120 research outputs found
Patterns and Drivers of Multimodal Signalling in Diurnal Geckos
No full textEffective communication in animals comprise emission of a signal by a signaller and a response by a receiver, such that the interaction is beneficial to either only the signaller, or both the signaller and the receiver. Although animals often communicate using a single sensory modality, use of multimodal signals is very prevalent, possibly to increase the efficacy of communication. The evolution of signalling traits in new sensory modalities, in the presence of signals in pre-existing sensory channels is intriguing, as it requires co-evolution between signals and receiver psychology. Furthermore, environmental conditions and energetic constraints of signallers, may govern the type and intensity of signals, as well as, their efficacy in reaching the sensory systems of the receivers.
In the first chapter, I studied the general ecology of a single species of a diurnal gecko in the genus Cnemaspis to understand its habitat use, activity patterns, and composition of population. I found that individuals of Cnemaspis mysoriensis are active throughout the day and found in areas with broad trees and numerous crevices. I also found that males of this species have colour morphs, which differ in their relative abundance in areas of high and low density. The population of this species has highly skewed adult to juvenile numbers in areas of high density. Finally, I found that individuals show low site fidelity and males avoid cohabiting.
In the second chapter, I determined the presence of multimodal signalling and the relative importance of signal components in chemical and visual sensory modalities for intraspecific communication in a single species of Cnemaspis. I found that male and female receivers differed in responses to signal components. Chemical stimuli were necessary and sufficient for female receivers; however, male receivers required both the chemical and visual stimuli as a multimodal signal to elicit a response.
In the third chapter, by comparing receiver responses of two closely related species of Cnemaspis, one with unimodal signals and another with multimodal signals, I investigated whether the evolution of receiver responses were associated with elaboration of traits in a new signal modality. I found that movement-based responses of male receivers of the species with multimodal signalling were highest towards multimodal signal, providing some support for the evolution of receiver response with trait elaboration.
Finally in the fourth chapter, I determined whether complexity and elaboration of various components of a multimodal signal across multiple species of Cnemaspis were associated with environmental parameters. I also investigated whether components in different modalities had trade-offs in their expression and intensity, possibly due to constraints. I found that some visual and chemical traits of signallers were well-associated with the environment to either increase the conspicuousness of signallers to conspecifics (visual traits) or decrease the loss of signal in the environment (chemical traits). I also found some evidence for trade-offs between components of signals between the two sensory modalities.
Overall, I found that in multiple diurnal gecko species, the elaboration of traits in the visual sensory channel shows some trade-off with chemical trait expression, and seems to have evolved to enhance interactions among males
Dynamic colour change in Psammophilus dorsalis: role of natural and sexual selection
No full textOverall, the results from this study support the idea that animal signals arise from a balance between increased conspicuousness for social signalling and inconspicuousness to avoid predation risk. Animals that can change colour provide a unique opportunity to examine the trade-offs between different evolutionary forces. I conclude that colour change may have evolved in P. dorsalis as an evolutionary solution to actively balance the costs of predation risk with the benefits of sexual signalling. The work from this thesis provides novel insights about the function and evolution of physiological colour change in a terrestrial system and is an important contribution to the understanding of visually complex signals in genera
Urbanisation and Shifting Phenotypes Behavioural, Physiological and Cognitive Strategies of the Indian Rock Agama Psammophilus Dorsalis
