Understanding foraging is important in ecology, as it determines the energy gains and, ultimately, the fitness of animals. However, monitoring prey captures of individual animals is difficult. Direct ...observations using animal-borne videos have short recording periods, and indirect signals (e.g., stomach temperature) are never validated in the field. We took an integrated approach to monitor prey captures by a predator by deploying a video camera (lasting for 85 min) and two accelerometers (on the head and back, lasting for 50 h) on free-swimming Adélie penguins. The movies showed that penguins moved the heads rapidly to capture krill in midwater and fish (Pagothenia borchgrevinki) underneath the sea ice. Captures were remarkably fast (two krill per second in swarms) and efficient (244 krill or 33 P. borchgrevinki in 78–89 min). Prey captures were detected by the signal of head acceleration relative to body acceleration with high sensitivity and specificity (0.83–0.90), as shown by receiver-operating characteristic analysis. Extension of signal analysis to the entire behavioral records showed that krill captures were spatially and temporally more variable than P. borchgrevinki captures. Notably, the frequency distribution of krill capture rate closely followed a power-law model, indicating that the foraging success of penguins depends on a small number of very successful dives. The three steps illustrated here (i.e., video observations, linking video to behavioral signals, and extension of signal analysis) are unique approaches to understanding the spatial and temporal variability of ecologically important events such as foraging.
Environmental temperature affects physiological functions, representing a barrier for the range expansions of ectothermic species. To understand the link between thermal physiology and biogeography, ...a key question is whether among-species thermal sensitivity of metabolic rates is mechanistically constrained or buffered through physiological remodeling over evolutionary time. The former conception, the Universal Temperature Dependence hypothesis, predicts similar among- and within-species thermal sensitivity. The latter conception, the Metabolic Cold Adaptation hypothesis, predicts lower among-species thermal sensitivity than within-species sensitivity. Previous studies that tested these hypotheses for fishes overwhelmingly investigated teleosts with elasmobranchs understudied. Here, we show that among-species thermal sensitivity of resting metabolic rates is lower than within-species sensitivity in teleosts but not in elasmobranchs. Further, species richness declines with latitude more rapidly in elasmobranchs than in teleosts. Metabolic Cold Adaptation exhibited by teleosts might underpin their high diversity at high latitudes, whereas the inflexible thermal sensitivity approximated by Universal Temperature Dependence of elasmobranchs might explain their low diversity at high latitudes.
Billions of birds migrate to exploit seasonally available resources. The ranges of migration vary greatly among species, but the underlying mechanisms are poorly understood. I hypothesise that flight ...mode (flapping or soaring) and body mass affect migration range through their influence on flight energetics. Here, I compiled the tracks of migratory birds (196 species, weighing 12–10 350 g) recorded by electronic tags in the last few decades. In flapping birds, migration ranges decreased with body mass, as predicted from rapidly increasing flight cost with increasing body mass. The species with higher aspect ratio and lower wing loading had larger migration ranges. In soaring birds, migration ranges were mass‐independent and larger than those of flapping birds, reflecting their low flight costs irrespective of body mass. This study demonstrates that many animal‐tracking studies are now available to explore the general patterns and the underlying mechanisms of animal migration.
Animal daily routines represent a compromise between maximizing foraging success and optimizing physiological performance, while minimizing the risk of predation. For ectothermic predators, ambient ...temperature may also influence daily routines through its effects on physiological performance. Temperatures can fluctuate significantly over the diel cycle and ectotherms may synchronize behaviour to match thermal regimes in order to optimize fitness. We used bio-logging to quantify activity and body temperature of blacktip reef sharks (Carcharhinus melanopterus) at a tropical atoll. Behavioural observations were used to concurrently measure bite rates in herbivorous reef fishes, as an index of activity for potential diurnal prey. Sharks showed early evening peaks in activity, particularly during ebbing high tides, while body temperatures peaked several hours prior to the period of maximal activity. Herbivores also displayed peaks in activity several hours earlier than the peaks in shark activity. Sharks appeared to be least active while their body temperatures were highest and most active while temperatures were cooling, although we hypothesize that due to thermal inertia they were still warmer than their smaller prey during this period. Sharks may be most active during early evening periods as they have a sensory advantage under low light conditions and/or a thermal advantage over cooler prey. Sharks swam into shallow water during daytime low tide periods potentially to warm up and increase rates of digestion before the nocturnal activity period, which may be a strategy to maximize ingestion rates. "Hunt warm, rest warmer" may help explain the early evening activity seen in other ectothermic predators.
