bluuebunny/crossref_metadata_2025 huggingface dataset:
The functional morphology of weight bearing: limb joint surface area allometry in anthropoid primates
Authors: SWARTZ SHARON M.
Published: March 2009

Biomechanical scaling of long bone joint surface areas was investigated in 13 species of anthropoid primates. It was proposed that joint surface areas should scale with positive allometry with respect to body size in order to maintain relatively constant safety factors for joints in small and large animals and that modifications from the overall pattern of scaling may be expected in the limb joints of species exhibiting specialized locomotor behaviours that radically alter limb loading. Within anthropoids, the brachiating primates, white‐handed gibbons (Hylobates lar) and black‐handed spider monkeys (Ateles geoffroyi), were used to test this hypothesis. Total joint surface areas were found to scale with significant positive allometry in 11 of 12 limb joints. The observed pattern of interspecific allometry supports the hypothesis that weight bearing is a major constraint on the design of joints. This positive interspecific allometry is reflected at the intraspecific level as well, with larger joints of larger species showing significant intraspecific scaling. Suspensory species showed no significant deviations from the overall anthropoid pattern, despite their reduced compressive loading of the limb joints, even after controlling for joint mobility. These results suggest that, while evolutionary changes in locomotor behaviour that produce significant increases in loading of a joint may be accompanied by selection for increased joint surface areas, adoption of locomotor repertoires that reduce limb loading may have no selective effect on joint morphology, and joint design in these cases will reflect the biomechanics of the ancestral locomotor condition.
Observations on the ontogeny and homology of the pterygoid bones in Corydoras paleatus and some other catfishes
Authors: Howes G. J. , Teugels G. G.
Published: March 2009

There has been much uncertainty in the past concerning the identity of the pterygoid bones in Siluroidei (catfishes). This confusion stems from the often increased number of pterygoid elements and their modified development, as compared with other teleosts. The ontogeny of the hyomandibula‐pterygoquadrate series in a 20‐day developmental sequence of Corydoras paleatus (Jenyns, 1842) embryos is described and supplemented with observations on a clariid and an ageniosid. A historical résumé of previous interpretations of siluroid pterygoid bone homologies is given together with our own which regards the metapterygoid as the central, densely ossified area of the pterygoquadrate, surrounded by the membranodermal ento‐ and ectopterygoids.
Life‐history characteristics and sexual strategy of Mytilopsis sallei (Bivalvia: Dreissenacea), introduced into Hong Kong
Authors: Morton Brian
Published: March 2009

First recorded from Hong Kong in 1980, Mytilopsis sallei now dominates the intertidal pier community within the Government Dockyard, Victoria Harbour. Analysis of monthly samples of M. sallei has demonstrated aspects of the reproductive strategy and life‐history characteristics correlated with seasonal changes in local water quality.

Mytilopsis sallei is dioecious, has a high fecundity, matures early (at 8–10 mm shell length), grows fast and the majority of the population is probably semelparous. These are characteristic traits of opportunistic r‐strategists. Comparable characteristics are typical of other introduced bivalves. Maximum life span of M. sallei in the Dockyard is probably less than 20 months with, however, most of the population dying before that. Heavy recruitment, particularly during spring‐summer, suffocates older individuals. The shells of dead animals similarly last for little more than one year, dissolution and crushing effecting this. A mat of byssal threads serves to bind the mass and anchor it to the substratum.

Mytilopsis sallei exhibits two periods of reproductive activity and settlement per year. These are possibly two elements of a single recruitment divided into minor (autumn‐winter) and major (spring‐summer) components by either high summer temperatures or low salinities. Summer and winter recruits of M. sallei, respectively, mature to produce the summer and winter juveniles of the following year. Over‐stepping generations plus survival of a few individuals into their second year thus ensure continued success of M. sallei, and account for its spread and dominance in its introduced range. Such a bimodal pattern appears typical of many Hong Kong intertidal, estuarine and freshwater bivalves.
Asymmetries in the sense organs and central nervous system of the squid Histioteuthis
Authors: Wentworth S. L. , Muntz W. R. A.
Published: March 2009

The visual system of Histioteuthis is markedly asymmetrical, in that the eyes and optic lobes are considerably larger on the left side, and the lens of the left eye is often yellower in colour than that of the right eye. At the histological level, the rhabdomes of the retinas of both eyes show the usual rectilinear pattern typical of cephalopods. Unlike other species described, however, the orientation of the pattern is not uniform over the retina. The optic lobes are well developed on both sides, again following the typical squid pattern, although the plexiform and inner granular layers are thicker on the left side. In life it is likely that the animals orient at an oblique angle with the arms downward, and the left eye pointing upwards and the right eye downwards, and the asymmetries of the visual system are probably related to this posture. No corresponding asymmetries in the statocysts or other parts of the central nervous system have, however, been detected
A comparison of the stoloniferous octocorallian genera Scyphopodium, Stereotelesto, Bathytelesto and Rhodelinda, with the description of a new species from south eastern Africa (Anthozoa, Chavulariidae)
Authors: Williams Gary C.
Published: March 2009

