nils-herrmann/clean_scirepeval huggingface dataset:
The pathophysiology of survival in harsh environments
Venue: Journal of Comparative Physiology B

An individual’s ability to survive harsh conditions might depend on its available energy, and also on its health, which is expected to decline as conditions deteriorate. Yet, we know little about how health and energy expenditure are shaped by harsh environmental conditions in free-living vertebrates. Here, we studied how African striped mice (Rhabdomys pumilio) that survived summer droughts differed in their energy expenditure and health from non-survivors. Specifically, we tested whether: (1) survivors’ and non-survivors’ health and energy expenditure differed before environmental conditions declined; (2) non-survivors were in poorer health and had greater energy expenditure than survivors when conditions were harshest; (3) non-survivors’ health deteriorated more than that of survivors as conditions deteriorated; and (4) survivors recovered once conditions improved. Survivors and non-survivors’ health was assessed using VetsScan ABAXIS, while energy expenditure was measured as resting metabolic rate (RMR). Before conditions declined, non-survivors had lower energy stores and higher globulin levels than survivors. As conditions became harsher, survivors’ and non-survivors’ health deteriorated but only non-survivors showed signs of permanent pathology (increased glucose and decreased globulin). Once conditions improved, survivors’ health improved but was not fully restored (increased alanine aminotransferase and decreased globulin). Furthermore, while survivors and non-survivors had similar RMR before conditions became harsh; their levels diverged considerably when conditions deteriorated, with survivors having a decreased RMR and non-survivors having an increased RMR. Our results show that an individual’s health before facing an environmental challenge and the way it regulates its RMR influences its ability to maintain homeostasis when conditions become more taxing.
An unusual recruitment strategy in a mass-recruiting stingless bee, Partamona orizabaensis
Venue: Journal of Comparative Physiology A

Foragers of several stingless bee species deposit attractive scent marks on solid substrates to precisely recruit nestmates to food. Interestingly, Partamona workers quickly recruit large numbers of nest mates to resources, likely even without the deposition of attractive scent marks. However, systematic studies of the recruitment system of these bees are lacking. We now studied the recruitment behavior of P. orizabaensis. Our findings show that foragers of this species can recruit large numbers of nestmates to food sources at a particular location. The precise nestmate recruitment does not rely on attractive scent marks deposited on substrates. We never observed any scent marking behavior and feeders baited with labial or mandibular gland extracts were not attractive for the bees. Chemical analyses showed that the foragers’ labial gland secretions exclusively contain long chain hydrocarbons, which render their role in recruitment communication unlikely. Whether mandibular gland secretions, which contain esters and alcohols that are known as attractive pheromones in other bee species, are used to guide recruits toward food during flight, remains elusive. We conclude that Partamona’s quick recruitment system that does not rely on conspicuous scent marks has evolved as a strategy against competition with sympatrically occurring and more aggressive bee species.
Agrochemical-induced stress in stingless bees: peculiarities, underlying basis, and challenges
Venue: Journal of Comparative Physiology A

The toxicological stress induced by pesticides, particularly neonicotinoid insecticides, and its consequences in bees has been the focus of much recent attention, particularly for honey bees. However, the emphasis on honey bees and neonicotinoids has led to neglect of the relevance of stingless bees, the prevailing pollinators of natural and agricultural tropical ecosystems, and of other agrochemicals, including other pesticides and even leaf fertilizers. Consequently, studies focusing on agrochemical effects on stingless bees are sparse, usually limited to histopathological studies, and lack a holistic assessment of the effects of these compounds on physiology and behavior. Such effects have consequences for individual and colony fitness and are likely to affect both the stingless bee populations and the associated community, thereby producing a hierarchy of consequences thus far overlooked. Herein, we review the current literature on stingless bee-agrochemical interactions and discuss the underlying mechanisms involved in reported stress symptoms, as well as the potential consequences based on the peculiarities of these pollinators.
Synuclein expression in the lizard Anolis carolinensis
Venue: Journal of Comparative Physiology A

The synuclein (syn) family comprises three proteins: α-, β- and γ-syns. In humans, they are involved in neurodegenerative diseases such as Parkinson’s disease and in tumors. Members of the syn family were sequenced in representative species of all vertebrates and the comparative analysis of amino acid sequences suggests that syns are evolutionarily conserved, but information about their expression in vertebrate lineages is still scarce and completely lacking in reptiles. In this study, the expression of genes coding for α-, β- and γ-syns was analyzed in the green lizard Anolis carolinensis by semiquantitative RT-PCR and Western blot. Results demonstrate good expression levels of the three syns in the lizard nervous system, similarly to human syns. This, together with the high identity between lizard and human syns, suggests that these proteins fulfill evolutionarily conserved functions. However, differences between lizard and humans in the expression of syn variants (two different variants of γ-syn were detected in A. carolinensis) and differences in some amino acids in key positions for the regulation of protein conformation and affinity for lipid and metal ions also suggest that these proteins may have acquired different functional specializations in the two lineages.
Flower detection and acuity of the Australian native stingless bee Tetragonula carbonaria Sm.
Venue: Journal of Comparative Physiology A

