Behavior Of Different Species Research Articles

Quantitative Analysis of the Brachialis and Triceps Brachii Insertion Sites on the Proximal Epiphysis of the Ulna in Modern Hominid Primates and Fossil Hominins.

In several species of hominid primates with different types of locomotor behavior, we quantitatively studied the insertion sites of the brachialis and triceps brachii on the proximal epiphysis of the ulna. Our main objective was to evaluate the possibility of using the anatomical features of these insertion sites to infer the locomotor behavior of different species of fossil hominins. We measured the area of these muscle insertion sites using 3D bone meshes and obtained the value of each insertion site relative to the total size of the two insertion sites for each of the species studied. We also compared these relative values of the osteological samples with the relative mass of the brachialis and triceps brachii, which we obtained by dissecting these muscles in the same primate species. The relative values for the brachialis insertion were highest in orangutans, followed by bonobos, chimpanzees, gorillas, and humans. Fossil Australopithecus and Paranthropus had values similar to those of bonobos, while fossil Homo had values similar to those of Homo sapiens. The observed similarity in ulnar attachment sites between Australopithecus and Paranthropus and extant bonobos suggest that these hominins used arboreal locomotion to complement their bipedalism. These adaptations to arboreal locomotion were not observed in Homo.

The use of attenuators in Amazonian forest species under heavy metal stress: a literature review

Anthropogenic activities such as industrial and mining activities have caused biotic and abiotic stress in plants through contamination by heavy metals deposited in the environment. Some of these are toxic to the plant in any concentration. Phytoremediation and its techniques then emerged as a measure capable of reducing heavy metal contamination. In addition to phytoremediation techniques, research shows the use of growth regulators to act as attenuators and mitigators of stress caused by heavy metals in plants. Thus, the objective of this bibliography was to gather information on contamination by heavy metals in Amazonian forest species, and to outline possible pathways and mechanisms capable of reducing this problem, enabling the use of specific species that can carry out phytoremediation of the soil, making contaminated and unproductive areas into productive ones and capable of being used in forest restoration programs and recovery of degraded areas. Understanding and studies on phytoremediation and its techniques have been deepened. However, it is necessary to increasingly understand the behavior of different species in the presence of heavy metals in the soil.

The origin of the phrase comparative psychology: an historical overview.

Comparative psychology, in its narrow meaning, refers to the study of the similarities and differences in the psychology and behavior of different species. In a broader meaning, it includes comparisons between different biological and socio-cultural groups, such as species, sexes, developmental stages, ages, and ethnicities. This broader meaning originated by extension from the former narrow meaning, which historically was the original meaning of the phrase (interspecies psychological and behavioral comparisons) and which still today is the focus of the field. Currently, comparative psychology is a subject of study in hundreds of universities all over the world. Nevertheless, a question that is often asked but seldom answered is: when did the phrase comparative psychology first appear and where did it come from? In the present work, we tracked down the origins of the phrase comparative psychology. In order to do so, at first we described the origin of the word psychology, coined in the decade 1510-1520 in the Republic of Venice by Dalmatian Renaissance humanist Marko Marulić Splićanin (1450-1524). Then, to explain where, within the phrase comparative psychology, the term comparative came from, we outlined the origin of the use of the word comparative in reference to interspecies comparisons. Finally, we reported the origin of the combination of the words comparative and psychology to form the phrase comparative psychology, the first usage of which was in 1778 by German scholar Michael Hissmann (1752-1784) from the University of Göttingen. Origins of the phrase in Latin, German, French and English languages are described.