A new species of stoloniferous octocoral assignable to the genus Bathytelesto Bayer, 1981 is described from the Indian Ocean coast of southern Africa. The new taxon represents the fifth described species of the family Clavulariidae with rigid cylindrical or tubular anthosteles composed of inseparably‐fused sclerites. Four genera are currenly in use to accommodate these species. However, only one of these (Scyphopodium) seems to be morphologically well differentiated from the rest. The other three (Stereotelesto, Bathytelesto and Rhodelinda) are here considered as nominal at present until more material representing all of the taxa can be accumulated and a detailed comparative examination made. Of these four genera, the new species is morphologically most closely aligned with the genus Bathytelesto.
Cephalopods in the diet of the South African fur seal (Arctocephalus pusillus pusillus)
Authors: Lipinski M. R. , David J. H. M.
Published: March 2009

The stomach contents of 1522 adult seals (Arctocephalus pusillus pusillus) and 673 pups, which were collected around the West and South Coasts of Southern Africa, were examined and cephalopod prey identified. About 20 cephalopod species (some identifications were uncertain) were found in the stomachs, of which only six were significant: Loligo vulgaris reynaudii. Sepia spp., Octopus sp., Todaropsis eblanae, Todarodes angolensis and Ocythoe tuberculata. This list suggests that A. pusillus feeds exclusively on the continental shelf, frequently on or near the bottom. Among adults, cephalopod prey varied in importance around the coast. It was most important on the South Coast of South Africa where it comprised 35.0% of the weight of all prey, of which L. v. veynaudii constituted about 88%. On the West Coast cephalopods comprised about 26.6% by weight of all prey, and Octopus sp. predominated, whereas in Namibian waters cephalopods were least important, constituting only 3.4% by weight of all prey, with Todarodes angolensis and Octopus sp. being most significant. Among pups (aged 8–10 months) in the Lüderitz (Namibia) area, cephalopods were about 16.9% of prey by weight, of which Ocythoe tuberculata, small Sepia spp. and Octopoda were most important.
A new genus and species of Sarcoglanidinae from the Río Mamoré, Amazon Basin, with comments on subfamilial phylogeny (Teleostei, Trichomycteridae)
Authors: DePinna Mário C. C. , Starnes Wayne C.
Published: March 2009

Stenolicmus sarmientoi is described as a new genus and species of the trichomycterid subfamily Sarcoglanidinae, from the RíAo Mamoré Basin, Bolivia. It can be distinguished from all other sarcoglanidines by: five‐rayed pectoral fin; elongate body shape (HL about 15% of SL); absence of fontanelles on cranial roof; well‐developed patches of opercular and interopercular odontodes (five or six on each bone); numerous accessory caudal‐fin rays (13 dorsal and 11 ventral); and presence of extensive dark pigmentation on the surface of the body. Three synapomorphies support a hypothesis that the new taxon forms a monophyletic group with other sarcoglanidines: presence of an anterior ossification of the palatine cartilage; quadrate with a dorsal expansion directed posteriorly; and premaxilla with a long lateral process. Stenolicmus lacks some synapomorphies shared by Stauroglanis, Malacoglanis and Sarcoglanis, and shares some other synapomorphies exclusively with Sarcoglanis and Malacoglanis. These character distributions make it uncertain whether Stenolicmus is the sister group of all other sarcoglanidines or only of Malacoglanis plus Sarcoglanis, because the two positions imply equally parsimonious cladograms.
Some Antarctic and sub‐Antarctic species of Smittinidae (Bryozoa: Cheilostomata)
Authors: Hayward P. J. , Thorpe J. P.
Published: March 2009

Twenty‐six species of Bryozoa, in the ascophoran cheilostome family Smittinidae Levinsen, 1909, are described from Antarctic and sub‐Antarctic localities. Fourteen species are considered to be new to science. Aspericreta gen. nov. is introduced for Smittina crassatina Waters, 1904, and Platychelyna gen. nov. for Cellarinella planulata Hayward, 1980.
Field observations on scent‐marking behaviour in saddle‐back tamarins, Saguinus fuscicollis (Callitrichidae, Primates)
Authors: Bartecki Ursula , Heymann Eckhard W.
Published: March 2009

The scent‐marking behaviour of a group of six saddle‐back tamarins, Saguinus fuscicollis nigrifrons, was studied in the Amazon rain forest of north‐eastern Peru. Three types of scent marking were recognized: anogenital marking, suprapubic marking and sternal marking. Anogenital marking was the most frequent type. Two or more scent‐marking acts of the same or different type were generally combined into sequences. Most scent‐marking was performed on branches and lianas; trunks were infrequently used. The tamarins mainly marked on horizontal or inclined substrata with diameters between 3 and 10 cm and a height between I and 10 m. The temporal distribution of scent‐marking exhibited a maximum in the early morning between 06:00 and 07:00h and a minimum between 16:00 and 17:00h. The majority of scent‐marking occurred in the peripheral areas of the home‐range. The spatial distribution of scent‐marking was correlated with the intensity of home‐range use. No elevated frequencies of scent‐marking were observed during intergroup encounters. The results of this field study are compared with findings from laboratory studies, and hypotheses concerning the function of scent‐marking are discussed.
Scaling of speed and endurance in garter snakes: a comparison of cross‐sectional and longitudinal allometries
Authors: Jayne Bruce C. , Bennett A. F.
Published: March 2009

