bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative Dimensions of Testes, Epididymides and Spermatozoa of Australian Dingoes (Canis-Familiaris-Dingo) and Domestic Dogs (Canis-Familiaris-Familiaris) - Some Effects of Domestication
Authors: Woodall PF , Pavlov P , Tolley LK
Published: June 2005

The dimensions of testes, epididymides and spermatozoa of Australian dingoes (Canis familiaris dingo) and a sample of domestic dogs (Canis familiaris familiaris), chosen to lie within the range of dingo body weights, were compared. There were no significant differences for body weight or testis weight but total epididymal weight, the caput + corpus weights and sperm numbers in the cauda epididymidis were significantly larger in dogs. Dimensions of the spermatozoa were similar for dogs and dingoes except for a small but significantly larger head length in dingoes. Seminiferous tubule diameters were significantly larger in dingoes and epididymal tubule diameters were similar in dogs and dingoes except for significantly wider tubules in the cauda of dogs. The estimated length of tubules in the total epididymis and in the cauda was significantly greater in dogs than in dingoes. Greater size of the epididymis and especially of the cauda epididymidis probably reflect selection for larger sperm stores in free-ranging domestic dogs where there is a greater chance of intermale sperm competition. Two possible hybrids (determined by skull morphometry) were intermediate between dogs and dingoes for some of these dimensions.
Aspects of Lactation in the Crab-Eater Seal (Lobodon-Carcinophagus)
Authors: Green B , Fogerty A , Libke JA , Newgrain K , Shaughnessy P
Published: June 2005

Milk samples were obtained from seven crabeater seals (Lobodon carcinophagus) at various stages of lactation. The milk was high in solids (67%), with lipid (51%) accounting for most of the solids and energy. The fatty acid profiles were similar to the milk of other phocid seals and to krill, the major dietary item. Our preliminary results from four animals suggest that about 90 L of milk are transferred from the cow to the pup during the lactation period, estimated to be 17 days in length.
Ultrastructure of the Statocyst in an Undescribed Species of Luridae (Platyhelminthes, Rhabdocoela, Luridae)
Authors: Rohde K , Watson NA , Faubel A
Published: June 2005

The statocyst of an undescribed species of Luridae is described by electron microscopy. it is located between the brain and the intestine, suspended on a cytoplasmic band, and contains a nucleus and three statoliths. The statoliths are surrounded by many mitochondria. Fibres from the brain enter the statocyst wall through dark lamellae with a lamellate substructure, and form part of the wall that contains many basal bodies with short axonemes which, however, do not protrude into the statocyst cavity as free cilia. It is not clear whether intestinal cells contribute to the formation of the statocyst wall. Three small statoliths, also surrounded by many mitochondria, lie in cytoplasm latero-posteriorly to the statocyst.
Vocal Communication Between the Mother and Young of the Eastern Gray Kangaroo, Macropus-Giganteus, and the Red Kangaroo, M-Rufus (Marsupialia, Macropodidae)
Authors: Baker MWD , Croft DB
Published: June 2005

The structure, development and function of the isolation call produced by the young of the eastern grey kangaroo, Macropus giganteus, and the red kangaroo, M. rufus were compared. A total of 416 isolation calls from 26 eastern grey kangaroos and 272 isolation calls from 14 red kangaroos in four age classes during pouch life were analysed sonagraphically. Twenty structural parameters were measured from each call. Results showed that the isolation call identifies the caller as a dependent young and potentially transmits a variety of other information including the species of kangaroo, the caller's sex, degree of arousal, individual identity, age and location. The main information processed by the young's mother is likely to be that the young is calling and its location. However, the locational qualities of the call decline as the young becomes more independent, presumably to counteract location by predators. The young of both species produced individually distinct isolation calls but mother-young recognition by auditory cues alone seems unlikely. Habitat differences may have led to divergence in the call structure of the two species. The factors that affect the evolution of this type of call structure are discussed.
Phylogeny and Rates of Character Evolution Among Ringtail Possums (Pseudocheiridae, Marsupialia)
Authors: Springer MS
Published: June 2005

A total of 47 craniodental characters seen in fossil and extant ringtail possums (Pseudocheiridae: Marsupialia) were examined using Wagner, Camin-Sokal, and Dollo parsimony. All extant species form a clade to the exclusion of Miocene genera. Hemibelideus and Petauroides are sister taxa, as are Petropseudes and Pseudochirops. All species of Pseudocheirus are united together, except Pseudocheirus peregrinus, the phylogenetic position of which is uncertain on the basis of craniodental information. Overall, the agreement between cladistic analyses of craniodental characters and biochemical analysis is excellent, although the latter provide much stronger evidence that P. peregrinus is a sister taxon to other Pseudocheirus species. Rates of evolution of craniodental characters are highest in the Pseudochirops-Petropseudes lineage, where widening of the molars, elaboration of cusps and conules, accentuation of cristae and cristids, and the development of highly crenulated enamel create a dental battery that is better equipped to process plant material. Pseudocheirus displays the least modification of the presumed primitive dental condition.
Ant Communities in the Gulf Region of Australia Semiarid Tropics - Species Composition, Patterns of Organization, and Biogeography
Authors: Andersen AN
Published: June 2005