Disease ecology of bats—the Canadian scene

Bats are hosts to a range of pathogens, which include zoonotic pathogens and pathogens of conservation concern. Brock Fenton’s research on bat ecology has always balanced clear communication of potential health risks associated with bats and the need to communicate these risks precisely to avoid unnecessary persecution of bats. Here, we integrate Brock’s work in the field of disease ecology with that of his students and collaborators and consider the potential advantages of studying disease ecology of bats within the Canadian context. The broad distribution of a few common species across the vast landscape of present-day Canada provides an opportunity to untangle the impacts of environmental variation on host–pathogen interactions and disease severity, particularly in the context of climate change. The varying migratory strategies and social structure of the bat species found in Canada could also facilitate informative interspecific studies to better understand how bat health is affected by interactions among rapid environmental changes, physiological traits, and the social behaviour of different species. We propose a series of priority research questions and approaches that could further our understanding of bat health and disease ecology in Canada, inspired by the work of Brock, his colleagues, and students.

Are there disciplinary boundaries in the comparative study of primate cognition?

A view continues to gain momentum that regards investigation of the cognition of great apes in captive settings as affording us a model for human cognitive evolution. Researchers from disciplines such as comparative psychology, anthropology, and even archaeology, seem eager to put their theories to the test by using great apes as their chosen experimental model. Questions addressed currently by comparative psychologists have long been the object of attention by neurophysiologists, psychobiologists and neuroscientists, who, however, often use rodents and monkeys as the species of choice. Whereas comparative psychology has been influenced greatly by ethology, much neuroscience has developed against a background of physiology and medicine. This separation of the intellectual contexts wherein they have arisen and flourished has impeded the development of fluid interaction between comparative psychologists and researchers in the other disciplines. We feel that it would be beneficial for comparative psychologists and neuroscientists to combine research endeavours far more often, in order to address common questions of interest related to cognition. We regard interdisciplinary cross-pollination to be particularly desirable, even if many comparative psychologists lack deep expertise about the workings of the brain, and even if many neuroscientists lack expert knowledge about the behaviour of different species. Furthermore, we believe that anthropology, archaeology, human evolutionary studies, and related disciplines, may well provide us with significant contextual knowledge about the physical and temporal background to the evolution in humans of specific cognitive skills. To that end, we urge researchers to dismantle methodological, conceptual and historical disciplinary boundaries, in order to strengthen cross-disciplinary cooperation in order to broaden and deepen our insights into the cognition of nonhuman and human primates.

Putative Activation of Cannabinoid Receptor Type 1 Prevents Brain Oxidative Stress and Inhibits Aggressive-Like Behavior in Zebrafish.

Background: Aggression is a set of complex behaviors commonly described in different neurological disorders, such as schizophrenia, autistim spectrum disorder, and anxiety. Previous studies have described that some changes in the redox status of the brain are closely associated with aggressive behavior in different species. In addition, the endocannabinoid system acts as a neuromodulator of the central nervous system, however, its participation in aggressive behavior needs to be elucidated. Danio rerio (zebrafish) is an important model in the study of aggression, in this context, the present study investigated whether the activation of type 1 cannabinoid receptors (CB1r) alters the cerebral redox state and aggressive behavior in zebrafish. Materials and Methods: We performed pharmacological manipulations with the CB1r agonist (ACEA) and antagonist (AM-251) to assess the role of this receptor in aggressive behavior. Individuals were isolated in pairs, without physical contact for 24 h, treated with the drugs of interest, and after 30 minutes of pharmacokinetics, the fights were filmed for 30 min, and the individuals were identified as dominant or subordinate. Results: A consistent decrease in the strike and bite aggressive behavior was observed in the group treated with the ACEA agonist compared with that in the control and AM-251 groups. When evaluating the cerebral redox state, we observed that treatment with the ACEA agonist reduced malondialdehyde (MDA) levels and increased the levels of sulfhydryl groups compared with those in the control group. These results indicate that the activation of CB1r by the ACEA agonist inhibited aggressiveness and attenuated the levels of oxidative stress in both subjects (dominant or subordinate) in the treated group. Conclusion: Thus, we suggest that zebrafish is an alternative model to study common aggressive behavior disorders among species and that CB1r represent a potential target for the development of treatments for aggressive disorders.