No full textHumans directly or indirectly cause changes in the environment, and urbanisation is currently one of the most important threats to biodiversity. Urbanisation exposes organisms to novel pressures that are drastically different from those in their native habitats, as human modification rapidly and dramatically changes natural environments, alters habitats as well as shifts resources and predator communities. Organisms can cope with the novel challenges by modifying their behaviour, physiology, morphology and cognition. To understand the impacts of urbanisation on phenotypic traits, the goal of my research was to study the social and survival strategies of the Indian rock agama, Psammophilus dorsalis. Using a combination of field and laboratory-based experiments, I examined differences in signal-receiver dynamics in communication, anti-predator strategies, stress physiology, and spatial learning. Social interactions in this species involve rapid physiological colour changes and behavioural displays. My work shows that colour patterns are diametrically different between courtship and aggressive interactions. Males change their dorsal body region to red, and their lateral body region to black when courting females, whereas these regions turn yellow and orange respectively when fighting with competitive males. Regardless of social context, suburban males express lower colour contrast and are also slower to change colours than rural males. Using robotic lizard stimuli, I found that receiver responses match the population-specific intensity of male signals. For the first time in any lizard species, I find that perception and responsiveness to motion and colour are lateralized in different ways. Psammophilus dorsalis is left visual field dominant when responding to social display colours, but motion stimuli elicit similar responses from both visual field. Along with shifts in colour signalling strategies, stress physiology and social behavioural display was also affected by urbanisation. Suburban males had significantly higher circulating corticosterone levels during both control conditions and immediately following social interactions compared to rural males. Proportion and rate of courtship displays was also significantly lower in suburban males compared to rural males. In the field, escape strategies of males, but not females differed between suburban and rural populations, such that suburban males were more tolerant of simulated predator attacks than rural males. As expected from their cryptic body patterns, females, regardless of habitat, relied more heavily on crypticity rather than flight to minimize predation risk. Suburban males also had stronger cognitive skills, as spatial learning and reversal learning in suburban males was faster than in rural males. In sum, differences in these behavioural, physiological, and cognitive responses of suburban and rural populations of lizards demonstrated in my thesis, indicate human-induced changes in selective pressures that support shifted survival and reproductive strategies. Psammophilus dorsalis promises to be an excellent system to further examine the specific selective pressures that shift in urban landscapes. The study of multiple integrated phenotypic traits in response to urbanisation gives a broader perspective as to how a species can flexibly adapt to rapid environmental disturbances, which is currently one of the greatest threats to biodiversity worldwide
Sensory Cues, Association Preferences, and Social Interactions of the San Marcos Salamander
No full textI studied the sensory communication, association preference, and social interactions of the threatened San Marcos salamander (Eurycea nana) in the laboratory. Eurycea nana (Plethodontidae) is endemic to the headwaters of the spring-fed San Marcos River (Texas). Within the geographic distribution of this species, temperature, chemical properties, and nutrient concentrations of the water are fairly constant. I expected that this stable habitat and year-round breeding would affect their communication and social behavior.
In chapter II, I examined the additive and multiplicative effectiveness of different sensory cues in the association preference of males and females of E. nana. The mode and effectiveness of signals depends on the environmental conditions and activity patterns of animal species. Visual cues frequently are involved in social interactions, although in nocturnal species, chemical and acoustic cues are more important. Multiple cues, however, can increase the accuracy of communication. Therefore, I examined association preferences of male and female salamanders based on conspecific (1) chemical cues, (2) visual cues, and (3) chemical & visual cues when simultaneously exposed to one individual of each sex. Both sexes significantly preferred to associate with the opposite sex when exposed to both chemical, and chemical and visual cues. There was no significant preference for either sex with visual cues alone. The simultaneous inclusion of both chemical and visual cues did not increase male or female preference for the opposite sex, thus chemical cues alone were sufficient to identify sex. I further tested male association preference for the chemical and visual cues of gravid versus non-gravid females. Males did not significantly prefer either type of female. Overall, my results suggest that although chemosensory communication is sufficient for females and males to distinguish between the sexes at close range, the ability of males to discriminate between females of different gravidity may require a different sensory modality.
