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1.
Early environment influences later performance in fishes   总被引:1,自引:0,他引:1  
Conditions fish encounter during embryogenesis and early life history can leave lasting effects not only on morphology, but also on growth rate, life‐history and behavioural traits. The ecology of offspring can be affected by conditions experienced by their parents and mother in particular. This review summarizes such early impacts and their ecological influences for a variety of teleost species, but with special reference to salmonids. Growth and adult body size, sex ratio, egg size, lifespan and tendency to migrate can all be affected by early influences. Mechanisms behind such phenotypically plastic impacts are not well known, but epigenetic change appears to be one central mechanism. The thermal regime during development and incubation is particularly important, but also early food consumption and intraspecific density can all be responsible for later life‐history variation. For behavioural traits, early experiences with effects on brain, sensory development and cognition appear essential. This may also influence boldness and other social behaviours such as mate choice. At the end of the review, several issues and questions for future studies are given.  相似文献   
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Knowledge of breeding ecology is required for many conservation interventions. The Seychelles Black Parrot Coracopsis barklyi, endemic to the island of Praslin, is vulnerable to extinction. We aimed to improve understanding of C. barklyi breeding ecology to aid conservation planning. We present the results of four years of research, including nesting cavity characteristics and availability, reproductive success, breeding parameters, parental behaviour and reproductive strategy. Thirty-six breeding attempts were studied over the four seasons. Nests were mainly located in Coco de Mer palms Lodoicea maldivica. Deeper cavities with more canopy cover were preferred. There may be a shortage of high-quality nesting cavities in intensive breeding seasons. Average clutch size was 2.2 eggs, incubation period was c. 15 d and egg fertility was 71%. Rats were key nest predators, causing the failure of up to 33% of breeding attempts. The probability of nest success was 53%. At least 57% of fledglings survived their first year. This species breeds cooperatively and practices a highly unusual side-by-side copulation. We discuss the implications of the results in the context of former, ongoing and potential conservation measures for C. barklyi including translocation, invasive species management, nest box provisioning, habitat restoration and further research.  相似文献   
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调亏灌溉对菘蓝水分利用及产量的影响   总被引:4,自引:0,他引:4  
通过探究水分调亏对河西地区膜下滴灌菘蓝(Isatis indigotica)各项生理指标、产量和水分利用的影响,为菘蓝高效节水种植提供理论指导。于2016年在河西走廊中部张掖市民乐县益民灌溉试验站进行菘蓝水分调亏研究,在保持苗期和肉质根成熟期充分灌溉的情况下,在菘蓝营养生长期和肉质根生长期分别进行轻度、中度和重度的水分亏缺处理,并测定各项光合生理指标、产量和水分利用率。结果表明,营养生长期和肉质根生长期的中度与重度水分亏缺显著降低了菘蓝叶片净光合速率、叶面积指数、株高及主根长,并且随水分亏缺程度加重降幅增大;而轻度水分亏缺与对照组的差异不显著。营养生长期和肉质根生长期轻度水分亏缺处理的菘蓝产量与水分利用效率最高,分别达到8 239.56 kg·hm~(–2)和24.11kg·hm~(–2)·mm~(–1);其它水分亏缺处理组产量和水分利用效率均有所降低,与对照组之间差异显著(P0.05),重度水分亏缺处理各项指标均最低。因此,最优的菘蓝水分调控处理为营养生长期和肉质根生长期的轻度水分调亏,能够降低菘蓝耗水量,提高水分利用效率且其产量不会降低。  相似文献   
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Pleiotrophin (Ptn) plays an important role in bone growth through regulating osteoblasts’ functions. The underlying signaling mechanisms are not fully understood. In the current study, we found that Ptn induced heparin-binding epidermal growth factor (HB-EGF) release to trans-activate EGF-receptor (EGFR) in both primary osteoblasts and osteoblast-like MC3T3-E1 cells. Meanwhile, Ptn activated Akt and Erk signalings in cultured osteoblasts. The EGFR inhibitor AG1478 as well as the monoclonal antibody against HB-EGF (anti-HB-EGF) significantly inhibited Ptn-induced EGFR activation and Akt and Erk phosphorylations in MC3T3-E1 cells and primary osteoblasts. Further, EGFR siRNA depletion or dominant negative mutation suppressed also Akt and Erk activation in MC3T3-E1 cells. Finally, we observed that Ptn increased alkaline phosphatase (ALP) activity and inhibited dexamethasone (Dex)-induced cell death in both MC3T3-E1 cells and primary osteoblasts, such effects were alleviated by AG1478 or anti-HB-EGF. Together, these results suggest that Ptn-induced Akt/Erk activation and some of its pleiotropic functions are mediated by EGFR trans-activation in cultured osteoblasts.  相似文献   
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运用相邻格子法及聚集度指标测定法,在植被调查的基础上,对云南普洱不同恢复阶段(恢复15a、30a和老龄林)季风常绿阔叶林的刺栲(Castanopsis hystrix)、短刺栲(Castanopsis echidnocarpa)和红木荷(Schima wallichii)3个优势物种进行种群空间分布格局研究,以阐明种群分布格局与生境条件、种群年龄结构的动态关系,揭示种群发育过程中空间动态与生物学机理。结果发现:在所有恢复阶段内,刺栲、短刺栲、红木荷均为聚集分布。在不同尺度下,刺栲在原始林中10m×10m尺度下为均匀分布,而在恢复15年中20m×20m尺度为随机分布;红木荷在10m×20m尺度下为均匀分布,在其它所有恢复阶段和尺度下3个物种均为聚集分布。研究结果表明,不同恢复阶段和不同尺度下刺栲、短刺栲和红木荷3个优势物种绝大多数为聚集分布,说明聚集分布为3个优势种的基本属性。  相似文献   
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Background and Aims Ontogenetic changes in anti-herbivore defences are common and result from variation in resource availability and herbivore damage throughout plant development. However, little is known about the simultaneous changes of multiple defences across the entire development of plants, and how such changes affect plant damage in the field. The aim of this study was to assess if changes in the major types of plant resistance and tolerance can explain natural herbivore damage throughout plant ontogeny.Methods An assessment was made of how six defensive traits, including physical, chemical and biotic resistance, simultaneously change across the major transitions of plant development, from seedlings to reproductive stages of Turnera velutina growing in the greenhouse. In addition, an experiment was performed to assess how plant tolerance to artificial damage to leaves changed throughout ontogeny. Finally, leaf damage by herbivores was evaluated in a natural population.Key Results The observed ontogenetic trajectories of all defences were significantly different, sometimes showing opposite directions of change. Whereas trichome density, leaf toughness, extrafloral nectary abundance and nectar production increased, hydrogen cyanide and compensatory responses decreased throughout plant development, from seedlings to reproductive plants. Only water content was higher at the intermediate juvenile ontogenetic stages. Surveys in a natural population over 3 years showed that herbivores consumed more tissue from juvenile plants than from younger seedlings or older reproductive plants. This is consistent with the fact that juvenile plants were the least defended stage.Conclusions The results suggest that defensive trajectories are a mixed result of predictions by the Optimal Defence Theory and the Growth–Differentiation Balance Hypothesis. The study emphasizes the importance of incorporating multiple defences and plant ontogeny into further studies for a more comprehensive understanding of plant defence evolution.  相似文献   
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