Predictive maps in rats and humans for spatial navigation

Much of our understanding of navigation comes from the study of individual species, often with specific tasks tailored to those species. Here, we provide a novel experimental and analytic framework integrating across humans, rats, and simulated reinforcement learning (RL) agents to interrogate the dynamics of behavior during spatial navigation. We developed a novel open-field navigation task ("Tartarus maze") requiring dynamic adaptation (shortcuts and detours) to frequently changing obstructions on the path to a hidden goal. Humans and rats were remarkably similar in their trajectories. Both species showed the greatest similarity to RL agents utilizing a "successor representation," which creates a predictive map. Humans also displayed trajectory features similar to model-based RL agents, which implemented an optimal tree-search planning procedure. Our results help refine models seeking to explain mammalian navigation in dynamic environments and highlight the utility of modeling the behavior of different species to uncover the shared mechanisms that support behavior.

Biphasic reward effects are characteristic of both lorcaserin and drugs of abuse: implications for treatment of substance use disorders.

Lorcaserin is a modestly selective agonist for 2C serotonin receptors (5-HT2CR). Despite early promising data, it recently failed to facilitate cocaine abstinence in patients and has been compared with dopamine antagonist medications (antipsychotics). Here, we review the effects of both classes on drug reinforcement. In addition to not being effective treatments for cocaine use disorder, both dopamine antagonists and lorcaserin can have biphasic effects on dopamine and reward behavior. Lower doses can cause enhanced drug taking with higher doses causing reductions. This biphasic pattern is shared with certain stimulants, opioids, and sedative-hypnotics, as well as compounds without abuse potential that include agonists for muscarinic and melatonin receptors. Additional factors associated with decreased drug taking include intermittent dosing for dopamine antagonists and use of progressive-ratio schedules for lorcaserin. Clinically relevant doses of lorcaserin were much lower than those that inhibited cocaine-reinforced behavior and can also augment this same behavior in different species. Diminished drug-reinforced behavior only occurred in animals after higher doses that are not suitable for use in patients. In conclusion, drugs of abuse and related compounds often act as biphasic modifiers of reward behavior, especially when evaluated over a broad range of doses. This property may reflect the underlying physiology of the reward system, allowing homeostatic influences on behavior.

The relationship between personality, season, and wounding receipt in zoo-housed Japanese macaques (Macaca fuscata): A multi-institutional study.

It is important to those managing Japanese macaques (Macaca fuscata) in captive settings to understand predictors of wounding. While studies have demonstrated that season (breeding or nonbreeding) and sex predict rates of wounding received by zoo-housed Japanese macaques, we investigated whether individual differences in personality ratings also might explain some of the observed interindividual variance in wounding. Such patterns were previously observed in rhesus macaques (M. mulatta), such that individuals rated higher on Anxiety and Confidence received greater wounding. Here, we collected wounding data over 24 months on 48 Japanese macaques from eight AZA-accredited zoos. Each macaque was also rated by keepers using a 26-item personality questionnaire. Principle components analysis of these ratings revealed four personality components: Openness, Friendliness, Dominance, and Anxiety/Reactivity. The model with the best fit revealed an interaction effect between season (breeding vs. nonbreeding) and the personality component Friendliness, such that individuals rated higher on Friendliness incurred fewer wounds in the nonbreeding season. The second-best model revealed both a main effect of the season as well as an interaction effect between season and Openness, such that macaques rated higher in Openness received more wounds in the nonbreeding season than those rated lower in Openness. Thus, as with rhesus macaques, personality mediated wounding receipt rate in Japanese macaques, although different personality components explained interindividual variance in wounding for these two species. These differences likely reflect species differences in behavior and personality structure, as well as the influence of differing management practices, highlighting the importance of species-specific approaches for captive primate care and welfare. This study provides further support for understanding primate personality to create individualized strategies for their care.

Restored and remnant Banksia woodlands elicit different foraging behavior in avian pollinators.

