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The shell of the oldest true turtle (Testudinata) branch (Proterochersidae) from the Late Triassic (Norian) of Poland and Germany was built in its anterior and posterior part from an osteodermal mosaic which developed several million years after the plastron, neurals, and costal bones. The most detailed description of the shell composition in proterochersids thus far is provided together with a review of the shell composition in other Triassic pantestudinates, the scenario of early evolution of the turtle shell is proposed based on new data, and the possible adaptive meaning of the observed evolutionary changes is discussed. These observations are consistent with the trend of shell simplification previously reported in turtles. Several aspects of proterochersid shell anatomy are intermediate between O. semitestacea and more derived turtles, supporting their stem phylogenetic position. Three additional ossifications were sutured to xiphiplastra and pelvis in Proterochersis spp. and at least in some individuals the nuchal bone was paired. The peripherals, suprapygals, and pygal bone are most likely of osteodermal origin and homologous to the proterochersid shell mosaic.
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Lack of sleep incurs physiological costs that include increased inflammation and alterations in the hypothalamic-pituitary-adrenal (HPA) axis. Specifically, sleep restriction or deprivation leads to increased pro-inflammatory cytokine expression and elevated glucocorticoids in rodent models, but whether birds exact similar costs is unknown. In this study, we examined whether zebra finch (Taeniopygia guttata), an avian model species, exhibits physiological costs of sleep loss using a novel automated sleep fragmentation/deprivation method; a horizontal wire sweeps across a test cage to disrupt sleep every 120 s. We measured pro-inflammatory (IL-1β and IL-6) and anti-inflammatory (IL-10) cytokine gene expression in the periphery (fat, liver, spleen, and heart) and brain (hypothalamus, hippocampus, and apical hyperpallium) of captive finches after 12 h of exposure to a moving or stationary (control) bar during the night or the day. Plasma corticosterone, body mass, and behavioral profiles were also assessed. We predicted that birds undergoing sleep loss would exhibit elevated pro-inflammatory and reduced anti-inflammatory gene expression in brain and peripheral tissues compared with control birds. In addition, we predicted an increase in plasma corticosterone levels after sleep loss. As predicted, sleep loss increased pro-inflammatory gene expression, specifically in adipose tissue (IL-6), spleen (IL-1), and hippocampus (IL-6), but a decrease in anti-inflammatory expression (IL-10) was not detected. However, sleep loss elevated baseline concentrations of plasma corticosterone. Taken together, these results suggest that a diurnal, non-migratory songbird is sensitive to the costs of sleep loss.
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Large-scale cooperation is a hallmark of our species and appears to be unique among primates. Yet the evolutionary mechanisms that drove the emergence of humanlike patterns of cooperation remain unclear. Studying the cognitive processes underlying cooperative behavior in apes, our closest living relatives, can help identify these mechanisms. Accordingly, we employed a novel test battery to assess the willingness of 40 chimpanzees to donate resources, instrumentally help others, and punish a culpable thief. We found that chimpanzees were faster to make prosocial than selfish choices and that more prosocial individuals made the fastest responses. Further, two measures of self-control did not predict variation in prosocial responding, and individual performance across cooperative tasks did not covary. These results show that chimpanzees and humans share key cognitive processes for cooperation, despite differences in the scope of their cooperative behaviors.
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1. Fencing is one of the commonest methods for mitigating human-wildlife conflicts. At the same time, fencing is considered to be of one of the most pressing emerging threats to conservation globally. Although fences act as barriers and eventually can cause population isolation and fragmentation, it is challenging to quantitatively predict the possible consequences fences have for wildlife. 2. Here, we model how fencing designed to mitigate human-elephant conflict (HEC) on the Borderlands between Kenya and Tanzania will affect functional connectivity and movement corridors for African elephants. Specifically, we (1) model functional landscape connectivity integrating natural and anthropogenic factors; (2) predict seasonal movement corridors used by elephants in non-protected areas; and (3) evaluate whether fencing in one area can potentially intensify human-wildlife conflicts elsewhere. 3. We used GPS movement and remote sensing data to develop monthly step-selection functions to model functional connectivity. For future scenarios, we used a currently ongoing fencing project designed for human-elephant conflict mitigation within the study area. We modelled movement corridors using least-cost path and circuit theory methods, evaluated their predictive power and quantified connectivity changes resulting from the planned fencing. 4. Our results suggest that fencing will not cause landscape fragmentation and will not change functional landscape connectivity dramatically. However, fencing will lead to a loss of connectivity locally and will increase the potential for HEC in new areas. We estimated that wetlands important for movement corridors will be more intensively used by the elephants, which may also cause problems of overgrazing. Seasonal analysis highlighted an increasing usage of non-protected lands in the dry season and equal importance of the pinch point wetlands for preserving overall function connectivity. 5. Synthesis and applications. Fencing is a solution to small-scale HEC problems, but will not solve the issue at a broader scale. Moreover, our results highlight that it may intensify the conflicts and overuse of habitat patches in other areas, thereby negating any conservation benefits. If fencing is employed on a broader scale, then it is imperative that corridors are integrated within the protected area network to ensure local connectivity of affected species.
