nils-herrmann/clean_scirepeval huggingface dataset:
How the humble insect brain became a powerful experimental model system
Venue: Journal of Comparative Physiology A

In the 21st century, neurobiological studies focused on the insect brain are revealing unprecedented insight into the molecular, cellular, developmental, and circuit aspects of brain organization and function, notably in the genetic model system of Drosophila melanogaster. Underlying this accelerating progress in understanding the insect brain is a century-long history of ground breaking experimental investigation, methodological advance, and conceptual insight catalyzed by the integration of two emerging research fields, neuroscience and genetics. This review traces some of the key early steps in this remarkable historical scientific adventure of exploring the brain of “these apparently humble representatives of life”.
The mechanisms underlying the production of discontinuous gas exchange cycles in insects
Venue: Journal of Comparative Physiology B

This review examines the control of gas exchange in insects, specifically examining what mechanisms could explain the emergence of discontinuous gas exchange cycles (DGCs). DGCs are gas exchange patterns consisting of alternating breath-hold periods and bouts of gas exchange. While all insects are capable of displaying a continuous pattern of gas exchange, this episodic pattern is known to occur within only some groups of insects and then only sporadically or during certain phases of their life cycle. Investigations into DGCs have tended to emphasise the role of chemosensory thresholds in triggering spiracle opening as critical for producing these gas exchange patterns. However, a chemosensory basis for episodic breathing also requires an as-of-yet unidentified hysteresis between internal respiratory stimuli, chemoreceptors, and the spiracles. What has been less appreciated is the role that the insect’s central nervous system (CNS) might play in generating episodic patterns of ventilation. The active ventilation displayed by many insects during DGCs suggests that this pattern could be the product of directed control by the CNS rather than arising passively as a result of self-sustaining oscillations in internal oxygen and carbon dioxide levels. This paper attempts to summarise what is currently known about insect gas exchange regulation, examining the location and control of ventilatory pattern generators in the CNS, the influence of chemoreceptor feedback in the form of O2 and CO2/pH fluctuations in the haemolymph, and the role of state-dependent changes in CNS activity on ventilatory control. This information is placed in the context of what is currently known regarding the production of discontinuous gas exchange patterns.
The sensory substrate of multimodal communication in brown-headed cowbirds: are females sensory ‘specialists’ or ‘generalists’?
Venue: Journal of Comparative Physiology A

Many animals communicate with multimodal signals. While we have an understanding of multimodal signal production, we know relatively less about receiver filtering of multimodal signals and whether filtering capacity in one modality influences filtering in a second modality. Most multimodal signals contain a temporal element, such as change in frequency over time or a dynamic visual display. We examined the relationship in temporal resolution across two modalities to test whether females are (1) sensory ‘specialists’, where a trade-off exists between the sensory modalities, (2) sensory ‘generalists’, where a positive relationship exists between the modalities, or (3) whether no relationship exists between modalities. We used female brown-headed cowbirds (Molothrus ater) to investigate this question as males court females with an audiovisual display. We found a significant positive relationship between female visual and auditory temporal resolution, suggesting that females are sensory ‘generalists’. Females appear to resolve information well across multiple modalities, which may select for males that signal their quality similarly across modalities.
Audiogram of the mallard duck (Anas platyrhynchos) from 16 Hz to 9 kHz
Venue: Journal of Comparative Physiology A

The pure-tone thresholds of three mallard ducks were determined from 16 Hz to 9 kHz. The purpose was to determine whether the mallard duck hears infrasound, which then may potentially be used for navigation, similar to how it is proposed that pigeons use it for homing. At a level of 60 dB sound pressure level (re 20 μN/m2), their hearing range extends 6.85 octaves from 66 Hz to 7.6 kHz, with a best sensitivity of 12.5 dB at 2 kHz. However, at no frequency, including the lowest tested, were the ducks’ thresholds lower than those of humans. Therefore, unlike pigeons and chickens, but like budgerigars, mallard ducks do not hear infrasound. Thus, the fact that a bird may fly long distances does not necessarily indicate that it hears infrasound.
Body temperatures of hibernating little brown bats reveal pronounced behavioural activity during deep torpor and suggest a fever response during white-nose syndrome
Venue: Journal of Comparative Physiology B

