bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nematode growth patterns and the moulting cycle: the population growth profile
Authors: Wilson Peter A. G. 
Published: August 2009

Population growth profiles of Caenorhabditis elegans and Panagrellus redivivus constructed from length frequencies have a number of steps in them coinciding with the number of extrauterine moults. Each step has a constant size relationship with that of one of the midmoults measured directly.The profiles could only have the shape they do if there are corresponding steps in the true growth curve of individual worms: the fact that previous workers have been unable to detect these steps being due to the limitations of techniques available for the study of synchronous and individual growth curves. Nevertheless, a synchronous system with Trichostrongylus retortaeformis gives qualitative support to the findings from population profiles.The population growth profile is a new tool in the study of environmental effects on moulting, though there are theoretical reasons why the true growth curve cannot be derived from it.Abandonment of the “continuous growth” model for post‐embryonic development simplifies the framing of hypotheses to explain ecdysis in nematodes.
The nature and basis of sexual dimorphism in the primate skeleton
Authors: Wood B. A. 
Published: August 2009

This study sets out to document and analyse sexual dimorphism in the teeth and bones of five primate groups, including man. Specimens were only included in the analysis if their sexual attribution was reliable and was based on non‐osteological criteria. Ninety raw measurements, both cranial and post‐cranial, were used and 11 indices were computed from them.The parameters of each sample were computed in order to compare these results with previous estimates of dimorphism which have not always been based on reliably sexed samples. Correlation matrices were computed.The overall sex differences were subdivided into “shape” and “size” components using Penrose's size and shape distances and by computing the principal components of each data set. The visually apparent shape differences were confirmed metrically and then examined to see whether they could be explained by allometric effects or whether there was evidence for sexual differences in growth patterns.Using femur length as the independent variable, because of its correlation with overall size, allometric coefficients were computed for the logarithmically transformed data. The coefficients were in some cases very different between sexes but the majority did not achieve statistical significance. Of those that were significantly different only in Homo did such differences narrowly exceed the number that would be expected by chance alone.As the vast majority of allometric coefficients for the pooled male and female data differed from unity, the hypothesis that most of the considerable shape differences that exist between some male and female primates are due to underlying growth differences must be rejected. It is suggested that such differences are simply the result of disproportionate change in size.
The buoyancy and orientation of the upside‐down catfishes of the genus Synodontis (Pisces: Siluroidei)
Authors: Willoughby N. G. 
Published: August 2009

The forces involved in the buoyancy of the genus Synodontis are unusually large owing to the well‐developed cephalo‐nuchal shield possessed by all members of the genus, and the large swim bladder and high levels of body fat needed to counteract this. A new method of determining the quantity of crude lipid in the tissues was developed and tested against a recognized method. Negative correlations were found between the total quantities of fat present and the volumes of the swim bladder for several species. Two species which maintained neutral buoyancy but occupied different ecological niches were found to achieve neutrality by different means, one possessing an abnormally large swim bladder and the other very large quantities of fat. The amount of bone present was found to be considerably greater than in species from other genera.Several species of this genus regularly invert and swim on their backs. Three of the species known to do this were found amongst the 16 species present in the man‐made Lake Kainji on the River Niger in Nigeria. The orientations of many of the species were studied both under natural conditions and in the laboratory. Several possible causes of inversion were investigated, including both physical and behavioural factors. The position of the food source was found to be the most important factor controlling the orientation of the species. By manipulating this it was possible to persuade normally orientating species to invert, and inverting species to return to normal orientation. Three theories to explain the inverting habit are advanced and their merits discussed.
The determination of age and growth from the scales in Barbus liberiensis (Pisces, Cyprinidae)
Authors: Payne A. I. 
Published: August 2009

The predictability of scale check formation in Barbus liberiensis has been investigated. Scale length is shown to be linearly related to body length. The formation of the check can be interpreted in terms of the reproductive cycle and changes in somatic condition. Throughout the population check formation takes place in two phases, resorption of material from the scale edges coinciding with the early and middle phases of gonad maturation, and the formation of the check itself as a result of repair as maturation is completed. Check formation is not correlated with actual spawning activity and fluctuations in food intake and temperature are insignificant.The first scale check is formed at the end of the first year and from analysis of check frequency the mean body lengths at the end of the first, second and third years were 6·9 cm, 8·3 cm and 9·3 cm. There was no significant difference in the growth rate of males and females although the females tend to live longer and therefore attain a greater maximum size. Some individuals may not have formed a check at the end of the first year.The difference between check formation in tropical and temperate fish and also between forest and savanna types are discussed. The predictability and the factors affecting check formation in tropical freshwater fish are considered.
Studies on the skull of the Henophidia (Reptilia: Serpentes)
Authors: Rieppel Olivier 
Published: August 2009

