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Author Vasquez, R A url  doi
openurl 
  Title Assessment of predation risk via illumination level: facultative central place foraging in the cricetid rodent Phyllotis darwini Type Journal Article
  Year 1994 Publication (up) Behavioral Ecology and Sociobiology Abbreviated Journal  
  Volume 34 Issue 5 Pages 375-381  
  Keywords animals; rodents; foraging behaviour  
  Abstract It is well known that the risk of predation affects prey decision making. However, few studies have been concerned with the cues used by prey to assess this risk. Prey animals may use indirect environmental cues to assess predation hazard since direct evaluation may be dangerous. I studied the assessment of predation risk, manipulated via environmental illumination level, and the trade-off between foraging and predation hazard avoidance in the nocturnal rodent Phyllotis darwini (Rodentia: Cricetidae). In experimental arenas I simulated dark and full moon nights (which in nature correlate with low and high predation risk, respectively) and measured the immediate responses of animals to flyovers of a raptor model. Second, varying illumination only, I evaluated patch use, food consumption, central place foraging, and nocturnal variation of body weight. During flyover experiments, animals showed significantly more evasive reactions under full moon illumination than in moonless conditions. In the patch use experiments, rodents significantly increased their giving-up density and decreased their total food consumption under moonlight. On dark nights, rodents normally fed in the food patch, but when illumination was high they became central place foragers in large proportion. Moreover, the body weight of individuals decreased proportionately more during bright nights. These results strongly suggest that P. darwini uses the level of environmental illumination as a cue to the risk of being preyed upon and may sacrifice part of its energy return to avoid risky situations.  
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  Call Number LoNNe @ schroer @ Serial 1604  
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Author Rojas, L.M.; McNeil, R.; Cabana, T.; Lachapelle, P. url  doi
openurl 
  Title Diurnal and Nocturnal Visual Capabilities in Shorebirds as a Function of Their Feeding Strategies Type Journal Article
  Year 1999 Publication (up) Brain, Behavior and Evolution Abbreviated Journal Brain Behav Evol  
  Volume 53 Issue 1 Pages 29-43  
  Keywords foraging; Catoptrophorus semipalmatus; Territorial Willets; Black-winged Stilt; Himantopus himantopus; Scolopax minor; Limnodromus griseus; birds; Wilson's Plover; Charadrius wilsonia; Short-billed Dowitcher; Limnodromus griseus  
  Abstract Some shorebird species forage with the same feeding strategy at night and during daytime, e.g. visual pecking in the Wilson's Plover (Charadrius wilsonia) or tactile probing in the Short-billed Dowitcher (Limnodromus griseus). The Limnodromus griseus (Scolopax minor) uses tactile probing, by day and by night, but sometimes pecks for insects during daytime. The Black-winged Stilt (Himantopus himantopus) is a visual pecker, both by day and by night, and sometimes forages tactilely on windy (agitated water surface) moonless nights. Territorial Willets (Catoptrophorus semipalmatus) are visual peckers during daylight and on moonlight conditions but switch to tactile feeding under lower light conditions. It could be postulated that some shorebird species would switch from visual feeding during daytime to tactile foraging at night because they have poor night vision compared to species that are always sight foragers irrespective of the time of the day. This issue was examined by comparing retinal structure and function in the above species. Electroretinograms (ERGs) were obtained at different light intensities from anesthetized birds, and the retinae were processed for histological observations. Based on ERGs, retinal sensitivity, and rod:cone ratios, both plovers and stilts are well adapted for nocturnal vision. Although they have low rod density compared to that of stilts and plovers, Willets and woodcocks have a scotopic retinal sensitivity similar to that of stilts and plovers but rank midway between plovers and dowitchers for the b-wave amplitude. Dowitchers have the lowest scotopic b-wave amplitude and retinal sensitivity and appear the least well adapted for night vision. Based on photopic ERGs and cone densities, although stilts, Willets and dowitchers appear as well adapted for daytime vision, plovers occupy the last rank of all species examined. Compared to the nighttime tactile feeders and those that switch from daytime visual pecking to tactile feeding at night, nighttime sight feeders have a superior rod function and, consequently, potentially superior nocturnal visual capabilities.  
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  ISSN 0006-8977 ISBN Medium  
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  Notes Approved no  
  Call Number IDA @ john @ Serial 47  
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Author Topping, M.G.; Millar, J.S.; Goddard, J.A. url  doi
openurl 
  Title The effects of moonlight on nocturnal activity in bushy-tailed wood rats (Neotoma cinerea) Type Journal Article
  Year 1999 Publication (up) Canadian Journal of Zoology Abbreviated Journal Can. J. Zool.  
  Volume 77 Issue 3 Pages 480-485  
  Keywords animals; mammals; rats; bushy-tailed wood rat; Neotoma cinerea; Canada; foraging; reproduction; moonlight; predation risk  
  Abstract The nocturnal activity of bushy-tailed wood rats (Neotoma cinerea) was monitored for two breeding seasons (1993 and 1994) in the Canadian Rockies. Radiotelemetry was used under three levels of moonlight to assess two measures of nocturnal activity: (i) the proportion of animals crossing rocky outcrops and entering the surrounding forest to forage, search for mates, or both, and (ii) the distance moved from the den site while in the forest. Males and females exhibited significant differences among moonlight levels, with greater activity on nights of intermediate-level moonlight and less activity on nights with bright or dark moonlight. There was no difference in the proportions of males and females active at any moonlight level. The distances moved from the den did not differ among moonlight levels for either males or females. Having traversed the rocks and entered the forest, individuals moved similar distances regardless of light level. These results suggest that wood rats respond to moonlight only when making the decision to cross rocks and enter the forest. This behaviour presumably serves to counteract the increased risk of predation on bright nights.  
