bluuebunny/crossref_metadata_2025 huggingface dataset:
Bistable properties of the hock joint of horses (Equusspp.)
Authors: ALEXANDER R. McN. , TRESTIK CHRISTINE L.
Published: March 2009

The hock (ankle) joint of horses is bistable: if placed in an intermediate position it springs either to full extension or to strong flexion. We have performed experiments to measure the torques involved and to elucidate the mechanism. The torques were much smaller in hocks of Przewalski's horse (E. ferus) and zebra (E. grevyi) than in those of domestic horses. We suggest that the bistability of the hock is too slight to have much importance for wild horses but may have been enhanced in the breeding of domestic horses by selection for elegance of gait. The elbow joint is also bistable but the stifle (knee) and carpal joints are not.
Total body water and adaptive water turnover rate in four chromosomal species of subterranean mole rats of the Spalax ehrenbergi superspecies in Israel
Authors: YAHAV S. , SIMSON S. , NEVO E.
Published: March 2009

Total body water (TBW) and water turnover rate (WTR) were measured in 24 subterranean mole rats comprising four populations, each belonging to a different chromosomal species of the Spalax ehrenbergi superspecies in Israel. The four species range in different climates: humid‐cool (2n = 52); semiarid‐cool (2n = 54); humid‐warm (2n = 58) and arid‐warm (2n = 60). TBW, as a percentage of body weight, measured by tritiated water (HTO), was 72.4%±4–7 in 2n = 52, significantly (P< 005) higher than the similar estimates 61.7%± 7.2, and 59.4%± 5–3, for 2n = 60 and 58, respectively. A comparison of HTO space, as a percentage of TBW, closely approximated TBW, ranging from 97% to 108%. WTR was high, 218.1 and 230.9 ml/kg0‐75/day in the mesic populations of 2n = 58 and 52, respectively. By contrast, WTR estimates were significantly lower, (P < 0.001), 150.2 and 148.9 ml/kg0‐75/day in the xeric populations of 2n = 54 and 60, respectively. The biological half‐life time, T1/2, was similar and faster, 32.7 and 27.9 hours in the mesic populations of 2n = 52 and 58, as compared with slower, 47.9 and 40.8 hours in the xeric populations of 2n = 54 and 60, respectively. Urine osmolarity in the most xeric northern Negev steppic population of 2n = 60 (737 ± 45 mmol/kg) was significantly (P < 0.001) higher than in the other species.

We conclude that adaptive radiation in the Spalax ehrenbergi superspecies involves speciation in semiarid (2n = 54) and arid (2n = 60) climates by physiological adaptations of kidney water conservation, along with multiple morphological, physiological and behavioural syndromes of climatic adaptations to increasing aridity (Nevo, 1986).
The functional morphology of Propeamussium lucidum (Bivalvia: Pectinacea), a deep‐sea predatory scallop
Authors: MORTON B. , THURSTON M. H.
Published: March 2009

The abyssal propeamussiid Propeamussium is well known from studies of shell structure and is believed to be representative of a relict lineage, sister to the group which gave rise to all shallow‐water pectinaceans.

From analyses of stomach contents, species of Propeamussium have been reported to be predators. This study confirms this and shows that small meiobenthos or epibenthic planktonic larvae and crustaceans constitute the diet. Prey is thought to be caught by an inrush of water to the mantle cavity and pushed into the mouth with the foot. The stomach is small, secondarily simplified and adapted for the digestion of small creatures. It is convergent with the stomachs of similarly predatory, abyssal anomalodesmatans. Palps are vestigial. The ctenidia are of a new type (B(4)), perhaps derivable from the dimyid ctenidium by the loss of the ascending lamellae of all four demibranchs and the ventral fusion of inner and outer descending lamellae on each side of the body to create a gill where the apices of the filaments are internal. Filter feeding is thus impossible, the ctenidia now wholly subserving a respiratory function.

Aspects of shell structure, adductor muscle arrangement and form of the pallial margin suggest that P. lucidum is a proficient swimmer. It is concluded, however, that prey is not caught during swimming, and that the two activities are mutually incompatible. Probably swimming is used only for escape.

Ctenidial structure forges links with the Plicatulacea (Dimyidae, Plicatulidae), shell structure with the Pectinacea (Pectinidae, Spondylidae) and it is concluded that the Propeamussiidae is indeed a relict group with links back to more primitive plicatulaceans and with the modern shallow‐water Pectinacea, but evolving, in the isolation of the abyss, remarkable adaptations for a predatory mode of life. The Propeamussiidae also demonstrate striking convergence with the abyssal predatory Anomalodesmata.
Structure and histochemistry of the dermis of a chequered water snake, Natrix piscator
Authors: Singh Jai Prakash Narain , Mittal Ajay Kumar
Published: March 2009

The histology and the protein, carbohydrate, lipid and enzyme histochemistry of the dermis of the chequered water snake, Natrix piscator, have been examined throughout the sloughing cycle.

The structural organization and staining properties of the dermis do not show any changes in different stages of the cycle.

The dermis is divided into the stratum laxum and the stratum compactum. Acid mucopolysaccharide deposits in the stratum laxum, which possibly bind water, may be involved in prevention of desiccation.