We tested the endemic Australian Tetragonula carbonaria bee as a model of how colour vision may allow these small bees to find flowers. In a Y-Maze apparatus, we presented stimuli that contained both chromatic- and green-receptor contrasts, or only had chromatic contrast to free flying bees. Stimuli were detected at visual angles of 9.5° and 9.3°, respectively. We next made morphological measurements of the compound eye under high magnification using a digital microscope, and despite a relatively small eye size with a surface area of 0.64 ± 0.02 mm2, the compound eye contained 3010 ± 10 ommatidia. Measurements of diverging rays of light using antidromic illumination revealed a mean interommatidial angle in the frontal visual field measures 1.56° ± 0.10°. Finally, we calculate that the minimum number of ommatidia that need to be excited for object detection is 33, which is much higher than for object detection in bumblebees and for the detection of objects providing both colour and green contrasts by honeybees, but lower for the detection of an object lacking green contrast in honeybees. We discuss reasons that may explain potential tradeoff for foraging bees.
Male meliponine bees (Scaptotrigona aff. depilis) produce alarm pheromones to which workers respond with fight and males with flight
Venue: Journal of Comparative Physiology A

In highly social hymenopteran societies, males mainly serve reproductive purposes. Semiochemicals enable the different hymenopteran sexes and castes to communicate with each other and to coordinate important functions within colonies. I hereby show that sexual dimorphism in meliponine bees incorporates the alarm and defence communication system. I chemically analysed the mandibular glands of Scaptotrigona aff. depilis using GCMS methods and conducted behavioural experiments in both males and female workers using cephalic and mandibular gland extracts. In addition, behaviour studies with male cephalic extracts were also conducted in Scaptotrigona bipunctata and Partamona cupira. Males and female worker bees showed differences in the content of the mandibular glands, which are responsible for alarm communication in meliponines. Males never attacked but usually fled when confronted with the mandibular gland extract content of other conspecific males or females. Interestingly, however, meliponine males were still able to raise alarm and to induce substantial amounts of aggression at nest entrances, which is different from the much better known and studied honey bees. Potential reasons are briefly discussed.
A new device for monitoring individual activity rhythms of honey bees reveals critical effects of the social environment on behavior
Venue: Journal of Comparative Physiology A

Chronobiological studies of individual activity rhythms in social insects can be constrained by the artificial isolation of individuals from their social context. We present a new experimental set-up that simultaneously measures the temperature rhythm in a queen-less but brood raising mini colony and the walking activity rhythms of singly kept honey bees that have indirect social contact with it. Our approach enables monitoring of individual bees in the social context of a mini colony under controlled laboratory conditions. In a pilot experiment, we show that social contact with the mini colony improves the survival of monitored young individuals and affects locomotor activity patterns of young and old bees. When exposed to conflicting Zeitgebers consisting of a light–dark (LD) cycle that is phase-delayed with respect to the mini colony rhythm, rhythms of young and old bees are socially synchronized with the mini colony rhythm, whereas isolated bees synchronize to the LD cycle. We conclude that the social environment is a stronger Zeitgeber than the LD cycle and that our new experimental set-up is well suited for studying the mechanisms of social entrainment in honey bees.
Stingless bees (Melipona scutellaris) learn to associate footprint cues at food sources with a specific reward context
Venue: Journal of Comparative Physiology A

Foraging insects leave chemical footprints on flowers that subsequent foragers may use as indicators for recent flower visits and, thus, potential resource depletion. Accordingly, foragers should reject food sources presenting these chemical cues. Contrasting this assumption, experimental studies in stingless bees (Apidae, Meliponini), so far, demonstrated an attractive effect of footprints. These findings lead to doubts about the meaning of these chemical cues in natural foraging contexts. Here, we asked whether foragers of stingless bees (Melipona scutellaris) use footprints according to the previously experienced reward level of visited food sources. Bees were trained to artificial flower patches, at which the reward of a flower either decreased or, alternatively, increased after a visit by a forager. Individuals were allowed a total of nine foraging bouts to the patch, after which their preference for visited or unvisited flowers was tested. In the choice tests, bees trained under the decreasing reward context preferred unvisited flowers, whereas individuals trained under the increasing reward context preferred visited flowers. Foragers without experience chose randomly between visited and unvisited flowers. These results demonstrate that M. scutellaris learns to associate unspecific footprint cues at food sources with differential, specific reward contexts, and uses these chemical cues accordingly for their foraging decisions.
The origins and diversity of bat songs
Venue: Journal of Comparative Physiology A