This study used cross‐sectional (one observation per each of several individuals of different size) and longitudinal (more than one observation through time per individual) methods to determine the effects of size on speed and endurance of Thamnophis sirtalis fitchi. The cross‐sectional sample consisted of 497 snakes from a single population. Log of mean burst speed in this group measured over 50 cm (V50) was a quadratic function of log of snout‐vent length (SVL); the slope of this polynomial ranged from about 1.6 to ‐0.3 for the smallest to the largest snakes (maximal V50 at 50.6 cm SVL). Longitudinal measurements of log V50 also were quadratically related to log SVL, but the slopes varied depending on year in which performance was measured. Cross‐sectional allometry revealed that the slope of the regression relating log(endurance) to log(SVL) was about 2.3, and longitudinal estimates of this quantity ranged from 0.5 to 3.2, depending on the year. Sex did not affect burst speed, but females had significantly less endurance than males of equal SVL, and pregnancy had a significant detrimental effect on both speed and endurance. Regressions with SVL as the independent variable were used to generate size‐corrected (residual) values of speed, endurance and mass, and each of these residuals had significant repeatability. For example, during 1986 the short‐term repeatabilities (Pearson's r) of speed and endurance residuals were 0.65 (P < 0.001) and 0.57 (P < 0.001). From 1986 to 1987, year‐to‐year repeatabilities of speed, endurance and mass residuals were 0.25 (P= 0.001), 0.22 (P= 0.005) and 0.47 (P < 0.001), respectively. Analysis of these three respective residual values of 264 neonatal snakes from 34 litters revealed highly significant percent variance components attributable to litter of 14%, 34% and 36%, yielding respective heritabilities of 0.28, 0.68 and 0.72. Speed and endurance residuals had a low but significant positive correlation (r= 0.26, n= 497), due apparently to snakes with poor performance: high speed is not linked with high endurance. A squared value of the mass residual had a significant negative correlation with both speed residual (r= ‐0.105, n= 497) and endurance residual (‐0.24), suggesting that snakes deviating from a mean value of mass relative to length have a slight decrement in locomotor performance. Longitudinal estimates of the scaling of mass with length revealed significant variation associated with different ages of snakes and different years of the study that could not be obtained from cross‐sectional data.
Biomechanics of the masticatory apparatus of Pteropus giganteus (Megachiroptera)
Authors: De Gueldre Greet , De Vree Frits
Published: March 2009

Jaw mechanics in Pteropus were studied by means of a three‐dimensional model. The model included several parameters of muscle architecture, combined with quantified movement and electromyographical data. Estimates of the nature of the applied forces that act upon the mandible during a chewing cycle, and subsequent estimates of reaction forces at the bite point and joints during the powerstroke, were thus obtained for different food consistencies. The resultant muscle force (relative to the palate) shifts from upward and slightly backward at large gapes to upward and markedly backward at the end of closing. The resultant simultaneously moves anteriorly. During the powerstroke it retains a constant position and orientation along the thickened anterior edge of the coronoid process. The early stages of opening are guided by the slope of the teeth and mandibular fossa; during the remaining part of opening the working line of the resultant crosses the skull behind the joint and thus acquires an opening moment. The bite force has downward and forward components, and a slight transverse component. For a given applied muscular force its magnitude is larger in more posteriorly positioned bite points. Both joints are loaded, the contralateral one more than the ipsilateral. Food consistency affects magnitude and orientation of the applied force, and hence, magnitude and orientation of the bite force and magnitude of the joint reaction forces. The magnitude of masseter activity relative to temporalis activity appears to be the key factor for the orientation of the bite force, and hence for the mechanical optimal position of the food. The adaptive value of the general topography of the masticatory muscles in Pteropus is discussed.
Behaviour of the yellow‐eyed penguin chick
Authors: Seddon Philip J.
Published: March 2009

The ontogeny of yellow‐eyed penguin (Megadyptes antipodes) chick behaviour follows the order of development determined by Nice (1962) for several species of birds, and by Spurr (1975) for the Adélie penguin (Pygoscelis adeliae). Feeding and comfort behaviours are the first to develop, followed by locomotion and aggressive behaviour.

Active solicitation of food may occur at one day of age. Chicks initially use non‐visual cues to mediate begging. After their eyes open on the third or fourth day there is an increase in the use of visual stimuli, and begging occurs most often following adult nest relief. Sibling rivalry is not intense, occurring least during feeding, and in general both chicks are fed at each session.

The chicks are brooded for the first 21–25 days. At sparsely vegetated nest sites overheating may occur after 21 days and down‐covered chicks will seek shade and pant in hot weather.

Throughout the 6–7 weeks of the guard phase there is a decrease in the amount of time spent resting in a prone posture, and an increase in exploratory, locomotory behaviour. During the post‐guard phase, and until fledging and independence at 15 weeks after hatching, chicks may wander up to 20 m from the nest bowl during exploration, shade‐seeking and feeding.

Adults feed only their own chicks, and chicks appear to beg only from their parents. Dense vegetation and long distances between nests tend to restrict contact between adults and chicks from neighbouring nests, and prevent the formation of large chick crèches.
The effect of scavenger mutilation on insect succession at impala carcasses in southern Africa
Authors: Ellison G. T. H.
Published: March 2009

Two impala (Aepyceros melampus) carcasses were subjected to varying degrees of mutilation by large mammalian scavengers.

