Unpredictable environments lead to the evolution of parental neglect in birds

A nest of begging chicks invites an intuitive explanation: needy chicks want to be fed and parents want to feed them. Surprisingly, however, in a quarter of species studied, parents ignore begging chicks. Furthermore, parents in some species even neglect smaller chicks that beg more, and preferentially feed the biggest chicks that beg less. This extreme variation across species, which contradicts predictions from theory, represents a major outstanding problem for the study of animal signalling. We analyse parent–offspring communication across 143 bird species, and show that this variation correlates with ecological differences. In predictable and good environments, chicks in worse condition beg more, and parents preferentially feed those chicks. In unpredictable and poor environments, parents pay less attention to begging, and instead rely on size cues or structural signals of quality. Overall, these results show how ecological variation can lead to different signalling systems being evolutionarily stable in different species

The effect of atmospheric acid processing on the global deposition of bioavailable phosphorus from dust

The role of dust as a source of bioavailable phosphorus (Bio-P) is quantified using a new parameterization for apatite dissolution in combination with global soil data maps and a global aerosol transport model. Mineral dust provides 31.2 Gg-P yr-1 of Bio-P to the oceans, with 14.3 Gg-P yr-1 from labile P present in the dust, and an aditional 16.9 Gg-P yr from acid dissolution of apatite in the atmosphere, representing an increase of 120%. The North Atlantic, north west Pacific, and Mediterranean Sea are identified as important sites of Bio-P deposition from mineral dust. The acid dissolution process increases the fraction of total-P that is bioavailable from ~10% globally from the labile pool to 23% in the Atlantic Ocean, 45% in the Pacific Ocean, and 21% in the Indian Ocean, with an ocean global mean value of 22%. Strong seasonal variations, especially in the North Pacific, northwest Atlantic, and Indian Ocean, are driven by large-scale meteorology and pollution sources from industrial and biomass-burning regions. Globally constant values of total-P content and bioavailable fraction used previously do not capture the simulated variability. We find particular sensitivity to the representation of particle-to-particle variability of apatite, which supplies Bio-P through acid-dissolution, and calcium carbonate, which helps to buffer the dissolution process. A modest 10% external mixing results in an increase of Bio-P deposition by 18%. The total Bio-P calculated here (31.2 Gg-P yr-1) represents a minimum compared to previous estimates due to the relatively low total-P in the global soil map used

Pathogenesis, diagnosis and management of pneumorrhachis

Pneumorrhachis (PR), the presence of intraspinal air, is an exceptional but eminent radiographic finding, accompanied by different aetiologies and possible pathways of air entry into the spinal canal. By reviewing the literature and analysing a personal case of traumatic cervical PR after head injury, we present current data regarding the pathoanatomy, clinical and radiological presentation, diagnosis and differential diagnosis and treatment modalities of patients with PR and associated pathologies to highlight this uncommon phenomenon and outline aetiology-based guidelines for the practical management of PR. Air within the spinal canal can be divided into primary and secondary PR, descriptively classified into extra- or intradural PR and aetiologically subsumed into iatrogenic, traumatic and nontraumatic PR. Intraspinal air is usually found isolated not only in the cervical, thoracic and, less frequently, the lumbosacral regions but can also be located in the entire spinal canal. PR is almost exceptional associated with further air distributions in the body. The pathogenesis and aetiologies of PR are multifold and can be a diagnostic challenge. The diagnostic procedure should include spinal CT, the imaging tool of choice. PR has to be differentiated from free intraspinal gas collections and the coexistence of air and gas within the spinal canal has to be considered differential diagnostically. PR usually represents an asymptomatic epiphenomenon but can also be symptomatic by itself as well as by its underlying pathology. The latter, although often severe, might be concealed and has to be examined carefully to enable adequate patient treatment. The management of PR has to be individualized and frequently requires a multidisciplinary regime

Variation in the bitter-taste receptor gene TAS2R38, and adiposity in a genetically isolated population in Southern Italy.

OBJECTIVE: Variation in the bitter-taste receptor gene, TAS2R38 confers the ability to taste 6-n-propylthiouracil (PROP). The objective of this study was to relate TAS2R38 haplotypes and PROP-tasting phenotypes to adiposity in a genetically isolated population. We hypothesized that the nontaster phenotype would be associated with higher BMI and waist circumference (WC) in females, and that dietary restraint would mediate this relationship. METHODS AND PROCEDURES: Participants were 540 healthy inhabitants of the genetically isolated village of Carlantino in southern Italy who were 15-89 years of age at the time of the study. Haplotype analyses were performed and PROP tasting was assessed using a filter paper method. Height, weight, and WC were measured and restrained eating was assessed using a brief questionnaire. RESULTS: Nontaster females had higher BMI and WC than females who were phenotypic tasters, and this relationship was specific to females with low dietary restraint. Regression analysis showed that BMI declined by 1.7 units across taster groups in females when the model included the PROP by restraint interaction. PROP phenotype was not significantly associated with WC in the regression models. Polymorphisms in TAS2R38 were not associated with BMI or WC in females. Neither TAS2R38 haplotype nor PROP phenotype was strongly related to BMI or WC in males. DISCUSSION: These data support previous findings of a relation between the nontaster phenotype and higher BMI in females that is modified by dietary restraint. Assessment of PROP phenotypes might provide unique information about adiposity that is not captured by haplotype analysis alone