Some fishes and sea turtles are distinct from ectotherms by having elevated core body temperatures and metabolic rates. Quantifying the energetics and activity of the regionally endothermic species ...will help us understand how a fundamental biophysical process (i.e. temperature-dependent metabolism) shapes animal ecology; however, such information is limited owing to difficulties in studying these large, highly active animals. White sharks,
, are the largest fish with regional endothermy, and potentially among the most energy-demanding fishes. Here, we deployed multi-sensor loggers on eight white sharks aggregating near colonies of long-nosed fur seals,
, off the Neptune Islands, Australia. Simultaneous measurements of depth, swim speed (a proxy for swimming metabolic rate) and body acceleration (indicating when sharks exhibited energy-efficient gliding behaviour) revealed their fine-scale swimming behaviour and allowed us to estimate their energy expenditure. Sharks repeatedly dived (mean swimming depth, 29 m) and swam at the surface between deep dives (maximum depth, 108 m). Modal swim speeds (0.80-1.35 m s
) were slower than the estimated speeds that minimize cost of transport (1.3-1.9 m s
), a pattern analogous to a 'sit-and-wait' strategy for a perpetually swimming species. All but one shark employed unpowered gliding during descents, rendering deep (>50 m) dives 29% less costly than surface swimming, which may incur additional wave drag. We suggest that these behavioural strategies may help sharks to maximize net energy gains by reducing swimming cost while increasing encounter rates with fast-swimming seals.
The electrical transport property of the reduced graphene oxide (rGO) thin-films synthesized from defective GO through thermal treatment in a reactive ethanol environment at high temperature above ...1000 °C shows a band-like transport with small thermal activation energy (Ea~10 meV) that occurs during high carrier mobility (~210 cm(2)/Vs). Electrical and structural analysis using X-ray absorption fine structure, the valence band photo-electron, Raman spectra and transmission electron microscopy indicate that a high temperature process above 1000 °C in the ethanol environment leads to an extraordinary expansion of the conjugated π-electron system in rGO due to the efficient restoration of the graphitic structure. We reveal that Ea decreases with the increasing density of states near the Fermi level due to the expansion of the conjugated π-electron system in the rGO. This means that Ea corresponds to the energy gap between the top of the valence band and the bottom of the conduction band. The origin of the band-like transport can be explained by the carriers, which are more easily excited into the conduction band due to the decreasing energy gap with the expansion of the conjugated π-electron system in the rGO.
Recent schizophrenia (SCZ) studies have reported an increased burden of de novo copy number variants (CNVs) and identified specific high-risk CNVs, although with variable phenotype expressivity. ...However, the pathogenesis of SCZ has not been fully elucidated. Using array comparative genomic hybridization, we performed a high-resolution genome-wide CNV analysis on a mainly (92%) Japanese population (1699 SCZ cases and 824 controls) and identified 7066 rare CNVs, 70.0% of which were small (<100 kb). Clinically significant CNVs were significantly more frequent in cases than in controls (odds ratio=3.04, P=9.3 × 10
, 9.0% of cases). We confirmed a significant association of X-chromosome aneuploidies with SCZ and identified 11 de novo CNVs (e.g., MBD5 deletion) in cases. In patients with clinically significant CNVs, 41.7% had a history of congenital/developmental phenotypes, and the rate of treatment resistance was significantly higher (odds ratio=2.79, P=0.0036). We found more severe clinical manifestations in patients with two clinically significant CNVs. Gene set analysis replicated previous findings (e.g., synapse, calcium signaling) and identified novel biological pathways including oxidative stress response, genomic integrity, kinase and small GTPase signaling. Furthermore, involvement of multiple SCZ candidate genes and biological pathways in the pathogenesis of SCZ was suggested in established SCZ-associated CNV loci. Our study shows the high genetic heterogeneity of SCZ and its clinical features and raises the possibility that genomic instability is involved in its pathogenesis, which may be related to the increased burden of de novo CNVs and variable expressivity of CNVs.
Recently, the concept of oral frailty, defined as accumulated deficits in oral health, has been introduced in Japan. However, data about its association with nutritional status are limited. Thus, ...this cross-sectional study aimed to investigate the association between oral frailty and malnutrition among community-dwelling older adults.
Cross-sectional study.
Community.
One thousand and fifty-four individuals (428 men and 626 women, mean age: 77.0 years) from the Takashimadaira Study.
Based on a multifaceted oral health assessment, oral frailty was defined as greater than or equal to three of the following components: (1) low number of remaining teeth, (2) decreased masticatory performance, (3) reduced articulatory oral motor skill, (4) low tongue pressure, and difficulties in (5) eating and (6) swallowing. The nutritional status was evaluated using the Mini Nutritional Assessment®-Short Form (MNA®-SF) and serum albumin. An ordinal logistic regression model was used to evaluate the association between oral frailty and nutritional status.
Oral frailty was observed in 217 (20.4%) participants. After adjusting for potential confounders, the participants with oral frailty had higher odds of more severe malnutrition evaluated using MNA®-SF (adjusted odds ratio: 2.17; 95% confidence interval: 1.58-2.98) and serum albumin level (adjusted odds ratio: 1.59; 95% confidence interval: 1.10-2.31).
Oral frailty was associated with nutritional status among Japanese older adults. Maintaining comprehensive oral health and function may be effective for malnutrition prevention in community-dwelling older adults. However, further studies must be conducted to validate the generalizability of the results of the current study.
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