Daily observations of carcass surface condition revealed that the timing and frequency of scavenger feeding visits had a profound effect upon carcass decomposition: a single feeding visit 10 days after death at the first carcass produced an extended sequence of decay. At the second carcass, repeated visits two, three and five days after death, resulted in a faster rate of decay.

The colonization of the carcasses by necrophagous insects was characterized by a distinct sequence of arrival. The abundance of Calliphoridae, Histeridae and Dermestidae was correlated with surface condition at both carcasses. Thus, these insects provided an indication of the state of carcass decay. However, as the rate of decomposition was different at each carcass, the temporal abundance of necrophagous insects was not the same at both carcasses.

The results suggest that the temporal abundance of key insect families provide an inaccurate indication of the time of death in circumstances when carcasses have subsequently been mutilated.
The effect of protein and salt loading on urinary concentrating ability in four chromosomal species of Spalax ehrenbergi
Authors: YAHAV S. , SIMSON S. , NEVO E.
Published: March 2009

Urinary concentrating ability was tested under protein and salt load in the four chromosomal species of subterranean mole‐rats (Spalax ehrenbergi superspecies) found in Israel. Protein stress induced by a diet of soyabeans supplemented by agar gel, demonstrated a significant increase in urinary osmolarity (UO). In the species living in the driest and warmest region (2n = 60). UO (1423·101 mOsmol/kg) was significantly (P<0·05) higher than in the other three species (2n = 52. 1172·31 mOsmol/kg; 2n = 54, 1160·116 mOsmol kg; and 2n = 58, 1216·145 mOsmol/kg). Upon salt loading this diet with 0·3 mol NaCl, UO increased significantly. However, when the salt load was increased to 0·45 mol NaCl, UO decreased significantly in all but one species (2n = 60) which maintained UO at 1522·65 mOsmol/kg. A decline in UO was attributed to diuresis resulting from a significant increase in urine and sodium excretion. The kidney, of only the xeric ranging species (2n = 60), demonstrated the ability to produce a hyperosmotic urine, in spite of the high salt load. These results might explain the restricted distribution of S. ehrenbergi: the only species (2n = 60) found in an environment rich in succulents and halophyte plants (steppe). This species appears to push speciation and adaptive radiation to the southern limit of its superspecies.
The colony structure and dominance hierarchy of the Damaraland mole‐rat, Cryptomys damarensis (Rodentia: Bathyergidae), from Namibia
Authors: Jacobs D. S. , Bennett N. C. , Jarvis J. U. M. , Crowe T. M.
Published: March 2009

Cryptomys damarensis is one of the few subterranean rodents which is social. This species is found in the semi‐arid regions of southwestern and central Africa. The Damaraland mole‐rat occurs in coloniesof up to 25 individuals, in which reproduction is limited to one or two of the largest males and the largest female in the colony.

The mean colony size is 18 mole‐rats (n=6 colonies). The mean colony biomass is 2.32 kg and the sex ratio is female biased (0.71–0.78). The number of mole‐rats in each colony, the mean body mass and the sex ratio are described for six field‐captured colonies, three of which were captured in their entirety.

The dominance hierarchy of two colonies of C. damarensis was found to be linear with a value of between 0.94 and 1.00 calculated from Landau's linearity index. Dominance was found to be related to gender, with the males more dominant than females. The reproductive individuals are the dominant animals within each respective gender. The non‐reproductive females rank lowest in the hierarchy.
Growth and development in six species of African mole‐rats (Rodentia: Bathyergidae)
Authors: Bennett N. C. , Jarvis J. U. M. , Aguilar G. H. , McDaid E. J.
Published: March 2009

The bathyergid mole‐rats provide a unique example of a family of subterranean rodents exhibiting a broad spectrum of sociality. Three genera comprise solitary, strongly territorial individuals whereas two genera are social. This sociality culminates in the eusocial naked mole‐rat, Heterocephalus glaber. The pups of solitary mole‐rats disperse, establish and thereafter defend their own burrow systems when approximately two months old, whereas those of social genera join an established natal colony. This paper examines whether these different lifestyles are reflected in the early development and rate of growth of pups of mole‐rats.

Although the trends are not clear‐cut, it is apparent that the pups of solitary genera grow and mature more rapidly than those from social genera. Thus, the growth rate constant (K) for the first70–80 days of postnatal growth (using the Gompertz equation) for the solitary genera was between 0.042 and 0.052 day−1, whereas that of the social mole‐rats was considerably lower (0.01 5 day−1). Similarly the mean growth rates of solitary genera ranged between 3.3 and 1.227g/day while those of the social mole‐rats were 0.229‐0.233 g/day.