The numerous elastin fibres in the hinge regions are related to the greater elasticity of the skin in these sites.
The social structure and reproductive biology of the common mole‐rat, Cryptomys h. hottentotus and remarks on the trends in reproduction and sociality in the family Bathyergidae
Authors: Bennett N. C.
Published: March 2009

Cryptomys h. hottentotus occurs in mesic and semi‐arid regions of South Africa. It lives in colonies ofup to 14 individuals, in which reproduction is limited to one ofthe largest males and the largest female in the colony.

Reproduction and details of colony size and the number of breeding animals in a colony are described for one complete and two incomplete field‐captured colonies. One incomplete colony was kept in captivity for more than 3 years, whereas the complete colony was autopsied.

The social hierarchy of the common mole‐rat is almost linear and has a value of 0.7 1 calculated from Landau's linearity index. Subordinate mole‐rats weighed less than dominant mole‐rats. The reproductive mole‐rats are the dominant animals within the colony. The non‐reproductive females rank lowest in the hierarchy.

Mating was not confined to a particular season, but occurred more frequently during the summer months. The alpha male initiated pre‐copulatory behaviour. The gestation length is 55 to 66 days (n = 2). Two litters each of three pups were born to the colony during captivity. The pups were relatively altricial. They wandered out of the nest 5 days after birth, began to eat solids when 10 days old, and were fully weaned at 4 weeks. When 2 weeks old the pups began to spar with each other and with some of the adult colony members, but levels of aggression were never high. The pups did not disperse but were incorporated into the colony, this suggesting that C. h. hottentotus colonies are largely composed of related individuals.
The effect of size on the optimal shapes of gliding insects and seeds
Authors: Ennos A. Roland
Published: March 2009

Conventional aerodynamic arguments suggest that possession of high aspect ratio wings will always improve the flight performance of glides. Drag and power will be minimized at intermediate flight speeds. It is shown, however, that as the aspect ratio increases, these minimum drag speeds are reduced, and will fall below the stall speed of the glider. This will happen at lower aspect ratios in small gliders, which operate at higher profile drag coefficients. Increasing the aspect ratio further will improve performance less than this analysis suggests.

A detailed analysis is developed to calculate the optimum shape of small gliders. Profile drag increases with aspect ratio, owing to the fall in the Reynolds number, while induced drag falls with increasing aspect ratio. Minimum drag will be encountered and hence the glide angle will be minimized at intermediate values of aspect ratio. Best glide angles are achieved at low speeds (high lift coefficients) and the optimum aspect ratio increases with the mass of the glider.

Small natural gliders possess large, low aspect ratio wings. The aspect ratios are generally somewhat below those which would produce the best glide angle at stall speed, but should give a reasonable performance over a range of speeds.
The development of an enzyme‐immunoassay for urinary pregnanediol‐3‐glucuronide and its application to reproductive assessment in exotic mammals
Authors: Hodges J. K. , Green D. I.
Published: March 2009

Measurement of urinary pregnanediol‐3‐glucuronide (PdG) provides a practical, non‐invasive method for monitoring ovarian function and pregnancy in diverse mammalian species. To date, however, methods of laboratory analysis have relied on radio‐immunoassay procedures which, because of their cost and the problems associated with the use and disposal of radioactive substances, have limited potential for routine application in zoos and other animal collections with limited laboratory facilities. The present paper reports the development of a non‐isotopic enzyme‐immunoassay for the measurement of urinary PdG in a wide range of exotic mammals and describes its application to reproductive assessment in the gorilla and rhinoceros.

The assay is based on an homologous competitive binding system and utilizes antiserum raised against PdG‐bovine serum albumen and alkaline phosphatase‐PdG, prepared by the active ester technique, as conjugate. Sensitivity of the assay is between 12.5 and 25 pg/well and precision, expressed as the intra‐ and inter‐assay coefficients of variation, is between 5.3 and 7.8% and 9.2 and 16.1%, respectively. Serial dilutions of human, gorilla, orang‐utan, mangabey, blackbuck, okapi, gaur, giant panda and Indian, black and white rhinoceros urine gave displacement curves parallel to that of the PdG standard, indicating the potential of the assay for multi‐species application.

The pattern of excretion of immunoreactive PdG during successive menstrual cycles and two complete pregnancies in a gorilla is described. Follicular phase levels of PdG were low (0.07–0.13 μg/mg creatinine (Cr)), in contrast to the high levels of excretion during the luteal phase (maximum values 1.5–2.1 μg/mg Cr). Mean cycle length was 29.6±1.5 days with a range of 26–34 (n = 5). The pattern of PdG excretion during pregnancy showed a slow increase during the first 60 days and a more rapid rise to values of 8–12 μg/mg Cr after 120 days, with no further consistent increase during the remaining period of pregnancy. Estimated gestation lengths were 280 and 256 days.