The ant communities of nine sites near Lawn Hill (540 mm mean annual rainfall) in semi-arid north-western Queensland are documented, and compared with the known faunas of arid, semi-arid and seasonally arid sites elsewhere in Australia. The sites were surveyed primarily by pitfall trapping, during April (end of wet season) 1991, September (late dry season) 1991, and February (mid-wet season) 1992. A total of 111 ant species was recorded, with the most common being Iridomyrmex spp. and Rhytidoponera rufithorax. The richest genera were Melophorus (26 species), Monomorium (17), Iridomyrmex (16) and Camponotus (10) and Pheidole (10). The maj or functional groups were Dominant Dolichoderinae (Iridomyrmex spp.; 14% of the total number of species, 47% of the total number of ants in traps), Hot-climate specialists (mostly Melophorus spp.; 39%, 22%) and Generalised Myrmicinae (mostly Monomorium and Pheidole spp.; 20%, 11%). Multivariate analysis indicated that site differences in species composition were related primarily to landform, geology and soil type. Comparisons with other ant faunas show the Lawn Hill fauna to have closer affinities with those of the central arid zone than with those of high rainfall areas of the seasonal tropics. The arid-zone characteristics of the Lawn Hill fauna include a high proportion (38%) of Eyrean species, a high mean number of species per genus (6.5), and a very high combined representation of Iridomyrmex, Melophorus and Camponotus (45% of the total number of species, 69% of the total number of ants in traps).
Ultrastructure of the Epidermis and Protonephridium of an Undescribed Species of Luridae (Platyhelminthes, Rhabdocoela)
Authors: Rohde K , Watson NA , Faubel A
Published: June 2005

The epidermis of an undescribed species of Luridae possesses many large cavities filled with a medium-dense material, intraepidermal nuclei, glandular ducts, cilia with vertical and horizontal rootlets, surface microvilli, and a thick basal lamina. Cilia have narrow tips, the peripheral axonemal doublets lose one of the microtubules and, finally, whole doublets are lost near the tip. Flame bulbs have a single row of longitudinal ribs containing microtubules and connected by a 'membrane' apparently of extracellular matrix; cilia of flame bulbs possess cross-striated rootlets, and capillary walls are smooth. The nucleus of the protonephridium was observed near the tip of the flame bulb, along the capillary. It is not clear whether one perikaryon forms more than one flame bulb. The structure of the epidermal ciliary rootlets, the presence of intraepidermal nuclei, and flame bulbs composed of a single row of longitudinal ribs containing microtubules formed by a single cell are typical rhabdocoel characteristics.
Metabolic Depression During Estivation in the Australian Frogs, Neobatrachus and Cyclorana
Authors: Withers PC
Published: June 2005

The standard metabolic rate (SMR) of a number of species of Western Australian frogs is similar to that predicted for other anuran amphibians. The metabolic rate during activity is elevated 10-20 times above SMR, in close agreement with other studies of the energetics of amphibian activity. Species of two genera, Neobatrachus and Cyclorana, readily enter aestivation, which involves cessation of activity, formation of an epidermal cocoon, and depression of metabolic rate below SMR. The magnitude of metabolic depression varies between species from 70 to 80% (i.e. aestivation metabolic rate is 20-30% of SMR). The variation in magnitude of metabolic depression most likely reflects, in part, the difficulty of distinguishing the early stages of aestivation from the normal resting state. Both standard and aestivating metabolic rate are strongly mass-dependent, but the magnitude of metabolic depression is remarkably consistent in a number of different genera of frogs, salamanders and fish. The metabolic rate of aestivating amphibians is similar to that predicted for a unicellular organism of equivalent body mass, but is substantially lower than the metabolic rate of aestivating mammals.
Effects of Restricted Water-Intake on Digestion, Urea Recycling and Renal-Function in Wombats (Marsupialia, Vombatidae) From Contrasting Habitats
Authors: Barboza PS
Published: June 2005

Responses to limited water availability were studied in two species of wombats from mesic (Vombatus ursinus) or xeric (Lasiorhinus latifrons) habitats. Four Vombatus and three Lasiorhinus were fed a low-quality straw-based diet containing 0.6% nitrogen and 68% neutral detergent fibre (dry-matter basis). Restriction to 50% of ad libitum intakes of drinking water reduced dry-matter intakes by 30% but did not alter digestibilities of fibre or nitrogen. Nitrogen balances were negative and similar between species and water intakes. Urea pool size (C-14 urea) increased during water restriction but urea-entry rates and the proportion of urea recycled to the gut were similar between water intakes (78-89%). Tritiated water was given to wombats in single intramuscular or intraperitoneal doses. Times to equilibration of tritium in urinary water were large and variable (45 +/- 36 h). Urinary tritium concentrations often declined erratically after equilibration, and were 14 +/- 14% lower than the tritium concentration in the blood. These irregular kinetics for tritiated water suggest that the water-dilution method requires validation for the wombats. Urinary and faecal water losses were reduced by 60% during water restriction. Water was mainly lost in the faeces, which were drier in Lasiorhinus (41 % dry matter) than in Vombatus (31 %). As blood haematocrit and plasma osmolality were similar between water intakes, extracellular spaces were apparently maintained during water restriction. Glomerular filtration rates (creatinine clearance) were low (12 mL min-1) and similar between water intakes. Therefore, a more concentrated urine was produced by tubular resorption in water-restricted wombats. Lasiorhinus had greater urinary osmolalities and urine: plasma ratios of creatinine, which reflected a greater urine-concentrating ability than Vombatus. Apparent water intakes and the ability to reduce urinary and faecal water losses in the wombats are similar to those of kangaroos. The contrasting abilities of Vombatus and Lasiorhinus to minimise both these water losses are directly related to their separate distributions.
Maternal Strategies of Phascogale-Tapoatafa (Marsupialia, Dasyuridae) .1. Breeding Seasonality and Maternal Investment
Authors: Soderquist TR
Published: June 2005

