bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activity and thermoregulation of the snake Natrix maura. 1. r and K thermoregulation
Authors: Hailey A. , Davies P. M. C. 
Published: March 2009

Natrix maura was active by day and night throughout its annual activity season (March to October), with body temperatures (Tb) between 14–35 C. Body temperatures during foraging (aquatic, for fish) were constrained by water temperature. Snakes also raised Tb by basking. Basking in the laboratory was analysed by fitting logistic curves to heating rates, and determining half times (HT) as a descriptive statistic. Snakes in the field often basked for much longer than necessary to reach an equilibrium Tb; these basking times often exceeded HT more than ten‐fold. This led to the concept of two strategies of thermoregulation, here designated r‐thermoregulation and K‐thermoregulation.In r‐thermoregulators the heating rate, r, is maximized until the preferred Tb is reached, and then the behaviour for which the high Tb has been achieved is pursued. The advantage of high Tb is short term, usually for increased performance during foraging. This is the commonly studied form of thermoregulation, and is typical of the behaviour of small lizards where it leads to a shuttling pattern of activity, r thermoregulation is usually by basking.In K thermoregulators an equilibrium Tb, K*, is reached and maintained for long period. K* may be lower than the equilibrium of logistic heating in the conditions, K, if this is too hot. The behaviour of N. maura was often consistent with this pattern; the snakes moved into shade while basking, and at air temperatures above 26 C most of the body was in shade. Increasing the rate of longer term physiological processes, such as maturation of reproductive products or (as in N. maura) rate of digestion, are the benefit of maintaining K*. K thermoregulation is by basking or thigmothermy.
The role of the coelom as a hydrostatic skeleton in lingulid brachiopods
Authors: Trueman E. R. , Wong T. M. 
Published: March 2009

Anatomical and experimental studies of the perivisceral coelom and pedicel ofLingula ana linaindicate that the coelomic fluid functions as a hydrostatic skeleton in respect of valve and pedicel movements, valve opening always being associated with positive pressures. The perivisceral coelom is surrounded by a body wall containing circumferential muscle fibres, whilst all muscles passing between the valves (principally adductor and oblique fibres) are located within the body wall. These two sets of muscles function similarly to the circular and longitudinal muscles of a classical hydrostatic skeleton.Pressure recordings from the lumen of the pedicel and perivisceral coelom, during opening or rotary movements of the valves, were similar and showed pressure pulses of up to 0.8 kPa. During the initial stages of burrowing, pulses of up to 2.5 kPa were observed when the valves were being pressed into the sand. These values are well within the capability of the circumferential muscles of the body wall.
Active and resting metabolism in birds: allometry, phylogeny and ecology
Authors: Bennett P. M. , Harvey P. H. 
Published: March 2009

Variation in resting metabolic rate is strongly correlated with differences in body weight among birds. The lowest taxonomic level at which most of the variance in resting metabolic rate and body weight is evident for the sample is among families within orders. The allometric exponent across family points is 0.67. This exponent accords with the surface area interpretation of metabolic scaling based on considerations of heat loss. Deviations of family points from this allometric line are used to examine how resting metabolic rates differ among taxa, and whether variation in resting metabolic rate is correlated with broad differences in ecology and behaviour. Despite the strong correlation between resting metabolic rate and body weight, there is evidence for adaptive departures from the allometric line, and possible selective forces are discussed.The allometric scaling of active metabolic rate is compared with that of resting metabolic rate. The allometric exponents for the two levels of energy expenditure differ, demonstrating that active small‐bodied birds require proportionately more energy per unit time above resting levels than do active large‐bodied birds. No consistent evidence was found to indicate that the different methods used to estimate active metabolic rate result in systematic bias. Birds require more energy relative to body size when undertaking breeding activities than at other stages of the annual cycle.
Hormones, sexuality and fertility in women
Authors: Bancroft John 
Published: March 2009

The extent to which the sexuality of women shows a predictable menstrual cyclicity varies considerably from woman to woman, though the most common times for peaks of sexual interest are the pre‐ and post‐menstrual weeks, not the middle of the cycle. Evidence is presented suggesting that mood is an important determinant of the post‐menstrual peak of sexuality, whereas the pre‐menstrual peak may depend on other mechanisms such as a delayed effect of the mid‐cycle rise in testosterone.Generally, the evidence for a relationship between hormones and sexual behaviour is much more variable and inconsistent in women than in men. Various explanations for this difference have been proposed, including a greater genetic variability of hormone‐behaviour relationships in women. Evidence, relevant to this hypothesis, of a relationship between frequency of sexual activity and the fertility of the ovarian cycle is reviewed and alternative explanations for the findings are considered.
Comparison of the fatty acid component in structural lipids from dolphins, zebra and giraffe: possible evolutionary implications
Authors: Williams G. , Crawford M. A. , Perrin W. F. 
Published: March 2009