The levels of immunoreactive PdG excreted during mid‐to‐late pregnancy varied considerably between the three species of rhinoceros, maximum values ranging from up to 10 μg/mg Cr in the Indian to 0.08 μg/mg Cr in the white rhinoceros. Despite this variation pregnancy was associated with elevated PdG excretion in all three species and each profile showed a marked fall in levels at the end of the gestation period. The results suggest potential for urinary PdG determination as a practical method of pregnancy detection in both Indian and African rhinoceros, although species differences in the relative importance of PdG as a progesterone metabolite probably exist.
Assessment of errors associated with harbour seal (Phoca vitulina) faecal sampling
Authors: Harvey James. T.
Published: March 2009

Six harbour seals, ages 4–8 years, were held as pairs in a 10 times 20 times 2 m tank filled with sea water, and on 60 occasions were fed a meal of a specific species of fish or cephalopod of known size. The tank was drained periodically, and harbour seal faeces were collected on a 0.5 mm sieve. Number and size of otoliths and beaks found in faeces were determined. Fifty‐eight percent of 670 fish and 37% of 36 cephalopods fed to harbour seals were represented by their otoliths or beaks in faeces. Estimated number of prey consumed was determined from the greatest number of left or right otoliths or upper or lower beaks collected in faeces. Estimated length ofprey was determined from measurements of otoliths and beaks recovered in the tank and relationships of otolith and beak measurements to prey length. Estimated number of fish eaten was not significantly different among pairs of harbour seals, but was different among species of fishes. Only 24–35% of fish species with small otoliths were represented in faeces, whereas more robust otoliths from other species were less apt to be completely dissolved. Estimated length of fishes was significantly less than lengths of fishes fed to harbour seals in 39 (76.5%) of 51 trials. Cephalopod beaks were not affected by passage through the harbour seal digestive tract. Amount of otolith dissolution was not related to species of fish; estimated fish length was underestimated by an average 27.5%. Although some (7.4%) of the otoliths were collected within 100 h after the fish were ingested, more than 90% were recovered within 24 h after the fish was eaten. Correction factors were developed which will allow researchers to estimate more reliably number and size of fish and cephalopod prey eaten by harbour seals.
The use of first vertebrae in separating, and estimating the size of, trout (Salmo trutta) and salmon (Salmo salar) in bone remains
Authors: Feltham M. J. , Marquiss M.
Published: March 2009

A method is described in which a single bone, the first vertebra, is used to distinguish bone remains of juvenile salmon (Salmo salar) and trout (Salmo trutta) with 90% certainty. A single regression of salmon and trout first vertebra‐width versus fish‐length of fish predicted the latter with an accuracy of ±<10 mm (95% confidence limits) for salmonids of 45–150 mm fish‐length. First vertebrae were assigned to salmon or trout based on three visual characters with 89%,–90% certainty. Salmon are more variable than trout for the three characters. Of first vertebrae, 6.5% were not readily identifiable as either salmon or trout, and a further 3.0%) were misclassified using our criteria.
Functional and evolutionary morphology of lingual feeding in squamate reptiles: phylogenetics and kinematics
Authors: Schwenk K. , Throckmorton G. S.
Published: March 2009

Use of the tongue as a prehensile organ during the ingestion stage of feeding in lizards was studied cinegraphically in seven species. Within Squamata, lingual prehension is limited to a single clade, the Iguania (Iguanidae, Agamidae and Chamaeleontidae), which includes all ‘fleshy‐tongued’ lizards. All remaining squamates (Scleroglossa) use the jaws alone for prey prehension. Lingual prehension and a ‘fleshy’ tongue are primitive squamate characteristics. Kinematically, lingual ingestion cycles are similar to previously described transport cycles in having slow open, fast open, fast close and slow close‐power stroke phases. Tongue movements are sequentially correlated with jaw movements as they are in transport. However, during ingestion, anterior movement of the tongue includes an extra‐oral, as well as intra‐oral component. Tongue protrusion results in a pronounced slow open‐II phase at a large gape distance. A high degree of variability in quantitative aspects of ingestion and transport cycles suggests that modulation through sensory feedback is an important aspect of lizard feeding. Preliminary evidence indicates an important role for hyoid movement in tongue protrusion. Our results are consistent with the Bramble & Wake (1985) model generalized feeding cycle and support their contention that specialized feeding mechanisms often represent modifications of a basic pattern, particularly modification of the slow open phase.
Population dynamics of the narwhal Monodon monoceros: an initial assessement (Odontoceti: Monodontidae)
Authors: Kingsley Michael
Published: March 2009

A simplified population equation for Monodon Pnonoceros shows that current estimates of the values of the life history variables are inconsistent with the hypothesis of a stationary population. Instantaneous adult mortality must be less than 0,10/yr, not the published estimate of 12–13%/yr, for accepted values of the other variables to be consistent with stationarity. For sustainable harvest, permissible exploitation rates are no larger than 3–4%/yr, and instantaneous natural mortality must then be well below 10%/yr. Present uncertainty in the values of survival rates, both of adults and young, contributes twice as much to uncertainty in population growth rate as does uncertainty in reproductive rates.
Liver and plasma retinol (vitamin A) in wild, and liver retinol in captive penguins (Spheniscidae)
Authors: Ghebrmeskel K. , Williams G. , Keymer I. F. , Horsley D. T.
Published: March 2009

In rockhopper penguins (Eudyptes crestatus), liver concentrations of retinol (vitamin A) were significantly higher in post‐moult than in pre‐moult birds. In Magellanic penguins (Spheniscus magelianicus), plasma concentrations of retinol were significantly higher in post‐moult than in pre‐moult birds; liver retinol concentrations were also higher, but not significantly so.