The skulls of Cylindrophis, Anilius, Uropeltis and other genera of Uropeltidae, Xenopeltis and Loxocemus are described and figured.On the basis of cranial characters, a separation of the Aniliidae into two subfamilies, the Aniliinaeand theCylindrophinaeis suggested. The Uropeltidae, separated from the Aniliidae by a set of derived characters, are grouped together with the Aniliidae as the superfamily Anilioidea. The skulls of Xenopeltis and Loxocemus are described and the systematic position of the genera discussed. General remarks as to the bearing of the skull on the reconstruction of henophidian phylogeny conclude the study.
A preliminary investigation into Natterjack toad (Bufo calamita) breeding site characteristics in Britain
Authors: Beebee TrevorJ. C. , Griffin JohnR. 
Published: August 2009

A routine was established for sampling pH in aquatic environments which permitted assessment of an “average site pH”±0.5 units by measuring that of a single sample at any time of year. Requisites for accuracy were that samples should be taken in clear water away from weed, and at least three days after significant rainfall.pH measurements were taken in a number of ponds and compared with the use of these waters for breeding purposes by Common toads (Bufo bufo) and frogs (Rana lemporaria). Toads were found breeding in water slightly more acid than those tolerated by frogs. Similar measurements of pond pH in dune and heath habitats frequented by Natterjack toads (Bufo calamita) were compared with breeding site choices by these anurans. A marked avoidance of acid waters was evident in the predominantly acid heathland habitats. This was probably not directly related to the concentrations of inorganic ions in the pools.Development of Rana lemporaria, Bufo bufo and B. calamita spawn under various pH conditions was examined. Survival rates were optimal in the pH ranges found to be chosen in the wild, and no differences were observed between Bufo calamita spawn taken from dune or heathland populations. Developmental abnormalities in the tadpoles were more frequent under acid conditions.A preliminary study of ponds used by the three species of anurans native to Britain was carried out by measuring pH with a tested field procedure. Differences between Bufo bufo and Rana temporaria breeding sites were not significant on the basis of pH in the areas studied, but B. calamita populations on heathland were found to avoid the acid pools. The field data correlated well with the pH tolerance of the anuran larvae reared in captivity. The significance of these findings is discussed.The authors wish to thank Dr A. Cooke (Institute of Terrestrial Ecology) and Dr D. Sutcliffe (Freshwater Biological Association) for analyses of selected water samples; Mrs M. Beebee for statistical treatment of the data; and the Carnegie (U.K.) Trust for financial support.
Behavioural ecology of the Sloth bear (Melursus ursinus)
Authors: Laurie Andrew , Seidensticker John 
Published: August 2009

The Sloth bear (Melursus ursinus), which is endemic to the Indian subcontinent and Sri Lanka, has declined in numbers in many areas in recent years probably as the result of over‐killing and habitat alteration. In the 544 km2 Royal Chitawan National Park in the Nepal terai, we estimated there were a minimum of 55 bears or a crude density of 0˙1/km2. During peak concentrations in the lowlying riverine forest/tall grass habitat in March, the ecological density was 0˙5/km2.Cubs still with their mothers comprised 24 % of the 161 bears classified between December 1972 and November 1975. Females comprised 48% of the adults classified. Average size of 24 litters was 1˙6 (1–2). Seventy‐two per cent of the observations were of lone individuals. Three (an adult female with two cubs), was the largest group of bears seen. The only extended social group observed was the female‐young unit although newly independent siblings may remain together for a short time. Maternal relations, adult interactions, tree marking, ranging, feeding and anti‐predatory behaviour are described.Examination of 139 droppings showed that these bears fed on at least 17 different fruits (47% occurrence), flowers, grass, honey, and six different insects (52% occurrence). Fruits were an important food from March to June with individual species predominating throughout their fruiting season. Termites, including Odontotermes obesus, were in the diet for most of the year. The Sloth bear was not observed preying on mammals and according to other observers, only rarely feeds on carrion. The ecological basis for selected aspects of Sloth bear biology and behaviour is discussed.
Allometry of the limbs of antelopes (Bovidae)*
Authors: Alexander R. McN. 
Published: August 2009

