Find research datasets worth reusing

opencc-zeroJan 2020View details →

Macroalgal blooms caused by marine nutrient changes resulting from human activities

1. Macroalgal blooms (green tides) are occurring more frequently in many regions of the world, leading to significant impacts on marine ecology and economies. Although many studies and hypotheses have been proposed, the exact mechanism of green tide formation remains unclear. 2. The world's largest green tides recur in the Yellow Sea and this area is representative for studying the origin and mechanism of green tide formation. We conducted a meta-analysis of studies related to green tides and associated hypotheses for their formation. 3. Rapid industrialization/urbanization and environmental protection actions in coastal zones have led to an increase in nitrate (nitrite) and decline in ammonium (ammonia), and this has resulted in increasing levels of dissolved inorganic nitrogen in seawater. 4. We found that presence of appropriate attachment substrates for Ulva including laver culture rafts and certain hydrological conditions are supplementary factors to green tide formation in the Yellow Sea. 5. Changes in marine nutrient levels promote the production of nitric oxide, which is essential for Ulva sporulation. Consequently, numerous spores are created and attach to substrates including laver culture rafts and parent Ulva thalli. These spores then develop into new thalli that are capable of producing further spores. As a result, Ulva thalli rapidly occupy vast areas of the sea and develop into green tides. 6. Synthesis and applications. Our synthesis identifies that escalating marine nitric oxide generation caused by various factors and its essential role in Ulva sporulation are underlying and significant components in the mechanism of green tide formation. We provide solutions such as the improvement of comprehensive management of aquaculture and strict restriction of marine nitrate pollution, to prevent green tides. Furthermore, we propose an innovative wastewater treatment programme combined with Ulva application to fulfil the standard of sustainable development and circular economy.

Data from: Human activities and landscape features interact to closely define the distribution and dispersal of an urban commensal.

The rock pigeon, Columba livia, is a cosmopolitan human commensal, domesticated thousands of years ago. However, the human-mediated factors governing its distribution and dispersal are not well understood. In this study, we performed (1) hierarchical distance sampling on ~400 island-wide point transects, (2) a population genomic inquiry based on ~7000 SNPs from almost 150 individuals, and (3) landscape-genomic analyses on the basis of extensive ecological and social-economic databases to characterize the distribution and dispersal patterns of rock pigeons across Singapore. Our distance sampling results indicated that the volume of intentional 'mercy feeding' and availability of high-rise buildings are the most reliable predictors of high pigeon densities in Singapore. Genomic analyses demonstrated that rock pigeons in Singapore form a single population possibly derived from rapid expansion from a genetically homogenous group of founder individuals. Specifically, rock pigeons in Singapore lack sex-biased dispersal and are clustered with a genetic patch size of ~3km. Landscape genomic analyses of great precision pointed to the presence of dense trees as agents of resistance to dispersal whereas a high road density reduces this resistance. By pinpointing a range of ecological and socio-economic variables determining the distribution and dispersal of pigeons, our study provides urban planners with the tools for optimal management of this human commensal, such as a curtailment of the practice of mercy feeding and modifications to the urban landscape to reduce pigeon density and to lower the likelihood of repopulation by dispersal.

Data from: How to quantify animal activity from radio-frequency identification (RFID) recordings

Automated animal monitoring via radio-frequency identification (RFID) technology allows efficient and extensive data sampling of individual activity levels, and is therefore commonly used for ecological research. However, processing RFID data is still a largely unresolved problem, which potentially leads to inaccurate estimates for behavioural activity. One of the major challenges during data processing is to isolate independent behavioural actions from a set of superfluous, non-independent detections. As a case study, individual blue tits (Cyanistes caeruleus) were simultaneously monitored during reproduction with both video recordings and RFID technology. We demonstrated how RFID data can be processed based on the time spent in- and outside a nest box. We then validated the number and timing of nest visits obtained from the processed RFID dataset by calibration against video recordings. The video observations revealed a limited overlap between the time spent in- and outside the nest box, with the least overlap at 23 seconds for both sexes. We then isolated exact arrival times from redundant RFID registrations by erasing all successive registrations within 23 seconds after the preceding registration. After aligning the processed RFID data with the corresponding video recordings, we observed a high accuracy in three behavioural estimates of parental care (individual nest visit rates, within-pair alternation and synchronization of nest visits). We provide a clear guideline for future studies that aim to implement RFID technology in their research. We argue that our suggested RFID data processing procedure improves the precision of behavioural estimates, despite some inevitable drawbacks inherent to the technology. Our method is useful, not only for other cavity breeding birds, but for a wide range of (in)vertebrate species that are large enough to be fitted with a tag and that regularly pass near or through a fixed antenna.

