bluuebunny/crossref_metadata_2025_split huggingface dataset:
Food resource partitioning of a community of snakes in a swamp rainforest of south‐eastern Nigeria
Authors: Luiselli Luca , Akani Godfrey C. , Capizzi Dario 
Published: February 2006

AbstractThe food resource partitioning in a community of snakes from a moist rainforest of south‐eastern Nigeria (Eket, Akwa‐Ibom State) is studied in the present paper. The community consisted of 24 different species, belonging to different families and ecological guilds: some species were terrestrial, some were semi‐aquatic, and others were arboreal. Six species were primarily mammal‐eating, two were bird‐eating, four were lizard‐eating, three were frog‐eating, one species fed on both mammals and birds, and one species fed on both fish and frogs. A UPGMA tree diagram showed that three clusters of snakes are formed on the basis of their diet composition: a cluster formed by the two large arboreal species (Dendroaspis jamesoni and Boiga blandingi), another formed by the group of the terrestrial mammal‐eating Calabaria reinhardti, Bitis gabonica, and Bitis nasicornis, and the third cluster formed by the lizard‐eating Psammophis phillipsi, Thelotornis kirtlandii, and Gastropyxis smaragdina. The relationships between these and the other taxa remain unclear. In terms of both frequency of occurrence of the various prey types and biomass contribution of each prey type, the semi‐aquatic snakes showed the narrowest niche breadth values and the terrestrial snakes showed the widest niche breadth values. The overlap values were not significantly correlated with the rank of phylogenetic distance. The mean overlap values calculated between species belonging to a same guild were significantly higher than those calculated between species belonging to different guilds, but the mean overlap values between species belonging to a same guild did not differ significantly among guilds. Prey size and predator size (total length) were positively correlated. There was no statistically significant difference between snake guilds as far as mean prey size is concerned, but the various species within each guild differed significantly in terms of mean prey size.
Comparison between the ecology of the new European frog Rana pyrenaica and that of four Pyrenean amphibians
Authors: Serra‐Cobo Jordi , Lacroix Gérard , White Sue 
Published: February 2006

AbstractThe objectives of the present study are to provide information about the habitat, behaviour, and reproduction of the new European frog species Rana pyrenaica, endemic in the central and western Pyrenees, and to compare the breeding characteristics of R. pyrenaica with those of four amphibians present in the same geographical area (Rana temporaria, Alytes obstetricans, Euproctus asper, and Triturus helveticus). Unlike R. temporaria, A. obstetricans, and T. helveticus, which are typically found in standing waters and are rather ubiquitous species, R. pyrenaica is a stenothermic, rheophilous species. Small torrents with cold, well‐oxygenated waters constitute its typical habitat. This species – which seems much more aquatic than R. temporaria– has been most often found in sympatry with the endemic urodele E. asper. Unlike R. temporaria, the females of R. pyrenaica lay small clutches of large eggs.
Movement of bottlenose dolphins around the south‐west coast of Britain
Authors: Wood C. J. 
Published: February 2006

AbstractAfter an absence of two decades a group of bottlenose dolphins, Tursiops truncatus, became resident in the coastal waters of Cornwall, U.K. in 1991. Using a combination of field techniques and information from the general public, the movements of this group were monitored. The dolphins demonstrated a seasonal residency pattern, spending the winter in southern Cornwall and moving further north‐eastward during spring and summer. Residency was flexible with a number of individual dolphins using the region intermittently. The dolphins occupied a linear range of coast of 650 km. Within this range they repeatedly made long‐distance journeys. Mean swimming speed was documented at 7.9 km·h−1, with the dolphins travelling the coast at a mean of 3.6 km·h−1. The longest journey recorded covered 1076 km and took 20 days. In one confirmed case the dolphins left the south‐west of England and were resighted in Wales. Such wide ranging movements have important implications for the conservation of bottlenose dolphins in U.K. waters.
Evolutionary implications of developmental and functional integration in bat wings
Authors: Adams Rick A. 
Published: February 2006