Phascogale tapoatafa, an arboreal carnivorous marsupial, is the largest mammal in which an obligate yearly die-off of all males occurs. The species is one of the most widespread of Australian marsupials, being found in tropical, subtropical and temperate forests and woodlands of Australia. Its breeding season varies little throughout this range, with most births occurring in July. In three Victorian populations, 2-year-old females typically gave birth earlier than first-year females, births were spread on average over 15 days, and, in some years, occurred two weeks earlier than average. Modal litter size equalled the number of teats (8), but litters of 1-6 young comprised 29% of the sample (n = 45), and litter size averaged 6.6 young. The sex ratio of litters produced by second-year females was significantly male-biased (0.62); that of first-year females was 0.48. When juveniles first released the teats (c. 48 days of age), they weighed about 4 g. Weight gain by captive juveniles was more rapid than that of wild conspecifics prior to weaning, but skeletal growth rate and morphological development were similar. Total lactational investment by P. tapoatafa is much greater than expected for a dasyurid of its size (wild litters at weaning average 313% of maternal weight; captive litters average 370%). The high mortality of wild adult females during lactation may reflect this energetic drain.
Maternal Strategies of Phascogale-Tapoatafa (Marsupialia, Dasyuridae) .2. Juvenile Thermoregulation and Maternal Attendance
Authors: Soderquist TR
Published: June 2005

When juvenile Phascogale tapoatafa first release the maternal teats and are left in the nursery nest (c. 48 days of age), they lack fur, weight about 4 g, and are poikilothermic. Thermoregulation of wild litters was measured using a temperature-sensitive radio-transmitter inserted into the huddled litter after the mother's departure at night. On cold nights (less-than-or-equal-to 10-degrees-C), juveniles lose heat rapidly in the absence of their mother, with litter temperatures declining to an average of 6-degrees-C in 4 h. Litter temperatures of 3-degrees-C were common. Maternal attendance (incubation) is frequent and of long duration during the early-nesting period, then decreases as juveniles acquire fur and develop endothermy. The mother contributes to litter thermoregulation and security by constructing a large nest of bark, feathers and fur in a tree cavity with a small entrance hole.
The Evolution of Species of the Varanidae - Microcomplement Fixation Analysis of Serum Albumins
Authors: Baverstock PR , King D , King M , Birrell J , Krieg M
Published: June 2005

Phylogenetic relationships among 30 of the 40 species in the Varanidae were examined in the light of molecular information on albumin evolution derived from microcomplement fixation. A phylogeny based on these results is compared with proposed phylogenies based on data obtained using other techniques. Three separate radiations of Varanus are found in Australia, The movement of varanids to Australia from south-east Asia is thought to have occurred approximately 15-20 million years ago.
Field Bioenergetics of Mammals - What Determines Field Metabolic Rates
Authors: Nagy KA
Published: June 2005

Field metabolic rates (FMRs) of 61 species of mammals, as measured with doubly labelled water, range from 29 kJ day-1 (0.34 W) in pipistrel bats to 49 MJ day-1 (570 W) in northern elephant seals, which is a range of 1678 times. Most of this variation is due to differences in body mass; the least-squares, log-log regression of mammalian FMR on body mass (kJ day-1 = 5.27 g0.723) has a coefficient of determination (r2) of 0.961, indicating that variation in log(body mass) accounts for 96% of variation in log(FMR). The scaling of FMR in marsupials (kJ day-1 = 10.83 g0.582, 17 species) differs significantly from that in eutherian mammals (kJ day-1 = 4.63 g0.762, 44 species), and the respective r2-values (0.978 and 0.972) indicate that these taxonomic infraclasses explain another 1% of variation in log(FMR). After adjusting for mass and infraclass effects, residual variation is still substantial (2.5-fold among marsupials and 6-fold among eutherians). What accounts for this variation? Neither taxonomic order (or family within the Marsupialia), diet category (e.g. herbivore, camivore), nor habitat (e.g. marine, tundra) explained much residual variation, except that desert-dwelling eutherians had significantly lower FMRs than expected for eutherians of their mass. The failure of taxonomic and ecological categories to account for residual variation may be due, in part, to small sample sizes and skewed distributions of these categories along the mass axis, but it seems likely that other sources of variation, such as season, sex, age, ambient temperature, daily behaviour pattern and food availability may have large effects on FMR that are not accounted for in this analysis.
The Amplitude of Circadian Body-Temperature Rhythms in 3 Rodents (Aethomys-Namaquensis, Thallomys-Paedulcus and Cryptomys-Damarensis) Along an Arboreal-Subterranean Gradient
Authors: Lovegrove BG , Heldmaier G
Published: June 2005