Data from: Social facilitation is a better predictor of frog reproductive activity than environmental factors

Anuran breeding activity is frequently linked to environmental factors, mainly temperature and rainfall. However, a key feature of anuran reproductive behavior—gathering in choruses and producing loud advertisement calls to attract females—generates a conspicuous social cue that may also facilitate reproductive behavior. Here, I examine the relative importance of environmental and social factors in explaining the intensity of reproductive activity in the Neotropical treefrog Hypsiboas rosenbergi. I show that social cues generally play an important role, but that there are sex differences: male behavior is associated with a combination of environmental and social factors, while female behavior is associated almost exclusively with social cues. I discuss the potential benefits of using social cues in regulating breeding activity, and suggest that conservation efforts may take advantage of the apparently widespread pattern of social facilitation in anuran reproductive ecology.

Data from: Accelerometers can measure total and activity-specific energy expenditure in free-ranging marine mammals only if linked to time-activity budgets

Energy expenditure is an important component of foraging ecology, but is extremely difficult to estimate in free-ranging animals and depends on how animals partition their time between different activities during foraging. Acceleration data have emerged as a new way to determine energy expenditure at a fine scale but this needs to be tested and validated in wild animals. This study investigated whether vectorial dynamic body acceleration (VeDBA) could accurately predict the energy expended by marine predators during a full foraging trip. We also aimed to determine whether the accuracy of predictions of energy expenditure derived from acceleration increased when partitioned by different types of at-sea activities (i.e. diving, transiting, resting and surface activities). To do so, we equipped 20 lactating northern (Callorhinus ursinus) and 20 lactating Antarctic fur seals (Arctocephalus gazella) with GPS, time-depth recorders and tri-axial accelerometers and obtained estimates of field metabolic rates using the doubly labelled water (DLW) method. VeDBA was derived from tri-axial acceleration, and at-sea activities (diving, transiting, resting and surface activities) were determined using dive depth, tri-axial acceleration and travelling speed. We found that VeDBA did not accurately predict the total energy expended by fur seals during their full foraging trips (R2 = 0·36). However, the accuracy of VeDBA as a predictor of total energy expenditure increased significantly when foraging trips were partitioned by activity and when activity-specific VeDBA was paired with time-activity budgets (R2 = 0·70). Activity-specific VeDBA also accurately predicted the energy expenditures of each activity independent of each other (R2 > 0·85). Our study confirms that acceleration is a promising way to estimate energy expenditures of free-ranging marine mammals at a fine scale never attained before. However, it shows that it needs to be based on the time-activity budgets that make up foraging trips rather than being derived as a single measure of VeDBA applied to entire foraging trips. Our activity-based method provides a cost-effective means to accurately calculate energy expenditures of fur seals using acceleration and time-activity budgets, that can be transfered to studies on other species.