The pattern of development and the rates of growth in solitary bathyergids are similar to those of other solitary subterranean rodents. One interesting feature common to all the social genera studied to date was that the first pups recruited to a ‘new colony’, consisting of a reproductive pair of adult mole‐rats, grew at a significantly faster rate than pups born to an established colony.
The courtship and mating of the Iberian midwife toad Alytes cisternasii (Amphibia: Anura: Discoglossidae)
Authors: Marquez R. , Verrell P.
Published: March 2009

Sexual encounters were staged in the laboratory among hormonally‐primed Iberian midwife toads, Alytes cisternasii. In this species, pairing and fertilization are terrestrial. The male cares for the developing embryos on land, carrying them twined around his hind limbs until they hatch into tadpoles which he releases into water; his investment in the offspring then ends. The courtship of A. cisternasii can be divided into a pre‐ and post‐ovulatory phase. An encounter is initiated when the female approaches the male and is clasped by him in inguinal amplexus. Both the male and the female produce vocalizations during the period prior to the initiation of amplexus. During amplexus, only the female vocalizes, changing her call to one that is of lower intensity, longer duration and more regularly emitted than before. During inguinal amplexus, the male engages in bouts of intense pedalling and gentle rocking behaviour, each bout being initiated when the female repositions herself beneath him. Rocking and pedalling cease when the female ovulates, at which time she exhibits a posture that we call Unkenkrampf. Ovulation occurs at this time, and is followed by sperm release by the male (seen as a series of lateral compressions of his body). After sperm release, the male moves forwards to engage the female in cervical amplexus and then manoeuvres his hind limbs such that the egg string becomes tangled around his ankles. The female may exhibit additional episodes of Unkenkrampf during this period, but these are not accompanied by further egg release. Episodes of Unkenkrampf (without ovulation) also may occur after the male dismounts from the female. Similar behaviour patterns to those observed in the laboratory are seen in natural populations of A. cisternasii. We compare and contrast our observations of A. cisternasii with those of other authors for this species and also for the common midwife toad, A. obstericans.
Changes in female anatomy associated with the reproductive moult in Paracerceis sculpta, a semelparous isopod crustacean
Authors: Shuster Stephen M.
Published: March 2009

Paracerceis sculpta (Holmes) is a sexually dimorphic sphaeromatid isopod crustacean inhabiting intertidal zones in the northern Gulf of California. Adult females in this species undergo a biphasic moult that initiates their sexual receptivity. Coincident with this moult, females experience anatomical changes associated with oviposition and gestation of young within the female marsupium. These modifications restrict female mobility, prevent females from feeding, and ultimately result in obligate female semelparity. In this paper, I describe the external and internal anatomy of premoult, half‐moulted and postmoult females collected from breeding aggregations in intertidal sponges. Field‐collected premoult females possessed hard, lustrous cuticles, and did not contain sperm. Females in half‐moulted condition contained sperm masses in both oviducts. Postmoult females contained developing embryos in internal brood pouches, and possessed cuticles that were pliable, translucent and setose. Embryos completed their development within postmoult females and dispersed from their mothers as mancae. Gestation duration decreased with increasing ambient temperature, from a maximum of 75 days at 12 dGC to a minimum of 13 days at 35 dGC. Female fecundity correlated positively with female body length. Spent females, depleted of lipid stores and muscle mass, died within two weeks of releasing mancae. ‘Female metamorphosis’ is considered a taxonomic character in certain sphaeromatid species descriptions. Anatomical changes in reproductive females similar to those in P. sculpta may occur in these species as well.
Extraoral and intraoral feeding: flexible foraging tactics in the South American sun‐star, Heliaster helianthus
Authors: Tokeshi Mutsunori
Published: March 2009

The South American sun‐star, Heliaster helianthus, is capable of adopting both the extraoral and intraoral mode of feeding. Observations were made on the feeding activities of H. helianthus in an intertidal habitat in central Peru. The proportion of individuals engaged in intraoral feeding was high amongst small H. heliunthus of less than 14 cm in diameter and gradually declined in larger size classes. Extraoral feeders had significantly larger meal sizes (total prey biomass) than intraoral feeders in all the size categories of H. heliunthus. Extraoral feeders also consumed larger individuals of the most important prey species, Semimytilus algosus, than intraoral feeders. The advantages and disadvantages of the two feeding modes are discussed and the meaning of the dual foraging tactics in H. helianthus is considered.
Seasonal changes in the reproductive organs and plasma and pituitary hormone content of the male Bennett's wallaby (Macropus rufogriseus vufogriseus)
Authors: Curlewis J. D.
Published: March 2009

In a number of species of seasonally breeding marsupial, the male is fertile throughout the year but there is a marked seasonal change in weight of the accessory sexual glands. In this study, body weight, prostate, epididymis and testis weights and plasma concentrations of testosterone, LH and prolactin and pituitary content of LH and prolactin were determined in male Bennett's wallabies shot at 1–2 month intervals over a period of 17 months. There was a highly significant increase in prostate weight which was coincident with the breeding season for this species. A small but significant increase in testis weight was also observed but epididymis weight remained unchanged. Plasma testosterone concentrations were significantly increased at a time coincident with the increase in prostate weight. Plasma prolactin and LH concentrations were low in most animals and remained unchanged during the study. In contrast, pituitary prolactin and LH contents showed highly significant changes, with increasing and peak hormone content preceding maximum prostate weight and plasma testosterone concentrations by several months. While these latter results suggest a role for prolactin and LH in the seasonal control of the reproductive organs in the male wallaby, a more intensive study of the pattern of secretion of these hormones and possibly more sensitive hormone assays are required to understand their relative roles in regulating the annual cycle of prostate growth.
Detection of two coexisting species of Oxystele (Gastropoda: Trochidae) by morphological and electrophoretic analyses
Authors: Heller Joseph , Dempster Yvonne
Published: March 2009

Oxystele variegata (Anton, 1838) is one of the commonest intertidal topshells on the coast of South Africa. In this study we show that the so‐called O. variegata actually consists of two sympatric species, which differ in shell colour patterns, in the proportions of the central tooth of the radula, and in the electrophoretic mobilities of some enzymes: O. impervia (Menke, 1843) (which tends to occur higher up the shore), and O. variegata (Anton, 1838) (occurring further down the shore).