The maximum amplitudes of circadian rhythms of body temperature (R(t)) of three species of desert rodents inhabiting an arboreal-subterranean gradient were correlated with habitat-dependent thermoregulatory parameters such as minimal thermal conductance and the magnitude of ambient temperature tolerance by endotherms. It was shown that R(t) differed by 87-181% of expected values. The data for two rodents (Thallomys paedulcus and Aethomys namaquensis) that forage aboveground displayed higher-than-expected R(t) values, whereas the strictly subterranean species (Cryptomys damarensis) had lower-than-expected R(t) values. These data are interpreted in terms of the Endothermic Temperature Range Hypothesis, which argues that the large range of diel ambient temperature fluctuations found in desert habitats may account for the physiological parameters that generate the higher-than-expected body temperature rhythms, a low and fairly inflexible minimal thermal conductance and low resting metabolic rate. Further discussion centres on the possible functional significance of circadian energetic rhythms, particularly in terms of an endotherm's fitness. It is proposed that, at least, functions of the rhythms should be considered: diel thermoregulatory adjustments and energy conservation.
Influence of Hydrodynamic-Design and Propulsive Mode on Mammalian Swimming Energetics
Authors: Fish FE
Published: June 2005

Optimisation of energy by aquatic mammals requires adaptations that reduce drag, and improve thrust production and efficiency. Drag is minimised by streamlining the body and appendages. Highly derived aquatic mammals have body shapes close to the optimal hydrodynamic design for drag reduction. There is no conclusive evidence for specialised drag reduction mechanisms, although decreasing hair density is associated with reduced drag. Improvement in thrust production and efficiency is accomplished by changes in propulsive mode and appendage design. Semiaquatic mammals employ. drag-based propulsion using paddles, whereas fully aquatic mammals use lift-based propulsion with hydrofoils. Because paddling generates thrust through half the stroke cycle, propulsive efficiency is low and energetic cost is high compared with that for mammals using hydrofoils. Lift-based swimming is a rapid and high-powered propulsive mode. Oscillations of the hydrofoil generate thrust throughout the stroke cycle. For cetaceans and pinnipeds, propulsive efficiency is approximately 80%, and transport cost is below that of semiaquatic mammals. Behavioural adaptations help minimise energy expenditure by swimming mammals. Submerged swimming avoids increased drag from energy lost in formation of surface waves. Porpoising and wave riding, characteristic of dolphins, can reduce the transport costs, allowing for longer-duration swimming at high speeds.
Kidney Structure and Renal Indexes of Dasyurid Marsupials
Authors: Brooker BM , Withers PC
Published: June 2005

Examination of kidney structure for 25 dasyurid marsupials showed that kidneys of species from arid habitats tend to have a relatively thicker medulla and higher renal indices than those of species from semi-arid, mesic and tropical areas. Arid-dwelling species such as Ningaui ridei and Pseudantechinus macdonnellensis had the highest renal indices while Antechinus swainsonii, collected from alpine environments, had the lowest renal index values. Renal indices were significantly correlated also with body weight, average daily maximum temperature and average annual rainfall of the habitat. The renal indices for xeric species differed significantly by discriminant analysis from the indices for other species. There was no obvious phylogenetic conservatism in renal indices; for example, renal indices varied almost as much within the genus Sminthopsis as between all of the other genera of Dasyuridae examined.
Activity and Resting Metabolism of Varanid Lizards Compared With Typical Lizards
Authors: Christian KA , Conley KE
Published: June 2005

We examined whether Australian varanids as a group are more aerobic than other lizards. The standard metabolic rate (SMR) and maximal oxygen consumption (V-O2max) were measured for four species of varanid lizards and the skink Tiliqua rugosa at 35 degrees C. These were compared to each other and to the V-O2max of the iguanid lizard Cyclura nubila by analysis of covariance with body mass as a covariate. There were no differences with respect to SMR, but the V-O2max of the lizards fell into three groups: Varanus rosenbergi, V. gouldii and V. panoptes had higher aerobic capacities than V. mertensi and Cyclura nubila, and Tiliqua rugosa had a V-O2max lower than the other species. There is no simple relationship between V-O2max and the time these lizards spend in natural activity. The summer SMRs of V. rosenbergi and T. rugosa were significantly higher than during other seasons. The V-O2max of V. rosenbergi was higher in summer than in other seasons, but T. rugosa showed no seasonal differences in V-O2max. These results indicate that the SMRs of the varanids were similar to those of other lizards, and, despite generalisations in the literature, not all varanid lizards have high aerobic capacities. Varanid lizards may be as physiologically diverse as other lizard families.
Histological Observations on the Wing of the Grey-Headed Flying-Fox (Pteropus-Poliocephalus) (Chiroptera, Pteropodidae)
Authors: Crowley GV , Hall LS
Published: June 2005