Data from: Active and reactive behaviour in human mobility: the influence of attraction points on pedestrians

Human mobility is becoming an accessible field of study thanks to the progress and availability of tracking technologies as a common feature of smart phones. We describe an example of a scalable experiment exploiting these circumstances at a public, outdoor fair in Barcelona (Spain). Participants were tracked while wandering through an open space with activity stands attracting their attention. We develop a general modeling framework based on Langevin Dynamics, which allows us to test the influence of two distinct types of ingredients on mobility: reactive or context-dependent factors, modelled by means of a force field generated by attraction points in a given spatial configuration, and active or inherent factors, modelled from intrinsic movement patterns of the subjects. The additive and constructive framework model accounts for some observed features. Starting with the simplest model (purely random walkers) as a reference, we progressively introduce different ingredients such as persistence, memory, and perceptual landscape, aiming to untangle active and reactive contributions and quantify their respective relevance. The proposed approach may help in anticipating the spatial distribution of citizens in alternative scenarios and in improving the design of public events based on a facts-based approach.

Data from: Developmental changes in hippocampal CA1 single neuron firing and theta activity during associative learning

Hippocampal development is thought to play a crucial role in the emergence of many forms of learning and memory, but ontogenetic changes in hippocampal activity during learning have not been examined thoroughly. We examined the ontogeny of hippocampal function by recording theta and single neuron activity from the dorsal hippocampal CA1 area while rat pups were trained in associative learning. Three different age groups [postnatal days (P)17-19, P21-23, and P24-26] were trained over six sessions using a tone conditioned stimulus (CS) and a periorbital stimulation unconditioned stimulus (US). Learning increased as a function of age, with the P21-23 and P24-26 groups learning faster than the P17-19 group. Age- and learning-related changes in both theta and single neuron activity were observed. CA1 pyramidal cells in the older age groups showed greater task-related activity than the P17-19 group during CS-US paired sessions. The proportion of trials with a significant theta (4–10 Hz) power change, the theta/delta ratio, and theta peak frequency also increased in an age-dependent manner. Finally, spike/theta phase-locking during the CS showed an age-related increase. The findings indicate substantial developmental changes in dorsal hippocampal function that may play a role in the ontogeny of learning and memory.

opencc-zeroFeb 2020View details →

Comparative study on photocatalytic activity of transition metals (Ag and Ni doped ZnO) nanomaterials synthesised via sol-gel method

Ag and Ni/ZnO photocatalyst nanostructures were successfully synthesized by a sol-gel method. In this work, the photocatalyst sample was systematically studied based on several factors affecting the performance of photocatalyst which are size, morphology, band gap, textural properties and the number of active sites presence on the surface of the nanocatalyst. X-ray Diffraction (XRD) revealed that Ag/ZnO nanomaterials experienced multiple phases, meanwhile for Ni/ZnO the phase of nanomaterials were pure and single phase for stochiometry less than 5%. Field emission scanning electron microscope (FESEM) showed almost all of the synthesised nanomaterials possessed a mixture of nanorods and spherical-like shape morphology. The Ag/ZnO showed high photocatalytic activity, producing at least 14th trials of nanocatalyst reusability on the degradation of Methyl Orange under UV irradiation. Interestingly this phenomenon was not observed in larger surface area of Ni/ZnO nanomaterials which supposedly favour photocatalytic activity, but instead producing poor photocatalytic performance. The main reason were studied and exposed by temperature-programmed desorption of carbon dioxide (TPD–CO2) which showed that incorporation of Ag into ZnO lattice has enhanced the number of active sites on the surface of the nanocatalyst. Whereas incorporation of Ni in ZnO has lowered the number of active sites with respect to undoped ZnO. Active sites measurement is effective and significant, providing opportunities in developing an intensive study as an additional factor.

Data from: Vegetation connectivity increases ant activity and potential for ant-provided biocontrol services in a tropical agroforest

