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Author |
Ikeno, T.; Weil, Z.M.; Nelson, R.J. |
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Title |
Dim light at night disrupts the short-day response in Siberian hamsters |
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Journal Article |
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Year |
2014 |
Publication |
General and Comparative Endocrinology |
Abbreviated Journal |
Gen Comp Endocrinol |
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Volume |
197 |
Issue |
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Pages |
56-64 |
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Keywords |
2,4-dinitro-1-flourobenzene; Dnfb; Dth; Eya3; Eyes absent 3; GnIH; GnRH; Immune function; Ld; Lps; Light pollution; Pt; Pelage; Per1; Period1; Photoperiodism; Rfrp; RFamide-related peptide; Scn; Sd; Seasonality; Tsh; TSH receptor; Tshr; dLAN; delayed-type hypersensitivity; dim light at night; gonadotropin-inhibiting hormone; gonadotropin-releasing hormone; lipopolysaccharide; long days; pars tuberalis; short days; suprachiasmatic nuclei; thyroid-stimulating hormone |
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Abstract |
Photoperiodic regulation of physiology, morphology, and behavior is crucial for many animals to survive seasonally variable conditions unfavorable for reproduction and survival. The photoperiodic response in mammals is mediated by nocturnal secretion of melatonin under the control of a circadian clock. However, artificial light at night caused by recent urbanization may disrupt the circadian clock, as well as the photoperiodic response by blunting melatonin secretion. Here we examined the effect of dim light at night (dLAN) (5lux of light during the dark phase) on locomotor activity rhythms and short-day regulation of reproduction, body mass, pelage properties, and immune responses of male Siberian hamsters. Short-day animals reduced gonadal and body mass, decreased spermatid nuclei and sperm numbers, molted to a whiter pelage, and increased pelage density compared to long-day animals. However, animals that experienced short days with dLAN did not show these short-day responses. Moreover, short-day specific immune responses were altered in dLAN conditions. The nocturnal activity pattern was blunted in dLAN hamsters, consistent with the observation that dLAN changed expression of the circadian clock gene, Period1. In addition, we demonstrated that expression levels of genes implicated in the photoperiodic response, Mel-1a melatonin receptor, Eyes absent 3, thyroid stimulating hormone receptor, gonadotropin-releasing hormone, and gonadotropin-inhibitory hormone, were higher in dLAN animals than those in short-day animals. These results suggest that dLAN disturbs the circadian clock function and affects the molecular mechanisms of the photoperiodic response. |
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Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA. Electronic address: randy.nelson@osumc.edu |
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0016-6480 |
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PMID:24362257 |
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Call Number |
IDA @ john @ |
Serial |
82 |
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Author |
Prugh, L.R.; Golden, C.D. |
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Title |
Does moonlight increase predation risk? Meta-analysis reveals divergent responses of nocturnal mammals to lunar cycles |
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Journal Article |
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Year |
2013 |
Publication |
The Journal of Animal Ecology |
Abbreviated Journal |
J Anim Ecol |
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Volume |
83 |
Issue |
2 |
Pages |
504-514 |
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Keywords |
foraging efficiency; giving-up density; illumination; indirect effects; lunar cycles; moonlight; nocturnality; phylogenetic meta-analysis; predation risk; risk-sensitive foraging |
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Abstract |
The risk of predation strongly affects mammalian population dynamics and community interactions. Bright moonlight is widely believed to increase predation risk for nocturnal mammals by increasing the ability of predators to detect prey, but the potential for moonlight to increase detection of predators and the foraging efficiency of prey has largely been ignored. Studies have reported highly variable responses to moonlight among species, calling into question the assumption that moonlight increases risk. Here, we conducted a quantitative meta-analysis examining the effects of moonlight on the activity of 59 nocturnal mammal species to test the assumption that moonlight increases predation risk. We examined patterns of lunarphilia and lunarphobia across species in relation to factors such as trophic level, habitat cover preference and visual acuity. Across all species included in the meta-analysis, moonlight suppressed activity. The magnitude of suppression was similar to the presence of a predator in experimental studies of foraging rodents (13.6% and 18.7% suppression, respectively). Contrary to the expectation that moonlight increases predation risk for all prey species, however, moonlight effects were not clearly related to trophic level and were better explained by phylogenetic relatedness, visual acuity and habitat cover. Moonlight increased the activity of prey species that use vision as their primary sensory system and suppressed the activity of species that primarily use other senses (e.g. olfaction, echolocation), and suppression was strongest in open habitat types. Strong taxonomic patterns underlay these relationships: moonlight tended to increase primate activity, whereas it tended to suppress the activity of rodents, lagomorphs, bats and carnivores. These results indicate that visual acuity and habitat cover jointly moderate the effect of moonlight on predation risk, whereas trophic position has little effect. While the net effect of moonlight appears to increase predation risk for most nocturnal mammals, our results highlight the importance of sensory systems and phylogenetic history in determining the level of risk. |
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Institute of Arctic Biology, University of Alaska Fairbanks, 311 Irving 1, Fairbanks, AK, 99775, USA |
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0021-8790 |
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PMID:24102189 |
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IDA @ john @ |
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83 |
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Author |
Rockhill, A.P.; DePerno, C.S.; Powell, R.A. |
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Title |
The effect of illumination and time of day on movements of bobcats (Lynx rufus) |
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Journal Article |
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Year |
2013 |
Publication |
PloS one |
Abbreviated Journal |
PLoS One |
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Volume |
8 |
Issue |
7 |
Pages |
e69213 |
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Keywords |