The principal bones, muscles and tendons in the legs of seven species of antelope of varying size have been measured, and aliometric equations have been derived. Some data published by Sachs (1967) have also been analysed. Most of the exponents of the aliometric equations agree well with McMahon's (1973, 1975a) theory of elastic similarity: lengths are approximately proportional to (mass)0˙25, diameters to (mass)0˙375 and cross‐sectional areas to (mass)0˙75. However, some of the exponents for diameters and areas in the hind leg are significantly different from those predicted by the theory.The results are discussed in conjunction with previously published data on fast galloping. It is shown that maximum stresses in bones, muscles and tendons are probably more or less independent of body mass in antelopes galloping at their maximum speed. The tensile stresses in the tibia and humerus approach the tensile yield strength of bone. The total work which is done by the muscles in each stride at maximum speed and the energy saved by elastic storage are probably more or less proportional to body mass. The deviations of some of the allometric exponents for diameter from the expected value of 0middot;375 are partially explained.
The influence of snow conditions on the date of breeding of wading birds in north‐east Greenland
Authors: Green G. H. , Greenwood J. J. D. , Lloyd C. S. 
Published: August 2009

The young of wading birds that breed in some parts of the arctic hatch when their insect food supply is most abundant. This appears to be the ultimate factor determining the date of egg‐laying. In various other arctic birds the date of breeding may be influenced, directly or indirectly, by the time at which snow or ice melts. The Joint Biological Expedition to N.E. Greenland 1974 studied Ringed ploversCharadrius hiaticula, DunlinsCalidris aplina, SanderlingsCalidris alba, KnotsCalidris canutus, and TurnstonesArenaria interpresbreeding in various areas within 80 km of each other.In 1974 the thaw was two or three weeks later than normal in the region. The time at which snow cleared and the dates of breeding of the waders differed considerably between valleys: breeding was delayed in valleys that cleared late. In all areas egg‐laying ceased early in July, probably because chicks hatching from eggs laid later would not be ready to migrate by the end of the summer. Hence the mean date and length of the egg‐laying period were determined by the date of snow clearance from the breeding areas.Studies of the potential food resources indicate that the waders in N.E. Greenland do not appear to time their breeding so that the young hatch at some peak of food abundance. Sufficient food resources are probably available over a long period of time.
The significance of morphological variation in the finch species on Gough, Inaccessible and Nightingale Islands, South Atlantic Ocean
Authors: Abbott Ian 
Published: August 2009

Uni‐ and multivariate analyses were made of nine morphological characters on three species of finches Nesospiza acunhae (Inaccessible, Nightingale), N. wilkinsi (Nightingale) and Rowettia goughensis (Gough). The results of the univariate analysis were used to test four predictions about morphological changes with altered competitive backgrounds. Finch species that occur alone on an island or on an island where other finch species are rare have longer characters and more variable character distributions.A multivariate analysis of six bill characters showed that the bill of Rowettia is more similar to that of acunhae than either is to wilkinsi. A multivariate analysis on wing length, tarsus length and hallux length shows that Rowettia is morphologically closer to wilkinsi than it is to acunhae. It is suggested that nothing is gained by treating the Gough I. finch as belonging to a monotypic genus.
The annual pattern of reproduction of Talitrus saltator (Crustacea: Amphipoda: Talitridae)
Authors: Williams John A. 
Published: August 2009

The reproductive cycle and breeding biology of Talitrus saltator (Montagu), a supralittoral talitrid amphipod, were investigated over a 15 month period on a sandy beach in the Isle of Man. The species is shown to have an annual, univoltine reproductive cycle with a period of high reproductive activity between May and late August. Two generations are present throughout most of the year and the life spans of female and male T. saltator were calculated to be approximately 18 months and 21 months respectively. Initial juvenile growth was rapid, juveniles attaining sexual differentiation within three to four months of hatching. Juvenile growth rates averaged 5–5 mm in 100 days decreasing to 1–3 mm in 100 days after sexual differentiation at around 8.0 mm.The relative brood size of incubating females was shown to be dependent on at least two factors, the length of the female and the stage of embryological development of the brood.It is suggested that photoperiod is the major exogenous factor controlling gonadal maturation and the duration of reproductive activity in T. saltator.
Feeding and development of Sparrowhawk Accipiter nisus nestlings
Authors: Newton I. 
Published: August 2009

At three nests of Accipiter nisus the young were brooded almost continuously for the first seven or eight days, then steadily less until days 12–15, and thereafter chiefly during rain. The male provided almost all the food for the first seven or eight clays, after which his rate of prey delivery slackened off. This coincided with increased hunting by the female and, by the late nestling stage, both parents provided about the same number of items. The numbers of prey deliveries fluctuated greatly from watch to watch, and were significantly depressed during rain. On average, males brought significantly smaller prey than females (up to 80 and 500 g respectively), and the total weight of prey brought to the nests was greater when both sexes hunted than when the male hunted alone. For the three nests, the total food consumed over 32 days from hatching was estimated at 5900 g (four young depleted to three), 5900 g (four young depleted to two) and 13,800 g (four young throughout). These widely varying estimates are all in line with previous published figures.Both sexes were hatched from eggs of similar weight, but soon diverged in growth and, before they left the nest, females were almost twice as heavy as males. No difference in food consumption was detected between the sexes but, while females achieved greater weight, males showed more rapid development of plumage and body skills, and flew about four days earlier. The more rapid development of the males is regarded as a means of alleviating competition with their larger sisters.Among the three nests, the best and most even growth among all young was associated with: (a) regular and frequent deliveries of prey items; (b) good attentiveness by the female, including almost continuous brooding in the early nestling phase, and remaining near the nest to hunt towards the end; (c) the partitioning of prey by the female until a late stage in nestling growth; and (d) when the young fed themselves, minimum aggression among them and the ready surrender of prey by one young to another. Poor, uneven growth and starvation were associated with the opposite conditions.
The daily cycle of activity in the mole (Tabu europaea) and its seasonal changes, as revealed by radioactive monitoring of the nest
Authors: Woods J. A. , Mead‐Briggs A. R. 
Published: August 2009

