4种阔叶幼苗对PEG模拟干旱的生理响应

研究了PEG模拟干旱胁迫环境下的火力楠(Michelia macclurel)、尾叶桉(Eucalyptus urophylla)、枫香(Liquidambar formosana)、荷木(Schima superba)幼苗的生理变化。结果表明,干旱胁迫下,4种幼苗叶片的相对含水量小于对照,其中,尾叶桉和枫香下降明显;不同干旱胁迫条件下,4种树种幼苗叶片的相对电导率均显著大于对照,其中尾叶桉和枫香上升幅度大;干旱胁迫下的火力楠和荷木幼苗叶片的脯氨酸含量呈现波动,尾叶桉和枫香幼苗则显著大于对照;不同干旱胁迫时间下的幼苗叶片的叶绿素含量小幅波动;4个树种幼苗的过氧岐化酶(SOD)活性随胁迫时间增加而呈现先升后降的趋势,其中火力楠和荷木的幼苗的SOD活性持续维持在较高水平;荷木叶片的丙二醛(MDA)含量先升后降,最后和对照水平相近,其余幼苗的MDA含量均大于对照;干旱胁迫下4种幼苗叶片的可溶性糖含量增加幅度较大。主成分分析表明,4种幼苗的抗旱能力排序为荷木>火力楠>尾叶桉>枫香。     

星斑川鲽幼鱼胆碱需求量的研究

胆碱是维持鱼类正常生长的营养物质,饲料中胆碱缺乏会导致鱼类生长受阻、饲料利用率低、脂肪代谢能力低下以及肠道和肾脏出血等症状。研究表明,斑点叉尾     

North Pacific right whale (Eubalaena japonica) seasonal and diel calling patterns from long‐term acoustic recordings in the southeastern Bering Sea, 2000–2006

We assessed North Pacific right whale (Eubalaena japonica) seasonal and daily calling patterns in the southeastern Bering Sea (SEBS) using long‐term hydrophone recordings from October 2000 through January 2006. We detected right whale calls on the SEBS middle shelf (<100 m depth) as early as May, intermittently throughout summer and fall, and as late as December. Calls also were detected on one day in June 2005 on the SEBS slope (>1,000 m), but were not detected near Kodiak Island from April to August 2003. In months with calls, detections occurred on more days in July–October (≥6 d/mo), than from May to June or November to December (≤3 d/mo). Calls were clustered in time and were usually detected on 1–3 consecutive days with a median interval of 6.5 d for calls >1 d apart. Hourly calling rates were significantly higher at night than during the day. These data indicate that right whales occur in the SEBS later in the year than previously known, intermittently pass through the middle‐shelf study region, and usually remain there no longer than a few days. Right whale habitat use in the SEBS may intensify in mid‐summer through early fall based on higher monthly and daily call detection rates.     

Evaluation of the water quality of future tributaries to the planned Dobczyce reservoir (Poland) using macroinvertebrates

The bottom fauna of 5 tributaries of the planned Dobczyce reservoir and the River Raba below the dam was investigated in the preimpoundment period (1983–84). The abundance of macrofauna varied between 46 taxa (Wolnica stream) and 66 taxa (Brzezówka stream). Each station showed individual taxa composition except for the RABA-u and RABA-d (84% similarity). On the basis of 7 different biological indices the stations were divided into 3 categories: unpolluted (Brzezówka), slightly polluted (Bulinka, Trzemésnia and both Raba stations), and moderately polluted (Wolnica). Most sensitive to chemical pollution was the BIOTIC-index. The combination of environmental variables was used to predict biological indices. The most significant relationship (P < 0.01, R ² = 0.71) was found between the BIOTIC-index and physico-chemical factors. Some problems in the application of indices (sampling, indicator organisms and interpretation of the results) are discussed and local adaptations of methods used are recommended.     

Scale effects and constraints for sound production in katydids (Orthoptera: Tettigoniidae): correlated evolution between morphology and signal parameters

Male katydids (Orthoptera: Tettigoniidae) produce mating calls by rubbing the wings together, using specialized structures in their forewings (stridulatory file, scraper and mirror). A large proportion of species (ca. 66%) reported in the literature produces ultrasonic signals as principal output. Relationships among body size, generator structures and the acoustic parameters carrier frequency (f_c) and pulse duration (p_d), were studied in 58 tropical species that use pure‐tone signals. A comparative analysis, based on the only available katydid phylogeny, shows how changes in sound generator form are related to changes in f_c and p_d. Anatomical changes of the sound generator that might have been selected via f_c and p_d are mirror size, file length and number of file teeth. Selection for structures of the stridulatory apparatus that enhance wing mechanics via file‐teeth and scraper morphology was crucial in the evolution of ultrasonic signals in the family Tettigoniidae.     

Non-visual crypsis: a review of the empirical evidence for camouflage to senses other than vision

I review the evidence that organisms have adaptations that confer difficulty of detection by predators and parasites that seek their targets primarily using sensory systems other than vision. In other words, I will answer the question of whether crypsis is a concept that can usefully be applied to non-visual sensory perception. Probably because vision is such an important sensory system in humans, research in this field is sparse. Thus, at present we have very few examples of chemical camouflage, and even these contain some ambiguity in deciding whether they are best seen as examples of background matching or mimicry. There are many examples of organisms that are adaptively silent at times or in locations when or where predation risk is higher or in response to detection of a predator. By contrast, evidence that the form (rather than use) of vocalizations and other sound-based signals has been influenced by issues of reducing detectability to unintended receivers is suggestive rather than conclusive. There is again suggestive but not completely conclusive evidence for crypsis against electro-sensing predators. Lastly, mechanoreception is highly understudied in this regard, but there are scattered reports that strongly suggest that some species can be thought of as being adapted to be cryptic in this modality. Hence, I conclude that crypsis is a concept that can usefully be applied to senses other than vision, and that this is a field very much worthy of more investigation.