Metabolic cold adaptation (MCA), the hypothesis that species from cold climates have relatively higher metabolic rates than those from warm climates, was first proposed nearly 100 years ago and ...remains one of the most controversial hypotheses in physiological ecology. In the present study, we test the MCA hypothesis in fishes at the level of whole animal, mitochondria and enzyme. In support of the MCA hypothesis, we find that when normalized to a common temperature, species with ranges that extend to high latitude (cooler climates) have high aerobic enzyme (citrate synthase) activity, high rates of mitochondrial respiration and high standard metabolic rates. Metabolic compensation for the global temperature gradient is not complete however, so when measured at their habitat temperature species from high latitude have lower absolute rates of metabolism than species from low latitudes. Evolutionary adaptation and thermal plasticity are therefore insufficient to completely overcome the acute thermodynamic effects of temperature, at least in fishes.
We report on the search for dark matter weakly interacting massive particles (WIMPs) in the mass range below 10 GeV=c2 from the analysis of the entire dataset acquired with a low-radioactivity argon ...target by the DarkSide-50 experiment at Laboratori Nazionali del Gran Sasso. The new analysis benefits from more accurate calibration of the detector response, improved background model, and better determination of systematic uncertainties, allowing us to accurately model the background rate and spectra down to 0.06 keVer. A 90% C.L. exclusion limit for the spin-independent cross section of 3 GeV=c2 mass WIMP on nucleons is set at 6 × 10-43 cm2, about a factor 10 better than the previous DarkSide-50 limit. This analysis extends the exclusion region for spin-independent dark matter interactions below the current experimental constraints in the 1.2, 3.6 GeV=c2 WIMP mass range.
Burrowing is an important form of locomotion in reptiles, but no study has examined the energetic cost of burrowing for reptiles. This is significant because burrowing is the most energetically ...expensive mode of locomotion undertaken by animals and many burrowing species therefore show specialisations for their subterranean lifestyle. We examined the effect of temperature and substrate characteristics (coarse sand or fine sand) on the net energetic cost of burrowing (NCOB) and burrowing rate in two species of the Egernia group of skinks (Liopholis striata and Liopholis inornata) compared with other burrowing animals. We further tested for morphological specialisations among burrowing species by comparing the relationship between body shape and retreat preference in Egernia group skinks. For L. striata and L. inornata, NCOB is 350 times more expensive than the predicted cost of pedestrian terrestrial locomotion. Temperature had a positive effect on burrowing rate for both species, and a negative effect on NCOB for L. striata but not L. inornata. Both NCOB and burrowing rate were independent of substrate type. Burrows constructed by skinks had a smaller cross-sectional area than those constructed by mammals of comparable mass, and NCOB of skinks was lower than that of mammals of similar mass. After accounting for body size, retreat preference was significantly correlated with body shape in Egernia group skinks. Species of Egernia group skinks that use burrows for retreats have narrower bodies and shorter front limbs than other species. We conclude that the morphological specialisations of burrowing skinks allow them to construct relatively narrow burrows, thereby reducing NCOB and the total cost of constructing their burrow retreats.
Carbohydrates, proteins and lipids are essential nutrients to all animals; however, closely related species, populations, and individuals can display dramatic variation in diet. Here we explore the ...variation in macronutrient tolerance in Drosophila melanogaster using the Drosophila genetic reference panel, a collection of ~200 strains derived from a single natural population. Our study demonstrates that D. melanogaster, often considered a "dietary generalist", displays marked genetic variation in survival on different diets, notably on high-sugar diet. Our genetic analysis and functional validation identify several regulators of macronutrient tolerance, including CG10960/GLUT8, Pkn and Eip75B. We also demonstrate a role for the JNK pathway in sugar tolerance and de novo lipogenesis. Finally, we report a role for tailless, a conserved orphan nuclear hormone receptor, in regulating sugar metabolism via insulin-like peptide secretion and sugar-responsive CCHamide-2 expression. Our study provides support for the use of nutrigenomics in the development of personalized nutrition.
Organisms use energy to grow and reproduce, so the processes of energy metabolism and biological production should be tightly bound. On the basis of this tenet, we developed and tested a new theory ...that predicts the relationships among three fundamental aspects of life: metabolic rate, growth, and reproduction. We show that the optimization of these processes yields the observed allometries of metazoan life, particularly metabolic scaling. We conclude that metabolism, growth, and reproduction are inextricably linked; that together they determine fitness; and, in contrast to longstanding dogma, that no single component drives another. Our model predicts that anthropogenic change will cause animals to evolve decreased scaling exponents of metabolism, increased growth rates, and reduced lifetime reproductive outputs, with worrying consequences for the replenishment of future populations.
When we think of green building, we tend to picture new construction. But Robert A. Young argues that the greenest building is often the one that has already been built. In Stewardship of the Built ...Environment, he shows howrehabilitating and reusing existing structures holds untapped potential for achieving sustainable communities. Students and professionals alike will discover the multifaceted benefits of reuse.Young begins by describing how historic preservation in the United States, often overlooked because of the predominant focus on new construction, is actually an important sustainable design strategy. He then examines thesocial, environmental, and economic benefits of preservation—from the societal value of reusing existing buildings to financial incentives available for rehabilitation. Young concludes with insights into the future of reusing buildings as a sustainability strategy.He also provides several informative appendices, including a glossary of key terms and acronyms and recommendations for further reading.Readers will become familiar with essential terminology; sustainability and historic preservation metrics; government oversight processes; and opportunities for smart growth afforded by rehabilitation. This knowledge is key to preserving the past while building a sustainable future.
The NuTeV Collaboration has extracted the electroweak parameter sin(2)theta(W) from the measurement of the ratios of neutral current to charged current nu and (-)nu cross sections. Our value, ...sin(2)theta((on-shell))(W) = 0.2277 +/- 0.0013(stat) +/- 0.0009(syst), is 3 standard deviations above the standard model prediction. We also present a model independent analysis of the same data in terms of neutral-current quark couplings.
Aim
Physiological responses to climate can be used to quantify the environmental limits that a species can tolerate and are, therefore, key to biogeographical studies. Several ecophysiological ...responses to climatic factors may shape the distribution of species, but our knowledge is mostly centred in thermal ecophysiology. We applied an integrative approach to investigate how ecophysiological responses of a small ectotherm are modulated by climatic variation across an elevational gradient.
Location
Victoria, Australia.
Taxon
Lampropholis guichenoti (Scincidae, Squamata).
Methods
We examined metabolic rate, evaporative water loss, thermal physiology and locomotor performance, of four populations of the skink Lampropholis guichenoti across an elevational gradient in Australia (17–1546 m). We applied biophysical modelling to test how behaviour impacts the survival and activity of these skinks.
Results
Populations from the lowlands had lower metabolic rates and evaporative water loss, lower thermal preferences, higher optimal temperatures and increased locomotor performance compared populations from high elevations. Biophysical models revealed that behaviour allows skinks from high elevation to maintain their body temperatures above freezing and is key to determining activity patterns.
Main conclusions
Our holistic study shows that a combination of physiological and behavioural responses allows ectotherms to survive in different climatic environments. The interplay between physiology and behaviour can help to explain how climate sets limits for the geographical range of ectotherms.
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