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Predator dietary studies often assume that diet is reflective of the diversity and relative abundance of their prey. This interpretation ignores species-specific behavioural adaptations in prey that could influence prey capture. Here, we develop and describe a scalable biologging protocol, using animal-borne camera loggers, to elucidate the factors influencing prey capture by a seabird, the gentoo penguin (Pygoscelis papua). From the video evidence, we show, for the first time, that aggressive behavioural defence mechanisms by prey can deter prey capture by a seabird. Furthermore, we provide evidence demonstrating that these birds, which were observed hunting solitarily, target prey when they are most discernible. Specifically, birds targeted prey primarily while ascending and when prey were not tightly clustered. In conclusion, we show that prey behaviour can significantly influence trophic coupling in marine systems because despite prey being present, it is not always targeted. Thus, these predator-prey relationships should be accounted for in studies using marine top predators as samplers of mid to lower trophic level species.
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Left-right (L-R) asymmetry in the body plan is determined by nodal flow in vertebrate embryos. Shinohara et al. used Dpcd and Rfx3 mutant mouse embryos and showed that only a few cilia were sufficient to achieve L-R asymmetry. However, the mechanism underlying the breaking of symmetry by such weak ciliary flow is unclear. The flow-mediated signals related to L-R asymmetry have not been clarified; there are two models for L-R symmetry breaking: vesicle transport and mechanosensing. In this study, we developed a computational model of the node system reported by Shinohara et al. and examined feasibilities of two hypotheses with a small number of cilia. With the small number of rotating cilia, flow was induced locally and global strong flow was not observed in the node. Particles were then effectively transported only when they were close to the cilia, and particle transport was strongly dependent on the ciliary positions. Although the maximum wall shear rate was also influenced by ciliary position, the mean wall shear rate at the perinodal wall increased monotonically with the number of cilia. We also investigated membrane tension of immotile cilia, which is relevant to the regulation of mechanotransduction. The results indicated that tension of about 0.1 uN/m was exerted at the base even when the fluid shear rate was applied about 0.1 1/s. The area of high tension was also localised at the upstream side, and negative tension appeared at the downstream side. Such localisation may be useful to sense the flow direction at the periphery, as time-averaged anticlockwise circulation was induced in the node by rotation of a few cilia. Our numerical results support the mechanosensing hypothesis, and we expect that our study will stimulate further experimental investigations of mechanotransduction in the near future.
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Life stages of some animals, including amphibians and insects, are so different that they have historically been seen as different species. ‘Metamorphosis’ broadly encompasses major changes in organism bodies and, importantly, concomitant shifts in trophic strategies. Many marine animals have a biphasic lifestyle, with small pelagic larvae undergoing one or more metamorphic transformations before settling into a permanent, adult morphology on the benthos. Post-settlement, the hydrothermal vent gastropod Gigantopelta chessoia experiences a further, cryptic metamorphosis at body sizes around 5-7 mm. The terminal adult stage is entirely dependent on chemoautotrophic symbionts; smaller individuals do not house symbionts, and presumably depend on grazing. Using high resolution x-ray microtomography to reconstruct the internal organs in a growth series, we show this sudden transition in small but sexually mature individuals dramatically reconfigures the organs, but is in no way apparent from external morphology. We introduce the term ‘cryptometamorphosis’ to identify this novel phenomenon of a major body change and trophic shift, not related to sexual maturity, transforming only the internal anatomy. Understanding energy flow in ecosystems depends on the feeding ecology of species; the present study highlights the possibility for adult animals to make profound shifts in biology that influence energy dynamics.
