bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comparative study of ultrasound‐triggered behaviour in tiger beetles (Cicindelidae)
Authors: Yager David D. , Cook Aaron P. , Pearson David L. , Spangler Hayward G. 
Published: February 2006

AbstractThis study examines the behavioural responses to ultrasound in 52 species from the family Cicindelidae using both tethered flight and non‐flight assays. Tethered flying tiger beetles respond to trains of bat‐like ultrasonic pulses with a short‐latency, multi‐component behaviour. There was no variation in the nature of the behavioural responses regardless of geographical distribution or phylogenetic position. Lowest mean behavioural thresholds lie predominantly between 30 and 45 kHz. Sensitivity, however, varies widely, and several species do not respond at all in these assays. The lowest thresholds for responders are most often between 70 and 80 dB SPL. Almost all subgenera of North American tiger beetles in the genus Cicindela have at least some species with low‐threshold acoustic behaviour. The single exception is the large subgenus Cicindela where all species are completely unresponsive or have very high thresholds. There was little relationship between habitat and responsiveness to ultrasound, but there is a strong correlation with seasonal activity – species with adults active in the spring and autumn (all in the subgenus Cicindela) do not show ultrasound‐triggered behaviour whereas summer‐active species generally do. Superimposing these data on a current phylogeny of the North American tiger beetles suggests that acoustic behaviour (and hearing) is a shared primitive trait among the taxa examined here and that there have been at least five independent losses of this character.
Differential microdistributions and interspecific interactions in coexisting native and introduced Gammarus spp. (Crustacea: Amphipoda)
Authors: MacNeil Calum , Prenter John 
Published: February 2006

AbstractIn Northern Ireland, the native Gammarus duebeni celticus and introduced Gammarus tigrinus occur in the same river and lake systems. This study examined the outcome of encounters between the two amphipod species in the same patch of lake/pooled area of river. A laboratory simulation of a lake/river habitat indicated that G. d. celticus and G. tigrinus differed in distribution within the same complex habitat. Cannibalism was low for both species in single and mixed species treatments. However, G. tigrinus suffered heavy intraguild predation (IGP) from G. d. celticus in mixed species treatments, with 22% of the laboratory population of G. tigrinus being eliminated within 4 days. There was negligible reciprocal predation of G. d. celticus by G. tigrinus. It is proposed that IGP may account for G. tigrinus occurring more frequently and in greater abundance in patches of lotic and lentic systems where predatory G. d. celticus is absent or scarce.
Food selection by beavers (Castor fiber albicus) in relation to plant chemicals and possible effects of flooding on food quality
Authors: Ganzhorn Jörg U. , Harthun Mark 
Published: February 2006

AbstractThe goal of this study was to investigate whether or not beavers Castor fiber albicus improve the quality of their food plants by dam construction, resulting in periodic flooding associated with the deposition of mud and nutrients on their feeding grounds. For this, food selection of beavers was studied in relation to plant chemicals in the Spessart mountains (central Germany). The concentrations of the preferred plant chemicals were compared between individuals of the same plant species growing in areas that were flooded periodically and areas that were edaphically dry. Plants eaten by beavers contained higher concentrations of nitrogen and lower concentrations of neutral detergent fibre and hemicellulose than neighbouring plants that were not eaten. Neither nitrogen concentrations nor neutral detergent fibre contents differed significantly between plants from the dry and wet sites. Thus, beaver activities did not improve the chemical quality of their food plants.
Individual signatures in scent gland secretions of Eurasian deer
Authors: Lawson R. E. , Putnam R. J. , Fielding A. H. 
Published: February 2006