AbstractThis paper addresses how the wing membrane and skeletal system in bats are developmentally and functionally integrated during morphogenesis in the little brown bat (Myotis lucifugus). A truss network is used to quantify changes in the size and shape of the wing membrane during morphogenesis. Growth of the forearm and of third and fifth digits of the manus are also quantified. Principal component analysis indicates that changes in size of the wing (PC‐1) contribute 78% of growth variation, whereas shape changes (PC‐2, PC‐3) contribute only about 18% of growth variation. ANOVA run on component scores shows significant differences in size (PC‐1) of the wing between juveniles and sub‐adults, whereas no significant difference in shape (PC‐2 and 3) of the wing occurs during morphogenesis. In addition, growth compensation is shown to occur among sequentially developing skeletal elements comprising the hand wing. Coefficients of variation were significantly higher for phalangeal lengths than for total wing length and width. Compensation scores generated by summing residual scores produced by bivariate plots of wing bone elements show variable levels of compensation among individuals. However, a plot of scores against wing length shows compensation to occur throughout morphogenesis as scores are not correlated with wing size (r= 0.089). Apparently, selection has favoured a developmental system within which wing shape is conserved while simultaneous plasticity in the hand skeleton helps maintain functional integrity during rapid morphogenesis.
The social structure and dominance hierarchy of the highveld mole‐rat Cryptomys hottentotus pretoriae (Rodentia: Bathyergidae)
Authors: Moolman M. , Bennett N. C. , Schoeman A. S. 
Published: February 2006

AbstractThe highveld mole‐rat Cryptomys hottentotus pretoriae occurs in the summer rainfall region of the highveld of South Africa. It lives in colonies of up to 10 individuals, in which reproduction is limited to one to two of the largest males and the largest female in the colony. Of three field captured colonies, the mean colony size was 10 ± 0 animals with a mean biomass of 900 ± 147 g. The study colony had a sex ratio of 1.5:1 in favour of males.The social hierarchy of the highveld mole‐rat is non‐linear and has a value of 0.3 calculated from Landau's linearity index. Dominance was negatively correlated with capture order.Histological examination of the gonads of reproductively active and sexually quiescent members of both sexes of two colonies provides further support of there being a single reproductive male and female responsible for procreation in the colony.The non‐reproductives of both sexes appear to be important in burrow maintenance activity and in foraging for geophytes upon which the mole‐rats feed. The non‐reproductive members of the colony cannot be subdivided into different worker groups based on body mass. The available evidence suggests that the highveld mole‐rat is a transiently social species, at one extreme of a sociality continuum in the genus Cryptomys. The position of this subspecies in respect to the sociality continuum is discussed.
Costs of reproduction and the evolution of sexual dimorphism in a ‘flying lizard’Draco melanopogon (Agamidae)
Authors: Shine Richard , Keogh Scott , Doughty Paul , Giragossyan Hamlet 
Published: February 2006

AbstractLife‐history models suggest that ‘costs of reproduction’ can influence the evolution of sexual dimorphism, but empirical data on this effect are scarce. We tested the idea using ‘flying lizards’ (Asian agamids of the genus Draco), because the evolution of ‘flight’ (gliding) is likely to have increased the degree to which pregnancy affects maternal locomotor ability (and hence, we infer, has increased the ‘costs of reproduction’). As predicted, Draco display patterns of sexual dimorphism that are different from those seen in most other lizards. The ‘wings’ (gliding membranes) of female D. melanopogon are significantly larger than those of males of the same body size, a dimorphism that we attribute to natural selection on the ability to glide while encumbered with eggs. Comparisons with non‐flying lizards suggest that the same selective pressure has also reversed pre‐existing patterns of sexual dimorphism in body size and body proportions (relative head size, relative tail length). Measurements of wing‐loading, centre of balance and gliding distances of preserved specimens support the hypothesis that a larger body, relatively larger head, and longer tail may improve a female's aerial mobility when she is gravid. Thus, selection for locomotor ability in egg‐burdened females (reduction in ‘costs of reproduction’) may have been responsible for a reversal of sexually‐selected traits in this lineage.
Phylogenetic relationships of the Pomacanthidae (Pisces: Teleostei) inferred from allozyme variation
Authors: Chung K. C. , Woo N. Y. S. 
Published: February 2006