The pre‐ and post‐moult Magellanics had higher liver and lower plasma retinol concentrations than the pre‐ and post‐moult rockhoppers.

Captive blackfooted (jackass) (Spheniscus demersus), king (Aptenodytes patagonica) and Humboldt (Spheniscus humboldti) penguins had liver vitamin A stores significantly lower than those of the free‐living rockhopper, Magellanic, gentoo (Pygoscelis papua), emperor (Aptenodytes forsteri), chinstraps (Pygoscelis antarctica) and Adélie (Pygoscelis adeliae) penguins.
Velocity and displacement receptors in the skin of the hagfish Myxine glutinosa.
Authors: McVvean Alistair
Published: March 2009

The skin of Myxine glutinosn contains both velocity‐sensitive and displacement‐sensitive mechanoreceptors. These can be distinguished from each other by the different time course of their response to skin indentation. Velocity receptors gave a brief response, consisting usually of three to four action potentials which could only be elicited by movement of the skin. No velocity receptor was spontaneously active. Displacement receptors, some of which were spontaneously active, gave a prolonged discharge which continued, with only slight adaptation, while the skin was indented. Velocity receptors code for velocity of indentation and continue to respond to repeated stimuli. Displacement receptor action potentials occur irregularly, with a Poisson‐like distribution of interspike interval. The mean frequency of displacement receptor discharge increases with depth of skin indentation, while the interspike interval distribution becomes progressively biased towards shorter intervals. The threshold of displacement receptors is related to displacement velocity; sinusoidal indentations of the skin produce a minimum threshold around 60 Hz. These receptors fail to respond to oscillations in excess of 120 Hz. The structure of the skin is described. Stress‐strain curves are given both for static and dynamic compression of the skin and these are discussed in relation to the properties of the skin mechanoreceptors.
Life history differences among the eutherian radiations
Authors: Read A. F. , Harvey P. H.
Published: March 2009

In this paper, we critically evaluate the view that eutherian life history diversity arises because of constraints imposed by the allometric consequences of body size, rather than selection acting on a broad array of possible life histories. Using life history data from over 700 species of eutherians, we examine covariation of life history variables across the 18 orders represented. Eutherian orders can be arranged from those characterized by small rapidly reproducing, rapidly developing, short‐lived species, such as lagomorphs, to large, slowly developing, slowly reproducing, long lived species, such as elephants. When the effect of body weight is controlled for, this pattern remains, but the relative positions ofthe orders on the new fast‐slow continuum are very different. There is a trade‐off between the weight and number of offspring in a litter which is independent of adult body weight. Maximum recorded lifespan is the best identified predictor of annual fecundity: high fecundity is associated with short lives. This is not easily explained as a cost of reproduction, because it is a function of the whole lifetime, rather than just the maximum reproductive lifespan. Those mechanisms said to underlie the allometric scaling of life histories, and which make testable predictions–growth constraints imposed by basal metabolic rate, brain weight and the rate of neuronal tissue growth–are not associated with life history variation once the effects of body weight are removed. Thus these variables have no greater explanatory power than body weight itself, since they cannot explain the variation in life histories which is not correlated with weight. Rates of litter growth rate are associated with life history variation independent of body weight, but until we understand why litter growth rates vary, they are unable, on their own, to explain considerable amounts of life history diversity. Differences in life histories among orders, whether or not the effect of body weight is controlled for, are associated with differences in mortality rates. We suggest that eutherian life histories are better thought of as adaptive strategies, and that mortality patterns offer considerably more promise in the understanding of eutherian life history diversity than loosely defined ideas about scaling principles and the allometric consequences of body size.
A phylogeny for the Old World newts, genus Triturus: biochemical and behavioural data
Authors: Arntzen J. W. , Sparreboom M.
Published: March 2009

A reconstruction is presented of the phylogenetic relationships withing Triturus. Two different data sets are used. Protein electrophoretic data were scored for 19 presumptive gene loci in nine species (Rafinski & Arntzen, 1987) and a set of 16 behaviour characters from the courtship of Triturus was scored for the same nine species. When these are analysed in concernt, a single, fully resolved and robust solution is found. Consequently, two subgenera are recognized: Triturus and Palaeotriton, the former including all te medium‐ and large‐bodied species: T. alpestris, T. vittatus, T. marmoratus, T. cristatus and its three former subspecies (T. carnifex, T. dobrogicus and T. Karelini); the latter comprising the small‐bodied species: T. bascai, T. italicus, T. helveticus, T. vulgaris and T. montandoni. Within the subgenus Triturus, T. alpestris and T. vittatus are sister taxa to the remaining members of the subgenus. Similarly, T. boscai and T. italicus are a monophyletic group, sister to T. vulgaris, T. helveticus and T. montandoni. Alternative solutions may be found on the basis of a quantitative analysis of the behavioural characters employed in this study. An alternative phylogenetic tree is included as an example.
Suckling behaviour in the pipistrelle bat (Pipistrellus pipistrellus)
Authors: Hughes P. M. , Speakman J. R. , Jones G. , Racey P. A.
Published: March 2009