AbstractEvidence for individuality of odour profile, coding for individual identity, was sought in scent profiles derived from natural secretions of the preorbital gland of red deerCervus elaphus(n= 26), sika deerC. nippon(15), fallow deerDama dama(50), Chinese muntjacMuntiacus reevesi(23) and Chinese water deerHydropotes inermis(53); from metatarsal secretions from red deer (n= 35), sika (30), fallow (193) and roe deerCapreolus capreolus(26), and from roe deer interdigital glands (n= 48). Volatiles were eluted from sample materials at body temperature, to restrict analysis to those elements that would occur within the natural odour signal; the different volatile elements were then separated by gas chromatography. For each species considered, secretions from at least one scent gland were individually distinct and sufficiently complex to code for identity. Within our samples no two individuals produced identical odour profiles; yet in analysis of metatarsal gland secretions of individual fallow deer sampled in successive years, odour signatures of individuals remained consistent over time. The wider potential for individual coding was assessed through calculation of the number of different possible combinations of all volatiles recovered in any species×gland system. Every secretion considered seems to have the potential to provide individually characteristic signals (with the exception of secretions from the fallow deer preorbital gland, which notably contained no odour information under any analytical system). Complexity of signals differed markedly between species as did the gland‐type responsible for production of the most complex or distinctive signal. No simple evolutionary patterns are apparent to account for this variation and we suggest that the form of gland selected for production of a signal carrying information about individual identity is a function of habitat type and sociality.
Between‐year differences in the feeding ecology of highland marmosets (Callithrix auritaandCallithrix flaviceps) in south‐eastern Brazil
Authors: Corrêa H. Kátia M. , Coutinho Paulo E. G. , Ferrari Stephen F. 
Published: February 2006

AbstractThe behaviour of free‐ranging groups ofCallithrix auritaandCallithrix flaviceps, small‐bodied omnivorous marmosets, was monitored at two sites (Cunha and Caratinga, respectively) in south‐eastern Brazil during equivalent periods in consecutive years. Quantitative behavioural data were collected using a standard scan‐sampling protocol, with scans being taken at 5‐min intervals throughout the daily activity period. Data were collected during the wet season months of January and February at Cunha in 1993 and 1994, and during the dry season months of July and August at Caratinga in 1985 and 1986. In both cases, wet‐season precipitation levels were considerably higher during the first year. Activity budgets, daily ranging and the foraging behaviour of both species were compared between years. Significant between‐year differences were observed in several behaviour categories in both species, and were consistent with seasonal and longitudinal variation in resource abundance. InC. aurita, apparent changes in fruiting patterns resulted in a significant increase in exudate feeding in the second year, both in relative and absolute terms, but little change in prey foraging. By contrast, a marked reduction in arthropod prey in 1986 resulted in major changes in most aspects ofC. flavicepsbehaviour, with the exception of plant feeding. While consistent with behaviour patterns in other marmoset species, the numerous significant differences observed in the present study further highlight the problems associated with the evaluation of intertaxon differences in the behaviour and ecology of primates, in particular marmosets, on the basis of relatively short‐term studies of a few individuals, often at only a single study site.
Daily and seasonal activity of the mountain tapir (Tapirus pinchaque) in the Central Andes of Colombia
Authors: Lizcano Diego J. , Cavelier Jaime 
Published: February 2006

AbstractDaily and seasonal activity of the mountain tapir Tapirus pinchaque was measured along trails and at two salt licks in mature and secondary montane forests of the Central Andes of Colombia using active and passive infrared monitors. Daily activity of the mountain tapir showed a clear bimodal pattern, with maxima during the early hours of the day (5:00–7:00) and early hours of the evening (18:00–20:00). This bimodal activity pattern has also been found in radio‐tracking studies of T. terrestris and T. bairdii. Overall, there was more activity in mature than in secondary forest and at lower (3100 m) than higher altitudes (3600 m). Night‐time activity was higher during full moon than during quarter and new moons. There was no correlation between monthly rainfall and seasonal activity. The time the mountain tapir was at the salt licks varied between 1 and 190 min. Daily activity at Quebrada Paraiso salt lick (3400 m) showed a clear bimodal pattern with maxima around midnight (0:00–2:00) and midday (11:00–14:00). These patterns of diurnal and nocturnal activity of the mountain tapir could be used in combination with future radio‐tracking studies to better understand habitat use by this species.
Pituitary sensitivity to exogenous GnRH in giant Zambian mole‐rats, Cryptomys mechowi (Rodentia: Bathyergidae): support for the ‘socially induced infertility continuum’
Authors: Bennett N. C. , Molteno A. J. , Spinks A. C. 
Published: February 2006