AbstractPhylogenetic relationships of 31 pomacanthid species representing all genera were investigated by horizontal starch gel electrophoresis. Nei's genetic distances (D) were calculated and dendrograms constructed from allozyme variation in 23 loci. The average D value was 0.03 between conspecific colour variants, 0.40 between congeneric subgenera, and 1.27 between confamilial genera. From the dendrograms the following were revealed: (1) the generic status of Apolemichthys arcuatus and Holacanthus venustus, as well as the generic and subgeneric status of Centropyge multifasciata were confirmed; (2) the subgeneric status of Xiphypops was confirmed; (3) Pygoplites diacanthus was found to be closely related to members of the subgenus Pomacanthus; (4) Pomacanthus zonipectus was found to be biochemically distinct from its con‐subgeners; (5) the genera Pomacanthus and Holacanthus are more closely related than currently thought; (6) the Genicanthus species might warrant a subfamily of their own.
Reconstruction of the predatory behaviour of the extinct marsupial thylacine (Thylacinus cynocephalus)
Authors: Jones Menna E. , Stoddart D. Michael 
Published: February 2006

AbstractThe European colonists of Tasmania named the thylacine Thylacinus cynocephalus a ‘marsupial wolf’ or the ‘Tasmanian tiger’ or ‘hyena’, in reference to its resemblance to large canids and the bold stripes on its rump. The largest marsupial carnivore in historic times, it was persecuted for alleged sheep killing and became extinct before its ecology was documented. We have reconstructed the likely prey size and the hunting and killing methods of the thylacine by comparing canine tooth strength and limb bone length ratios with those of extant marsupial and placental carnivores. The thylacine was probably a pounce–pursuit predator of fairly open habitats, which killed medium‐sized prey (1–5 kg) that were small relative to its body size (15–30 kg), with a crushing, penetrating bite. The trophic niche of the thylacine was similar to that of smaller canids such as the coyote Canis latrans (rather than the wolf C. lupus), but ecomorphological convergence of the thylacine with canids was superficial. Phylogenetic constraint has resulted in unique patterns of tooth eruption, molar tooth and jaw geometry, calcaneum architecture, and perhaps FMT/running speed relationships in the Dasyuroidea.
Impacts of invasions by alien species
Authors: Rainbow Philip 
Published: February 2006

AbstractAre British animals and plants being threatened by the invasion of alien species? This was the question addressed at a Scientific Meeting of the Zoological Society of London on 10 March 1998 in three talks exploring the potential impacts of invading Chinese mitten crabs in the Thames catchment (Paul Clark and Philip Rainbow, The Natural History Museum), introduced foreign crayfish (David Holdich, University of Nottingham) and alien terrestrial flatworms (Hugh Jones, University of Manchester).
Factors affecting movements and home ranges in the jay (Garrulus glandarius)
Authors: Rolando Antonio 
Published: February 2006

AbstractThe winter home ranges, movements and density of the jay Garrulus glandarius in the Maremma Natural Park (Tuscany, Italy) are presented, and compared with those already known for the other seasons. The movements of jays were studied for short periods over 6 years by radiotelemetric techniques (26 home ranges), direct observations of movements from vantage points, and transect counts. Summer and autumn ranges were much larger than spring and winter ones. Incremental area plots and auto‐overlap analyses showed that, on average, spring ranges increased in area with time without shifting, whereas winter ranges were rather stable. In both periods, however, some birds moved as floaters since the degree of range auto‐overlap decreased significantly with time. In winter and spring, range sizes of jays inhabiting different habitats were significantly different, being larger in sites with higher habitat heterogeneity. The structure of home ranges was variable in all seasons; birds showed jointed and disjointed ranges, with one or more activity centres, in all the possible combinations. In every season the average degree of range overlap between jays caught at the same site was rather high and overall actual overlap, when non‐tagged birds were also considered, was even higher. No territorial behaviour was ever observed. During summer jays moved into the pinewood for the greater part of the day to collect cicadas, Cicada orni, and returned to the maquis in the evening. During autumn birds regularly moved within the maquis or from the maquis to the pinewood to cache oak (Quercus ilex) acorns. No regular long movements between habitats were observed during spring and winter. Direct observations and analyses of pellets suggested that food was abundant and highly diversified throughout the year. Thus, seasonal movements and home ranges were flexible and mainly controlled by food availability and its distribution in space and time.
Limited intra‐specific variation in male grey seal (Halichoerus grypus) dominance relationships in relation to variation in male mating success and female availability
Authors: Twiss S. D. , Anderson S. S. , Monaghan P. 
Published: February 2006

