien Ourselin Anna L. David 《黑龙江环境通报》2015,35(12):1159-1166
Fetal surgery has become a clinical reality, with interventions for twin-to-twin transfusion syndrome (TTTS) and spina bifida demonstrated to improve outcome. Fetal imaging is evolving, with the use of 3D ultrasound and fetal MRI becoming more common in clinical practise. Medical imaging analysis is also changing, with technology being developed to assist surgeons by creating 3D virtual models that improve understanding of complex anatomy, and prove powerful tools in surgical planning and intraoperative guidance. We introduce the concept of computer-assisted surgical planning, and present the results of a systematic review of image reconstruction for fetal surgical planning that identified six articles using such technology. Indications from other specialities suggest a benefit of surgical planning and guidance to improve outcomes. There is therefore an urgent need to develop fetal-specific technology in order to improve fetal surgical outcome. © 2015 The Authors. Prenatal Diagnosis published by John Wiley & Sons Ltd. 相似文献