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  ISSN 0008-4301 ISBN Medium  
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  Notes Approved no  
  Call Number IDA @ john @ Serial 88  
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Author Anisimov, V.N.; Vinogradova, I.A.; Panchenko, A.V.; Popovich, I.G.; Zabezhinskii, M.A. url  openurl
  Title Light-at-Night-Induced Circadian Disruption, Cancer and Aging Type Journal Article
  Year 2012 Publication (up) Current Aging Science Abbreviated Journal  
  Volume 5 Issue 3 Pages 170-177  
  Keywords Animals; Light-at-night; aging; cancer; cardiovascular diseases; circadian; circadian rhythm; diabetes; disruption; melatonin; shift-work  
  Abstract Light-at-night has become an increasing and essential part of the modern lifestyle and leads to a number of health problems, including excessive body mass index, cardiovascular diseases, diabetes, and cancer. The International Agency for Research on Cancer (IARC) Working Group concluded that “shift-work that involves circadian disruption is probably carcinogenic to humans” (Group 2A) [1]. According to the circadian disruption hypothesis, light-at-night might disrupt the endogenous circadian rhythm and specifically suppress nocturnal production of the pineal hormone melatonin and its secretion into the blood. We evaluated the effect of various light/dark regimens on the survival, life span, and spontaneous and chemical carcinogenesis in rodents. Exposure to constant illumination was followed by accelerated aging and enhanced spontaneous tumorigenesis in female CBA and transgenic HER-2/neu mice. In male and female rats maintained at various light/dark regimens (standard 12:12 light/dark [LD], the natural light [NL] of northwestern Russia, constant light [LL], and constant darkness [DD]) from the age of 25 days until natural death, it was found that exposure to NL and LL regimens accelerated age-related switch-off of the estrous function (in females), induced development of metabolic syndrome and spontaneous tumorigenesis, and shortened life span both in male and females rats compared to the standard LD regimen. Melatonin given in nocturnal drinking water prevented the adverse effect of the constant illumination (LL) and natural light (NL) regimens on the homeostasis, life span, and tumor development both in mice and rats. The exposure to the LL regimen accelerated colon carcinogenesis induced by 1,2-dimethylhydrazine (DMH) in rats, whereas the treatment with melatonin alleviated the effects of LL. The maintenance of rats at the DD regimen inhibited DMH-induced carcinogenesis. The LL regimen accelerated, whereas the DD regimen inhibited both mammary carcinogenesis induced by N-nitrosomethylurea and transplacental carcinogenesis induced by N-nitrosoethylurea in rats. Treatment with melatonin prevented premature aging and tumorigenesis in rodents. The data found in the literature and our observations suggest that the use of melatonin would be effective for cancer prevention in humans at risk as a result of light pollution.  
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  Call Number LoNNe @ christopher.kyba @ Serial 377  
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Author Haag, C.R.; Riek, M.; Hottinger, J.W.; Pajunen, V.I.; Ebert, D. url  doi
openurl 
  Title Genetic diversity and genetic differentiation in Daphnia metapopulations with subpopulations of known age Type Journal Article
  Year 2005 Publication (up) Genetics Abbreviated Journal Genetics  
  Volume 170 Issue 4 Pages 1809-1820  
  Keywords Plants; Aging; Animals; Daphnia/*genetics/*physiology; *Genetic Variation; *Genetics, Population  
  Abstract If colonization of empty habitat patches causes genetic bottlenecks, freshly founded, young populations should be genetically less diverse than older ones that may have experienced successive rounds of immigration. This can be studied in metapopulations with subpopulations of known age. We studied allozyme variation in metapopulations of two species of water fleas (Daphnia) in the skerry archipelago of southern Finland. These populations have been monitored since 1982. Screening 49 populations of D. longispina and 77 populations of D. magna, separated by distances of 1.5-2180 m, we found that local genetic diversity increased with population age whereas pairwise differentiation among pools decreased with population age. These patterns persisted even after controlling for several potentially confounding ecological variables, indicating that extinction and recolonization dynamics decrease local genetic diversity and increase genetic differentiation in these metapopulations by causing genetic bottlenecks during colonization. We suggest that the effect of these bottlenecks may be twofold, namely decreasing genetic diversity by random sampling and leading to population-wide inbreeding. Subsequent immigration then may not only introduce new genetic material, but also lead to the production of noninbred hybrids, selection for which may cause immigrant alleles to increase in frequency, thus leading to increased genetic diversity in older populations.  
  Address Unite d'Ecologie et d'Evolution, Departement de Biologie, Universite de Fribourg, CH-1700 Fribourg, Switzerland. christoph.haag@ed.ac.uk  
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  Language English Summary Language Original Title  
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  ISSN 0016-6731 ISBN Medium  
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  Notes PMID:15937138; PMCID:PMC1449778 Approved no  
  Call Number LoNNe @ kagoburian @ Serial 660  
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