Singing plays an important role in the social lives of several disparate bat species, but just how significant the behavior may be among bats generally is unknown. Recent discoveries suggest singing by bats might be surprisingly more diverse and widespread than anticipated, but if true then two questions must be addressed: firstly why has singing been so rarely documented among bats, and secondly do bats sing for the same reasons as songbirds? We address the first question by reviewing how sampling bias and technical constraints may have produced a myopic view of bat social communication. To address the second question, we review evidence from 50 years of batsong literature supporting the supposition that bat singing is linked to the same constellation of ecological variables that favored birdsong, including territoriality, polygyny, metabolic constraints, migratory behaviors and especially powered flight. We propose that bats sing like birds because they fly like birds; flight is energetically expensive and singing reduces time spent flying. Factoring in the singular importance of acoustic communication for echolocating bats, it seems likely that singing may prove to be relatively common among certain groups of bats once it becomes clear when and where to look for it.
Avoidance of a moving threat in the common chameleon (Chamaeleo chamaeleon): rapid tracking by body motion and eye use
Venue: Journal of Comparative Physiology A

A chameleon (Chamaeleo chamaeleon) on a perch responds to a nearby threat by moving to the side of the perch opposite the threat, while bilaterally compressing its abdomen, thus minimizing its exposure to the threat. If the threat moves, the chameleon pivots around the perch to maintain its hidden position. How precise is the body rotation and what are the patterns of eye movement during avoidance? Just-hatched chameleons, placed on a vertical perch, on the side roughly opposite to a visual threat, adjusted their position to precisely opposite the threat. If the threat were moved on a horizontal arc at angular velocities of up to 85°/s, the chameleons co-rotated smoothly so that (1) the angle of the sagittal plane of the head relative to the threat and (2) the direction of monocular gaze, were positively and significantly correlated with threat angular position. Eye movements were role-dependent: the eye toward which the threat moved maintained a stable gaze on it, while the contralateral eye scanned the surroundings. This is the first description, to our knowledge, of such a response in a non-flying terrestrial vertebrate, and it is discussed in terms of possible underlying control systems.
Innate colour preferences of the Australian native stingless bee Tetragonula carbonaria Sm.
Venue: Journal of Comparative Physiology A

Innate preferences promote the capacity of pollinators to find flowers. Honeybees and bumblebees have strong preferences for ‘blue’ stimuli, and flowers of this colour typically present higher nectar rewards. Interestingly, flowers from multiple different locations around the world independently have the same distribution in bee colour space. Currently, however, there is a paucity of data on the innate colour preferences of stingless bees that are often implicated as being key pollinators in many parts of the world. In Australia, the endemic stingless bee Tetragonula carbonaria is widely distributed and known to be an efficient pollinator of both native plants and agricultural crops. In controlled laboratory conditions, we tested the innate colour responses of naïve bees using standard broadband reflectance stimuli representative of common flower colours. Colorimetric analyses considering hymenopteran vision and a hexagon colour space revealed a difference between test colonies, and a significant effect of green contrast and an interaction effect of green contrast with spectral purity on bee choices. We also observed colour preferences for stimuli from the blue and blue–green categorical regions of colour space. Our results are discussed in relation to the similar distribution of flower colours observed from bee pollination around the world.
Nectar profitability, not empty honey stores, stimulate recruitment and foraging in Melipona scutellaris (Apidae, Meliponini)
Venue: Journal of Comparative Physiology A

In stingless bees (Meliponini) like in many other eusocial insect colonies food hoarding plays an important role in colony survival. However, very little is known on how Meliponini, a taxon restricted to tropical and subtropical regions, respond to different store conditions. We studied the impact of honey removal on nectar foraging activity and recruitment behaviour in Melipona scutellaris and compared our results with studies of the honey bee Apis mellifera. As expected, foraging activity increased significantly during abundance of artificial nectar and when increasing its profitability. Foraging activity on colony level could thereby frequently increase by an order of magnitude. Intriguingly, however, poor honey store conditions did not induce increased nectar foraging or recruitment activity. We discuss possible reasons explaining why increasing recruitment and foraging activity are not used by meliponines to compensate for poor food conditions in the nest. Among these are meliponine specific adaptations to climatic and environmental conditions, as well as physiology and brood rearing, such as mass provisioning of the brood.
Resources or landmarks: which factors drive homing success in Tetragonula carbonaria foraging in natural and disturbed landscapes?
Venue: Journal of Comparative Physiology A