A sub‐colony of 20 pipistrelle bats was studied during late pregnancy and lactation. Seventeen females gave birth to single young, with 16 young surviving to weaning. Free association and flight were permitted, and mother‐infant pairs were identified and marked on the day of birth (day 0). Suckling associations were identified daily (n = 195) and females were never found suckling young other than their own. A series of choice experiments using young aged 0–10 days and 15–25 days indicated that females would permit only their own offspring to suckle during both early and late lactation. During early lactation, mothers actively selected their young and encouraged suckling but did not do so during late lactation. Mothers were most often indifferent to approaches by alien young but occasionally aggressively rejected them. Mothers never aggressively rejected their own young but frequently were indifferent to them. Young attempted to suckle from any mother without discrimination.
Comparative studies on the timing of reproduction and foetal number in six species of Australian conilurine rodents (Muridae: Hydromyinae)
Authors: Breed W. G.
Published: March 2009

The timing of reproduction and number of foetuses in the wild caught conilurine rodents Notomys mitchelli, N. alexis, Pseudomys albocinereus, P. hermannsburgensis, P. delicatulus and P. nanus was ascertained from museum preserved specimens. The two species from southern Australia (N. mitchelli, P. albocinereus) appeared to have a breeding season from late winter to early summer, whereas in those from the central region (N. alexis and P. hermannsburgensis) no such breeding season was evident. The little data available for the northern species, P. delicatulus, suggests at least reproduction during the winter. Foetal number was similar for the four species from southern and central Australia but tended to be slightly less in the two northern species. The significance of these findings in relation to the control of reproduction is briefly discussed.
A new genus of dimorphic soft coral from the south‐western fringe of the Indo‐Pacific (Octocorallia: Alcyoniidae)
Authors: Williams Gary C.
Published: March 2009

A new genus of dimorphic soft coral is named to accommodate Sarcophyton trochiforme Hickson, 1900. This species is found to differ markedly from members of the genus Sarcophyton as well as Anthomastus(to which it was later assigned), and thus becomes the type species of a new genus. A redescription of the species based on some of Hickson's original material is provided. Also, a new species assignable to the new genus is described from recently collected material. Both species are distributed along the south‐eastern coast of Africa, where the south‐western fringe of the Indo‐Pacific Province overlaps with the Cape Endemic Province of southern Africa. The new genus differs from other dimorphic alcyonacean genera by the possession of coenenchymal sclerites that are predominantly eight radiates or double stars or barrels and tuberculate spheroids, relatively small autozooids, and a slender capitate growth form. A key to the world genera of dimorphic alcyonaceans is included.
Spiracular transpiration in ticks: a passive diffusion barrier in three species of Ixodidae (Metastigmata: Acarina)
Authors: Pugh P. J. A. , P. E. King  , Fordy M. R.
Published: March 2009

In ixodid ticks the morphology of the spiracle, and in particular that of the labyrinth, differs between species. A reduction in transpiration of water vapour by the ‘mutual interference’ effect previously described in Ixodes ricinus (L.) is not significant in many species. Instead, transpiration is retarded by very restricted air movement within the labyrinth and by a high resistance to diffusion generated by numerous small aeropyles. These adaptations may be particularly useful in arid environments.
Genetic and taxonomic relations of the short‐tailed snakes, genus Stilosoma1
Authors: Dowling H. G. , Maxson Linda R.
Published: March 2009

Both morphological and immunological investigations show that Stilosoma is related to the American kingsnakes (Lampropeltis) and their allies. Immunological tests show an unexpectedly close relationship, indicating its derivation in the Pliocene.
The distribution of the millipede Ommatoiulus moreleti (Diplopoda, Julida: Julidae) in relation to other Ommatoiulus species on the south‐western Iberian Peninsula
Authors: Bailey P. T. , Mendonça Teresa Rita de
Published: March 2009

Ommatoiuius moreleti(Lucas) occurs naturally in Portugal and Spain, and has been introduced to some Atlantic Islands, South Africa and southern Australia, where it is widespread and numerous.

In southern Portugal and south‐west Spain, O. moreleti shares its range with O. oliveirae (Verhoeff), O. cingulatus (Attems) and several undescribed Ommatoiulus spp. In a study area where O. moreleti was confined to deep litter beneath Quercus trees, O. oliveirae predominated in litter of the bushes Cistus spp., while O. cingulatus was most numerous in an area dominated by grasses and herbs, but with little litter. The three species tended to eat different food items, but this probably reflected local availability rather than preference.

Ommatoiulus moreleti has a distinct western boundary which broadly corresponds with changes in the quantity of litter on the ground. The distribution of O. moreleti was related to the availability of deep litter, often provided by Pinus and Quercus trees, but also by dense shrubs and heath, and undisturbed grassland.