AbstractThe giant mole‐rat Cryptomys mechowi exhibits an extreme reproductive division of labour. Reproduction in the colony is restricted to a single breeding pair. Non‐reproductive individuals do not breed unless removed from the colony and paired with unfamiliar conspecifics. Circulating basal concentrations of luteinizing hormone (LH) as well as LH levels measured in response to a single exogenous gonadotropin hormone (GnRH) challenge are not significantly different between the reproductive and non‐reproductive groups of either sex. Neither non‐reproductive males nor females are physiologically suppressed at the level of the pituitary, as they do not exhibit a reduced pituitary secretion of LH or decreased sensitivity to hypothalamic GnRH. Rather, reproductive skew seems to result from an inhibition to mate with familiar conspecifics. Familiar individuals housed in the absence of the breeding pair did not breed, whereas pairing unfamiliar individuals of the opposite sex resulted in sexual activity and recruitment. The results from the giant mole‐rat suggest that reproductive skew may result from a predominantly behavioural repression in non‐reproductive females arising from an incest avoidance mechanism.
Plasma fatty acids, triacylglycerol and cholesterol of the tuatara (Sphenodon punctatus punctatus) from islands differing in the presence of rats and the abundance of seabirds
Authors: Blair T. A. , Cree A. , Skeaff C. M. 
Published: February 2006

AbstractNorthern tuatara Sphenodon punctatus punctatus survive on about 26 islands off the north‐east coast of the North Island, New Zealand. These rare, lizard‐like reptiles include seabirds in their diet. The presence of the Pacific rat Rattus exulans on some islands has been implicated in the decline of tuatara populations through predation and competition for food. Pacific rats and tuatara eat similar dietary items, including seabirds. Seabirds have high levels of the long chain n‐3 polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The potential contribution of seabirds to the diet of tuatara was investigated by measuring the composition of plasma fatty acids and the concentrations of triacylglycerol and cholesterol of adult tuatara from Green Island (rat‐free, numerous seabirds) and Coppermine Island (rat‐inhabited, relatively few seabirds). The composition of plasma fatty acids differed between islands and sexes. Specifically, tuatara from rat‐free Green Island had higher levels of the long chain PUFAs arachidonic acid, EPA and DHA compared to tuatara on rat‐inhabited Coppermine Island, and males had significantly higher levels of DHA than females on both islands. Concentrations of plasma triacylglycerol and cholesterol were higher in tuatara from Green Island than Coppermine Island. Males had higher cholesterol but lower triacylglycerol concentrations than females. Differences in fatty acid composition and lipid concentrations between groups of tuatara imply differences in diet. Tuatara on the rat‐free island evidently had a higher intake of n‐3 PUFAs compared with tuatara on the rat‐inhabited island. This is probably due to higher seabird consumption, or perhaps to the presence of other dietary items containing EPA and DHA. High concentrations of plasma triacylglycerol and cholesterol may be the result of a high intake of insect larvae. We recommend the direct investigation of the diets of northern tuatara and the consequences of differences in the composition of plasma fatty acids for reproduction.
Foraging behaviour of Cape clawless otters (Aonyx capensis) in a marine habitat
Authors: Somers Michael John 
Published: February 2006

AbstractThe foraging behaviour of Cape clawless ottersAonyx capensiswas investigated. Factors included: duration of dives, recovery times, processing times, hunting success, per cent time at the surface, and time foraging before each catch. Observations were made during the day on solitary adultA. capensisin a marine environment in False Bay, South Africa. There were significant differences in duration of unsuccessful dives, recovery times, and processing times as well as successful dives with various depths.Aonyx capensisprefer hunting at depths of 0.5–1.5 m. This is despite having a higher hunting success, catching larger, more energy‐rich prey (fish), and shortest time foraging per catch, at depths of 1.5–2.5 m. Some of the data presented support the optimal breathing hypothesis, which predicts that both surface and dive times should increase for dives of greater depths. However, diving efficiency does not decrease with increasing depth, and percentage time at the surface does not increase with increasing depth. These are contrary to the optimal breathing hypothesis.
Embryonic and larval development of a substrate‐brooding cichlid Cichlasoma dimerus (Heckel, 1840) under laboratory conditions
Authors: Meijide F. J. , Guerrero G. A. 
Published: February 2006