Hibernating animals use torpor [reduced body temperature (Tb) and metabolic rate] to reduce energy expenditure during winter. Periodic arousals to normal Tb are energetically expensive, so hibernators trade off arousal benefits against energetic costs. This is especially important for bats with white-nose syndrome (WNS), a fungal disease causing increased arousal frequency. Little brown bats (Myotis lucifugus) with WNS show upregulation of endogenous pyrogens and sickness behaviour. Therefore, we hypothesized that WNS should cause a fever response characterized by elevated Tb. Hibernators could also accrue some benefits of arousals with minimal Tb increase, thus avoiding full arousal costs. We compared skin temperature (Tsk) of captive Myotis lucifugus inoculated with the WNS-causing fungus to Tsk of sham-inoculated controls. Infected bats re-warmed to higher Tsk during arousals which is consistent with a fever response. Torpid Tsk did not differ. During what we term “cold arousals”, bats exhibited movement following Tsk increases of only 2.2 ± 0.3 °C, compared to >20 °C increases during normal arousals. Cold arousals occurred in both infected and control bats, suggesting they are not a pathophysiological consequence of WNS. Fever responses are energetically costly and could exacerbate energy limitation and premature fat depletion for bats with WNS. Cold arousals could represent an energy-saving mechanism for both healthy and WNS-affected bats when complete arousals are unnecessary or too costly. A few cold arousals were observed mid-hibernation, typically in response to disturbances. Cold arousals may, therefore, represent a voluntary restriction of arousal temperature instead of loss of thermoregulatory control.
Embryonic and post-embryonic development inside wolf spiders’ egg sac with special emphasis on the vitellus
Venue: Journal of Comparative Physiology B

The development of Pardosa saltans wolf spiders inside an egg sac includes two periods: an embryonic period and a post-embryonic period after hatching. We investigated spiderlings’ energy expenditure to assess energetic costs during the different embryonic and post-embryonic developmental stages during which they are confined within their egg sac. We focused on the following developmental stages: egg, embryonic stages 1 and 2, and two stages, separated by a moult, during post-embryogenesis inside the egg sac: “juvenile instars 1 and 2” until emergence of 2 instar juveniles from their egg sac. We present the first biochemical characterization of the vitellus of wolf spiders’ eggs, embryos and juveniles. Lipovitellins (LV) are composed of four apolipoproteins of 116, 87, 70 and 42 kDa, respectively, and LV represent 35–45% of total protein during development. The principal LV lipids are triglycerides, phospholipids, free fatty acids and sterols. Egg caloric content averaged 127 cal/g (proteins: 91 cal/g, lipids: 33 cal/g, carbohydrates: 3 cal/g). During development from undivided egg to emerged “juvenile 2”, 67% of proteins, 51% of carbohydrates and 49% of triglycerides stocks were depleted. At the end of the post-embryonic period, at emergence from egg sac, body energy stock of “juveniles 2” was 38% of the initial calorie stocks in the eggs.
Life history written in blood: erythrocyte parameters in a small hibernator, the edible dormouse
Venue: Journal of Comparative Physiology B

The oxygen delivery system is one major determinant of the performance of vertebrates and responds sensitively to a variety of internal and environmental factors. To understand physiological mechanisms underlying variations of fitness, we investigated effects of demanding conditions associated with certain life-history events, food availability, and population density on the oxygen delivery system in free-ranging edible dormice (Glis glis). We sampled blood (n = 248) and urine (n = 319), performed an erythrocyte haemogram and visually determined the presence of haemoglobinuria. Reproduction leads to increased mortality in edible dormice and our study now reveals severe haematological impairments during reproduction that were associated with nutrient and energy deficits and stress. These effects were even more pronounced in subsequent reproductive years, indicating prolonged physiological impairment. Under limited food availability, the rate of erythrocyte generation was reduced. This seems to be part of an energy saving strategy instead of representing a poor body condition as survival probability in this species is high in years of low food availability. A high prevalence ratio of haemoglobinuria (up to 85%) at the end of the active season indicated amplified erythrocyte destruction through haemolysis. This may be the result of a preparative mechanism to avoid massive oxidative damage during the long hibernation period. Most ecophysiological studies so far focus on single erythrocyte parameters on a short time scale, which could be misleading. Our results clearly highlight that a wide-array RBC approach is a powerful tool for investigating mechanisms underlying physiological performance and fitness, also for other vertebrate taxa.
Interspecies differences in plasma concentrations of 25-hydroxyvitamin D3 and dermal Vitamin D synthesis of kiwi (Apteryx mantelli), tuatara (Sphenodon punctatus), and New Zealand sea lions (Phocarctos hookeri)
Venue: Journal of Comparative Physiology B

