Getting to the core: Internal body temperatures help reveal the ecological function and thermal implications of the lions’ mane

It has been proposed that there is a thermal cost of the mane to male lions, potentially leading to increased body surface temperatures (Ts), increased sperm abnormalities, and to lower food intake during hot summer months. To test whether a mane imposes thermal costs on males, we measured core body temperature (Tb) continuously for approximately 1 year in 18 free-living lions. There was no difference in the 24-hr maximum Tb of males (n = 12) and females (n = 6), and males had a 24-hr mean Tb that was 0.2 ± 0.1°C lower than females after correcting for seasonal effects. Although feeding on a particular day increased 24-hr mean and 24-hr maximum Tb, this phenomenon was true of both male and female lions, and females had higher 24-hr mean and 24-hr maximum Tb than males, on both days when lions did not feed, and on days when lions did feed. Twenty-four-hour Tb was not influenced by mane length or color, and 24-hr mean Tb was negatively correlated with mane length. These data contradict the suggestion that there exists a thermal cost to male lions in possessing a long dark mane, but do not preclude the possibility that males compensate for a mane with increased heat loss. The increased insulation caused by a mane does not necessarily have to impair heat loss by males, which in hot environments is primarily through respiratory evaporative cooling, nor does in necessarily lead to increased heat gain, as lions are nocturnal and seek shade during the day. The mane may even act as a heat shield by increasing insulation. However, dominant male lions frequent water points more than twice as often as females, raising the possibility that male lions are increasing water uptake to facilitate increased evaporative cooling. The question of whether male lions with manes compensate for a thermal cost to the mane remains unresolved, but male lions with access to water do not have higher Tb than females or males with smaller manes.NCS201

Getting to the core: Internal body temperatures help reveal the ecological function and thermal implications of the lions’ mane

It has been proposed that there is a thermal cost of the mane to male lions, potentially leading to increased body surface temperatures (Ts), increased sperm abnormalities, and to lower food intake during hot summer months. To test whether a mane imposes thermal costs on males, we measured core body temperature (Tb) continuously for approximately 1 year in 18 free-living lions. There was no difference in the 24-hr maximum Tb of males (n = 12) and females (n = 6), and males had a 24-hr mean Tb that was 0.2 ± 0.1°C lower than females after correcting for seasonal effects. Although feeding on a particular day increased 24-hr mean and 24-hr maximum Tb, this phenomenon was true of both male and female lions, and females had higher 24-hr mean and 24-hr maximum Tb than males, on both days when lions did not feed, and on days when lions did feed. Twenty-four-hour Tb was not influenced by mane length or color, and 24-hr mean Tb was negatively correlated with mane length. These data contradict the suggestion that there exists a thermal cost to male lions in possessing a long dark mane, but do not preclude the possibility that males compensate for a mane with increased heat loss. The increased insulation caused by a mane does not necessarily have to impair heat loss by males, which in hot environments is primarily through respiratory evaporative cooling, nor does in necessarily lead to increased heat gain, as lions are nocturnal and seek shade during the day. The mane may even act as a heat shield by increasing insulation. However, dominant male lions frequent water points more than twice as often as females, raising the possibility that male lions are increasing water uptake to facilitate increased evaporative cooling. The question of whether male lions with manes compensate for a thermal cost to the mane remains unresolved, but male lions with access to water do not have higher Tb than females or males with smaller manes.EM201

Metal‐rich soils increase tropical tree stoichiometric distinctiveness

Background and aims: Ultramafic soils have high metal concentrations, offering a key opportunity to understand if such metals are strong predictors of leaf stoichiometry. This is particularly relevant for tropical forests where large knowledge gaps exist. Methods: On the tropical island of Sulawesi, Indonesia, we sampled forests on sand, limestone, mafic and ultramafic soils that present a range of soil metal concentrations. We asked how variation in 12 soil elements (metals and macronutrients) influenced leaf stoichiometry and whether stoichiometric distinctiveness (the average difference between a species and all others in a multivariate space, the axes of which are the concentrations of each leaf element) is influenced by increasing soil metal concentrations. Results: Positive correlations between corresponding elements in soils and leaves were only found for Ca and P. Noticeably, soil Cr had a negative effect upon leaf P. Whilst most species had low stoichiometric distinctiveness, some species had greater distinctiveness on stressful metal-rich ultramafic soils, generally caused by the accumulation of Al, Co, Cr or Ni. Conclusions: Our observation of increased stoichiometric distinctiveness in tropical forests on ultramafic soils indicates greater niche differentiation, and contrasts with the assumption that stressful environments remove species with extreme phenotypes

High temperature tolerance in chickpea and its implications for plant improvement

Abstract. Chickpea (Cicer arietinum L.) is an important food legume and heat stress affects chickpea ontogeny over a range of environments. Generally, chickpea adapts to high temperatures through an escape mechanism. However, heat stress during reproductive development can cause significant yield loss. The most important effects on the reproductive phase that affect pod set, seed set and yield are: (1) flowering time, (2) asynchrony of male and female floral organ development, and (3) impairment of male and female floral organs. While this review emphasises the importance of high temperatures >308C, the temperature range of 32-358C during flowering also produces distinct effects on grain yield. Recent field screening at ICRISAT have identified several heat-tolerant germplasm, which can be used in breeding programs for improving heat tolerance in chickpea. Research on the impact of heat stress in chickpea is not extensive. This review describes the status of chickpea production, the effects of high temperature on chickpea, and the opportunities for genetic improvement of chickpea tolerance to high temperatures

Different standards: engineers’ expectations and listener adoption of digital and FM radio broadcasting

As digital radio broadcasting enters its third decade of operation, few would argue that it has met all expectations expressed at the time of its launch in the mid-1990s. Observers are now more circumspect, with views divided on the pace of transition to an all-digital future. In exploring this mismatch between expectation and actuality, this article considers the introduction of FM radio from the 1950s. It too was expected to replace its forebear (AM) but, like digital radio, its adoption by listeners was slower than anticipated. An examination of published literature, in particular engineering and technical documents, reveals a number of similarities in the development of digital radio and FM. Assumptions about listeners’ needs and preferences appear to have been based on little actual audience research and, with continual reference in the literature to the supposed deficiencies of the predecessor technology, suggest an emphasis in decision making on the technical qualities of radio broadcasting over an appreciation of actual audience preferences

Co-limitation towards lower latitudes shapes global forest diversity gradients

The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers

Co-limitation towards lower latitudes shapes global forest diversity gradients

The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers