919 research outputs found

    Life-History Variation in the Sagebrush Lizard (Sceloporus graciosus): Phenotypic Plasticity or Local Adaptation?

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    We performed a laboratory common-environment study to determine the genetic and environmental sources of variation in growth rates of the sagebrush lizard (Sceloporus graciosus). Hatchling lizards were reared from gravid females collected from three study populations along an elevational gradient in southern Utah, USA. Hatchlings were fed ad libidum and were maintained on a 14:10 light:dark cycle, with temperatures at 33°C and 21°C during photophase and scotophase, respectively. Each hatchling was randomly assigned to either a water-supplementation treatment or a control group receiving no supplemental water. Once every five days, the water-supplemented lizards were administered orally a quantity of water equal to 5% of their body mass. Growth was quantified as the total change in body size (length and mass) for 30 d after hatching. Resting metabolic rates of a subset of lizards were measured at hatching and at the end of the study. After adjusting growth for food intake, change in length did not differ between water-supplemented and control lizards, and did not differ among the three populations. Metabolic rates were similar across the study for all treatment groups. Water-supplemented lizards did gain wet mass more rapidly than control lizards; however, the difference in growth between groups was attributed to hydration state, because growth in dry mass did not differ between groups. The effects of water supplementation on growth that were observed by other investigators were likely manifested through changes in thermoregulatory behavior or increased activity

    Torturing terrorists for national security imperatives: Mediated violence on 24

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    This study analyzed mediated violent content as seen on the FOX television program 24. The study covered a seven year period, or six seasons, of 24 , with a sample set of 43 episodes and 445 individual acts ofviolence. Three research questions guided this study. The first research question sought to determine if a relation exists between heroic characters inflicting torturous violence and justifying the act with a national security imperative. The second research question examined the prevailing mode of violence and the use of nonlethal and lethal weapons. The third research question examined the portrayed efficiency of violence on24. Findings suggest that while torture is rarely the intent and rarely justified with a national security imperative, 24 is nonetheless very violent, generally portraying violence as physical, involving the use of lethal weapons, intentionally gratuitous, and most often efficient

    An investigation of data compression techniques for hyperspectral core imager data

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    We investigate algorithms for tractable analysis of real hyperspectral image data from core samples provided by AngloGold Ashanti. In particular, we investigate feature extraction, non-linear dimension reduction using diffusion maps and wavelet approximation methods on our data

    Moistened Seeds Increase Rodent Trap Success

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    Seed moisture has been shown to influence the rates of seed cache removal by rodents. Although the precise mechanism is not known, this knowledge might prove useful in field applications. We examined whether moistened bait would increase trap success in desert rodent populations. We placed traps 15 m apart in grids within a 500-ha study area and randomly baited traps with either dry or moistened seeds. We found that traps baited with moistened seeds had 34.9% higher success than traps baited with dry seeds (n = 190, Χ2 = 5.389, df = 1, P = 0.020). Our results suggest that application of water to dry seed bait can lead to increased trap success for desert rodents

    Can lizard embryos survive climate warming? Thermal constraints on the physiology of developing Eastern fence lizards

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    Sublethal stressors will likely mediate an organism’s response to climate change. Mobile animals can change their behavior to maintain temperatures within preferred ranges. However, animals in immobile life stages are particularly vulnerable to warming. For example, lizard embryos experience recurrent thermal stress as they develop in shallow nests with daily temperature fluctuations. Nesting temperatures above 41.5°C can be lethal to Eastern fence lizard (Sceloporus undulatus) embryos. Although that is beyond the range experienced at current nest sites, rapid warming will push nest conditions toward critical limits. Therefore, it is important to examine the effects of sublethal high nest temperatures on developing lizards. We reared S. undulatus embryos under three thermal regimes—one to simulate contemporary nest conditions with a maximum daily temperature (Tmax) of 32.1°C, and two regimes to simulate warming scenarios in which the Tmax was raised to 35.6°C and 39.1°C. We tracked changes in physiology and survival through embryonic development, and we measured growth and metabolic rates of surviving hatchlings. Results showed reduced embryo survival and decreased hatchling growth for lizards reared under sublethal warming, suggesting that thermal constraints on the physiology of developing Eastern fence lizards may limit the persistence of the species under climate warming

    Spatial Dynamics of Nesting Behavior: Lizards Shift Microhabitats to Construct Nests with Beneficial Thermal Properties

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    Because temperature affects the growth, development, and survival of embryos,oviparous mothers should discriminate carefully among available nesting sites. We combined a radiotelemetric study of animal movements with a spatial mapping of environmental temperatures to test predictions about the nesting behavior of the eastern fence lizard (Sceloporus undulatus). Females made large excursions from their typical home ranges to construct nests in exposed substrates. These excursions appeared to be related solely to nesting because all females returned to forested habitat immediately afterward. On average, 1% (range ¼ 0–8%, n ¼ 19) of the area used by a female during nesting was contained within the area used before and after nesting. The selection of nesting sites matched predictions based on laboratory studies of embryonic performance; specifically, females nested in extremely open habitat at a mean of 6 cm depth. Spatial mapping of soil temperatures revealed that temperatures of nesting areas exceeded those of areas typically used by females, indicating that females preferred to construct warm nests that speed embryonic growth and development. However, this behavior could reduce the survivorship of females because of the need to rapidly navigate unfamiliar and exposed terrain

    Recurrent sublethal warming reduces embryonic survival, inhibits juvenile growth, and alters species distribution projections under climate change

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    The capacity to tolerate climate change often varies across ontogeny in organisms with complex life cycles. Recently developed species distribution models incorporate traits across life stages; however, these life-cycle models primarily evaluate effects of lethal change. Here, we examine impacts of recurrent sublethal warming on development and survival in ecological projections of climate change. We reared lizard embryos in the laboratory under temperature cycles that simulated contemporary conditions and warming scenarios. We also artificially warmed natural nests to mimic laboratory treatments. In both cases, recurrent sublethal warming decreased embryonic survival and hatchling sizes. Incorporating survivorship results into a mechanistic species distribution model reduced annual survival by up to 24% compared to models that did not incorporate sublethal warming. Contrary to models without sublethal effects, our model suggests that modest increases in developmental temperatures influence species ranges due to effects on survivorship

    Digital Security & Grantcraft Guide : an Introduction Guide for Funders

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    Digital security breaches can cause harm to grantees, as well as their clients, beneficiaries, and partner organizations. These threats also pose a risk to grantmakers and to the larger strategies of impacted organizations. Security leaks can compromise an organization's ability to carry out its work, and can erode trust between civil society actors.This guide is to help grant­makers both assess and address digital security concerns. It explores the types of digital threats against civil society and the obstacles to addressing them. It explains how to conduct a digital security "triage" of grants to elevate the digital security of your whole grant portfolio; while playing special attention to the highest risk grantees. And it provides suggestions for pathways to think more systematically about digital security
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