Vitamin D plays a central role in calcium homeostasis of most vertebrates, and is obtained in different species through diet, dermal synthesis, or a combination of both. The aim of this study was to determine the predominant routes of Vitamin D synthesis in three disparate species, brown kiwi (Apteryx mantelli), tuatara (Sphenodon punctatus), and New Zealand sea lions (Phocarctos hookeri). We surveyed plasma concentrations of 25-hydroxyvitamin D2 and D3, analysed environmental conditions and life history factors, and determined the ability of skin samples to synthesise Vitamin D3 on exposure to ultraviolet-B radiation. There was variation in the plasma/serum 25-hydroxyvitamin D3 concentrations between and within the species studied, with wild kiwi having the lowest concentrations and NZ sea lions the highest. Kiwi skin produced small but measurable amounts of Vitamin D3, while tuatara skin produced Vitamin D3 concentrations higher than that of kiwi. New Zealand sea lion skin produced the highest amount of Vitamin D3 and differed from the other two species in this study in that Vitamin D3 was present in skin before UV-B exposure. The results from this study show that all three species studied retained the ability to use both dietary and dermal sources of Vitamin D, although there was interspecies variation in the magnitude of dermal synthesis. Comparisons between these species show that there are differences in their Vitamin D pathways, but suggest that there are more factors contributing to these pathways than might be expected solely from life history characteristics.
Homing in a tropical social wasp: role of spatial familiarity, motivation and age
Venue: Journal of Comparative Physiology A

We captured foragers of the tropical social wasp Ropalidia marginata from their nests and displaced them at different distances and directions. Wasps displaced within their probable foraging grounds returned to their nests on the day of release although they oriented randomly upon release; however, wasps fed before release returned sooner, displaying nest-ward orientation. When displaced to places far from their nests, thus expected to be unfamiliar, only a third returned on the day of release showing nest-ward orientation; others oriented randomly and either returned on subsequent days or never. When confined within mosquito-net tents since eclosion and later released to places close to their nests (but unfamiliar), even fed wasps oriented randomly, and only older wasps returned, taking longer time. Thus, contrary to insects inhabiting less-featured landscapes, R. marginata foragers appear to have thorough familiarity with their foraging grounds that enables them to orient and home efficiently after passive displacement. Their initial orientation is, however, determined by an interaction of the information acquired from surrounding landscape and their physiological motivation. With age, they develop skills to home from unfamiliar places. Homing behaviour in insects appears to be influenced by evolutionarily conserved mechanisms and the landscape in which they have evolved.
Nonlinear processing of a multicomponent communication signal by combination-sensitive neurons in the anuran inferior colliculus
Venue: Journal of Comparative Physiology A

Diverse animals communicate using multicomponent signals. How a receiver’s central nervous system integrates multiple signal components remains largely unknown. We investigated how female green treefrogs (Hyla cinerea) integrate the multiple spectral components present in male advertisement calls. Typical calls have a bimodal spectrum consisting of formant-like low-frequency (~0.9 kHz) and high-frequency (~2.7 kHz) components that are transduced by different sensory organs in the inner ear. In behavioral experiments, only bimodal calls reliably elicited phonotaxis in no-choice tests, and they were selectively chosen over unimodal calls in two-alternative choice tests. Single neurons in the inferior colliculus of awake, passively listening subjects were classified as combination-insensitive units (27.9%) or combination-sensitive units (72.1%) based on patterns of relative responses to the same bimodal and unimodal calls. Combination-insensitive units responded similarly to the bimodal call and one or both unimodal calls. In contrast, combination-sensitive units exhibited both linear responses (i.e., linear summation) and, more commonly, nonlinear responses (e.g., facilitation, compressive summation, or suppression) to the spectral combination in the bimodal call. These results are consistent with the hypothesis that nonlinearities play potentially critical roles in spectral integration and in the neural processing of multicomponent communication signals.
Characterization of the first-order visual interneurons in the visual system of the bumblebee (Bombus terrestris)
Venue: Journal of Comparative Physiology A

The bumblebee (Bombus terrestris) has become a common model animal in the study of various aspects of vision and visually guided behavior. Although the bumblebee visual system has been studied to some extent, little is known about the functional role of the first visual neuropil, the lamina. In this work, we provide an anatomical and electrophysiological description of the first-order visual interneurons, lamina monopolar cells (LMCs), of the bumblebee. Using intracellular recording coupled with dye injection, we found that bumblebee LMCs morphologically resemble those found in the honeybee, although only the LMC type L1 cells could be morphologically matched directly between the species. LMCs could also be classified on the basis of their light response properties as spiking or non-spiking. We also show that some bumblebee LMCs can produce spikes during responses to stimulation with naturalistic light contrasts, a property unusual for these neurons.
Relative weighting of acoustic information during mating decisions in grasshoppers indicates signatures of sexual selection
Venue: Journal of Comparative Physiology A

The decision with whom to mate is crucial in determining an individual’s fitness and is often based on the evaluation of visual or acoustic displays produced during courtship. Accordingly, the algorithms for evaluating such courtship signals are shaped by sexual selection and should reflect the expected benefits and costs of mating: signals bearing heterospecific features should be rapidly rejected, since mating would produce no fertile offspring, while signals resembling conspecific ones should be weighted proportional to mate quality. We test these hypotheses in females of the grasshopper Chorthippus biguttulus who assess males by their song, which is produced as a sequence of subunits with species and individual specific signatures. We present mixed sequences of subunits with conflicting cues and use a computational model of decision-making to infer how sensory information is weighted and integrated over the song. Consistent with our hypothesis, females do weight sensory cues according to the expected fitness benefits/costs: heterospecific subunits are weighted particularly negatively and lead to a rejection of the male early in the song. Conspecific subunits are weighted moderately, permitting a more complete evaluation of the full song. However, there exists an overall negative bias against mating, possible causes of which are discussed.
Thermal physiology of three sympatric and syntopic Liolaemidae lizards in cold and arid environments of Patagonia (Argentina)
Venue: Journal of Comparative Physiology B