AbstractThere is a vast literature on the reproductive behaviour of cichlid fishes, most of which describes spawning strategies and parental care. However, descriptive information on the early development of cichlids is scarce. In this study, embryos and larvae of laboratory‐reared Cichlasoma dimerus are described. The early ontogeny is documented from oocyte activation until the beginning of the juvenile period. At a water temperature of 25 ± 0.5 °C and a 12:12 h photoperiod, cleavage is finished in 10 h and the first somites appear at 26 h of development. The larvae hatch during the beginning of the third day and are deposited by both parents in a pit they have dug out in advance. Yolk‐sac larvae present three pairs of adhesive glands over the head, these transient larval organs being characteristic of substrate‐brooding cichlids. After another 5 days, the fry swim freely and begin to feed exogenously. Since the yolk‐sac is not completely reabsorbed until 2 or 3 days later, there is a period of combined endogenous and exogenous food supply. The juvenile stage is reached on the 42nd day from spawning.
Ecomorphological patterns related to migration: a comparative osteological study with passerines
Authors: Calmaestra Ricardo G. , Moreno Eulalia 
Published: February 2006

AbstractAn analysis of forelimb and hindlimb skeletal morphology of 15 passerine genera was performed to investigate the likely existence of an ecomorphological pattern relating morphology to migratory behaviour. Each genus was represented by a pair of species, one being sedentary and another migrant. Using a phylogenetic comparative method we found migrant species having longer sternum, deeper keel and longer coracoids than non‐migrant species. Hindlimb morphology was not related to migration. These results are interpreted as adaptations for migrants favouring flight ability, as the larger the sternum and the coracoids the greater the surface available for attachment of the main muscles involved in active flight.
Interplay between acclimation time and diet quality on basal metabolic rate in females of degus Octodon degus (Rodentia: Octodontidae)
Authors: Veloso Claudio , Bozinovic Francisco 
Published: February 2006

AbstractThe effect of diet quality on basal metabolic rate (BMR) over time was studied in female Octodon degus. Degus fed on a low‐quality diet maintained a constant BMR over time, while those fed on a high‐quality diet showed an increased BMR after 30 days. After 120 days of dietary acclimation, individuals fed on a high‐quality diet exhibited comparatively higher BMRs. Thus, we hypothesize that when environmental food quality is high, degus are able to increase their BMR quickly, allowing high rates of biosynthesis.
Body weights in grey and red squirrels: do seasonal weight increases occur in conifer woodland?
Authors: Lurz P. W. W. , Lloyd A. J. 
Published: February 2006

AbstractSeasonal body weight changes were investigated in red and grey squirrels in spruce‐dominated conifer plantations in the north of England. Annual seed food availability, particularly in the spruce plantations, varies markedly and is characterized by years with large cone crops (‘mast crops’) followed by several years of intermediate or low crops. The last mast crop in Kielder Forest District occurred in 1991 and we studied the two squirrel species when food availability was intermediate and low between 1992 and 1999. Neither red nor grey squirrels in the conifer plantations significantly increased their body weight for the autumn or winter. The responses of red and grey squirrels to the different foraging conditions in deciduous and conifer woodlands and the accumulation of seasonal fat stores may have to be seen in the context of habitat type and the pattern and predictability of seed availability. Our findings suggest that fat accumulation is likely to be less pronounced in conifer habitats where autumn and winter food supplies are more predictable, and manoeuvrability to feed on cones in the canopy is important.
Allozyme variation in the Eurasian badgerMeles melesin Denmark
Authors: Pertoldi Cino , Loeschcke Volker , Madsen Aksel Bo , Randi Ettore 
Published: February 2006