AbstractInter‐male aggressive encounters were examined at three grey seal breeding colonies that differed in topography, adult dispersion patterns and operational sex ratios; North Rona and the Monach Isles (Scotland), and Sable Island (Nova Scotia). At North Rona, known males were observed over three successive breeding seasons, with a total of 275 males being individually identified. A single season's observations at both the Monach Isles and Sable Island provided data on 53 and 80 individual males respectively. Cardinal dominance ranks were computed for 68, 92 and 112 males on North Rona in each season respectively, 37 males on the Monach Isles and 68 males on Sable Island. All sites showed close approximation to dominance hierarchies when considering only interactions resulting in a clear outcome (wins), with less than 10% of interactions resulting in reversals. Measures of variance in male mating success showed no significant differences between colonies. These results show the existence of male dominance hierarchies in colonies from both east and west Atlantic populations and at breeding sites with widely differing habitat structure, seal dispersion patterns and levels of inter‐male competition, suggesting limited plasticity in the form of grey seal mating systems and limited variation in the degree of polygyny attained at these sites.
A second species of legless scuttle fly (Diptera: Phoridae) associated with ants (Hymenoptera: Formicidae)
Authors: Disney R. H. L. , Weissflog A. , Maschwitz U. 
Published: February 2006

Abstract Vestigipoda maschwitzi Disney sp. nov. is described from females and larvae collected from a colony of Aenictus gracilis in Malaysia. It is the second species in this remarkable genus, the type species being associated with a different species of Aenictus in Malaysia.
Cellular diversity in the epidermis of Raja clavata (Chondrichthyes)
Authors: Whitear M. , Moate R. 
Published: February 2006

AbstractThe epidermal layer of the skin of the cartilaginous fish Raja clavata taken from a suitable place on the ventral side of the head was examined by light and electron microscopy. Cells of the basal layer divide and differentiate as epithelial cells of the mid‐epidermis, characterized by numerous electron‐dense, membrane‐bound vesicles; their content is assumed to be mucus. Cells at the superficial layer of the epidermis lose these vesicles but have a palisade of mucous vesicles below the apical membrane. A modified glycocalyx coats the outer leaflet of the apical membrane.In addition to epithelial cells, there are epidermal cells differentiated as two kinds of mucous goblet cells, sacciform cells similar to those found in teleost fish epidermis, holocrine cells with some resemblance to the club cells of teleosts but differing in their cytology, and chemosensory cells similar to those found in the oral epithelium of Raja. Merkel cells were not found. Cells that might be interpreted as ionocytes were seen but their nature was not confirmed. The epidermis is penetrated by numerous nerve fibres; swellings contain mitochondria and glycogen granules. The nerve fibres also contain 50–70 nm vesicles with an indistinct core. Cells intrusive to the epidermis include melanocytes, lymphocytes, macrophages, and several types of granular leucocyte. The cytology of the various epidermal elements is generally similar to that known in teleost fishes.
Does food competition from red fox (Vulpes vulpes) influence the breeding density of goshawk (Accipiter gentilis)? Evidence from a natural experiment
Authors: Selås Vidar 
Published: February 2006

AbstractThe impact of food competition from the red fox Vulpes vulpes on the breeding density of the goshawk Accipiter gentilis was studied in a 650 km2 area in southern Norway by investigating the density of goshawks and their grouse prey before, during, and after a period when the red fox population was low because of an epizootic of sarcoptic mange Sarcoptes scabiei. The number of goshawk pairs per 100 km2 was approximately nine/year in the 1950s, three/year in 1972–75 and in 1980–85, and four/year in 1988–91. In each of these periods, nesting territories of goshawks were regularly spaced. There was a positive correlation between the breeding density of goshawk and the population size of grouse. Both grouse numbers and goshawk breeding density increased at the same time that fox populations declined in the 1980s, while the re‐establishment of the fox population in the 1990s was associated with decreases in grouse and goshawk numbers. During the partial absence of red foxes, there was a continuously high grouse population. It is concluded that the red fox may influence the goshawk breeding density negatively by limiting the numbers of grouse.
A 32‐year demography of yellow‐bellied marmots (Marmota flaviventris)
Authors: Schwartz Orlando A. , Armitage Kenneth B. , Van Vuren Dirk 
Published: February 2006