Pollinators and the pollination services they provide are critical for seed set and self‐sustainability of most flowering plants. Despite this, pollinators are rarely assessed in restored plant communities, where their services are largely assumed to re‐establish. Bird–pollinator richness, foraging, and interaction behavior were compared between natural and restored Banksia woodland sites in Western Australia to assess their re‐establishment in restored sites. These parameters were measured for natural communities of varying size and degree of fragmentation, and restored plant communities of high and low complexity for three years, in the summer and winter flowering of Banksia attenuata and B. menziesii, respectively. Bird visitor communities varied in composition, richness, foraging movement distances, and aggression among sites. Bird richness and abundance were lowest in fragmented remnants. Differences in the composition were associated with the size and degree of fragmentation in natural sites, but this did not differ between seasons. Restored sites and their adjacent natural sites had similar species composition, suggesting proximity supports pollinator re‐establishment. Pollinator foraging movements were influenced by the territorial behavior of different species. Using a network analysis approach, we found foraging behavior varied, with more frequent aggressive chases observed in restored sites, resulting in more movements out of the survey areas, than observed in natural sites. Aggressors were larger‐bodied Western Wattlebirds (Anthochaera chrysoptera) and New Holland Honeyeaters (Phylidonyris novaehollandiae) that dominated nectar resources, particularly in winter. Restored sites had re‐established pollination services, albeit with clear differences, as the degree of variability in the composition and behavior of bird pollinators for Banksias in the natural sites created a broad completion target against which restored sites were assessed. The abundance, diversity, and behavior of pollinator services to remnant and restored Banksia woodland sites were impacted by the size and degree of fragmentation, which in turn influenced bird–pollinator composition, and were further influenced by seasonal changes between summer and winter. Consideration of the spatial and temporal landscape context of restored sites, along with plant community diversity, is needed to ensure the maintenance of the effective movement of pollinators between natural remnant woodlands and restored sites.

Using chemical modeling for designing of optimal pH sensor based on analytical sensitivity enhancement

The behavior of chemical systems can be predicted based on the chemical model or the law of mass action in combining with Beer’s Law. The information about chemical behavior of different species in an equilibrium condition and pure responses of active species propound the idea of using this information for designing of sensors, systematically.In this contribution, we applied chemical modeling for designing pH sensors using common pH indicators. Because individually considered they display a limited dynamic range, two or more pH indicators are usually required for the pH measurements in a broad pH range. Two different aspects were considered: 1) finding the optimum approach for the combination of pH indicators (i.e. an array or a mixture of indicators in solution), in this regard, analytical sensitivity is used as an optimization criterion and 2) tuning equilibrium constants of indicators to produce new desired pH indicators. The tuning of apparent constants was performed using a surfactant solution. An array of a certain indicator in the aqueous and micellar phase increases its dynamic pH range. Three pH indicators including phenol red, neutral red, and methyl orange were selected and their interactions with the micellar phase of Brij-35 were investigated. Based on the obtained information about the behavior of the indicators in micellar solution, the optimum pH sensor was then designed and pH was predicted with the root mean square error of pH prediction value of 0.1.

Revealing the complexity of distinct manganese species-protein interactions through multi-spectroscopy

The effect of manganese (Mn) on protein conformation is closely related to its chemical species. To further realize the behavior of different species of Mn in vivo, this study is designed to analyze the separate and simultaneous interactions of Mn(ii) and Mn(iii) with bovine serum albumin (BSA) using multi-spectroscopy. The results demonstrated that the interaction of Mn(ii) or Mn(iii) with BSA is a process of static quenching and Mn(iii) formed a more stable complex. The binding constants and thermodynamic constants indicated that a 1:1 complex was formed between Mn(ii)/Mn(iii) and BSA through a moderate binding force, and hydrophobic interaction played an important role in the binding. UV–Vis spectroscopy, synchronous fluorescence spectroscopy and three-dimensional fluorescence spectroscopy results revealed that the conformation changes in BSA induced by Mn(ii)/Mn(iii) binding. The results of the ternary systems suggested that both Mn species interfered the interaction of the other with BSA. The conformation of BSA may change more to adapt to the simultaneous binding to Mn (ii) and Mn (iii) when two Mn species coexist.