The shell of O. impervia has a pattern of dark red, orange, yellow or brown maculations, on a ground colour that is red, orange, yellow or brown, respectively; that of O. variegata has a pattern of red maculations or lines on a ground colour that is either off‐white, or greenish‐grey. Both O. impervia and O. variegata exhibit an immense variety of shell colours and pattern and in both, shell colour variation is an interplay between two factors: ground colour and maculated spiral bands. By expanding the maculated spiral bands in breadth, at the expense of the ground colour, an original shell pattern of spiral bands may be transformed into one of axial or diagonal stripes.

The radula of both species resemble the typical trochid pattern. They are, however, consistently different: the central tooth of the radula of O. imperial usually has a shallow base and a cusp that is slightly indented, whereas that of O. variegata usually has a deep base, and a well indented cusp.

Further differences between the species were revealed by electrophoretic studies. Of six loci examined, two were found to be taxonomically diagnostic. Another two had at least one species‐specific allele at a frequency of 0·1 or greater, and significant heterogeneity in allelic frequency between the two species was found in the four non‐diagnostic loci.

The differences in shell colour patterns, radular tooth structure and enzyme mobilities support the conclusion that O. impervia and O. variegata are separate but closely related species, with similar geographic distributions and an overlapping zonation.
Field observations on some dwarf chameleons (Brookesia spp.) from rainforest areas of Madagascar, with description of a new species
Authors: Raxworthy C. J.
Published: March 2009

Six species of Brookesia dwarf chameleons were recorded during two rainforest expeditions in Madagascar. One of these is described as a new species Brookesia valerieae based on the arrangement of the nine pairs of dorso‐lateral spines, the lack of a pelvic shield, and dorsal chevron markings. Observations were made on the defence and roosting behaviours shown by these six species. Aspects concerning the evolution and conservation in Madagascar are discussed for this poorly studied group of endemic Malagasy reptiles.
Hepatozoon in grey squirrels (Sciurus carolinensis) trapped near Reading, Berkshire
Authors: Watkins Barbara M. , Nowell F.
Published: March 2009

Hepatozoon infections of Sciurus carolinensis were investigated by a 30‐month capture/recapture trapping programme. Details of trapping methods, squirrel husbandry and blood sampling techniques are discussed.

Hepatozoon gametocytes infected blood monocytes and could be detected in blood smears or by concentration of leucocytes. From blood smears, 71% (154/218) of the squirrels were infected. Prevalence appeared to be influenced by host hormonal and breeding patterns. Significantly more adult males than adult females were infected (P<0.025). Infections were significantly more prevalent in adults overall and in adult males than in juvenile males (P< 0.001 in both cases), but not significantly different between female adults and juveniles (P>0.05). Prevalence rates were generally higher: (i) in summer and winter, when animals mate, compared to spring and autumn; and (ii) in 1984 than in 1983, possibly relating to differences of squirrel breeding success and juvenile recruitment in the two years. Parasitaemias were overdispersed in the sampled host population and significantly lower in females (38%) than in males (48%) (P<0.05), although there was no significant difference between the age classes. Animals, either recaptured or laboratory‐maintained, showed chronic fluctuating parasitaemias with no obvious pattern. Squirrels with overt parasitaemias showed trophozoites and schizogonic stages of Hepatozoon in the lung and rarely in liver and spleen. Three out of 16 animals with no obvious parasitaemias had lung tissue stages of the parasite. Results suggest that Hepatozoon is more prevalent in grey squirrel populations than blood smears suggest.
The settlement and attachment of early stages of the salmon louse, Lepeophtheirus salmonis (Copepoda: Caligidae) on the salmon host, Salmo salar
Authors: Bron J. E. , Sommerville C. , Jones M. , Rae G. H.
Published: March 2009

A study was undertaken of the settlement and attachment of larvae of Lepeophtheirus salmonis (Krøyer, 1837) on a salmonid host Salmo salar Linnaeus, 1758. Preferred settlement sites were the fins and other protected areas. Initial, reversible settlement was followed by attachment with the hooked second antennae. The filament used for subsequent attachment was found to comprise three distinct regions; basal plate, stem and external lamina. The filament was secured to the epithelial basement membrane by the basal plate which was formed by secretion down the axial duct from the posterior A‐group of cells. The stem was fibrous and carried the axial duct along its length. A thin external lamina covered the stem and was apparently continuous with the chalimus cuticle. A number of filament‐associated organs are also described, comprising cell groups A‐C although only the function of A was characterized.
The effect of habitat on the helminth parasites of an island population of the Polynesian rat (Rattus exulans)
Authors: Roberts M. , Rodrigo A. , McArdle B. , Charleston W. A. G.
Published: March 2009

