scholarly journals A partial migrant relies upon a range-wide cue set but uses population-specific weighting for migratory timing

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Nils Linek ◽  
Paweł Brzęk ◽  
Phillip Gienapp ◽  
M. Teague O’Mara ◽  
Ivan Pokrovsky ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Day Length ◽  
Environmental Cues ◽  
Local Conditions ◽  
Ambient Temperatures ◽  
Partial Migrant ◽  
Migratory Timing ◽  
Migratory Strategies ◽  
Departure Decisions ◽  
High Atmospheric Pressure

Abstract Background Many birds species range over vast geographic regions and migrate seasonally between their breeding and overwintering sites. Deciding when to depart for migration is one of the most consequential life-history decisions an individual may make. However, it is still not fully understood which environmental cues are used to time the onset of migration and to what extent their relative importance differs across a range of migratory strategies. We focus on departure decisions of a songbird, the Eurasian blackbird Turdus merula, in which selected Russian and Polish populations are full migrants which travel relatively long-distances, whereas Finnish and German populations exhibit partial migration with shorter migration distances. Methods We used telemetry data from the four populations (610 individuals) to determine which environmental cues individuals from each population use to initiate their autumn migration. Results When departing, individuals in all populations selected nights with high atmospheric pressure and minimal cloud cover. Fully migratory populations departed earlier in autumn, at longer day length, at higher ambient temperatures, and during nights with higher relative atmospheric pressure and more supportive winds than partial migrants; however, they did not depart in higher synchrony. Thus, while all studied populations used the same environmental cues, they used population-specific and locally tuned thresholds to determine the day of departure. Conclusions Our data support the idea that migratory timing is controlled by general, species-wide mechanisms, but fine-tuned thresholds in response to local conditions.

scholarly journals Intermediate-duration day lengths unmask reproductive responses to nonphotic environmental cues

2009 ◽  
Vol 296 (5) ◽  
pp. R1613-R1619 ◽  
Author(s):  
Matthew J. Paul ◽  
Jerome Galang ◽  
William J. Schwartz ◽  
Brian J. Prendergast
Keyword(s):  
Pubertal Development ◽  
Late Summer ◽  
Early Spring ◽  
Day Length ◽  
Environmental Cues ◽  
Local Conditions ◽  
Siberian Hamsters ◽  
Reproductive Axis ◽  
And Behavior

Many animals time their breeding to the seasons, using the changing day length to forecast those months when environmental conditions favor reproductive success; in Siberian hamsters ( Phodopus sungorus), long summer days stimulate, whereas short winter days inhibit, reproductive physiology and behavior. Nonphotic environmental cues are also thought to influence the timing of breeding, but typically their effects on reproduction are minor and more variable under categorically long and short photoperiods. We hypothesized that the influence of nonphotic cues might be more prominent during intermediate photoperiods (early spring and late summer), when day length is an unreliable predictor of year-to-year fluctuations in food availability. In hamsters housed in an intermediate photoperiod (13.5 h light/day), two nonphotic seasonal cues, mild food restriction and same-sex social housing, induced gonadal regression, amplified photoperiod history-dependent reproductive responses to decreasing day lengths, and prevented pubertal development indefinitely. These cues were entirely without effect in hamsters maintained under a long photoperiod (16 h light/day). Thus intermediate photoperiods reveal a heightened responsiveness of the reproductive axis to nonphotic cues. This photoperiod-dependent efficacy of nonphotic cues may explain how animals integrate long-term photic and short-term nonphotic cues in nature: intermediate day lengths open a seasonal window of increased reproductive responsiveness to nonphotic cues at a time when such cues may be of singular relevance, thereby allowing for precise synchronization of the onset and offset of the breeding season to local conditions.