In chapter III, I examined aspects of social interactions in E. nana. Social interactions of conspecifics are a function of the complex relationships among resource defense, anti-predatory tactics, and mate acquisition. Individuals often associate non-randomly with conspecifics in their habitats, where spatial distributions of adults range from territorial spacing to aggregations, depending on the habitat conditions and breeding status of the interacting individuals. I examined the cohabitation patterns of intrasexual and intersexual pairs of salamanders under artificial shelters across a 20-day period. I also examined individual affinity to the two shelters as a measure of site tenacity. None of the salamanders exhibited significant affinity to a particular shelter. In fact, males in the intrasexual pair treatment affiliated with both shelters equally often, indicating that they move frequently. Female pairs and intersexual pairs were found cohabiting more often than expected from random, whereas pairs of males cohabited in a pattern not significantly different from random. These results demonstrate that females of E. nana preferred to cohabit with individuals of both sexes, and males did not cohabit with other males, which could be a non-aggressive tactic to reduce competition or an indication that males move more frequently than females.Biolog
A retrospective and prospective chart review with implementations: preventing non-urgent emergency department visits from a primary care practice
No full textPurpose: Often there are patients who visit the emergency department for non-urgent complaints that can be treated in the primary care setting. This can lead to overcrowding of the emergency department, increased costs, and delay in treatment times. Providers need to advise or educate patients on the use of the emergency department versus the primary care practice. Doing so may lead to better use of the primary care providers, decrease non-urgent visits to the emergency departments and improve patient outcomes.
Methodology: A retrospective chart review with implementation of a handout was on display at a privately owned primary care practice in northern New Jersey. The handout displayed examples of services available in the emergency department versus those in the primary care practice. Prospective evaluation via a chart review of patient utilization of the emergency department was collected after handout has been available to patients. Data was analyzed for a decrease in patients utilizing the emergency department. The retrospective chart review, implementation of patient viewing handouts, and prospective chart review was utilized to develop recommendations based on the findings to promote primary care use and help decrease non-urgent emergency department visits.
Results: The statistical results revealed that most of the emergency department visits were emergent. Although emergency department visits after the implementation, the results were not statistically significant due to small sample size.
Implications for Practice: One time evaluation of patient Rapid Estimate of Adult Literacy in Medicine (REALM) score to determine baseline healthcare literacy. This will assist in educating of the patient and providers to determine what level of counseling they can provide the patient. Recommendations for additional practice hours as well as having additional providers to assist with patient volume. Utilization of call service when office is closed. Documentation of counseling of the patient for reimbursement.D.N.P.Includes bibliographical reference
Signalling with physiological colours: high contrast for courtship but speed for competition
No full textDynamic physiological colour change allows animals to alter colours and patterns for communication, camouflage and thermoregulation. Using reflectance spectrometry and digital photography, we found that males of the Indian rock agama, Psammophilus dorsalis, can rapidly express intense colours that are different from the neutral state and specific to the social context. The distinct bands on males shifted between yellow and red (dorsal) and between orange and black (lateral) within seconds, and the resulting colour pattern was diametrically different depending on whether males were in courtship or aggressive interactions. Although males showed higher chromatic contrast when courting females, the colour change was faster during competitive encounters with other males. The nature of this social colour communication also differed across populations in anthropogenically disturbed landscapes. Compared to males from rural areas, suburban males were slower to change colour and showed duller and paler colours during staged social encounters. Consistent with other disturbance-induced shifts in phenotypic traits seen in numerous taxa, we provide the first evidence that social signalling through dynamic colour change in terrestrial vertebrates is also affected by urbanization. (C) 2017 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved
Lifetime reproductive output and life-history traits of lizards
No full textAim: Latitudinal gradients in life-history traits are apparent in many taxa and are expected to be strong for ectotherms that have temperature-driven constraints on performance and fitness. The strength of these gradients, however, should also be affected by diet. Because diet type (carnivory, omnivory, herbivory) influences accessibility to nutrition and assimilation efficiency, we aim to study how diet affects latitudinal gradients in lifetime reproductive output and the underlying life-history traits in ectotherms.
Location: Global.
Time period: Recent.
Major taxa studied: Lizards (Reptilia, Squamata, Sauria).
Methods: We used empirical (352 species) and phylogenetically imputed data (563 species) to analyse the interactive effects of latitude and diet on life-history traits (longevity, age at maturity, reproductive lifespan, hatchling mass, clutch/brood size, clutch/brood frequency, female mass) and lifetime reproductive output of lizards.