The histological features of the wing membrane of Pteropus poliocephalus are described at both the light and electron microscope level. A method is described for the processing of bat wing tissue for both light and electron microscopy. The flight membrane of P. poliocephalus had a dorsal and ventral layer of epidermis with a common dermis in between. There was no hypodermis and all layers were greatly reduced in comparison with the skin of other mammals. The epidermis consisted of three layers of active keratinocytes, covered by 7-10 layers of cornified cells. Melanocytes were generally confined to the basal layer and were more numerous in the dorsal epidermis. Prominent droplets of a lipid-like substance were found in the epidermal keratinocytes and these coalesced towards the superficial layers. It is postulated that the substance contained in these droplets is a waterproofing agent. The dermis consisted mainly of collagen bundles with a network of elastin bands. An array of hair-dome complexes were found on the wing membrane surface. These receptors are similar to those described in several microchiropterans, where it is thought they provide information on airflow patterns over the wing.
Sexual Dimorphism in the Pelvic Girdle of Australian Flying Foxes
Authors: Chapman A , Hall LS , Bennett MB
Published: June 2005

Sexual dimorphism was observed in the pelvic girdle of all individuals and age classes of Pteropus alecto, P. poliocephalus and P. scapulatus. In females the pelvic girdle is open (V-shaped) whereas it is closed (O-shaped) in males. This striking dimorphism enabled the sex of any individual, including skeletal material alone, to be determined with 100% accuracy. In females the interpubic distance (i.e. the distance between the two pubic bones) is correlated with forearm length. The first comparative photographs of the dimorphic pelvis are presented and the usefulness of this new diagnostic character explored.
Avian Egg Morphometrics - Allometric Models of Egg Volume, Clutch Volume and Shape
Authors: Olsen PD , Cunningham RB , Donnelly CF
Published: June 2005

This paper describes three comprehensive new models of the allometric relationships between egg volume, clutch volume and shape, and body weight. Mean egg dimensions, clutch sizes and adult body weights were obtained for 326 species, mainly of four bird types: raptors (including owls), shorebirds, frogmouths (including nightjars), and storks (including the New World vultures). These are groups in which there is a wide range of body sizes and of sexual dimorphism in body size (in direction and degree). Female body weight alone accounted for 92% of the variation in egg volume. Sexual dimorphism in body size, phylogenetic relationship, and clutch size were significant contributors to the model of egg volume; their addition increased the explained variance to over 98%. The model was curvilinear (quadratic) in form, rather than linear as assumed in previous models. Larger species laid smaller eggs than expected under a simple power function. For the fitted model, within bird types, generic groupings had parallel curvilinear slopes but differing intercepts. Between bird types, the slopes differed. Clutch volume was scaled to body weight; all the bird types had a common slope, which was curvilinear. Body weight and dimorphism accounted for 89.5% of the variation in clutch volume. For all bird types, eggs became proportionally longer in shape as body weight increased, according to a simple power law. The relevance of these relationships to hypotheses on the evolution and adaptive significance of sexual dimorphism and to the trade-off between egg size and clutch size is discussed briefly.
Convergences and Divergences in Communication and Social-Organization of Desert Rodents
Authors: Randall JA
Published: June 2005

Has behaviour of desert rodents evolved to show convergences in the same way as morphological and physiological traits? To answer this question, I compared social behaviour and communication of rodents from deserts in North America, Africa, Eurasia and Australia, Most desert rodents, except those from Australia, sandbathe and footdrum as primary modes of communication. In contrast, social behaviour in desert rodents has evolved across a wide spectrum of sociality. The most highly evolved social organisation in mammals occurs in two species of eusocial mole-rats from arid deserts in Africa, Asian gerbils live in stable family groups, and jerboas in northern Africa may be socially tolerant. The heteromyid rodents from North America, however, live alone in a social structure maintained by neighbour recognition. These communication convergences and social divergences may be explained by the evolutionary history of the rodents and by contrasts in resources, predation and climate. Mole-rats must cooperate to harvest dispersed underground tubers in arid environments. Varied diets and cold climates possibly selected for group living in the highly social gerbils. The long and successful evolution of heteromyid rodents as solitary granivores may explain why they have not taken the next step in social evolution.
Foraging Under Predation - a Comparison of Energetic and Predation Costs in Rodent Communities of the Negev and Sonoran Deserts
Authors: Brown JS , Kotler BP , Valone TJ
Published: June 2005

We used patch-use theory, giving-up densities in experimental food patches, and harvest-rate measurements within these patches to determine the relative contributions of predation risk and energy to foraging costs in four species of rodents from communities in the Sonoran and Negev deserts. To partition costs into components of energy and predation, we converted field measurements of giving-up densities into harvest rates (J min(-1)), used these harvest rates as an estimate of total foraging costs, estimated energetic foraging costs from published physiological measurements of activity and thermoregulatory costs, and assumed that missed opportunity costs were either zero or negative. Our results showed that predation costs predominate. Energetic costs represented only 24%, 19%, 16% and 13% of the foraging costs for Merriam's kangaroo rat (Dipodornys merriami; Sonoran), the round-tailed ground squirrel (Spermophilus tereticaudus; Sonoran), the greater Egyptian sand gerbil (Gerbillus pyramidum; Negev), and Allenby's gerbil (G. allenbyi; Negev), respectively. Equally important were predation-risk differences between bush and open microhabitats; the microhabitat differences in predation cost were often 2-4 times larger than the animals' energetic costs. Seasonal patterns in foraging costs also were predominantly influenced by predation rather than energetic costs. Predation costs appear to be greater in the Negev Desert, but rodents of the Sonoran desert experience greater seasonal and microhabitat variability in predation costs. As a result, predation risk may contribute more towards species coexistence in the community of the Sonoran Desert than that of the Negev Desert.
Computer-Simulation Analysis of Foraging by Heteromyid Rodents in Relation to Seed Distributions - Implications for Coexistence
Authors: Reichman OJ , Roberts E
Published: June 2005

