Bright artificial light at night is associated with increased body mass,poor reproductive success and compromised disease tolerance in Australian budgerigars (Melopsittacus undulatus)

Artificial light at night (ALAN) can cause circadian disruption and result in adverse behavioral and ecological effects in free‐living birds, but studies on captive pet birds as companion animals have been infrequent. We studied the effects of exposure to bright ALAN on body mass, melatonin sulfate levels, reproduction and disease severity in Australian budgerigars (Melopsittacus undulatus) kept in captivity. During the experiment, birds were kept under outdoor temperature, humidity and natural photoperiod from September to December. A total of 48 birds were equally split into 4 groups (6 mating pairs each) and concurrently exposed to ALAN of 200 lux with different duration (0, 30, 60 and 90 min). Monthly observations were recorded for all dependent parameters. ALAN exposure increased mass gain and suppressed melatonin levels in a dose‐dependent manner, especially during December. In addition, ALAN exposure in all duration groups decreased egg production and reduced hatchability from 61% ± 14% in the ALAN‐unexposed control group to 0% in the ALAN‐exposed birds. Disease severity was also found to increase in line with the duration of ALAN exposure. In captive M. undulatus, ALAN exposure was demonstrated to affect photoperiodic regulation with subsequent excess mass gain and reproduction impairment, and increased susceptibility to infections plausibly through duration dose‐dependent suppression of melatonin. To the best of our knowledge, this is the first study to demonstrate a possible association between acute bright ALAN of increasing duration and both natural development of infections as well as reproductive cessation in captive birds. Our findings could be used to improve breeding conditions of captive birds.     

Sulfate burial constraints on the Phanerozoic sulfur cycle

The sulfur cycle influences the respiration of sedimentary organic matter, the oxidation state of the atmosphere and oceans, and the composition of seawater. However, the factors governing the major sulfur fluxes between seawater and sedimentary reservoirs remain incompletely understood. Using macrostratigraphic data, we quantified sulfate evaporite burial fluxes through Phanerozoic time. Approximately half of the modern riverine sulfate flux comes from weathering of recently deposited evaporites. Rates of sulfate burial are unsteady and linked to changes in the area of marine environments suitable for evaporite formation and preservation. By contrast, rates of pyrite burial and weathering are higher, less variable, and largely balanced, highlighting a greater role of the sulfur cycle in regulating atmospheric oxygen.     

A sulfur dioxide climate feedback on early Mars

Ancient Mars had liquid water on its surface and a CO2-rich atmosphere. Despite the implication that massive carbonate deposits should have formed, these have not been detected. On the basis of fundamental chemical and physical principles, we propose that climatic conditions enabling the existence of liquid water were maintained by appreciable atmospheric concentrations of volcanically degassed SO2 and H2S. The geochemistry resulting from equilibration of this atmosphere with the hydrological cycle is shown to inhibit the formation of carbonates. We propose an early martian climate feedback involving SO2, much like that maintained by CO2 on Earth.     

Recently formed polyploid plants diversify at lower rates

Polyploidy, the doubling of genomic content, is a widespread feature, especially among plants, yet its macroevolutionary impacts are contentious. Traditionally, polyploidy has been considered an evolutionary dead end, whereas recent genomic studies suggest that polyploidy has been a key driver of macroevolutionary success. We examined the consequences of polyploidy on the time scale of genera across a diverse set of vascular plants, encompassing hundreds of inferred polyploidization events. Likelihood-based analyses indicate that polyploids generally exhibit lower speciation rates and higher extinction rates than diploids, providing the first quantitative corroboration of the dead-end hypothesis. The increased speciation rates of diploids can, in part, be ascribed to their capacity to speciate via polyploidy. Only particularly fit lineages of polyploids may persist to enjoy longer-term evolutionary success.     

Relationships between muscle growth potential,intramuscular fat content and different indicators of muscle fibre types in young Charolais bulls

Genetic selection in favor of muscle growth at the expense of fat should affect characteristics of muscles, and therefore beef quality. This study was conducted with two extreme groups of six animals selected among 64 Charolais young bulls ranked according to their genetic potential for muscle growth. Muscle characteristics were assessed in Rectus abdominis (RA, slow oxidative) and Semitendinosus (ST, fast glycolytic) muscles. Intramuscular fat content and proportions of myosin heavy chains I (slow) and IIA (fast oxido‐glycolytic) and certain indicators of oxidative metabolism (activities of citrate synthase (CS), isocitrate dehydrogenase and cytochrome‐c oxidase (COX); expression of H‐fatty acid binding protein (FABP)) were higher in RA than in ST muscle. Genetic selection for muscle growth reduced intramuscular fat content and the activities of some oxidative metabolism indicators (namely CS, COX only). The positive correlation between muscle triacylglycerol content and A‐FABP messenger RNA level (a marker of adipocyte differentiation) (r = 0.53, P < 0.05) suggests that A‐FABP may be a good marker of the ability of bovines to deposit intramuscular fat. In conclusion, the metabolic muscle characteristics which respond to the selection process in favor of muscle growth clearly differ from the muscle characteristics which allow muscle types to be differentiated.