Differences in helminth faunal composition, distribution and abundance were studied in three habitats on an island on which the Polynesian rat, Rattus exulans (Peale), is the only rodent present. The effects of season and of host age and sex were also included in the analysis. Habitat had a statistically significant effect on the prevalence and/or abundance of all seven parasites included in this study. Season influenced four species (Brachylaima apoplania, Capillaria sp., Heterakis spumosa and Mastophorus muris) but had little or no detectable effect on the remaining three (Capillaria hepatica, Hymenolepis diminuta and Syphacia muris). Of the two intrinsic variables, age but not sex was found to have an effect. A comparison of the effects of each variable on parasite prevalence confirmed that habitat was the most important of the four variables. In a prior study on the influence of habitat on host population dynamics on this island, between‐habitat differences were shown to include adult longevity, total population density and the seasonal availability and abundance of various food types. These factors, together with physical differences in the microhabitat and the parasite's life cycle, help to provide explanations for the observed results.
Seasonal shifts within juvenile recruit sex ratio of Pampas mice (Akodon azarae)
Authors: Zuleta G. A. , Bilenca D. N.
Published: March 2009

Sex ratio (SR) variation of Akodon azarae juvenile recruits was analysed during 1985–86 on a Pampean grassland in central Argentina. Rodents were intensively live‐trapped on a 0.81 ha grid. The SR (proportion of males) of the overall population did not differ significantly from evenness (0.49). In contrast, juvenile recruits (0.5–2.0 months of age) showed SR fluctuations according to their time of birth. SR was strongly female‐biased among spring and autumn juveniles (0.13 and 0.33, respectively), while males were predominant (0.72) among the summer juveniles.

Social and demographic implications of these results are discussed in the framework of current SR theory. Spring female recruits should be selected for summer reproduction and autumn female recruits for winter survival and spring reproduction. The overwintered population was characterized by 1:1 SR and an age structure composed of males older than females. Most of these males had been recruited as juveniles during the summer. They also made up most of the resident male population in the spring. A selective allocation of energy by the mothers among their offspring is the mechanism proposed to explain the seasonal changes in SR, as pregnant females which gave birth to the summer recruits were in better physical condition than the mothers of both spring and autumn recruits. These results are consistent with the predictions of Werren & Charnov (1978), based on temporal overproduction of one or the other sex according to differential changes in the life‐history expectations for both sexes.
Robertsonian translocations introduced into an island population of house mice
Authors: Scriven P. N.
Published: March 2009

In April 1982, 77 house mice from the Orkney Island of Eday were released by R. J. Berry and his associates on the Isle of May, Firth of Forth. The Isle of May had a standard house mouse karyotype (2n = 40), while those from Eday are homozygous for three centric fusions (2n = 34). Within 18 months of introduction (September 1983), each centric fusion had increased in frequency from an estimated starting value of 8% to a value close to 50%, and they were segregating in accordance with Hardy–Weinberg expectations. In essence, the transformed population was behaving as a panmictic unit. The frequencies of introduced chromosomes had apparently stabilized by September 1986 with values around 65% for all three fusions. The cytogenetic data obtained in the Isle of May introduction experiment accord well with data for single gene loci (represented by allozyme data) and morphometric data. Male Eday–May F1 hybrids were found to have a low frequency of non‐disjunction (13%). This study is unusual because the successful introduction of mice into an established population, and the introgression and stabilization of three centric fusions, could not have been predicted from previous studies on the mouse.
Induction and termination of reproductive diapause in a neotropical beetle, Chelymorpha alternans (Coleoptera: Chrysomelidae)
Authors: Pullin Andrew S. , Knight Theresa M.
Published: March 2009

The presence of a reproductive diapause in the life cycle of the neotropical cassidine beetle, Chelymorpha alternans, was investigated by exposing groups of beetles to conditions differing in photoperiod and humidity. Diapause was characterized by the absence of egg‐laying in females up to 70 days after emergence and was induced in response to a short photoperiod of 12:12 h L: D but averted under a longer photoperiod of 13:11 h L:D. High (>90% RH) and low (55–75% RH) humidity conditions did not influence diapause induction. Males appeared to court and attempt to mate with females under all conditions between 16 and 30 days after emergence, but declined after this time in short photoperiods and it is not known if matings in these groups were successful. Adults induced to diapause by exposure to a 12:12 h L:D photoperiod and subsequently exposed to a 13:11 h L: D photoperiod 70 or 72 days after emergence did not show a rapid response by commencing egg‐laying. However, all diapausing groups in long and short photoperiod and high and low humidity, in both experiments performed, had commenced egg‐laying after 128 days, suggesting an endogenous rhythm for diapause termination. Long photoperiod and high humidity combined may hasten diapause termination since egg‐laying began after only 95 days in this group in experiment two. This strategy of induction and termination is discussed with reference to the seasonality of the natural environment of C. alternans in Panama.
Albumin evolution and phylogenetic relationships among Greek rodents of the families Arvicolidae and Muridae
Authors: Nikoletopoulos N. P. , Chondropoulos B. P. , Fraguedakis‐Tsolis S. E.
Published: March 2009