In natural and managed systems, connections between trees are important structural resources for arboreal ant communities with ecosystem-level effects. However, ongoing agricultural intensification in agroforestry systems, which reduces shade trees and connectivity between trees and crop plants, may hinder ant recruitment rates to resources and pest control services provided by ants. We examined whether increasing connectivity between coffee plants and shade trees in coffee plantations increases ant activity and enhances biological control of the coffee berry borer, the most devastating insect pest of coffee. Further, we examined whether artificial connections buffer against the loss of vegetation connectivity in coffee plants located at larger distances from the nesting tree. We used string to connect Inga micheliana shade trees containing Azteca sericeasur ant nests to coffee plants to compare ant activity before and after placement of the strings, and measured borer removal by ants on coffee plants with and without strings. Ant activity significantly increased after the addition of strings on connected plants, but not on control plants. Borer removal by ants was also three times higher on connected plants after string placement. Greater distance from the nesting tree negatively influenced ant activity on control coffee plants, but not on connected plants, suggesting that connections between coffee plants and nest trees could potentially compensate for the negative effects that larger distances pose on ant activity. Our study shows that favoring connectivity at the local scale, by artificially adding connections, promotes ant activity and may increase pest removal in agroecosystems.

opencc-zeroDec 2014View details →

Data from: Effects of the selective stretch-activated channel blocker GsMtx4 on stretch-induced changes in refractoriness in isolated rat hearts and on ventricular premature beats and arrhythmias after coronary occlusion in swine

Mechanical factors may contribute to ischemic ventricular arrhythmias. GsMtx4 peptide, a selective stretch-activated channel blocker, inhibits stretch-induced atrial arrhythmias. We aimed to assess whether GsMtx4 protects against ventricular ectopy and arrhythmias following coronary occlusion in swine. First, the effects of 170-nM GsMtx4 on the changes in the effective refractory period (ERP) induced by left ventricular (LV) dilatation were assessed in 8 isolated rat hearts. Then, 44 anesthetized, open-chest pigs subjected to 50-min left anterior descending artery occlusion and 2-h reperfusion were blindly allocated to GsMtx4 (57 μg/kg iv. bolus and 3.8 μg/kg/min infusion, calculated to attain the above concentration in plasma) or saline, starting 5-min before occlusion and continuing until after reflow. In rat hearts, LV distension induced progressive reductions in ERP (35±2, 32±2, and 29±2 ms at 0, 20, and 40 mmHg of LV end-diastolic pressure, respectively, P<0.001) that were prevented by GsMTx4 (33±2, 33±2, and 32±2 ms, respectively, P=0.002 for the interaction with LV end-diastolic pressure). Pigs receiving GsMtx4 had similar number of ventricular premature beats during the ischemic period as control pigs (110±28 vs. 103±21, respectively, P=0.842). There were not significant differences among treated and untreated animals in the incidence of ventricular fibrillation (13.6 vs. 22.7%, respectively, P=0.696) or tachycardia (36.4 vs. 50.0%, P=0.361) or in the number of ventricular tachycardia episodes during the occlusion period (1.8±0.7 vs. 5.5±2.6, P=0.323). Thus, GsMtx4 administered under these conditions does not suppress ventricular ectopy following coronary occlusion in swine. Whether it might protect against malignant arrhythmias should be tested in studies powered for these outcomes.

Data from: Deconstruction of an African folk medicine uncovers a novel molecular strategy for therapeutic potassium channel activation

A third of the global population relies heavily upon traditional or folk medicines, such as the African shrub Mallotus oppositifolius. Here, we used pharmacological screening and electrophysiological analysis in combination with in silico docking and site-directed mutagenesis to elucidate the effects of M. oppositifolius constituents on KCNQ1, a ubiquitous and influential cardiac and epithelial voltage-gated potassium (Kv) channel. Two components of the M. oppositifolius leaf extract, mallotoxin (MTX) and 3-ethyl-2-hydroxy-2-cyclopenten-1-one (CPT1), augmented KCNQ1 current by negative shifting its voltage dependence of activation. MTX was also highly effective at augmenting currents generated by KCNQ1 in complexes with native partners KCNE1 or SMIT1; conversely, MTX inhibited KCNQ1-KCNE3 channels. MTX and CPT1 activated KCNQ1 by hydrogen bonding to the foot of the voltage sensor, a previously unidentified drug site which we also find to be essential for MTX activation of the related KCNQ2/3 channel. The findings elucidate the molecular mechanistic basis for modulation by a widely used folk medicine of an important human Kv channel and uncover novel molecular approaches for therapeutic modulation of potassium channel activity.