In addition to providing food, litter provides a refuge for O. moreleti. Grassland species such as O. cingulutus live where there is little litter, and probably have to dig deep in the soil to avoid summer desiccation and predation of immature stages. It is suggested that soil hardness and litter depth may be important determinants in the distribution of O. moreleti, and relative digging ability may explain the partitioning of the habitat between the three species studied.
Systematics of freshwater gobies from Greece (Teleostei: Gobiidae)
Authors: Economidis P. S. , Miller P. J.
Published: March 2009

Five species of gobiid fish are recognized in the fresh waters of Greece. Most distinctive is the south‐western Hellenic (West Balkanian component) endemic genus Economidichthys Bianco, Bullock, Miller & Roubal, 1987, with the type‐species E. pygmaeus (Holly, 1929) from Lefkas, Epirus and Lake Trichonis, and E. trichonis sp. nov., from Lake Trichonis, the latter probably the smallest freshwater European teleost at maturity (female, 18·0 mm) and maximum size (male, 30·0 mm). In tributaries of the northern Aegean basin (north‐eastern Hellenic freshwater fauna), two species of the Ponto‐Caspian genus Knipowitschia can be identified, the widespread Kn. caucasica (Kawrajsky in Berg, 1916) (coastal plain of Macedonia and Thrace) and the endemic Kn. ihessala (Vinciguerra, 1921) (Pinios river system, Thessaly). The larger Ponto‐Caspian tubenose goby, Prolerorhinus marmoratus (Pallas, 1811), occurs in the Evros (= Maritsa) (Thrace) and Strymon (Macedonia) systems. Only the genera Economidichthys and Knipowitschia are considered in this paper, being redefined in terms of osteology and head lateral‐line system, and the species described in detail, with special reference to meristic variation and squamation, and, in Economidichthys, the unique perianal organ of this genus. The relationships of Economidichthys and Kn. thessala are discussed and possible scenarios for their evolution are suggested in the light of Miocene to Recent events.
The food and feeding habits of two co‐occurring marine catfish Galeichthys feliceps and G. ater (Osteichthyes: Ariidae) along the south‐east coast of South Africa
Authors: Tilney R. L. , Hecht T.
Published: March 2009

The feeding‐associated morphological structures of the two Galeichthys species were found to be similar in all respects. Interspecific competition for food was avoided through habitat separation. Habitat preference, as established by dietary analysis and fishing trials, was based on substratum type. Galeichthys feliceps fed over sandy and muddy substrata in marine and estuarine environments, while G. ater fed exclusively over marine reefs. The two species have different caudal fin structures which are probably evolutionary responses to habitat‐associated behavioural requirements in the two different environments.

The diets of the two species were investigated and compared using calorific values of prey items. While both species fed predominantly on benthic crustaceans, polychaetes and molluscs, little dietary overlap occurred at the species level. In the estuarine environment, G. feliceps fed mainly on the anomurans Upogebia africana and Calianassa kraussi, crabs Hymenosoma orbiculare and Cleislosoma edwardsii, and several isopod species. In the marine environment G. feliceps fed mainly on two species of crabs, Thaumastoplax spiralis and Goneplax angulata, the echiurid Ochaetostoma capense and the sedentary polychaete Sternaspsis scutata. A high incidence of teleost scales in the diet of G. feliceps juveniles was found to be a consequence of scavenging rather than a lepidophagous habit. Galeichthys ater fed widely on several reef‐associated crabs, isopods, polychaetes and cephalopods.
An ecological study of small rodents in the woodland savanna of Liwonde National Park, Malawi
Authors: Happold D. C. D. , Happold M.
Published: March 2009

A community of small rodents was studied in the woodland savanna of Liwonde National Park, Malawi from September 1984 to June 1985. Seven species were recorded on two 11 ha grids, using a capture‐mark‐release technique. Three species (Aelhomys chrysophilus, Acomys spinosissimus and Tatera leucogasler) comprised 78% of all trapped individuals. Average population numbers fluctuated from 3 to 17 individuals/ha. The grid with the densest vegetation supported the greatest number of individuals. Highest population numbers occurred in the mid‐dry season (when the grids appeared to act as refugia) and in the early wet season (due to recruitment of young animals). Areas which had been burned during the dry season did not support as many individuals as unburnt areas. Population survival rates were low, with only about 50% of individuals surviving to the following month. The number of individuals/ha in Liwonde NP was lower than in similar habitats in other parts of eastern Africa, probably because of the shorter rainfall season and the consequent strong seasonal fluctuations in food resources, reduced opportunity for reproduction, and overall low productivity of the ecosystem.
Morphometrics and allometry in the trophically polymorphic cichlid fish, Cichlasoma citrinellum: Alternative adaptations and ontogenetic changes in shape
Authors: Meyer Axel
Published: March 2009

The Neotropical cichlid fish Cichlasoma citrinellum exhibits a distinct trophic polymorphism in the structure of its pharyngeal jaws. Fish have either strong, sturdy molariform pharyngeal jaws or weak papilliform jaws. Intermediate forms are rare among adults. Ontogenetically, however, all fish start as papilliform morphs. Differences in morphology and allometry between morphs in external measurements (25 measurements) and measurements of the lower pharyngeal jaws (nine measurements) were analysed using a multivariate morphometric approach. The ontogenetic growth trajectories for the pharyngeal jaws of the respective morphs start to diverge early in ontogeny and therefore seem to preclude the existence of adult intermediate morphs. The isometric growth of the tooth diameter in molariform morphs (in relation to standard length), versus its relatively retarded (negatively allometric) growth in the papilliform morph, is the main cause for the development of distinct trophic morphs in pharyngeal‐jaw morphology. At approximately 50 mm standard length, both pharyngeal morphs can be discerned clearly. In this study only larger fish of determined pharyngeal‐jaw morphology were considered (n= 30 for molariform morphs, n= 31 for papilliform morphs). External morphology differs between morphs as well, but less perceptibly. Principal‐components analyses revealed that only a few measures load highly on PC2 and therefore account for most of the differences between the two trophic morphs in the shape of the external morphology. Molariform morphs have blunter, shorter snouts, larger eyes and deeper, shorter bodies than papilliform morphs.