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Among over 30,000 species of ray-finned fishes, seahorses and pipefishes have a unique feeding mechanism whereby the elastic recoil of tendons allows them to rotate their long snouts extremely rapidly in order to capture small elusive prey. To understand the evolutionary origins of this feeding mechanism, its phylogenetic distribution among closely related lineages must be assessed. We present evidence for elastic recoil powered feeding in the snipefish (Macroramphosus scolopax) from kinematics, dynamics, and morphology. High-speed videos of strikes show they achieve extremely fast head and hyoid rotational velocities, resulting in rapid prey capture in as short at 2 ms. The maximum instantaneous muscle-mass-specific power requirement for head rotation in snipefish was above the known vertebrate maximum, which is evidence that strikes are not the result of direct muscle power. Finally, we show that the over-center conformation of the four-bar linkage mechanism coupling head elevation to hyoid rotation in snipefish can function as a torque reversal latch, preventing the head from rotating and providing the opportunity for elastic energy storage. The presence of elastic recoil feeding in snipefish means that this high-performance mechanism is not restricted to the Syngnathidae (seahorses and pipefish) and may have evolved in parallel.
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In numerous social species, males direct aggression towards female group members during intergroup fights, and this behaviour is commonly thought to function as mate guarding, even though males often target non-receptive females. In studying intergroup fights in a wild population of vervet monkeys, we found that male intragroup aggression was primarily directed towards individuals who had either just finished exhibiting, or were currently attempting to instigate intergroup aggression. Targeted females were less likely to instigate intergroup aggression in the future, indicating that male intragroup aggression functioned as coercion (when directed towards those who were currently trying to instigate a fight) and punishment (when directed towards those who had recently fought). These manipulative tactics effectively prevented intergroup encounters from escalating into fights and often de-escalated ongoing conflicts. Males who were likely sires were those most likely to use punishment/coercion, particularly when they were wounded, and therefore less able to protect vulnerable offspring should a risky intergroup fight erupt. This work, along with our previous finding that females use punishment and rewards to recruit males into participating in intergroup fights, highlights the inherent conflict of interest that exists between the sexes, as well as the role that social incentives can play in resolving this conflict. Furthermore, unlike other studies which have found punishment to be used asymmetrically between partners, these works represent a novel example of reciprocal punishment in a non-human animal.
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The pesticides paraquat (PQ) and maneb (MB) have been described as environmental risk factors for Parkinson’s disease (PD), with mechanisms associated with mitochondrial dysfunction and reactive oxygen species generation. A combined exposure of PQ and MB in murine models and neuroblastoma cells has been utilized to further advance understanding of the PD phenotype. MB acts as a redox modulator through alkylation of protein thiols and has been previously characterized to inhibit complex III of the electron transport chain and uncouple the mitochondrial proton gradient. The purpose of this study was to analyze ATP-linked respiration and glycolysis in human neuroblastoma cells utilizing the Seahorse extracellular flux platform. Employing an acute, subtoxic exposure of MB, this investigation revealed a MB-mediated decrease in mitochondrial oxygen consumption at baseline and maximal respiration, with inhibition of ATP synthesis and coupling efficiency. Additionally, MB-treated cells showed an increase in nonmitochondrial respiration and proton leak. Further investigation into mitochondrial fuel flex revealed an elimination of fuel flexibility across all 3 major substrates, with a decrease in pyruvate capacity as well as glutamine dependency. Analyses of glycolytic function showed a substantial decrease in glycolytic acidification caused by lactic acid export. This inhibition of glycolytic parameters was also observed after titrating the MB dose as low as 6 μM, and appears to be dependent on the dithiocarbamate functional group, with manganese possibly potentiating the effect. Further studies into cellular ATP and NAD levels revealed a drastic decrease in cells treated with MB. In summary, MB significantly impacted both aerobic and anaerobic energy production; therefore, further characterization of MB’s effect on cellular energetics may provide insight into the specificity of PD to dopaminergic neurons.
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