AbstractYellow‐bellied marmots Marmota flaviventris in the East River Valley of Colorado were live‐trapped and individually marked annually from 1962 through 1993. These pooled data were used to produce a demography and life table for these years. Females had significantly better survivorship than males beyond the first‐year age class, and the sex ratio became progressively female biased. The major mortality factors of predation and unsuccessful hibernation acted evenly on all age classes as shown by the constant rates of survivorship. The rate of senescence indicated that the probability of mortality did not increase with age. Females produced litters from ages 2 to 10 years. Mean litter size was 4.1 and did not differ among age classes. The female generation length of 4.49 years was 2.4 times the life expectancy and the median survivorship. The net reproductive rate (Ro) was 0.67, yet the population did not continually decline; adjustments to these data increased Ro to 0.85. Reproductive values (Vx) were approximately equal across the reproductive age classes. The polygynous mating system is both cause and effect of the demography. Marmot population size is affected by weather factors that influence reproduction and survival, by predation, and by movement into and out of the study area.
Reproductive biology of the neotropical harvestman (Goniosoma longipes) (Arachnida, Opiliones: Gonyleptidae): mating and oviposition behaviour, brood mortality, and parental care
Authors: Machado Glauco , Oliveira Paulo S. 
Published: February 2006

AbstractGoniosoma longipesis a neotropical cavernicolous harvestman that exhibits parental care. Reproductive activity inG. longipesis more intense during the wet season. Mating lasts up to 3 min, and the whole oviposition process may take over 5 h. During oviposition the female may be reinseminated once or twice by the mating male. Females oviposit 60–210 eggs on the cave wall and guard egg batches for nearly 2 months, until the 1st‐instar nymphs disperse. Four main factors can affect egg survival inG. longipes: dehydration, fungal attack, cannibalism, and interspecific predation. Frequency of fungal attack on egg batches was greater in the wet season and more intense near the river inside the study cave. Although egg‐guarding by females failed to prevent fungal attack on eggs inG. longipes, the choice of a suitable oviposition site by the gravid female can reduce fungal attack within the cave habitat of this species. Guarding females successfully repel conspecific egg predators, but unguarded eggs are frequently consumed by adult and juvenileG. longipes, as well as cave cricketsStrinatiasp. Field experiments in which females were removed from egg batches demonstrated that egg‐guarding by the mother has an anti‐predator role inG. longipes, with a significant positive effect on egg survival. MaleG. longipesactively patrol their egg‐guarding mates, and take over brood care for up to 2 weeks if the latter are experimentally removed. The degree to which male assistance can play a relevant role in parental care is still unclear for this species. Damage to the brood is regarded as a major force favouring the evolution of parental care in harvestman species. This field study provides the first experimental demonstration that egg‐guarding by females affords protection against egg predation in a harvestman species.
The effect of tooth shape on the breakdown of insects
Authors: Evans A. R. , Sanson G. D. 
Published: February 2006

AbstractThis study investigates the effect of tooth sharpness on the force and energy necessary for a tooth to divide foods of differing physical properties. The material properties of foods are likely to affect the shape that is best to divide them. In order to test the effect of sharpness on a tooth's proficiency in dividing insect prey, experiments involving penetrating and driving through insect prey of differing physical properties were carried out using specially designed punches that varied in tip‐ and cusp‐sharpness. A refinement of tooth measurements which are relevant to their effectiveness in penetrating and driving through food is expounded. ‘Tip‐sharpness’ is defined as the radius of curvature at the tip of a cusp. ‘Cusp‐sharpness’ is defined as the volume or surface area of the tooth per unit distance from the tip of a cusp. The experiments show that tooth shape is important in the force and energy needed for teeth to penetrate and drive through insects. Also, the scale of teeth is important – teeth of the same shape but different size vary in their effectiveness to divide foods.