Insights into the mechanism of lead species adsorption over Al2O3 sorbent

Al2O3 is regarded as an effective sorbent to capture lead from flue gas. The adsorption behaviors of different species of lead (Pb, PbO, PbCl and PbCl2) on the Al2O3 surfaces were explored based on density functional theory. The results show that the chemisorption mechanism is responsible for the adsorption of lead species on the Al2O3 surface. The high reactivity of Pb adsorption on the α-Al2O3 (110) surface is mainly attributed to the existence of unsaturated Al atoms. The Al hollow sites are identified as the effectively active sites for Pb adsorption on the (110) surface. The adsorption energies of different species of lead on the Al-terminated (110) surface are in the range of − 4.20 to − 6.30 eV. PbO adsorption at the Al hollow site of the Al-terminated (110) surface shows the highest adsorption energy (− 6.30 eV), suggesting that Al2O3 prefers to capture PbO among different species of lead. The strong interactions of PbO, PbCl and PbCl2 molecules with the unsaturated Al atoms of the α-Al2O3 (110) surface are responsible for PbO, PbCl and PbCl2 capture by Al2O3. Al2O3 has a good ability to capture different species of lead, and the adsorption capacity follows the order: PbO > Pb > PbCl > PbCl2.

Adaptive tuning of the exploitation-exploration trade-off in four honey bee species

Foraging animals continually face the decision of whether to exploit known resources or explore for new ones, a decision with large implications for their fitness. Though animal foraging decisions have been extensively studied, we currently lack a deep understanding of how the exploitation-exploration trade-off has evolved, including how it is shaped by divergent selection pressures between species. As a first step towards examining how the exploitation-exploration trade-off has been adaptively tuned by natural selection, we compared the exploratory behavior of four honey bee species that differ in traits such as nest architecture, body size, and colony size. In a common behavioral context—exploratory behavior triggered by a decrease in quality of a known food resource—we found species differences in exploratory behavior that are consistent with selection arising from evolved differences in nest architecture, though the behavioral differences were also strongly influenced by the magnitude of the reward decrease. We had expected that species that build their nests in the open, and hence face a higher fitness cost of worker attrition compared with species that inhabit protective cavities, would be less likely to prolong unrewarded search when food declines in quality. The behavioral data were partially consistent with this expectation. However, at times, the environmental context strongly modulated species differences in behavior that would be expected based on nest architecture. Overall, our results suggest that the resolution of the exploitation-exploration trade-off has been adaptively tuned between species by a number of interacting selection pressures. Foraging animals must constantly decide whether to exploit known resources or explore for new, potentially better, ones. How animals resolve this trade-off is likely to have a cumulative effect on their fitness, so natural selection should shape it according to species-specific differences in life history. Using an experimental approach comparing four honey bee species, our results suggest that the tendency to engage in costly search is shaped by multiple interactions among selection pressures differing between honey bee species. We found a correlation between search and how species build their nests, with species nesting in the open generally searching less than those nesting in cavities. However, past experience with a reward can sometimes interact with or overshadow the patterns expected based on nesting behavior. These patterns highlight the complicated effects of life history and ecology on the evolution of behavior.

Ecological and social drivers of neighbor recognition and the dear enemy effect in a poison frog