The two external morphologies resemble other known limnetic and benthic body shapes of polymorphic species of fishes, and are believed to enhance the ecological separation of the two pharyngeal‐jaw morphs. Evolutionary implications of ontogenetic changes and adult differences in morphology and trophic polymorphism are manifold. The alternative adaptations in this polymorphic species will decrease intraspecific competition by differential niche utilization and habitat choice, thus allowing for larger population sizes. Alternative adaptations may eventually lead to genetic isolation and possibly speciation of the two trophic morphs.
The maternal recognition of pregnancy in mammals
Authors: Flint A. P. F. , Hearn J. P. , Michael A. E.
Published: March 2009

Progesterone secreted by the corpora lutea stimulates uterine secretion of nutrients required for embryonic growth. But progesterone also blocks maturation of ovarian follicles and oestrous behaviour. When conception fails, therefore, the corpora lutea must lyse, in order to allow a second ovulation and oestrus, while in pregnancy the corpora lutea must be maintained. A number of different endocrine mechanisms exist to ensure the corpora lutea are controlled appropriately depending on pregnancy status; among the best studied of these are the secretion by the developing conceptus of interferons (in ungulates) or chorionic gonadotropins (in primates). These and other mechanisms are reviewed.
Spatial distribution, calling and interspecific acoustic interactions in two species of the Australian tettigoniid genusTympanophora(Orthoptera, Tettigoniidae)
Authors: Schatral Andrea , Yeoh P. B.
Published: March 2009

Two species of the Australian genusTympanophora, Tympanophoranew species 1 (T.n.sp.l)andT. similisshare the same habitat and are sympatric with several other bushcricket species. Males ofT. similiscall in aggregations, whilst males ofT.n.sp.lfrequently sing closer to heterospecific than to conspecific neighbours. Hence males ofT.n.sp.lmay have to cope with more severe problems of interspecific acoustic interference than males ofT. similis.Laboratory experiments support field data which indicate that the number of callingT.n.sp.lmales decreases when the number of singing males ofT. similisincreases. Acoustic interactions between the two species and sympatric bushcricket species occur in the laboratory. Heterospecific song affects chirp interval and/or chirp pattern in the twoTympanophoraspecies. Males ofT.n.sp.lrespond to the song of the sibling speciesT. similisdifferently than to the calls of the more distantly related tettigoniids tested. However, the response ofT. similismales appears to depend on the temporal structure of the heterospecific songs. The results do not suggest that the frequency content of the heterospecific calls is important for the song interference which has been observed inTympanophora.
Frequency of interspecific mating in salamanders of the plethodontid genus Desmognathus: different experimental designs may yield different results
Authors: Verrell Paul A.
Published: March 2009

Heterosexual courtship trials were staged between dusky salamanders of two species (Desmognathus fuscus and D. santeetlah) from two allopatric populations in the southern Appalachian Mountains of eastern North America. Two experiments were conducted in order to test for effects of experimental design on estimates of the strength of sexual isolation between these species. In Experiment 1, frequencies of interspecific mating were determined when: (1) a male was presented with a conspecific and a heterotypic female successively; and (2) both types of females were presented simultaneously to a male. The frequency of interspecific mating by male D. fuscus was greatest when females were presented successively. The frequency of interspecific mating by male D. santeetlah was not influenced by method of female presentation. An index of sexual isolation of +0.29 was obtained between D. fuscus and D. santeetlah when females were presented successively, and of +0.63 when females were presented simultaneously. In Experiment 2, interspecific mating frequencies were determined in courtship arenas of two different sizes. No significant effect of arena size on frequency of interspecific mating was found for D. fuscus. In D. santeetlah, a trend towards greater mating frequency in small arenas was almost significant. These results suggest that interspecific mating frequencies (and thus estimates of the strength of sexual isolation between populations or species) may be sensitive to the experimental design employed. The validity and generality of this conclusion for other animals is an urgent, empirical issue.
Habitat usage by red (Cervus elaphus) and roe (Capreolus capreolus) deer in a Scottish Sitka spruce plantation
Authors: Welch D. , Staines B. W. , Catt D. C. , Scott D.
Published: March 2009

Habitat usage in a 1825 ha block of mixed‐age forest was assessed by counts of accumulated pellet groups on permanent plots. This monitoring took place from 1978 to 1984 with some 300 plots in 13 types of habitat. Tests on the method are described; losses of pellet groups were insufficient to bias the conclusions.