The phylogenetic relationships of seven rodent species Microtus atticus, M. thomasi, M. epiroticus (family Arvicolidae) and Mus domesticus, Rattus norvegicus, Apodemus flavicollis and A. mystacinus (family Muridae) have been studied. In order to define these relationships we study the albumin evolution using the micro‐complement fixation test (MC'F). No phylogenetic (immunological) distance between M. atticus and M. thomasi was found, a fact which confirms from the biochemical point of view the opinion that the former taxon is a synonym of the latter one. A molecular time scale relating MC'F immunological distances and geological time was established based on the assumption of a rate of 100 amino acid substitutions per–20 million years. The time of divergence between M. epiroticus and M. thomasi was estimated to be 0.5–0.6 million years ago (Pleistocene). Such a recent divergence corroborates the opinion based on morphological and protein electrophoretic criteria according to which Terricola (formerly Pitymys) must be considered as a subgenus of the genus Microtus and not as a distinct genus Pitymys, as previously had been accepted. Apodemus flavicollis and A. mystacinus were separated about 0.65–0.8 million years ago (Pleistocene). The Rattus norvegicus lineage was separated–12.5 million years ago (end of Miocene), shortly before the Mus and Apodemus divergence. Our data indicate that the common ancestor of Arvicolidae and Muridae lived–25 million years ago (early Miocene). All these results are in agreement with paleontological and some recent DNA‐DNA hybridization and electrophoretic data.
The effects of pH, aluminium concentration and temperature on the embryonic development of the European common frog, Rana temporaria
Authors: Beattie R. C. , Tyler‐.Tones R. , Baxter M. J.
Published: March 2009

The individual and combined effects of pH, aluminium concentration and temperature, on the development of common frog (Rana temporaria) embryos from an upland area of northern England, were investigated in a controlled laboratory study. There was strong evidence to suggest that embryonic survival was lower at pH 4.5 compared with pH 6.0. At pH 4.5, embryonic survival was reduced at the highest aluminium concentrations. There was no strong evidence for a reduction in embryonic survival at lower aluminium concentrations.

Gastrulation and hatching appeared to be the most sensitive stages to both pH and aluminium concentration.

There was strong evidence to suggest that temperature‐shocked embryos had reduced survival when compared with those kept at a constant temperature, particularly at pH 4.5.

There was substantial variation in the survival of embryos from different clutches in the same pond with respect to low pH, aluminium concentration and temperatures. Thus R. temporaria has a wide genetic base from which to tolerate environmental changes. It is suggested, however, that the lethal and sublethal effects of low pH, high aluminium concentration and low temperature, could lead to a decrease in recruitment to the adult populations of R. temporaria in upland, northern England.
Emergence behaviour of rabbits, Oryctolagus cuniculus, in Central Otago, New Zealand
Authors: Fraser K. W.
Published: March 2009

The characteristic emergence behaviour of a rabbit population in Central Otago, New Zealand, involves a steady rise in the number of rabbits active throughout the afternoon to a peak near sunset. This differs from populations in Great Britain and Australia, where emergence occurs later and is more rapid. Young rabbits emerged slightly later than adults and were more susceptible to disturbances. Slightly earlier emergence by male rabbits, particularly between May and September, was possibly related to the increased levels of territoriality and social interaction just before and during the early stages of the breeding season. Three emergence indices (25% of the population feeding, 50% of the population emerged, and maximum number of rabbits emerged) were significantly correlated with season. Rabbits emerged earliest before sunset in winter and spring and latest in autumn. Daily variation in emergence times was considerable and was related to weather factors such as temperature and wind direction. A greater level of diurnal activity in New Zealand rabbit populations than in those in Great Britain and Australia is possibly associated with lower levels of diurnal predation in New Zealand.
Morphometric estimation of oxygen diffusing capacity for the air‐sac in the catfish Heteropneustes fossilis
Authors: Hughes G. M. , P. K. Roy  , Munshi J. S. D.
Published: March 2009

A detailed morphometric study has been made of the air‐sacs of this air‐breathing catfish using whole mounts, light and electron microscopy, of six specimens, body weight 40±2 g. Measurements of surface areas of the gas exchange and non‐respiratory surfaces have taken into account foldings of the surface at macro and ultramicroscopic levels. Area of the gas exchange surface was estimated as 23.915cm2 (=0.598cm2/g) which is 67%of the total surface area of the two air‐sacs. Significant differences were found in some morphometric parameters which were related to the three antero‐posterior regions into which air‐sacs were divided. Harmonic mean thickness of the tissue component of the air/blood barrier was estimated for the whole air‐sac as 0.342 μm. These and other measurements enabled the diffusing capacity for the air‐sacs to be calculated as 0.0638 m1O2/min/mmHg/kg.

These results show that Heteropneustes has an air‐breathing organ which is superior to that of Amphipnous cuchia, similar to that of Lepidosiren, but less well developed than that of Protopterus. In addition, Heteropneustes is well adapted to obtain oxygen directly from water by means of its gills and skin as indicated by both morphometric and physiological measurements which also correlate with its life in ponds and streams which are Iiable to dry up.