Growth of Ornamental Plants in Compacted Soils in Relation to Root Growth under Low Oxygen and High Atmospheric Pressure

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 479d-479
Author(s):  
Michael Knee ◽  
Ruth Brake
Keyword(s):  
Atmospheric Pressure ◽  
Root Elongation ◽  
Native Plants ◽  
Tagetes Patula ◽  
Low Oxygen ◽  
Compacted Soils ◽  
Bedding Plants ◽  
Four Levels ◽  
Physical Resistance ◽  
High Atmospheric Pressure

In urban situations, particularly after construction, herbaceous ornamentals may be planted into soils that are compacted or have poor structure so that plant roots may encounter poor aeration or physical resistance. Low oxygen concentrations may be the most important aspect of poor aeration and are readily reproduced in the laboratory. High atmospheric pressure might be used to screen for the ability to grow against physical resistance. We tested the suggestion that “native” plants would grow better in compacted soils than typical bedding plants and for differences in tolerance to low oxygen or high pressure. Plants were grown from seed in the greenhouse at four levels of compaction in peat-based medium and in field soil. Shoot dry weights of the native plants Asclepias tuberosa, Echinacea purpurea, and Schizachyrium scoparius, were less affected by growth in compacted soil or peat medium than those of the bedding plants, Antirrhinum majus, Gypsophila elegans, Impatiens balsamina, Tagetes patula and Zinnia elegans. The oxygen content of media declined with compaction to a minimum of 10 kPa. Half maximal root elongation was observed at 1 to 3 kPa oxygen for most species without any separation between the groups. A presure of 1100 kPa reduced root elongation of the bedding plants by 50 to 70% but only 5 to 20% for the native plants.

scholarly journals Barley yield formation under abiotic stress depends on the interplay between flowering time genes and environmental cues

2018 ◽  
Author(s):  
Mathias Wiegmann ◽  
Andreas Maurer ◽  
Anh Pham ◽  
Timothy J. March ◽  
Ayed Al-Abdallat ◽  
...  
Keyword(s):  
Grain Yield ◽  
Flowering Time ◽  
Plant Development ◽  
Abiotic Stresses ◽  
Wild Barley ◽  
Nitrogen Deficiency ◽  
Pleiotropic Effects ◽  
Day Length ◽  
Environmental Cues ◽  
Yield Formation

AbstractSince the dawn of agriculture, crop yield has always been impaired through abiotic stresses. In a field trial across five locations worldwide, we tested three abiotic stresses, nitrogen deficiency, drought and salinity, using HEB-YIELD, a selected subset of the wild barley nested association mapping population HEB-25. We show that barley flowering time genes Ppd-H1, Sdw1, Vrn-H1 and Vrn-H3 exert pleiotropic effects on plant development and grain yield. Under field conditions, these effects are strongly influenced by environmental cues like day length and temperature. For example, in Al-Karak, Jordan, the day length-sensitive wild barley allele of Ppd-H1 was associated with an increase of grain yield by up to 30% compared to the insensitive elite barley allele. The observed yield increase is accompanied by pleiotropic effects of Ppd-H1 resulting in shorter life cycle, extended grain filling period and increased grain size. Our study indicates that the adequate timing of plant development is crucial to maximize yield formation under harsh environmental conditions. We provide evidence that wild barley germplasm, introgressed into elite barley cultivars, can be utilized to improve grain yield. The presented knowledge may be transferred to related crop species like wheat and rice securing the rising global food demand for cereals.

Influence of high atmospheric pressure on flame spread over electric wire at different inclinations

2020 ◽  
Vol 136 ◽  
pp. 66-75 ◽  
Author(s):  
Yanli Zhao ◽  
Jian Chen ◽  
Xiao Chen ◽  
Youjie Sheng ◽  
Shouxiang Lu ◽  
...  
Keyword(s):  
Flame Spread ◽  
Atmospheric Pressure ◽  
High Atmospheric Pressure

scholarly journals Increasing photoperiod stimulates the initiation of spring migratory behaviour and physiology in a facultative migrant, the pine siskin

2018 ◽  
Vol 5 (8) ◽  
pp. 180876 ◽  
Author(s):  
Ashley R. Robart ◽  
Mali M. K. McGuire ◽  
Heather E. Watts
Keyword(s):  
Experimental Test ◽  
Spring Migration ◽  
Fat Deposition ◽  
Day Length ◽  
Environmental Cues ◽  
Migratory Restlessness ◽  
Migratory Behaviour ◽  
Behavioural Changes ◽  
Short Day

