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Large mammals that live in arid and/or desert environments can cope with seasonal and local variations in rainfall, food and climate

The fastest and most manoeuvrable terrestrial animals are found in savannah habitats, where predators chase and capture running prey. Hunt outcome and success rate are critical to survival, so both predator and prey should evolve to be faster and/or more manoeuvrable. Here we compare locomotor characteristics in two pursuit predator-prey pairs, lion-zebra and cheetah-impala, in their natural savannah habitat in Botswana. We show that although cheetahs and impalas were universally more athletic than lions and zebras in terms of speed, acceleration and turning, within each predator-prey pair, the predators had 20% higher muscle fibre power than prey, 37% greater acceleration and 72% greater deceleration capacity than their prey. We simulated hunt dynamics with these data and showed that hunts at lower speeds enable prey to use their maximum manoeuvring capacity and favour prey survival, and that the predator needs to be more athletic than its prey to sustain a viable success rate.

Flying birds often form flocks, with social, navigational and anti-predator implications. Further, flying in a flock can result in aerodynamic benefits, thus reducing power requirements, as demonstrated by a reduction in heart rate and wingbeat frequency in pelicans flying in a V-formation. But how general is an aerodynamic power reduction due to group-flight? V-formation flocks are limited to moderately steady flight in relatively large birds, and may represent a special case. What are the aerodynamic consequences of flying in the more usual 'cluster' flock? Here we use data from innovative back-mounted Global Positioning System (GPS) and 6-degrees-of-freedom inertial sensors to show that pigeons (1) maintain powered, banked turns like aircraft, imposing dorsal accelerations of up to 2g, effectively doubling body weight and quadrupling induced power requirements; (2) increase flap frequency with increases in all conventional aerodynamic power requirements; and (3) increase flap frequency when flying near, particularly behind, other birds. Therefore, unlike V-formation pelicans, pigeons do not gain an aerodynamic advantage from flying in a flock. Indeed, the increased flap frequency, whether due to direct aerodynamic interactions or requirements for increased stability or control, suggests a considerable energetic cost to flight in a tight cluster flock.

Yeasts, which have been a component of the human diet for at least 7,000 years, possess an elaborate cell wall α-mannan. The influence of yeast mannan on the ecology of the human microbiota is unknown. Here we show that yeast α-mannan is a viable food source for the Gram-negative bacterium Bacteroides thetaiotaomicron, a dominant member of the microbiota. Detailed biochemical analysis and targeted gene disruption studies support a model whereby limited cleavage of α-mannan on the surface generates large oligosaccharides that are subsequently depolymerized to mannose by the action of periplasmic enzymes. Co-culturing studies showed that metabolism of yeast mannan by B. thetaiotaomicron presents a ‘selfish’ model for the catabolism of this difficult to breakdown polysaccharide. Genomic comparison with B. thetaiotaomicron in conjunction with cell culture studies show that a cohort of highly successful members of the microbiota has evolved to consume sterically-restricted yeast glycans, an adaptation that may reflect the incorporation of eukaryotic microorganisms into the human diet.

Although the cheetah is recognised as the fastest land animal, little is known about other aspects of its notable athleticism, particularly when hunting in the wild. Here we describe and use a new tracking collar of our own design, containing a combination of Global Positioning System (GPS) and inertial measurement units, to capture the locomotor dynamics and outcome of 367 predominantly hunting runs of five wild cheetahs in Botswana. A remarkable top speed of 25.9 m s−1 (58 m.p.h. or 93 km h−1) was recorded, but most cheetah hunts involved only moderate speeds. We recorded some of the highest measured values for lateral and forward acceleration, deceleration and body-mass-specific power for any terrestrial mammal. To our knowledge, this is the first detailed locomotor information on the hunting dynamics of a large cursorial predator in its natural habitat. A novel tracking collar provides highly precise location, speed and acceleration data from 367 runs by five cheetahs in the wild; although a top speed of 58 m.p.h. was reported, few runs were above 45 m.p.h. with the average run around 31 m.p.h., and hunting success depended on grip, manoeuvrability and muscle power rather than outright speed. The cheetah is widely recognized as the fastest animal on land, with a reported top speed of 29 metres per second. However, few precise measurements have been made and only rarely have speeds faster than racing greyhounds (18 m s−1) been recorded. Now a team from the Royal Veterinary College, UK, working with the Botswana Predator Conservation Trust, has used custom-built tracking collars containing GPS and inertial measurement units to capture the locomotor dynamics of cheetahs hunting in the wild. The top speed observed was 25.9 m s−1 (93 kilometres per hour). Most hunts involved only moderate speeds, their success relying on a combination of power, acceleration and agility.