Abstract Navigating social relationships frequently rests on the ability to recognize familiar individuals using phenotypic characteristics. Across diverse taxa, animals vary in their capacities for social recognition, but the ecological and social sources of selection for recognition are often unclear. In a comparative study of two closely related species of poison frogs, we identified a species difference in social recognition of territory neighbors and investigated potential sources of selection underlying this difference. In response to acoustic playbacks, male golden rocket frogs (Anomaloglossus beebei) recognized the calls of neighbors and displayed a “dear enemy effect” by responding less aggressively to neighbors’ calls than strangers’ calls. In contrast, male Kai rocket frogs (Anomaloglossus kaiei) were equally aggressive to the calls of neighbors and strangers. This species difference in behavior is associated with key differences in reproductive ecology and characteristics of territories. Golden rocket frogs defend reproductive resources in the form of bromeliads, which is expected to create a threat asymmetry between neighbors and strangers favoring decreased aggression to neighbors. In contrast, Kai rocket frogs do not defend reproductive resources. Further, compared with Kai rocket frog territories, golden rocket frog territories occur at higher densities and are defended for longer periods of time, creating a more complex social environment with more opportunities for repeated but unnecessary aggression between neighbors, which should favor the ability to recognize and exhibit less aggression toward neighbors. These results suggest that differences in reproductive ecology can drive changes in social structure that select for social recognition.

Competitive ability and plasticity of Wedelia trilobata (L.) under wetland hydrological variations

Growth behavior of different species under different habitats can be studied by comparing the production of biomass, plasticity index and relative competitive interaction. However, these functional traits of invasive species received rare consideration for determining the invasion success of invasive species at wetlands. Here, we examined the effect of water depth at 5 cm and 15 cm (static and fluctuated) with different nutrient concentrations (full-strength (n1), 1/4-strength (n2) and 1/8-strength (n3) Hoagland solution) on functional traits of invasive Wedelia trilobata and its congener native Wedelia chinensis under mono and mixed culture. Water depth of 5 cm with any of the nutrient treatments (n1, n2 and n3) significantly restrained the photosynthesis, leaf nitrogen and photosynthetic nitrogen use efficiency (PNUE) of both W. trilobata and W. chinensis. While, increase in the water depth to 15 cm with low nutrient treatment (n3) reduced more of biomass of W. chinensis under mixed culture. However, relative competition interaction (RCI) was recorded positive for W. trilobata and seemingly W. trilobata benefited more from RCI under high-fluctuated water depth at 15 cm in mixed culture. Therefore, higher PNUE, more competitive ability and higher plasticity may contribute to the invasiveness of W. trilobata in wetlands.

Ecotype differences in aggression, neural activity and behaviorally relevant gene expression in cichlid fish.

In Lake Malawi, two ecologically distinct lineages of cichlid fishes (rock- vs sand-dwelling ecotypes, each comprised of over 200 species) evolved within the last million years. The rock-dwelling species (Mbuna) are aggressively territorial year-round and males court and spawn with females over rocky substrate. In contrast, males of sand-dwelling species are not territorial and instead aggregate on seasonal breeding leks in which males construct courtship "bowers" in the sand. However, little is known about how phenotypic variation in aggression is produced by the genome. In this study, we first quantify and compare behavior in seven cichlid species, demonstrating substantial ecotype and species differences in unconditioned mirror-elicited aggression. Second, we compare neural activity in mirror-elicited aggression in two representative species, Mchenga conophoros (sand-dwelling) and Petrotilapia chitimba (rock-dwelling). Finally, we compare gene expression patterns between these two species, specifically within neurons activated during mirror aggression. We identified a large number of genes showing differential expression in mirror-elicited aggression, as well as many genes that differ between ecotypes. These genes, which may underly species differences in behavior, include several neuropeptides, genes involved in the synthesis of steroid hormones and neurotransmitter activity. This work lays the foundation for future experiments using this emerging genetic model system to investigate the genomic basis of evolved species differences in both brain and behavior.

Using Data-Compressors for Classification Hunting Behavioral Sequences in Rodents as “Ethological Texts”

One of the main problems in comparative studying animal behavior is searching for an adequate mathematical method for evaluating the similarities and differences between behavioral patterns. This study aims to propose a new tool to evaluate ethological differences between species. We developed the new compression-based method for the homogeneity testing and classification to investigate hunting behavior of small mammals. A distinction of this approach is that it belongs to the framework of mathematical statistics and allows one to compare the structural characteristics of any texts in pairwise comparisons. To validate a new method, we compared the hunting behaviors of different species of small mammals as ethological “texts.” To do this, we coded behavioral elements with different letters. We then tested the hypothesis whether the behavioral sequences of different species as “texts” are generated either by a single source or by different ones. Based on association coefficients obtained from pairwise comparisons, we built a new classification of types of hunting behaviors, which brought a unique insight into how particular elements of hunting behavior in rodents changed and evolved. We suggest the compression-based method for homogeneity testing as a relevant tool for behavioral and evolutionary analysis.