A number of hypotheses have been proposed to explain the mechanisms that promote coexistence among sympatric rodents in North American deserts. In an effort to determine how the distribution of seeds influences foraging patterns and coexistence in a three-species community of heteromyid rodents, we developed a computer simulation model that determines the efficiency of foraging for animals of different sizes. Specifically, the simulation determines how long it would take a forager to gather sufficient energy for 24 h if the animal stopped at seed patches of certain densities. The analyses were conducted for naturally occurring seed distributions and densities, for simulated normal and uniform distributions at natural densities, and for natural distributions at seed densities one-third those known to occur naturally. The results indicate that, under natural distributions and densities, each of the three species possessed unique optima for utilising seed patches of different density. However, when either the seed distribution or density differed from actual values, all three species had identical optima. The implications of these results for promoting coexistence are discussed.
Microgeographic, Genetic and Morphological-Differentiation of Fresh-Water Snails - the Hydrobiidae of Wilson Promontory, Victoria, South-Eastern Australia
Authors: Ponder WF , Colgan DJ , Clark GA , Miller AC , Terzis T
Published: June 2005

Population differentiation and speciation in freshwater snails in a small geographic area were investigated in a study of the morphology and genetics of 75 populations of hydrobiid snails from streams on Wilsons Promontory, Victoria, Australia. At least four genetically definable species occur in sympatry. One (Fluvidona recta sp. nov.) is genetically isolated from the others and the other three (of which only F: turbata sp. nov. is named) appear to be closely related and distinguished by a nearly fixed allozyme (MPI) difference. Heterozygote frequencies for the diagnostic Mpi locus fall well below Hardy-Weinberg expectations in zones of sympatry. There is significant population subdivision within at least two of the genetic species, but as the partitions are allopatric they are not categorised taxonomically. The situation may be explained by the divergence of upland and lowland populations when sea levels fell during the Pleistocene with subsequent secondary contact and low levels of hybridisation in the contact zones. Generally, there is very low gene flow between even closely adjacent populations and extremely low flow between different catchments, F-ST between populations within the same tributary ranging from 0.02 to 0.14 and within adjacent tributaries of the same catchment ranging from 0.03 to 0.59. Some correlations between allozyme data and measured environmental variables were observed but none of these were consistent over all taxa. Size (shell length) appears to be influenced by environment, but shell shape and the length of the opercular smear are more correlated with genetic patterns. A notable lack of correlation between anatomy and genetic groupings was found, although there was some with shell and opercular morphology. Two additional species (F: gippslandica, sp. nov. and F: foris, sp. nov.) from areas adjacent to the Promontory are used as outgroups.
Locomotion in Dromiciops-Australis (Marsupialia, Microbiotheriidae)
Authors: Pridmore PA
Published: June 2005

Cinematography was used to record locomotion in two adult male Dromiciops australis. Both animals were run on five horizontal dowels varying in diameter from 6.3 to 39 mm and on a horizontal board 89 mm wide. Film records were analysed to determine locomotor velocity, stride length and gait. Locomotor speed and stride length were not affected by substratum, but gait was. Truly symmetrical gaits were used by both animals across a range of speeds on the narrowest dowel. These were characterised by diagnoal couplets of support and a diagonal sequence of limb activition. During locomotion on the other substrata, gaits characterised by slight asymmetry were generally used. The most common of these was one in which diagonal support couplets predominated and each hindlimb was activated slightly ahead of the contralateral forelimb. At higher speeds on the 39-mm dowel the animals sometimes used the half-bound and transverse gallop. The duration of the locomotor cycle decreased exponentially with increasing speed and seemed not to be influenced by substratum diameter, once speed was taken into account. Stride length increased exponentially with speed and also appeared independent of substratum. With symmetrical gaits, the relative phase lag of forelimbs with respect to their ipsilateral hindlimbs changed with speed so that a moderate walkig trot was replaced either by a fast waling trot or fast diagonal sequence walk and ultimately by a slow diagonal sequence run. Two of the symmetrical gaits used by Dromiciops are similar to those used by arboreal didelphids and phalangeroids and by most primates, but are rarely used by other mammals. These gaits appear especially suited to locomotion on narrow branches, suggesting that this species may utilise such substrata to a significant extent in nature. The asymmetrical gaits used by Dromiciops, the half-bound and transverse gallop, are used by various other quadrupedal marsupials, although not commonly by arboreal didelphids. It is conjectured that the symmetrical marsupials, although not commonly by arboreal didelphids and phalangeroids were present in ancestral marsupials and that the latter forms also used the half-bound or transverse gallop. Absolute speed at the transition from symmetrical to asymmetrical gaits ('trot-gallop transition') exceeded that predicted by allometric equations derived from data for terrestrial placental mammals. Relative speed (as measured by the square root of the Froude number) was also higher at this transition than in placentals.
Evolution in Some South-East Asian Murinae (Rodentia), as Assessed by Microcomplement Fixation of Albumin, and Their Relationship to Australian Murines
Authors: Watts CHS , Baverstock PR
Published: June 2005