Nature 517, 165–169 (2015); doi:10.1038/nature13995 In this Article focusing on the selfish metabolism of yeast mannan by Bacteroidetes, we also described a polysaccharide utilization locus (PUL) responsible for the degradation of high mannose mammalian N-glycan (HMNG) but omitted to cite two relevant papers 1,2 , for which we apologise.

THE hydroxyl radical, OH, is the chief oxidizing agent in the atmosphere, and is responsible for removing many natural and anthropogenic trace gases1. At present, OH cannot be measured directly with sufficient accuracy over the spatial and temporal scales needed for global models of atmospheric chemistry2. Consequently, estimates of atmospheric OH abundance rely on a combination of models incorporating OH chemistry and observations of trace gases sensitive to OH. 14CO is an important diagnostic of OH abundance3–6. It is produced in the atmosphere mainly by the immediate oxidation of 14C produced by cosmic radiation, and it is subsequently removed more slowly through oxidation to 14CO2 by hydroxyl radicals7. The mean lifetime of14CO in clean air during summer in the middle and low latitudes is about one month, which makes 14CO a more sensitive indicator of OH than the longer-lived trace gases commonly used. Until now, only a few Northern Hemisphere 14CO determinations have been published3,8. Using accelerator mass spectrometry we present here an extensive set of 14CO data in New Zealand and several new Northern Hemisphere results. We find that Southern Hemisphere14CO concentrations are ∼40% lower than at comparable latitudes in the Northern Hemisphere. Such a large difference is surprising because the dominant sources and sinks are believed to be similar in both hemispheres. Although there are several complicating factors, from our results we suggest that OH abundances may be significantly higher in the Southern Hemisphere than in the Northern Hemisphere, in contrast to predictions using current photochemical models.

Living terrestrial vegetation emits large amounts of methane into the atmosphere. This unexpected finding, if confirmed, will have an impact on both greenhouse-gas accounting and research into sources of methane.

Although methane in the atmosphere is clearly increasing, its sources are still poorly defined. Measurement of carbon isotope ratios allows constraints to be placed on relative source strengths of atmospheric methane because different potential sources have different isotope ratios. Unfortunately, interpreting 13C/12C ratios of atmospheric methane is subject to uncertainty because a correction for isotope fractionation in the oxidation of methane is not well determined. Interpreting 14C/12C ratios is also complicated by the need to correct for release of 14CH4 from nuclear power plants using rough estimates. Simultaneous use of both carbon isotope ratios, however, improves the confidence of interpretation. Here we show that measurements of the 14C/12C ratio, using accelerator mass spectrometry, and 13C/12C ratio of methane from clean Southern Hemisphere air are consistent with current estimates of both types of correction and imply that about 32% of atmospheric methane is derived from fossil carbon sources.

MONOAMINE oxidase (MAO) of sympathetically innervated organs has been classically considered to be involved in the regulation of intraneuronal catecholamine concentrations. This function of MAO implies that the enzyme is located within the presynaptic element of the adrenergic neuroeffector system. Recent studies, however, have indicated that MAO may be located extraneuronally1,2.