opencc-zeroDec 2013View details →

Data from: Abiotic constraints on the activity of tropical lizards

Many tropical ectotherms are considered vulnerable to anthropogenic climate change because they have evolved to become thermal specialists. Indeed, several recent studies have suggested that even small increases in mean operative temperature may lead to a reduction in activity and the subsequent extinction of populations. Within the tropics, lizards are considered particularly vulnerable due to the potential for climate change to directly impact physiology and alter community interactions. However, models usually focus on the effects of mean operative temperature at the expense of other climate variables that may also affect lizard physiology. We used daily variation in operative temperature, humidity, and wind speed to examine how changes in climate influence activity in two species of lizards from the island of Cayo Menor, Honduras. Anolis lemurinus is a forest species, whereas A. allisoni is an open-habitat species. We conducted daily surveys for active lizards in habitat typical to each species, while simultaneously measuring operative thermal environments with physical models. The effects of the thermal environment were considered in the context of the thermal sensitivity of sprint speed for each species, and compared with the effects of the hydric (humidity) and convective (wind) environments. When all surveys were combined into a single analysis, the activity of the forest species Anolis lemurinus was positively correlated with wind speed, the spatial heterogeneity of operative temperature, and the mismatch between mean operative temperature and the optimal temperature for sprint performance. Mean operative temperature did significantly effect Anolis lemurinus activity, but only when it was above their thermal optimum. Activity of the open-habitat species A. allisoni was negatively correlated with wind speed, but was not related to any other climate variable. Whereas the mismatch between mean operative temperature and the thermal optimum for performance predicted the activity level of the forest species in ways partially consistent with its use in models for the response of lizards to climate change, the effects of the abiotic environment were habitat-dependent. Our results suggest that successfully predicting the biological impacts of climate change will require holistic models that account for more than changes in mean temperature alone.

opencc-zeroDec 2016View details →

Data from: Livestock activity increases exotic plant richness, but wildlife increases native richness, with stronger effects under low productivity

1.Grazing by domestic livestock is one of the most widespread land uses worldwide, particularly in rangelands, where it co-occurs with grazing by wild herbivores. Grazing effects on plant diversity are likely to depend on intensity of grazing, herbivore type, coevolution with plants and prevailing environmental conditions. 2.We collected data on climate, plant productivity, soil properties, grazing intensity and herbivore type; and measured their effects on plant species richness from 451 sites across 0.4 M km2 of semi-arid rangelands in eastern Australia. We used structural equation modelling to examine the direct and indirect effects of increasing grazing intensity by different herbivores (cattle, sheep, kangaroos, rabbits) on native and exotic plant species richness across all sites, and in subsets focusing on three woodland communities spanning a gradient in productivity. 3.Direct effects of grazing by all herbivores were strongest under low productivity but waned with increasing productivity. Increases in the intensity of recent and historic livestock grazing corresponded with greater exotic plant richness under low productivity and less native plant richness under both low and moderate productivity. Rabbit effects were greatest under moderate productivity. Overall effects of kangaroos were benign. Grazing indirectly affected native and exotic plant richness by increasing soil phosphorus and reducing soil health (i.e., nutrient cycling). 4.Synthesis and applications. Our study shows that livestock grazing increases exotic species richness but reduces native richness, while kangaroo grazing increases native richness in environments with low productivity. The results provide clear messages for land managers and policy makers: (1) the coexistence of livestock grazing and plant diversity is only possible within more productive environments and (2) grazing under low or moderate productivity will impact upon native and exotic plant richness.