The interrelationships of 16 genera and 49 species of predominantly South-east Asian murine rodents were studied by means of microcomplement fixation of albumin to measure immunological distances among taxa. The results are viewed as a hypothesis of the phylogenetic relationship of these taxa that can be tested by other data sets. Three main groupings are suggested: (1) Maxomys; (2) Leopoldomys, Niviventer and Tokudaia; and (3) Bandicota, Berylmys, Bullimus, Bunomys, Komodomys, Nesokia, Papagomys, Paruromys, Rattus, Stenomys, Sundamys and Taeromys. Within this latter group, Bunomys chrsogasta, Komodomys and Rattus timorensis group together, as do Bullimus, Rattus and Stenomys, and Bandicota with Nesokia. The Australian murines, represented by Mesembriomys, may be part of this South-east Asian radiation but, if so, arose early in its history. Biogeographically, the results support South-east Asia as being a centre of murine evolution with secondary foci in Sulawesi, New Guinea and Australia. There is some evidence to suggest that a relatively recent land bridge between Sulawesi, Flores and Timor may have existed.
Early Growth and Milk-Composition in Southern Elephant Seals (Mirounga-Leonina)
Authors: Hindell MA , Bryden MM , Burton HR
Published: June 2005

Growth rates and changes in body composition of pups were monitored during the 3-week lactation period of southern elephant seals at Macquarie Island. Despite a slight decrease in weight in the first days post-partum, pups attained a mass of 114+/-16.6 kg (mean+/-s.d.) at weaning, representing an average growth rate of 3.53+/-0.80 kg day-1 over the entire lactation period. The proportion of body mass represented by fat was less than 3% at birth, increasing to 40.8+/-12.7% at weaning. Lean tissue mass altered little for most of the lactation period, but did show an increase in the last four days. The fat content of the milk reflected these changes, starting at 16.1+/-6.98% on Day 1 of lactation and increasing to 39.5+/-15.2% about the time of weaning. Fat content of the milk was, however, highly variable and at weaning ranged from 7% to 55%. Although the growth rate of the pup was correlated with mass lost by its mother during lactation, there was no relationship between maternal mass and weaning weight of pups. It is suggested that growth rates may be related to maternal condition and not simply mass, and, further, that differences in growth rates between populations of southern elephant seals are related to maternal energy reserves.
Cross-Generation Effects for Cold Resistance in Tropical Populations of Drosophila-Melanogaster and Drosophila-Simulans
Authors: Watson MJO , Hoffmann AA
Published: June 2005

Cross-generation effects on the cold resistance of Drosophila melanogaster and D. simulans were investigated by exposing adults to different levels of cold stress and testing the resistance of female F1s and F2s. Maternal and paternal treatments had different effects on progeny resistance. Maternal effects were not detected for either species when progeny were held at 25-degrees-C, but were detected when progeny were acclimated at 13-degrees-C prior to testing. When dams were exposed to a non-lethal cold stress following acclimation, the cold resistance of their progeny was increased, particularly in D. simulans. Grandmaternal exposure to 13-degrees-C and a non-lethal stress led to a small decrease in the cold resistance of D. melanogaster, and a small increase in the resistance of D. simulans. When sires of D. melanogaster and D. simulans were exposed to a cold stress, the resistance of their progeny decreased when progeny were tested without acclimation at 13-degrees-C, but decreased only in D. melanogaster when progeny were acclimated. Paternal effects were smaller than maternal effects and were not evident in the F2 generation.
Seasonal-Variation in Water Flux, Field Metabolic-Rate and Food-Consumption of Free-Ranging Koalas (Phascolarctos-Cinereus)
Authors: Ellis WAH , Melzer A , Green B , Newgrain K , Hindell MA , Carrick FN
Published: June 2005

Mass-corrected field metabolic rates of free-ranging male koalas in central Queensland, Australia, varied between 0.329 MJ kg0.75 day-1 in summer and 0.382 MJ kg0.75 day-1 in winter. Field water influx measured 50.8 mL kg-0.8 day-1 in winter, increasing to 59.9 mL kg0.8 day-1 in summer for the same koalas, and was positively correlated with values for leaf moisture of food. Winter rates of water influx for koalas from Springsure were lower than those recorded for koalas from Victoria for the same period of the year. Mass-corrected feeding rates were lower in summer than winter; wet food intake was significantly lower than reported for similar sized female koalas from Victoria. The preferred browse was Eucalyptus crebra in winter and E. tereticornis in summer. Our study indicates that in central Queensland seasonal changes in diet selection by male koalas reflect increased energy requirements in winter and increased water requirements in summer.
Interactions Between Introduced and Native Millipede Species in South Australia
Authors: Griffin TT , Bull CM
Published: June 2005