Animals; Female; *Lighting; Lynx/*physiology; Male; Moon; Movement/*physiology; North Carolina; Time Factors; Wetlands |
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Abstract |
Understanding behavioral changes of prey and predators based on lunar illumination provides insight into important life history, behavioral ecology, and survival information. The objectives of this research were to determine if bobcat movement rates differed by period of day (dark, moon, crepuscular, day), lunar illumination (<10%, 10 – <50%, 50 – <90%, >90%), and moon phase (new, full). Bobcats had high movement rates during crepuscular and day periods and low movement rates during dark periods with highest nighttime rates at 10-<50% lunar illumination. Bobcats had highest movement rates during daytime when nighttime illumination was low (new moon) and higher movement rates during nighttime when lunar illumination was high (full moon). The behaviors we observed are consistent with prey availability being affected by light level and by limited vision by bobcats during darkness. |
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Fisheries, Wildlife, and Conservation Biology, North Carolina State University, Raleigh, North Carolina, USA. aimee_rockhill@ncsu.edu |
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1932-6203 |
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PMID:23861963; PMCID:PMC3704646 |
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Call Number |
IDA @ john @ |
Serial |
84 |
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Author |
Raiewski, E.E.; Elliott, J.A.; Evans, J.A.; Glickman, G.L.; Gorman, M.R. |
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Title |
Twice daily melatonin peaks in Siberian but not Syrian hamsters under 24 h light:dark:light:dark cycles |
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Journal Article |
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Year |
2012 |
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Chronobiology International |
Abbreviated Journal |
Chronobiol Int |
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Volume |
29 |
Issue |
9 |
Pages |
1206-1215 |
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Keywords |
Animals; Circadian Rhythm/*physiology; Cricetinae; Male; Melatonin/blood/*secretion; Mesocricetus/blood/*physiology; Motor Activity/physiology; Phodopus/blood/*physiology; Photoperiod; Species Specificity |
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The daily pattern of blood-borne melatonin varies seasonally under the control of a multi-oscillator circadian pacemaker. Here we examine patterns of melatonin secretion and locomotor activity in Siberian and Syrian hamsters entrained to bimodal LDLD8:4:8:4 and LD20:4 lighting schedules that facilitate novel temporal arrangements of component circadian oscillators. Under LDLD, both species robustly bifurcated wheel-running activity in distinct day scotophase (DS) and night scotophase (NS) bouts. Siberian hamsters displayed significant melatonin increases during each scotophase in LDLD, and in the single daily scotophase of LD20:4. The bimodal melatonin secretion pattern persisted in acutely extended 16 h scotophases. Syrian hamsters, in contrast, showed no significant increases in plasma melatonin during either scotophase of LDLD8:4:8:4 or in LD20:4. In this species, detectable levels were observed only when the DS of LDLD was acutely extended to yield 16 h of darkness. Established species differences in the phase lag of nocturnal melatonin secretion relative to activity onset may underlie the above contrast: In non-bifurcated entrainment to 24 h LD cycles, Siberian hamsters show increased melatonin secretion within approximately 2 h after activity onset, whereas in Syrian hamsters, detectable melatonin secretion phase lags activity onset and the L/D transition by at least 4 h. The present results provide new evidence indicating multi-oscillator regulation of the waveform of melatonin secretion, specifically, the circadian control of the onset, offset and duration of nocturnal secretion. |
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Department of Psychology, and Center for Chronobiology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0109, USA. eraiewski@ucsd.edu |
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0742-0528 |
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PMID:23003567 |
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IDA @ john @ |
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85 |
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Author |
Rotics, S.; Dayan, T.; Kronfeld-Schor, N. |
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Title |
Effect of artificial night lighting on temporally partitioned spiny mice |
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Journal Article |
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Year |
2011 |
Publication |
Journal of Mammalogy |
Abbreviated Journal |
Journal of Mammalogy |
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92 |
Issue |
1 |
Pages |
159-168 |
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mice; animals; mammals; Acomys cahirinus; Acomys russatus; activity patterns; light night niche; light pollution |
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We studied the effect of ecological light pollution on a rocky desert community, focusing on 2 spiny mouse congeners, nocturnal Acomys cahirinus (common spiny mouse) and diurnal Acomys russatus (golden spiny mouse). We hypothesized that in response to artificial illumination A. cahirinus will decrease its activity and A. russatus will increase its activity, and thus temporal overlap and interspecific competition could increase. Our study took place in 4 field enclosures: the 1st and 3rd months were controls with natural light, and in the 2nd month artificial illumination, simulating low levels of light pollution, was set for the first 3 h of the night. We implanted temperature-sensitive radiotransmitters to monitor mouse activity, and individual identification tags with automonitored foraging patches were used to track foraging behavior. A. cahirinus decreased activity and foraging with artificial lighting, restricting movement particularly in less-sheltered microhabitats, probably because of increased predation risk. Because illumination restricted both activity time and space, intraspecific encounters of A. cahirinus over foraging patches increased during and following the illuminated hours. However, diurnal A. russatus did not expand its activity into the illuminated hours, possibly due to the presence of competing A. cahirinus, or to nonfavorable environmental conditions. Therefore, overt interspecific competition was not affected by experimental light pollution. Light pollution had a negative influence by reducing overall activity and producing a relatively underexploited temporal niche, which may promote invasion of alien species that are less light sensitive; and by increasing intraspecific overlap in foraging A. cahirinus. |
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0022-2372 |
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IDA @ john @ |
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86 |
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