Essential fatty acid compositional data on the structural lipids of mammals which predominantly eat n‐3 fatty acids suggests preferential incorporation of n‐6 essential fatty acids.The structural lipids of liver, muscle and brain of five species of dolphin (Tursiops truncatus, Stenella allenuata, Steno bredanesis, Delphinus delphis and Lagenorhynchus obliquidens), obtained from the wild, contained substantial amounts of arachidonic acid and other n‐6 long chain derivatives of linoleic acid. The n‐6 to n‐3 ratio was approximately 1:1.Data for two species of leaf‐eating land mammals, the zebra, Equus burchelli Gray and giraffe, Giraffa camelopardalis L., indicate that tissue phosphoglycerides were dominated by n‐6 fatty acids.
A long‐term study on fused subclones in the ascidian Botryllus schlosseri: the resorption phenomenon (Protochordata: Tunicata)
Authors: Rinkevich B. , Weissman I. L. 
Published: March 2009

Colonial tunicates have the property of forming a natural parabiotic union (chimera) in the wild with members of the same species, given that they share at least one allele at the fusibility‐histocompatibility locus. However, once such a vascular union has occurred, one of the two is often resorbed. To investigate this phenomenon in detail, 16 colonies of the colonial tunicate Botryllus schlosseri were subcloned and placed adjacent to 30 sets of fusible pairs. Subclones in each pair differed in their colour morph. Three other colonies and an additional 15 subclones of the experimental colonies served as controls for growth rate and survival. As the matched colonies grew, the adjacent colonies eventually came into contact. Fusion within a pair was established between the blood vessels, and 4–14 days later, a complete mixture of blood‐borne pigment cells was recorded. A significant correlation was found between the ratio of body size of the two colonies and the time for colour change.Fusion subsequently resulted in a partial resorption of at least one of the colonies in the pair (irrespective of the colour morph) and started in zooids lying in closest proximity to the contact zone. This process did not eliminate the blood vessels, and presumably allowed the process to extend to more distant zooids, which were gradually affected. This type of resorption was not recorded in the controls and took place in the ‘take‐over’ phase (the time when a new generation of zooids take over the colony from the previous generation). Resorption occurred when the new generation of zooids failed to develop to the mature phase, or when the new generation did not develop at all. The time scale for resorption varied from four days to six months. When larger colonies fused with smaller ones, the larger colony usually survived. When multiple subclones of two colonies were tested, usually all of the subclones from one of the colonies survived while the members of the other colony resorbed, implicating a possible genetic component. Because the fusion event usually leads to the resorption and death of at least one of the partners, it is necessary to re‐examine the proposal that fusion between closely related colonies is evolutionarily beneficial.
The timing of reproduction in the fruit bat Haplonycteris fischeri (Pteropodidae): geographic variation and delayed development
Authors: Heideman Paul D. 
Published: March 2009

In climatically seasonal habitats, favourable periods for reproduction may be simply determined by large annual changes in temperature or rainfall. In contrast, in climatically less seasonal habitats, reproductive timing may be determined by a wide variety of seasonal factors. Three hypotheses regarding reproductive timing were tested for a fruit bat, Huplonycteris Jischeri Lawrence, by comparing reproductive timing and climate at four moderately seasonal Philippine sites with differing climates. Bats were sampled in five years on Negros Island (9″22′N, 123″l I'E), and in one to four months on four other islands. Flower and fruit abundance was monitored in two years on Negros. In five years on Negros, parturition and lactation coincided with the time of the average dry‐wet season transition and early wct season, but did not vary in response to substantial annual variation in the onset of rains. Reproductive timing did not change in response to annual variations in Rower or fruit abundance; lactation coincided with a peak in fruit abundance in one year, but not in a second, and reproductive success appeared to be reduced when lactation coincided with scarce resources. At a second site with a different pattern of rainfall, reproduction was nevertheless synchronous with Negros. Samples from two of the three remaining localities indicate a two‐ to three‐month lag in reproductive events relative to Negros, despite rainfall patterns remarkably similar to that of Negros. All three hypotheses for reproductive timing were rejected. As an alternative, Huplonycteris may evolve timing patterns in response to local seasonal patterns of resource abundance.Huplonycteris has an eight‐month post‐implantation delay 'in embryonic development. Six hypotheses on the adaptive significance of this delay in Huplonyrferis were evaluated. Three were rejected, but the data were consistent with the remaining hypotheses: (1) The delay sets the time of parturition at a particular time of year; (2) the delay allows all females to produce young relatively synchronously; and (3) the delay allows females to resorb or abort defective embryos without losing an opportunity for reproduction.
Morphology and muscle stress of chelae of temperate and tropical stone crabs Menippe mercenaria
Authors: Blundon Jay A. 
Published: March 2009