Eardrum displacement and strain in the Tokay gecko (Gekko gecko) under quasi-static pressure loads

The eardrum is the primary component of the middle ear and has been extensively investigated in humans. Measuring the displacement and deformation of the eardrum under different quasi-static loading conditions gives insight in its mechanical behavior and is fundamental in determining the material properties of the eardrum. Currently, little is known about the behavior and material properties of eardrums in non-mammals. To explore the mechanical properties of the eardrum in non-mammalian ears, we investigated the quasi-static response of the eardrum of a common lizard: the Tokay gecko (Gekko gecko). The middle ear cavity was pressurized using repetitive linear pressure cycles ranging from −1.5 to 1.5 kPa with pressure change rates of 0.05, 0.1 and 0.2 kPa/s. The resulting shape, displacement and in-plane strain of the eardrum surface were measured using 3D digital image correlation. When middle-ear pressure is negative, the medial displacement of the eardrum is much larger than the displacement observed in mammals; when middle-ear pressure is positive, the lateral displacement is much larger than in mammals, which is not observed in bird single-ossicle ears. Peak-to-peak displacements are about 2.8 mm, which is larger than in any other species measured up to date. The peak-to-peak displacements are at least five times larger than observed in mammals. The pressure-displacement curves show hysteresis, and the energy loss within one pressure cycle increases with increasing pressure rate, contrary to what is observed in rabbit eardrums. The energy lost during a pressure cycle is not constant over the eardrum. Most energy is lost at the region where the eardrum connects to the hearing ossicle. Around this eardrum-ossicle region, a 5% increase in energy loss was observed when pressure change rate was increased from 0.05 kPa/s to 0.2 kPa/s. Other parts of the eardrum showed little increase in the energy loss. The orientation of the in-plane strain on the eardrum was mainly circumferential with strain amplitudes of about +1.5%. The periphery of the measured eardrum surface showed compression instead of stretching and had a different strain orientation. The TM of Gekko gecko shows the highest displacements of all species measured up till now. Our data show the first shape, displacement and deformation measurements on the surface of the eardrum of the gecko and indicate that there could exist a different hysteresis behavior in different species.

The influence of a single species on the space use of mixed-species flocks in Amazonian Peru

BackgroundThe drivers of space use patterns of multi-species groups have been poorly studied, although mixed-species avian flocks are common throughout the world. In a mixed-species flock, multiple species move together and maintain proximity. The different species may or may not have conflicting preferences of space use. We hypothesized that the space use patterns of the flock are driven by a single species.MethodsWe investigated the behavioral drivers of space use patterns of mixed-species flocks in Amazonian Peru by mapping 95% fixed-kernel home ranges of three flocks, which then we divided into high-use (inner 55% kernel utilization distribution) and low-use areas (lying outside the high-use area). We quantified the foraging and anti-predator behavior of individual birds in the flocks. We tested whether foraging and anti-predator behavior of different species were different in high use and low use areas of the flock.ResultsWe collected 455 spatial points and 329 foraging and anti-predator behavior observations on three flocks. The single best model for explaining the space use patterns of the flocks contained only vegetation density that surrounded Dusky-throated Antshrikes.ConclusionThe results are consistent with the hypothesis that a single species in mixed-species flocks has a disproportionately large influence on space use patterns. The surrounding vegetation density of the Dusky-throated Antshrike was the only driver of space use patterns of flocks supported by our data. The results may apply to flocks pantropically, many of which are led by species that behave similarly to the Dusky-throated Antshrike, e.g. Asian flocks led by drongos (Dicrurus spp.).