The thermal physiology determines the whole biology of ectotherm organisms, by limiting their acquisition and allocation of resources. Herein, we aim to add knowledge on how different species use the thermal resources when they coexist in a habitat, studying the thermal physiology of three sympatric and syntopic liolaemid lizards, Phymaturus querque, Phymaturus zapalensis, and Liolaemus elongatus during the summer season. We measured the body temperatures at capture places, the operative microenvironmental temperatures in the field, and the preferred body temperature in an experimental thermal gradient in the laboratory. We found that the three species are thermoregulators, selecting cooler thermal microenvironments than the ones expected by chance, and even cooler than the temperatures they selected in a laboratory environment. Liolaemus elongatus is a more efficient thermoregulator (E = 0.671) than the two Phymaturus species, P. querque (E = 0.441) and P. zapalensis (E = 0.471), which are moderate thermoregulators and, apparently, specialists in finding specific types of shelters, since they seem to select certain types of rock crevices. Herein, we found that during the summer season, although individuals have access to warm microenvironments, they spend time on cool refuges, probably to prevent overheating. This highlights the importance of an adequate spatial distribution of operative temperatures (Te), more than just a mere availability of appropriate temperatures.
Variations of cocoon external lipids during wolf spiderlings’ development
Venue: Journal of Comparative Physiology A

This study presents the first characterisation of the silk lipids of the cocoons of a wolf spider (Pardosa saltans). Wolf spiders’ maternal behaviour is complex and involves guarding a cocoon for several weeks, and so cocoons must emit cues to ensure their care and the development of juveniles. We investigated cues associated with the cocoon silk. We assessed qualitative changes of the lipid contents and the composition of cocoon silk in relation to the development of P. saltans wolf spider juveniles. Gas chromatography–mass spectrometry of P. saltans’ cocoon silk revealed 62 different lipid compounds. The compounds were aliphatic alcohols, glycerides, fatty acids and their methylesters containing 13–29 carbon atoms. We reveal for the first time the presence of ethanolamides and phytosterol on cocoon silk. Qualitative and quantitative changes occur during the embryonic period, as some polar compounds, such as diglycerides and ethanolamides, disappeared while hydrocarbons emerge, and fatty acids disappeared later during the post-embryonic period. Qualitative and/or quantitative changes could play a role in tactochemical communication between mothers and their cocoon. However, mothers do not modify their behaviour in relation to the developmental stage of their cocoon. Mothers’ behaviour appears to be linked to both internal (physiological state) and external mechanisms (signals from the cocoon).
Post-prandial physiology and intestinal morphology of the Pacific hagfish (Eptatretus stoutii)
Venue: Journal of Comparative Physiology B

Hagfishes are unique to the vertebrate lineage in that they acquire dissolved nutrients across multiple epithelia including the intestine, gill, and skin. This feat has been attributed to their immersive feeding behavior that likely simultaneously provides benefits (nutrient rich) and potentially adverse (hypercapnia, hypoxia, high environmental ammonia) physiological effects. Examinations have been conducted of the ex vivo transport capabilities of specific nutrients as well as in vivo effects of the hypothesized feeding environments, yet the physiological effects of feeding itself have never been elucidated. We examined the post-prandial physiology of Pacific hagfish (Eptatretus stoutii), identifying changes in oxygen consumption, acid–base balance, ammonia waste excretion, and intestinal morphology following feeding in captivity. Following voluntary feeding, post-prandial oxygen consumption was significantly elevated (1868 ± 272 µmol kg−1 h−1) 8 h following feeding when compared to control resting metabolic oxygen consumption (642 ± 51 µmol kg−1 h−1) and resulted in a factorial metabolic scope of 2.92. Changes in acid–base status were not observed following feeding in either the excreted components or the caudal blood samples; however, a significant alkalosis was observed 8 h post-feeding in the major intestinal blood vein. Significant increases (16-fold) in ammonia excretion were recorded in 36 h post-fed hagfish. Finally, significant post-prandial increases in intestinal mucosal thickness and microvilli length were observed, with mucosal thickness remaining significantly increased throughout 36 h and the microvilli length returning to fasted lengths by 36 h. These results demonstrate the post-feeding physiology of the earliest diverging extant craniate and identify correlations between physiology and hindgut morphology 8 h following feeding.