Demographic network and multi-season occupancy modeling of Rana sylvatica reveal spatial and temporal patterns of population connectivity and persistence     

William E. Peterman  Tracy A. G. Rittenhouse  Julia E. Earl  Raymond D. Semlitsch 《Landscape Ecology》2013,28(8):1601-1613

Many populations are spatially structured with frequent extinction–colonization events. A clear understanding of these processes is necessary for making informed and effective management decisions. Due to the spatially and temporally dynamic nature of many systems, population connectivity and local extinction–colonization processes can be difficult to assess, but graph theoretic and occupancy modeling approaches are increasingly being utilized to answer such vital ecological questions. In our study, we used 6 years of egg mass counts from 34 ponds for Rana sylvatica to parameterize spatially explicit demographic network models. Our models revealed that the studied populations have spatial structure with strong source–sink dynamics. We also assessed the colonization and persistence probability of each pond using multi-season occupancy modeling. We observed extreme fluctuation in reproductive effort among years, resulting in variable levels of connectivity across the landscape. Pond colonization and persistence were most influenced by local population dynamics, but colonization was also affected by precipitation. Our demographic network model had moderate ability to predict reproductive effort, but accuracy was hindered by variation in annual precipitation. Source populations had higher colonization and persistence rates as well as a greater proportion of ravine habitat within 1,000 m than sink populations. By linking a spatially explicit connectivity model with a temporal occupancy/persistence model, we provide a framework for interpreting patterns of occupancy and dispersal that can serve as an initial guide for future habitat management and restoration.  相似文献   

Utilization of potatoes for life support systems in space. I. Cultivar-photoperiod interactions     

Raymond M. Wheeler  Theodore W. Tibbitts 《American Journal of Potato Research》1986,63(6):315-323

The productive potential of potatoes (Solanum tuberosum L. cvs. Norland, Superior, Norchip, and Kennebec) was assessed for life support systems being proposed for space stations and/or lunar colonies. Plants were grown in walk-in growth rooms for 15 weeks at 20 C under 12-, 16- and 20-h photoperiods of 400 μmol m^t-2s^t-1 photosynthetic photon flux (PPF). Norland yielded the greatest tuber fresh weight, producing 2.3, 2.4, and 2.9 kg/plant under 12-, 16-, and 20-h photoperiods, respectively. The respective yields for the other cultivars under 12-, 16-, and 20-h were: Superior, 1.9, 1.5, and 1.8 kg/plant; Norchip, 1.8, 1.4, and 2.0 kg/plant; and Kennebec, 2.3, 0.2, and 0.8 kg/plant. Shoot and total plant biomass increased with lengthening photoperiods except for Kennebec, which showed increased shoot growth but no change in total growth with the longer photoperiods. Kennebec shoot growth under the 20-h photoperiod, and to some extent under 16-h, was noticeably stunted with shortened internodes. In addition, leaves of these plants showed mild chlorosis with rusty “flecking” of the surfaces. The harvest index (ratio of tuber yield/total biomass) was highest for all cultivars under the 12-h photoperiod, with a maximum of 0.69 for Norland. Similarly, the tuber yield per input of irradiant energy also was highest under 12-h for all cultivars. The tuber yield expressed on an area basis for the highest yielding treatment (Norland under 20-h) equaled 2.2 kg dry matter m^t-2. Over 15 weeks this equates to a productivity of 20.7 g tuber dry matter m^t-2 day^t-1. Assuming 3.73 kcal per g tuber dry matter and a daily human dietary requirement of 2800 kcal, then 36 m² of potatoes could supply the daily energy requirement for one human. Potential for increasing productivity is discussed.  相似文献   

STUDIES IN THE DIGESTIBILITY OF HERBAGE     

W. F. Raymond    C. D. Kemp    A. W. Kemp    C. E. Harris 《Grass and Forage Science》1954,9(1):69-82

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STUDIES ON THE DIGESTIBILITY OF HERBAGE     