Chela morphology and muscle stress were compared between temperate and tropical populations of stone crabs Menippe mercenuriu (Say) to test whether environmental differences might result in greater crushing strength in the tropics. Such differences include increased crab diversity in the tropics (which might lead to greater fighting among congeners), increased prey exoskeleton calcification in the tropics, and year round chela use in the tropics as opposed to seasonal chela use in the temperate population.No latitudinal differences were found in any aspect of chela morphology, including relative chela size, mechanical advantage, apodeme surface area, and angle of muscle fibre pinnation. Summer measurements of crusher chela muscle stress were also similar between the two populations.The maximum muscle stress determined for M. mercenariu was 220 N ∼r n ‐∼, much higher than stress levels previously reported for crustaceans. Other researchers have typically measured forces either from autotomized chelae or by measuring forces required to open a closed chelae. I have determined muscle stress using a force transducer that measures active gripping strength in live crabs.
An application of common principal component analysis to cranial morphometry of Microtus californicus and M. ochrogaster(Mammalia, Rodentia)
Authors: AlROLDI J.‐P. , FLURY B. K. 
Published: March 2009

Principal component analysis (PCA) is a one‐group method. Its purpose is to transform correlated variables into uncorrelated ones and to find linear combinations accounting for a relatively large amount of the total variability, thus reducing the number of original variables to a few components only.In the simultaneous analysis of different groups, similarities between the principal component structures can often be modelled by the methods of common principal components (CPCs) or partial CPCs. These methods assume that either all components or only some of them are common to all groups, the discrepancies being due mainly to sampling error.Previous authors have dealt with the k‐group situation either by pooling the data of all groups, or by pooling the within‐group variance‐covariance matrices before performing a PCA. The latter technique is known as multiple group principal component analysis or MGPCA (Thorpe, 1983a). We argue that CPC‐ or partial CPC‐analysis is often more appropriate than these previous methods.A morphometrical example using males and females of Microtus californicus and M. ochrogaster is presented, comparing PCA, CPC and partial CPC analyses. It is shown that the new methods yield estimated components having smaller standard errors than when groupwise analyses are performed. Formulas are given for estimating standard errors of the eigenvalues and eigenvectors, as well as for computing the likelihood ratio statistic used to test the appropriateness of the CPC‐ or partial CPC‐model.
Seasonal changes in rumen papillary development and body condition in free ranging Chinese water deer (Hydropotes inermis)
Authors: HOFMANN R. R. , KOCK R A. , LUDWIG J. , AXMACHER H. 
Published: March 2009

Available information on the history, population dynamics, body weight and kidney fat indices in free‐living Chinese water deer at Whipsnade Zoo were briefly reviewed.Fifty eight culled animals were examined quantitatively for changing rumen papilla morphology through different seasons using surface enlargement factors (SEF). The results show a much reduced SEF of below four in winter and rarely above eight in spring, summer and autumn. This is atypical for the entire group of concentrate selectors and even for intermediate feeding types. The inference from the data is that the seasonal rumen development was poorer than expected perhaps indicating that this population was undernourished.
Reproduction in females of the feathertail glider Acrobates pygmaeus (Marsupialia)
Authors: WARD S. J. , RENFREE M. B. 
Published: March 2009

The anatomy of female reproductive tracts collected from 28 Acrobates pygmaeus (Shaw) is described. The tract differs from that of other small possums of the families Burramyidae and Tarsipedidae by having a prominent septum that divides the left and right sides of the vaginal system for most of its length. A median birth canal occurs at parturition but closes within 3–4 days of birth.In south‐eastern Australia, most female A. pygmaeus produce two litters within the breeding season (July to February). A post‐partum oestrus follows the birth of the first litter and the resulting embryos undergo a period of embryonic diapause. The embryos grow slowly during diapause, until the unilaminar blastocysts become approximately 2.0 mm in diameter, and contain about 2,000 cells. The factors influencing reactivation after diapause remain unclear, since no embryos past the blastocyst stage were found. Post‐partum oestrus may follow the birth of the second litter, but if it occurs, the ova either remain unfertilized or degenerate after fertilization. Females are anoestrus during the non‐breeding season.Corpora lutea in the ovaries seldom outnumber blastocysts in the uteri or teats in the pouch. During diapause they undergo a pattern of growth similar to that of the blastocysts and enter a quiescent phase. Corpora lutea disappear within nine days of birth.The pattern of female reproduction in this species is similar to that of other small possums of the families Burramyidae and Tarsipedidae, but is distinct from those of other marsupials.
Reproduction in males of the feathertail glider Acrobates pygmaeus (Marsupialia)
Authors: WARD S. J. , RENFREE M. B. 
Published: March 2009