opencc-zeroJun 2021View details →

The Hydroperoxyl Radical Scavenging Activity of Sulfuretin: Insights from Theory

This dataset contains data from the calculations described in the paper: "Nguyen Thi Hoa, Do Thi My Hang, Do Phu Hieu, Huynh Van Truong, Loc Phuoc Hoang, Adam Mechler and Quan V. Vo*. (2021), The Hydroperoxyl Radical Scavenging Activity of Sulfuretin: Insights from Theory. Royal Society Open Science. 2021. The thermodynamic and kinetic calculations were applied to evaluate the HOO· radical scavenging activity of sulfuretin (SFR) in the gas phase and solvents (water and pentyl ethanoate) by the M06-2X/6-311++G(d,p) level of theory. SFR is predicted to be an excellent HOO• scavenger in water at pH = 7.40 with koverall = 4.75´107 M-1 s-1, principally due to an increase in the activity of the anionic form following the single electron transfer mechanism. Consistently the activity of the neutral form is more prominent in the nonpolar environment with koverall = 1.79´104 M-1 s-1 following the formal hydrogen transfer mechanism. Thus it is predicted that SFR exhibits better HOO· antiradical activity than typical antioxidants such as resveratrol, ascorbic acid, and Trolox in the lipid medium. The hydroperoxyl radical scavenging of SFR in the aqueous solution is ~530 times faster than that of Trolox and similar to ascorbic acid or resveratrol. This suggests that SFR is a promising radical scavenger in physiological environments.

opencc-zeroOct 2019View details →

Drosophila carboxypeptidase D (SILVER) is a key enzyme in neuropeptide processing required to maintain locomotor activity levels and survival rate

Neuropeptides are processed from larger preproproteins by a dedicated set of enzymes. The molecular and biochemical mechanisms underlying preproprotein processing and the functional importance of processing enzymes are well‐characterised in mammals, but little studied outside this group. In contrast to mammals, Drosophila melanogaster lacks a gene for carboxypeptidase E (CPE), a key enzyme for mammalian peptide processing. By combining peptidomics and neurogenetics, we addressed the role of carboxypeptidase D (dCPD) in global neuropeptide processing and selected peptide‐regulated behaviours in Drosophila. We found that a deficiency in dCPD results in C‐terminally extended peptides across the peptidome, suggesting that dCPD took over CPE function in the fruit fly. dCPD is widely expressed throughout the nervous system, including peptidergic neurons in the mushroom body and neuroendocrine cells expressing adipokinetic hormone. Conditional hypomorphic mutation in the dCPD‐encoding gene silver in the larva causes lethality, and leads to deficits in starvation‐induced hyperactivity and appetitive gustatory preference, as well as to reduced viability and activity levels in adults. A phylogenomic analysis suggests that loss of CPE is not common to insects, but only occurred in Hymenoptera and Diptera. Our results show that dCPD is a key enzyme for neuropeptide processing and peptide‐regulated behaviour in Drosophila. dCPD thus appears as a suitable target to genetically shut down total neuropeptide production in peptidergic neurons. The persistent occurrence of CPD in insect genomes may point to important further CPD functions beyond neuropeptide processing which cannot be fulfilled by CPE.

Data from: Mesoscale activity facilitates energy gain in a top predator

How animal movement decisions interact with the distribution of resources to shape individual performance is a key question in ecology. However, links between spatial and behavioural ecology and fitness consequences are poorly understood because the outcomes of individual resource selection decisions, such as energy intake, are rarely measured. In the open ocean, mesoscale features (~10-100 km) such as fronts and eddies can aggregate prey and thereby drive the distribution of foraging vertebrates through bottom-up biophysical coupling. These productive features are known to attract predators, yet their role in facilitating energy transfer to top predators is opaque. We investigated the use of mesoscale features by migrating northern elephant seals and quantified the corresponding energetic gains from the seals' foraging patterns at a daily resolution. Migrating elephant seals modified their diving behaviour and selected for mesoscale features when foraging. Daily energy gain increased significantly with increasing mesoscale activity, indicating that the physical environment can influence predator fitness at fine temporal scales. Results show that areas of high mesoscale activity not only attract top predators as foraging hotspots, but also lead to increased energy transfer across trophic levels. Our study provides evidence that the physical environment is an important factor in controlling energy flow to top predators by setting the stage for variation in resource availability. Such understanding is critical for assessing how changes in the environment and resource distribution will affect individual fitness and food web dynamics.