The daily cycle of activity in the mole (Talpa europaea) and its seasonal changes, as revealed by radioactive monitoring of the nestPublished information on the activity rhythm of the mole (Talpa europaea), although limited to observations on a very few moles during February‐April, had indicated a basic short‐term cycle of approximately 8 hours. The technique used, manual tracking of radioactively tagged individuals with portable monitors, was modified for the present study to record automatically the presence or absence of the tagged mole at its nest site. Data were obtained for all months of the year, with a total of 797 days of records from 14 male and 13 female animals. The most characteristic feature of the records, irrespective of the time of year and thus daylength, was the sharpness of the transition from inactivity to activity at dawn and the reverse shortly prior to dusk. During midwinter, when daylength was short the animals tended to be active throughout the day, with few or no rest periods at the nest, and there was only one other active period, during the night. With increasing daylength there was usually a short rest period about midday so that the animals had the classical 3‐cycle daily rhythm. In summer, with the longest days and shortest nights the timing of the daytime rest period was variable and there was often no active period during the night so that the short‐term cycles were less distinct.
The light organ and ink sac of Heteroteuthis dispar (Mollusca: Cephalopoda)
Authors: Dilly P. N. , Herring Peter J. 
Published: August 2009

There has previously been some dispute over the source of the light of Heteroteuthis. Light and electron microscopy have shown that there are no bacteria in the cavity of the luminous gland, but rather a population of spherical vesicles of varying size and content, surrounded by dense interstitial material. The contents are secreted by the cells surrounding the gland via a microvillous brush border that contains cilia. The gland is surrounded by a reflector layer made up of iridophores, whose structure differs considerably in the proximal, lateral and cap regions.The ink sac contains masses of spherical dense granules and its wall cells have many microvilli extending amongst these granules.
The post‐embryonic development and life history of the millipede, Ommatoiulus moreletii (Diplopoda: Iulidae), introduced in south‐eastern Australia
Authors: Baker G. H. 
Published: August 2009

The life cycle of Ommatoiulus moreletii consists of an egg, pupoid and up to sixteen stadia. Sexes are differentiated at the sixth stadium. Males may mature at any moult from the eighth to the twelfth stadia, but most are mature by the tenth or eleventh. Maturation is more difficult to determine in females but seems similar to the males with respect to stadial age. O. moreletii is periodomorphic.Field studies were made of O. moreletii in an open grassland and a dry sclerophyllous woodland in South Australia. Females matured their eggs in late summer‐autumn. They mated and oviposited during autumn‐winter. After one year, O. moreletii was in the seventh, eighth or ninth stadium. After two years, the tenth or eleventh stadia were reached and after three years the twelfth or thirteenth. The moulting of individuals older than about one year was confined to moults in (1) spring and (2) summer. Adult males were mature from summer to spring and intercalary from spring to summer.
Arm autotomy in brittlestars (Echinodermata: Ophiuroidea)
Authors: Wilkie I. C. 
Published: August 2009

Although ophiuroid arm shedding has long been accepted as an example of autotomy, there has been little investigation of the phenomenon to substantiate this. This paper describes the outwardly visible aspects of autotomy and the function of the internal components of the arm during detachment. Observations are focussed on Ophiocomina nigra, some comparisons being made with eight other species.Ophiuroid autotomy is characterized by its occurrence close to the point of stimulation, its rapidity, and by the pattern of intervertebral muscle separation at the insertions which is constant for a given species. Evidence is presented showing the important role played by the intervertebral ligament. Both this and the muscle insertions are collagenous, and it is suggested that they and the other intersegmental connective tissues facilitate autotomy by undergoing a drastic, nervously mediated loss in tensile strength which enables the animal to part from its arm with a minimum of effort. Comparable properties have been ascribed to other echinoderm connective tissues, and their role in asteroid and holothurian autotomy has been acknowledged, but such a mechanism has not previously been suggested for ophiuroid arm autotomy.