AbstractGenetic diversity in four populations of the Eurasian badgerMeles melesfrom Denmark was estimated by allozyme electrophoresis. Low genetic variability was found within populations as compared to the variability found in badger populations from other countries, whereas significant genetic differentiation was found between populations. The low genetic variability and the differentiation between populations is explained by the fragmentation of the Danish landscape, which reduces the effective population size of local populations and the gene flow between them. Low genetic variability found for Danish badgers also supports the hypothesis of a rapid recolonization following the last glaciation.
Varieties of attention in neutral trials: Linking RT to ERPs and EEG frequencies
Authors: Jongen Ellen M.M. , Smulders Fren T.Y. , van Breukelen Gerard J.P. 
Published: February 2006

AbstractIt is often assumed that when a neutral cue is presented in a spatial cueing task, attention remains at fixation until target onset. We hypothesized that variance in nonspatial attention and switches of attention toward target locations can account for variance in reaction times of neutral trials. Lateralized event‐related potentials (ERPs) and changes in electroencephalogram (EEG) frequency bands served as predictor variables in a single‐trial logistic regression analysis to predict the direction of spatial attention in cued and neutral trials. The contingent negative variation (CNV) and nonlateralized changes in the alpha band served as markers of nonspatial attention. The direction of attention in cued trials was reliably predicted from single‐trial lateralized ERP components. In neutral trials, only evidence for nonspatial attention was found, indicated by increases in the CNV and decreases in alpha preceding targets to which responses were relatively fast.
Reduced baroreflex cardiac sensitivity predicts increased cognitive performance
Authors: Yasumasu Tomiya , Reyes del Paso Gustavo A. , Takahara Kazuo , Nakashima Yasuhide 
Published: February 2006

AbstractThis study evaluated the relationship between baroreceptor reflex sensitivity and cognitive performance. Twenty normal subjects performed the Uchida–Kraepelin test, a serial arithmetic task. Baroreceptor reflex sensitivity during a 5‐min Uchida–Kraepelin test was assessed in minute periods by spectral analysis using the maximum‐entropy method. During the task, baroreceptor reflex sensitivity was significantly reduced. There was an inverse between‐subjects association between baroreceptor reflex sensitivity and the level of performance (number of additions completed) both at different time periods of the Uchida–Kraepelin test and during the whole task (r=−.51). This finding supports the existence of a pathway mediating mutual cardiovascular–central nervous system influences through the baroreceptors, establishing an essential mechanism facilitating adaptive reactions to stressful conditions.
Now you feel it—now you don't: ERP correlates of somatosensory awareness
Authors: Schubert Ruth , Blankenburg Felix , Lemm Steven , Villringer Arno , Curio Gabriel 
Published: February 2006

AbstractWe investigated correlates of somatosensory awareness for supratheshold stimuli using event‐related potentials in a masking paradigm: Conscious perception of a weak, but suprathreshold “target” stimulus was suppressed in a significant number of trials when followed by a higher‐intensity “mask” stimulus. ERPs were compared for trials with perceived versus unperceived target stimuli. Early ERPs (P60, N80), generated in the contralateral S1, were found independent of stimulus perception. In contrast, for consciously perceived target stimuli, amplitude enhancements were observed for the P100 and N140. Thus, early activation of S1 is not sufficient to warrant conscious stimulus perception. Conscious stimulus processing differs significantly from unconscious processing starting around 100 ms after stimulus presentation when the signal is processed in parietal and frontal cortices, brain regions crucial for stimulus access into conscious perception.
Effects of picture content and intensity on affective physiological response
Authors: Bernat Edward , Patrick Christopher J. , Benning Stephen D. , Tellegen Auke 
Published: February 2006

AbstractThis study evaluated the effects of affective intensity and thematic content of foreground photographic stimuli on various physiological response systems. This was accomplished by assessing responses to pictures that varied systematically in these parameters. Along with overall effects of picture valence reported in previous work, we found effects of thematic content (i.e., specific nature of objects/events depicted) for all measures except heart rate. In addition, we found that the magnitude of startle blink, skin conductance, and corrugator muscle reactions increased with increasing affective intensity of pictures. Additionally, for these three measures, intensity effects also interacted with effects of picture content. These results indicate that stimulus parameters of intensity and thematic content exert separate—and in some cases interactive—modulatory effects on physiological reactions to emotional pictures.