To date, no study has investigated how landscape structural (visual) alterations affect navigation and thus homing success in stingless bees. We addressed this question in the Australian stingless bee Tetragonula carbonaria by performing marking, release and re-capture experiments in landscapes differing in habitat homogeneity (i.e., the proportion of elongated ground features typically considered prominent visual landmarks). We investigated how landscape affected the proportion of bees and nectar foragers returning to their hives as well as the earliest time bees and foragers returned. Undisturbed landscapes with few landmarks (that are conspicuous to the human eye) and large proportions of vegetation cover (natural forests) were classified visually/structurally homogeneous, and disturbed landscapes with many landmarks and fragmented or no extensive vegetation cover (gardens and plantations) visually/structurally heterogeneous. We found that proportions of successfully returning nectar foragers and earliest times first bees and foragers returned did not differ between landscapes. However, most bees returned in the visually/structurally most (forest) and least (garden) homogeneous landscape, suggesting that they use other than elongated ground features for navigation and that return speed is primarily driven by resource availability in a landscape.
Exploring visual plasticity: dietary carotenoids can change color vision in guppies (Poecilia reticulata)
Venue: Journal of Comparative Physiology A

Differences in color vision can play a key role in an organism’s ability to perceive and interact with the environment across a broad range of taxa. Recently, species have been shown to vary in color vision across populations as a result of differences in regulatory sequence and/or plasticity of opsin gene expression. For decades, biologists have been intrigued by among-population variation in color-based mate preferences of female Trinidadian guppies. We proposed that some of this variation results from variation in color vision caused by plasticity in opsin expression. Specifically, we asked about the role of dietary carotenoid availability, because carotenoids (1) are the precursors for vitamin A, which is essential for the creation of photopigments and (2) have been linked to variation in female mate choice. We raised guppies on different carotenoid-level diets and measured opsin expression. Guppies raised on high-carotenoid diets expressed higher levels of long wavelength sensitive opsin (LWS) opsins than those raised on lower levels of carotenoids. These results suggest that dietary effects on opsin expression represent a previously unaccounted for mechanism by which ecological differences across populations could lead to mate choice differences.
The electrocardiogram signal of Seba’s short-tailed bat, Carollia perspicillata
Venue: Journal of Comparative Physiology A

A number of studies have successfully used electrocardiogram (ECG) signals to characterize complex physiological phenomena such as associative learning in bats. However, at present, no thorough characterization of the structure of ECG signals is available for these animals. The aim of the present study was to quantitatively characterize features of the ECG signals in the bat species Carollia perspicillata, a species that is commonly used in neuroethology studies. Our results show that the ECG signals of C. perspicillata follow the typical mammalian pattern, in that they are composed by a P wave, QRS complex and a T wave. Peak-to-peak amplitudes in the bats’ ECG signals were larger in measuring configurations in which one of the electrodes was attached to the right thumb. In addition, large differences in the instantaneous heart rate (HR) distributions were observed between ketamine/xylazine anesthetized and awake bats. Ketamine/xylazine might target the neural circuits that control HR, therefore, instantaneous HR measurements should only be used as physiological marker in awake animals.
Distress vocalization sequences broadcasted by bats carry redundant information
Venue: Journal of Comparative Physiology A

Distress vocalizations (also known as alarm or screams) are an important component of the vocal repertoire of a number of animal species, including bats, humans, monkeys and birds, among others. Although the behavioral relevance of distress vocalizations is undeniable, at present, little is known about the rules that govern vocalization production when in alarmful situations. In this article, we show that when distressed, bats of the species Carollia perspicillata produce repetitive vocalization sequences in which consecutive syllables are likely to be similar to one another regarding their physical attributes. The uttered distress syllables are broadband (12–73 kHz) with most of their energy focussing at 23 kHz. Distress syllables are short (~4 ms), their average sound pressure level is close to 70 dB SPL, and they are produced at high repetition rates (every 14 ms). We discuss that, because of their physical attributes, bat distress vocalizations could serve a dual purpose: (1) advertising threatful situations to conspecifics, and (2) informing the threatener that the bats are ready to defend themselves. We also discuss possible advantages of advertising danger/discomfort using repetitive utterances, a calling strategy that appears to be ubiquitous across the animal kingdom.