W. F. Raymond    C. E. Harris    V. G. Harker 《Grass and Forage Science》1953,8(4):315-320

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STUDIES IN THE DIGESTIBILITY OF HERBAGE     

W. F. Raymond    D. J. Minson  C. E. Harris 《Grass and Forage Science》1959,14(2):75-77

Results are reported from six digestibility experiments in which frozen herbage was fed to groups of sheep at HIGH and Low levels of intake. The sheep on the HIGH level of intake digested the dry matter, organic matter, nitrogen and normal-acid fibre in the herbage less efficiently than those on the LOW level, confirming earlier results reported in Part VI of this series. Evidence suggests that this difference results from the higher rate of passage of food through the digestive tract at the HIGH level of intake.
These results are discussed with reference to the errors introduced into the faecal-index method for estimating the digestibility of grazed herbage.  相似文献   

Susceptibility of potato (Solanum tuberosum L.) foliage and tubers to the US8 genotype ofPhytophthora infestans     

William W. Kirk  Kimberly J. Felcher  David S. Douches  Brendan A. Niemira  Raymond Hammerschmidt 《American Journal of Potato Research》2001,78(4):319-322

Late blight is an important disease of potato(Solanum tuberosum L.) worldwide, and therefore, many potato-breeding programs have prioritized the development of late blight-resistant potato cultivars. Although the emphasis has been to enhance foliar resistance, it is also necessary to evaluate tuber late blight resistance in new breeding lines and new sources of late blight resistance. We report here on the assessment of foliar and tuber resistance and the correlation between these aspects of resistance in a sample of Michigan State University potato breeding lines. Two MSU breeding lines had significantly less infected foliage than the susceptible check cultivars. Tuber susceptibility was significantly different (P < 0.05) only between the most susceptible and the least susceptible breeding lines/cultivars. Foliar and tuber susceptibility to potato late blight were not correlated as low tuber susceptibility was associated both with extremely low (e.g., MSG274-3) and high (e.g., MSE202-3Rus) foliar susceptibility.  相似文献   

Tibial tuberosity advancement for treatment of CrCL injury: complications and owner satisfaction     

Steinberg EJ  Prata RG  Palazzini K  Brown DC 《Journal of the American Animal Hospital Association》2011,47(4):250-257

The purpose of this retrospective study of 171 dogs that underwent 193 tibial tuberosity advancement (TTA) surgeries was to describe complications and owner satisfaction associated with the procedure. Complications occurred in 21 cases (11%). Subsequent meniscal tear was the most common complication (10/193, 5.2%). Increasing body weight (P=0.02-0.04) and small cage size (P=0.06) were significantly associated with postsurgical complications. Ninety-two percent of owners were satisfied with the outcome of the TTA procedure, but only 84% stated that they would be willing to have the procedure performed again. The authors concluded that TTA had a complication rate and owner satisfaction similar to other tibial osteotomies for the surgical correction of cranial cruciate ligament disease.  相似文献   

α-Melanocyte--stimulating hormone and adrenocorticotropin concentrations in response to thyrotropin-releasing hormone and comparison with adrenocorticotropin concentration after domperidone administration in healthy horses and horses with pituitary pars intermedia dysfunction     

Beech J  McFarlane D  Lindborg S  Sojka JE  Boston RC 《Journal of the American Veterinary Medical Association》2011,238(10):1305-1315

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Effect of water content in a canned food on voluntary food intake and body weight in cats     

Wei A  Fascetti AJ  Villaverde C  Wong RK  Ramsey JJ 《American journal of veterinary research》2011,72(7):918-923

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Validating an FFQ for intake of episodically consumed foods: application to the National Institutes of Health-AARP Diet and Health Study     

Midthune D  Schatzkin A  Subar AF  Thompson FE  Freedman LS  Carroll RJ  Shumakovich MA  Kipnis V 《Public health nutrition》2011,14(7):1212-1221

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