The transition to a migratory state involves coordinated changes in physiology and behaviour. In species with regular, predictable (obligate) migrations, increasing day length triggers the expression of a spring migratory state and androgens play an important role in stimulating its development. By contrast, we know little about the environmental cues and endocrine mechanisms that regulate migration in species with less predictable (facultative) migrations. Here, we tested whether photoperiod stimulates a migratory state in a facultative nomadic migrant, the pine siskin ( Spinus pinus ). We exposed wintering birds to either a naturally increasing or short-day photoperiod and measured physiological and behavioural changes indicative of a migratory state. We also examined changes in circulating hormones that may play a role in the migratory transition. Natural-day, but not short-day, birds displayed physiological preparations for migration, including increases in fat deposition, and showed increased levels of migratory restlessness. We found no evidence for a role of corticosterone in the migratory transition, but testosterone may be important. This study is the first experimental test of the role of photoperiod in regulating facultative migration and demonstrates that the predictive cue used by many obligate migrants to time spring migration is also important in a facultative migrant.

Effects of heat load and photoperiod on milk yield and composition in three dairy herds in Israel

1999 ◽  
Vol 69 (1) ◽  
pp. 37-47 ◽  
Author(s):  
Y. Aharoni ◽  
A. Brosh ◽  
E. Ezra
Keyword(s):  
Milk Yield ◽  
Heat Load ◽  
Peak Effect ◽  
Day Length ◽  
Seasonal Effects ◽  
Lactation Performance ◽  
Annual Fluctuation ◽  
Load Effect ◽  
Ambient Temperatures ◽  
Heat Load Index

AbstractEffects of heat load and of photoperiod on lactation performance were evaluated using milk test data of three Israeli Holstein herds over a period of 3 years, from 1994 to 1996. All together 2209 cows, with 28029 milk records, were included. Photoperiod effects were examined as associated with day length and daily changes in day length and heat load index was formulated as a function of the seasonal day and night ambient temperatures, to account for the heat load effect. The regression model included effects of cow, herd, year, lactation number and days in milk in addition to the seasonal effects. The dependent variables were milk yield and fat, protein and lactose concentrations. Milk yield was affected by both photoperiod and heat load, with the peak photoperiod effect in May and amplitude of 3·1 (s.d. 0·9) kg/day and negative heat load effect of-1-8 (s.d. 0·4) kg/day at its peak. Protein concentration was affected by photoperiod, with the peak effect in January (amplitude of 1·7 (s.e. 0·5) g/kg) but not by heat load (-0-2 (s.d. 0·6) glkg). Fat concentration was affected primarily by heat load (-3-4 (s.d. 0·7) g/kg), with a photoperiod effect which peaked in October (amplitude of 1·8 (s.d. 0·8) g/kg). Lactose concentration was affected by both environmental factors to a lesser extent (photoperiod amplitude of 0·6 (s.d. 0·2) g/kg and heat load effect of-0-03 (s.d. 0·16) g/kg). Comparison of the predicted seasonal effects on milk yield and composition with the annual fluctuation in the national herd showed a good match of the predicted effects with the national observations. It is concluded that while heat load relief may be beneficial, manipulation of the photoperiod may induce adverse effects on milk yield and composition.

Modeling, Simulation and Validation of the Fluid Temperature of a Physical Drilling Simulator for Experimental Planning

2018 ◽  
Author(s):  
Patrick Höhn ◽  
Roger Aragall ◽  
Michael Koppe ◽  
Joachim Oppelt
Keyword(s):  
Operation Time ◽  
Sensitivity Analyses ◽  
Drilling Process ◽  
Fluid Temperature ◽  
Flow Loop ◽  
Local Conditions ◽  
Ambient Temperatures ◽  
Pressure Losses ◽  
Basic Model ◽  
Operation Temperature

Drilling equipment tests during field operations are always affected by uncertainties and variations regarding the local conditions in the borehole. In order to provide a more controlled testing environment for research, a hardware simulator was established at the Drilling Simulator Celle, Clausthal University of Technology. The simulator replicates the last 25 meters of a horizontal borehole and permits the drilling of a five-meter long rock sample. The setup includes a flow loop with two pumps for borehole cleaning and cuttings transport during the drilling process. During operation, temperature of the fluid increases due to pressure losses in the loop. This paper introduces a basic model to determine the maximum allowable continuous operation time of the hardware setup. Further improvements can be achieved by doing sensitivity analyses of the parameters affecting the system behavior, e.g. ambient temperatures or mass flow rate. Measurements from the hardware setup are used for validation of the model and show consistent results.

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