Data from: Non-uniform evolutionary response of gecko eye size to changes in diel activity patterns

Geckos feature a large range of eye sizes, but what drives this phenotypic diversity is currently unknown. Earlier studies point towards diel activity patterns (DAP) and locomotory mode, but phylogenetic comparative studies in support of the proposed adaptive mode of eye evolution are lacking. Here we test the hypothesis of DAP as the driver of eye size evolution with a dataset on 99 species of gecko. Results from phylogenetic generalized least square analysis (PGLS) and multivariate model-fitting reveal smaller eyes in diurnal geckos consistent with different phenotypic optima. However, Bayesian analyses of selective regime shifts demonstrate that only 2 of 9 transitions from nocturnal to diurnal activity are coupled with decreases in eye size, and 2 other regime shifts are not associated with DAP transitions. This non-uniform evolutionary response suggests that eye size is not the only functionally relevant variable. Evolutionary adaptations may therefore include different combinations of several traits (e.g., photoreceptors), all with the same functional outcome. Our results further demonstrate that DAP only partially explains eye size diversity in geckos. As open habitats favor the evolution of large eyes while obstructed habitats favor small eyes, the degree of habitat clutter emerges as another potential axis of eye diversification.

opencc-zeroNov 2015View details →

Data from: Baseline immune activity is associated with date rather than with moult stage in the Arctic-breeding barnacle goose (Branta leucopsis)

Variation in immune defence in birds is often explained either by external factors such as food availability and disease pressure or by internal factors such as moult and reproductive effort. We explored these factors together in one sampling design by measuring immune activity over the time frame of the moulting period of Arctic-breeding barnacle geese (Branta leucopsis). We assessed baseline innate immunity by measuring levels of complement-mediated lysis and natural antibody-mediated agglutination together with total and differential leukocyte counts. Variation in immune activity during moult was strongly associated with calendar date and to a smaller degree with the growth stage of wing feathers. We suggest that the association with calendar date reflected temporal changes in the external environment. This environmental factor was further explored by comparing the immune activity of geese in the Arctic population with conspecifics in the temperate climate zone at comparable moult stages. In the Arctic environment, which has a lower expected disease load, geese exhibited significantly lower values of complement-mediated lysis, their blood contained fewer leukocytes, and levels of phagocytic cells and reactive leukocytes were relatively low. This suggests that lower baseline immune activity could be associated with lower disease pressure. We conclude that in our study species, external factors such as food availability and disease pressure have a greater effect on temporal variation of baseline immune activity than internal factors such as moult stage.

opencc-zeroDec 2014View details →

Data from: The importance of delineating networks by activity type in bottlenose dolphins (Tursiops truncatus) in Cedar Key, Florida

Network analysis has proved to be a valuable tool for studying the behavioural patterns of complex social animals. Often such studies either do not distinguish between different behavioural states of the organisms or simply focus attention on a single behavioural state to the exclusion of all others. In either of these approaches it is impossible to ascertain how the behavioural patterns of individuals depend on the type of activity they are engaged in. Here we report on a network-based analysis of the behavioural associations in a population of bottlenose dolphins (Tursiops truncatus) in Cedar Key, Florida. We consider three distinct behavioural states—socializing, travelling and foraging—and analyse the association networks corresponding to each activity. Moreover, in constructing the different activity networks we do not simply record a spatial association between two individuals as being either present or absent, but rather quantify the degree of any association, thus allowing us to construct weighted networks describing each activity. The results of these weighted activity networks indicate that networks can reveal detailed patterns of bottlenose dolphins at the population level; dolphins socialize in large groups with preferential associations; travel in small groups with preferential associates; and spread out to forage in very small, weakly connected groups. There is some overlap in the socialize and travel networks but little overlap between the forage and other networks. This indicates that the social bonds maintained in other activities are less important as they forage on dispersed, solitary prey. The overall network, not sorted by activity, does not accurately represent any of these patterns.