Between 1984 and 1986, reproductive tracts were collected from 17 male Acrobates pygmaeus (Shaw) from south‐eastern Australia and the anatomy of these tracts is described. The prostate is heart‐shaped and the arrangement of its three segments, anterior, central and posterior, is different to the patterns described for other marsupials. The testes are large in proportion to the body size but their structure and that of the remainder of the tract is typical of other marsupials. The sperm morphology is similar to that of the Phalangeridae and Burramyidae.Seasonal cycles were found in the sizes of testes and prostates. Increases in testes sizes, starting in April or May, were associated with increases in seminiferous tubule diameter and Leydig cell size. The weight of the prostate increased rapidly to a short peak in June when the testes also reached maximum weight. The first births occurred approximately one month later in this population. Following this peak, both the testes and the prostate decreased in size and had returned to the original weights by January. The beginning of this period when the testes and prostate were small coincided with the cessation of births in the population and was marked by an interruption in spermatogenesis.Males born early in a breeding season mature before the start of the next breeding season, but males born at the end of a breeding season may not mature until the second season after their birth, at which time they are approximately 18 months of age.
Reptilian endothermy: a field study of thermoregulation by brooding diamond pythons
Authors: SUP D. J. , SHINE R. 
Published: March 2009

Miniature temperature‐sensitive radiotransmitters were surgically implanted into free‐ranging adult diamond pythons (Morelia s. spilota), which are medium‐sized boid snakes of south‐eastern Australia. Four female pythons oviposited during the study, and constructed incubation mounds. These apparently provided excellent insulation, and the snakes maintained high (approx. 31 C) and relatively constant body temperatures throughout the two‐month incubation period. They apparently maintained these temperatures primarily by endogenous heat production (shivering thermogenesis), but also basked briefly on most mornings.Brooding females maintained a body temperature differential above ambient of about 9C, occasionally up to 13C; their temperatures were significantly higher amd less variable than those of non‐brooding females or males. The energetic cost of brooding must be high, but these costs may be outweighed by the benefits of rapid embryonic development and high embryonic survivorship.
Dentition and diet in snakes: adaptations to oophagy in the Australian elapid genus Simoselaps
Authors: SCANLON J. D. , SHINE R. 
Published: March 2009

Most small fossorial proteroglyphous Australian snakes of the genus Simoselaps feed on adult lizards, but the species of one lineage (the semifasciatus group) feed exclusively on the eggs of squamate reptiles. Examination of cleared, alizarin preparations showed that dentition of the saurophagous species is similar to that of other elapids, but dentition of the oophagous taxa is highly modified. The anterior (palatine and maxillary) teeth other than the fangs are reduced in size and number whereas those of the pterygoid (and in S. ‘ropert’, the dentary) are enlarged posteriorly, becoming compressed along a longitudinal plane and angled medially. The shape of the pterygoid and quadrate is also modified.Two Simoselaps species with broader diets (eating both adult lizards and their eggs) show typical ‘saurophagous’ dentition in one case, ‘oophagous’ dentition in the other, showing that either type of dentition can be used to capture and ingest either type of prey. We suggest functional explanations for the dentitional modifications in the egg‐eating snakes, primarily in terms of the advantages of applying considerable force to the eggshell. Oophagous modifications within Simoselaps are convergent with those seen in several independently‐derived lineages of oophagous colubrid snakes, but (perhaps because of the presence of the fang) differ in having the enlarged blade‐like teeth on the pterygoid or dentary rather than the maxilla.
An investigation into the variations in the fine surface details of the eggs of five species of Delia (Diptera: Anthomyiidae)
Authors: HARTMAN T. P. V. , SOUTHERN D. I. 
Published: March 2009

The eggs of five species of Delia have been examined for the external chorionic patterning, the size and shape of the micropyle and the number, characteristics and distribution of the aeropyles using the scanning electron microscope. The species concerned are the cabbage root fly Delia radicum, the onion fly Delia antiqua, the seed corn maggot Delia platura, the wheat bulb fly Delia coarclata and the turnip fly Delia floralis.Each species has its own clear characters and this, coupled with a significant difference in egg size, enables one species to be distinguished from another.
The development of the trigeminal jaw adductor musculature in the grass snake Natrix natrix
Authors: RIEPPEL OLIVIER 
Published: March 2009

The ontogenetic development of the jaw adductor musculature in Natrix natrix (L.) is described in detail and related to patterns of ossification in the skull. A comparison with the development of the jaw adductors in the lizard Podarcis sicula reveals some interesting differences of dynamics in the developing head. The problem of the establishment of topological relations of similarity (homology) in developing systems is discussed.The homologies of the external jaw adductor compartments in lizards and snakes are revised. Early ontogenetic divergence explains the reversal of fibre direction in the anterior portion of the external adductor of snakes, and renders the homologization of that fibre bundle with part of the external adductor in lizards impossible.