Usage was least in the forest stages lacking ground vegetation, i.e. thicket, pole and high‐canopy forest; stages with ground vegetation had moderately heavy usage. The most preferred habitats were of small extent, treeless, and situated near or within closed forest, i.e. rides, openings and the margin between forest and unplanted hill ground. Red and roe deer showed broadly similar patterns of preference but differed significantly in the use of some habitats. Thickets received more use from red than roe deer, whereas pre‐thicket and vegetated high‐canopy forest had most use from roe deer, being richer in forbs on which this species feeds heavily.
The reproductive cycle of the Nile crocodile (Crocodylus nilotkus)
Authors: Kofron Christopher P.
Published: March 2009

The reproductive cycle of the Nile crocodile (Crocodylus niloticus) was studied in Zimbabwe. Females attained sexual maturity after they had reached a total length of about 262 to 287 cm and males, 270 to 295 cm. Some adult females did not reproduce every year. Follicle growth and vitellogenesis occurred from April to mid August during the dry winter. During this time reproductive females had elevated levels of plasma oestradiol‐17β, testosterone, calcium and magnesium, but lowered levels of iron. The measuring of plasma calcium was an ‘early pregnancy’ test, reliable up to four months before nesting. Elevated levels of plasma testosterone in reproductive females corresponded to the time of courtship and mating. Ovulation occurred during the latter half of August. Males had viable sperm from mid May to mid September, during the winter. Courtship and mating occurred from late June to mid August, when crocodiles were confined to pools. Females nested on the higher sand ridges in the dry river bed from early September to early October, and eggs hatched during December.
The architecture of the spleen of the yellow‐bellied toad, Bombina variegata
Authors: Dulak Józef
Published: March 2009

The spleen of the yellow‐bellied toad, Bombina variegata, consists of distinct white and red pulps. The well‐developed white pulp is formed by a large central lymphocytic region around the numerous blood vessels and by its smaller peripheral ramifications, both surrounded by the more or less developed connective tissue boundary layer. Large peripheral sinuses of the white pulp, filled mostly with lymphocytes, are usually present at the inner side of this boundary. At the outer side of the boundary layer, the lymphocytic marginal zone is often observed. This zone merges into the erythrocyte‐rich red pulp formed by cellular cords and small venous sinusoids.

The structure of the spleen of Bombina variegata differs considerably from the spleens of other anuran species studied so far. The highly developed white pulp and its distinct separation from the red pulp may be connected with the important role of the spleen as the main secondary lymphoid organ of B. variegata. The splenic compartmentalization makes the yellow‐bellied toads a useful model for experimental immunobiological studies.
The morphology of the gills of the freshwater African crab Potamon niloticus (Crustacea: Brachyura: Potamonidae): A scanning and transmission electron microscopic study
Authors: Maina J. N.
Published: March 2009

The gills of the African freshwater crab Potamon niloticus‐Ortmann have been investigated by scanning and transmission electron microscopy. Potamon has seven pairs of phyllobranchiate gills contained in the branchial chambers. From the central axis of the gills arise bilaterally situated thin flaps, the lamellae. The afferent branchial vessel (the epibranchial vessel) is located on the dorsal aspect of the gill arch and the efferent vessel (the hypobrancial vessel) on the ventral side. Between these two blood vessels, the blood percolates through the lamellar vascular channels where it is oxygenated. The lamellae consist of an epithelial cell layer covered by a thin cuticle which consists of tightly fused but distinct layers. The epithelial cells approach each other at regular intervals and fuse in the middle of the lamellar sinus delineating the vascular channels. Apical profuse membranous infoldings and numerous mitochondria characterize the epithelial cells, features typical of cells involved in active transport of macro‐ and micromolecules. In Potamon, however, there were no distinct gas exchange and osmoregulatory regions of the gills. On average, the cuticle was 0.78 μm thick while the epithelial cell was 6 μm. Cells that were morphologically similar to the renal glomerular podocytes of the vertebrates were observed in the efferent gill vessel of Potamon. These cells have been said to be phagocytic and may play an important defensive role in the crustaceans. Although basically the morphology of the gills of Potamon is similar to that of the other decapods, fine structural differences were evident as would be intuitively expected in a group of animals that has undergone such remarkable adaptive radiation.
Sexual dimorphism of auditory function and structure in praying mantises (Mantodea; Dictyoptera)
Authors: Yager David D.
Published: March 2009

Sexual dimorphism of tympanate auditory systems in insects has bees described in only a few taxonomically isolated cases. However, widespread sexual dimorphism occurs in the ultrasound‐sensitive, midline ear of the praying mantis.

In dimorphic species, it is always the female mantis that shows a reduction in ultrasonic hearing. The dimorphism may be mild—a difference in tuning and small reduction in sensitivity—or extreme with no evidence of audition in the female. In all but the mildest cases, the reduction in hearing is accompanied by significant anatomical divergence from the male ear structure. Two distinct metathoracic groove (‘ear’) types are linked to hearing reduction in the females.

Anatomical evidence of auditory sexual dimorphism appears in 34% of the 183 mantis genera examined. The dimorphic genera are widely but non‐uniformly distributed within three of the four largest mantis families.

Auditory sexual dimorphism is closely correlated with dimorphism in wing length. In general, mantises with functional wings have sensitive ultrasonic hearing while those with short wings do not. These findings support the hypothesis that ultrasonic hearing in mantises is part of a defensive system against attack by echolocating bats.