Results: Lifetime reproductive output does not significantly differ in lizards across diet types, and only carnivores exhibit a small increase at higher latitudes. Diet type, however, influences latitudinal patterns of individual life-history traits. Carnivores exhibit a shift towards "slower-paced" life-histories at higher latitudes for most traits (increased longevity, age at maturity, reproductive lifespan, and decreased clutch frequency). By contrast, herbivores either display "faster-paced" life-histories (reduction in reproductive lifespan, hatchling mass, female mass) or no change (clutch frequency, clutch size, age at maturity) at higher latitudes. Omnivores exhibit intermediate and muted latitudinal patterns.
Main conclusions: We suggest that the nutritional challenges of herbivory, compounded by thermal constraints at higher latitudes, may explain differences in life-history characteristics of herbivorous ectotherms. Intermediate patterns exhibited by omnivores highlight how flexibility in diet can buffer environmental challenges at higher latitudes. Our results indicate that lizards with different diet types display various trends in their life-histories across latitudes, which eventually balance out to result in similar reproductive outputs throughout their lifetime, with little benefits to carnivory.Funding provided by: Department of Science and Technology, Ministry of Science and Technology, IndiaCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001409Award Number: SERB: EMR/2017/002228Funding provided by: The Wellcome Trust DBT India AllianceCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100009053Award Number: IA/I/19/2/50463
Author response
No full textA well-characterized metabolic landmark for aggressive cancers is the reprogramming from oxidative phosphorylation to aerobic glycolysis, referred to as the Warburg effect. Models mimicking this process are often incomplete due to genetic complexities of tumors and cell lines containing unmapped collaborating mutations. In order to establish a system where individual components of oncogenic signals and metabolic pathways can be readily elucidated, we induced a glycolytic tumor in the Drosophila wing imaginal disc by activating the oncogene PDGF/VEGF-receptor (Pvr). This causes activation of multiple oncogenic pathways including Ras, PI3K/Akt, Raf/ERK, Src and JNK. Together this network of genes stabilizes Hifα (Sima) that in turn, transcriptionally up-regulates many genes encoding glycolytic enzymes. Collectively, this network of genes also causes inhibition of pyruvate dehydrogenase (PDH) activity resulting in diminished ox-phos levels. The high ROS produced during this process functions as a feedback signal to consolidate this metabolic reprogramming
Lizards assess complex social signals by lateralizing colour but not motion detection
No full textVertebrates lateralize many behaviours including social interactions. Social displays typically comprise multiple components, yet our understanding of how these are processed come from studies that typically examine responses to the dominant component or the complex signal as a whole. Here, we examine laterality in lizard responses to determine whether receivers separate the processing of motion and colour signal components in different brain hemispheres. In Psammophilus dorsalis, males display colours that dynamically change during courtship and aggressive interactions. We tested the visual grasp reflex of both sexes using robotic stimuli that mimicked two signal components: (1) multiple speeds of head-bobbing behaviour and (2) multiple colours. We find no laterality in response to different motion stimuli, indicating that motion similarly attracts attention from both visual fields across sexes. Notably, receivers showed left visual field dominance to colours, especially when males were exposed to “aggression-specific” colours and females to “courtship-specific” colours.</jats:p
Lizards assess complex social signals by lateralizing colour but not motion detection
No full textVertebrates lateralize many behaviours including social interactions. Social displays typically comprise multiple components, yet our understanding of how these are processed comes from studies that typically examine responses to the dominant component or the complex signal as a whole. Here, we examined laterality in lizard responses to determine whether receivers separate the processing of motion and colour signal components in different brain hemispheres. In Psammophilus dorsalis, males display colours that dynamically change during courtship and aggressive interactions. We tested the visual grasp reflex of both sexes using robotic stimuli that mimicked two signal components: (1) multiple speeds of head-bobbing behaviour and (2) multiple colours. We found no laterality in response to different motion stimuli, indicating that motion similarly attracts attention from the two visual fields across sexes. Notably, receivers showed left visual field dominance to colours, especially when males were exposed to `aggression-specific' colours and females to `courtship-specific' colours
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