The Portugese millipede Ommaroiulus moreleti (Lucas) (Diplopoda:Julidae) has recently been introduced to South Australia where it has reached very high densities. In parts of the Adelaide Hills it now co-occurs with two native millipedes, Oncocladosoma clavigerum Jeekel (Diplopoda: Paradoxosomatidae) and Dimerogonus orophilus (Attems) (Diplopoda: Cambalidae). We attempted to show whether the introduced species, which has successfully invaded the detrivore community, has affected the ecology or behaviour of the native millipede members of that community. Experiments in laboratory and field arenas showed that the three species overlap broadly in activity time and microhabitat. The two native species showed no significant difference in habitat choice or aggregating behaviour when alone or mixed with the introduced O. moreleti, and the natives commonly aggregated with the introduced species. Although D. orophilus had reduced feeding activity in the presence of O. moreleti, neither native species rejected food that had been in contact with O. moreleti. We conclude that direct interactions between the introduced invader and the native species cause few behavioural or ecological changes within the detrivorous millipede community.
A Chromosomal Hybrid Zone in the Australian Huntsman Spider, Delena Cancerides (Araneae, Sparassidae) - Evidence for a Hybrid Zone Near Canberra, Australia
Authors: Hancock AJ , Rowell DM
Published: June 2005

Data are presented that indicate the presence of a hybrid zone between two chromosomal races of the endemic Australian spider Delena cancerides. Electrophoretic data verify the hybridising taxa as members of the Victorian telocentric race and a chain-carrying race. Evidence is presented that indicates the hybrid zone is of natural origin, as opposed to being the result of human introductions.
Seasonal-Variation in the Ranging Behavior of the Platypus (Ornithorhynchus-Anatinus) on the Goulburn River, Victoria
Authors: Gust N , Handasyde K
Published: June 2005

Radio-telemetry was used to study the effects of changing reproductive condition and water levels on the ranging behaviour and activity patterns of adult male platypuses in the Goulburn River, Victoria. Home-range size varied greatly between individuals, from 2 . 45 to 15 . 45 ha, but differences in the body weight of individuals did not account for this variability. There was no correlation between the number of burrows used by males and their body size or home-range length. Changing river levels or the animal's breeding condition did not appear to affect the duration of activity periods, which remained constant throughout the study. All radio-tracked animals foraged in a submerged backwater area during high-water conditions, suggesting that platypuses are opportunistic in their habitat usage and may avoid fast-flowing water if calmer areas are available. Although the home ranges of adult males overlapped extensively during the non-breeding period, there was evidence of spatial separation during the breeding season, when animals occupied separate core areas. In addition there appeared to be some temporal separation between adult males during the breeding season. During this period there was greater variation in the times at which animals emerged from their burrows, and some animals became diurnal.
Renal Vasculature of 2 Dasyurid Marsupials, Sminthopsis-Dolichura and S-Crassicaudata
Authors: Brooker BM , Oshea JE , Stewart T
Published: June 2005

The renal vasculature of two dasyurid marsupials, Sminthopsis dolichura and S. crassicaudata, was examined using scanning electron microscopy of vascular corrosion casts of the kidney. Each species had a pair of unipapillary kidneys and the structural organisation of the major renal arterial vessels was similar to that of other placental mammals. The glomerulus of both species consisted of a network of dividing and anastomosing capillary loops. The glomeruli varied markedly in size, shape and complexity. Some afferent arterioles extended back towards the renal medulla, positioning the glomeruli closer to the cortico-medullary border. This placement of glomeruli may extend the loop of the nephron further into the medulla and thereby enhance counter-current water reabsorption and the final urine concentration. In both S. crassicaudata and S. dolichura, a dense mesh of numerous fine capillaries lined the wall of the renal pelvis adjacent to the inner medulla, with a unique configuration in that they were aligned perpendicular to the vasa recta. The function of these fine capillaries is unknown.
The Life-Cycle and Biology of Anilocra-Pomacentri (Isopoda, Cymothoidae), an Ectoparasitic Isopod of the Coral-Reef Fish, Chromis-Nitida (Perciformes, Pomacentridae)
Authors: Adlard RD , Lester RJG
Published: June 2005

The life cycle of Anilocra pomacentri, an ectoparasitic isopod that infests the pomacentrid fish Chromis nitida, in the southern section of the Great Barrier Reef, is described in detail. Embryonated eggs developed through four ontogenic stages within the brood pouch (marsupium) of adult females. Released mancas were free-swimming and infective immediately to suitable hosts. Mancas were negatively buoyant and displayed strong negative rheotaxis and positive phototaxis. The appendix masculina that characterises the male stage was found on isopods between 4.1 and 7.2 mm in telson length. Males developed into females and remained attached permanently to their hosts. Adult females produced an average of three broads during their lifespan of 12-14 months. The number of mancas (average 3.2 mm in telson length) in each brood positively correlated with the telson length of the parent and ranged from 37 to 182. Isopod telson length was correlated positively with fish caudal fork length, which indicated that early infection of the host was followed by simultaneous growth of both host and parasite. In laboratory trials mancas fed successfully on small (14-29 mm length to caudal fork) C. nitida. Infection of larger fish was limited to transient attachment of mancas to the fins. Adult female isopods fed on host blood, with feeding limited to only those periods that correlated with the onset of vitellogenesis. Fish that carried feeding isopods showed a significant reduction in the number of circulating erythrocytes.
Movements of Feral House Mice in Agricultural Landscapes
Authors: Krebs CJ , Kenney AJ , Singleton GR
Published: June 2005

From September 1992 to May 1993 we radio-collared 155 house mice (Mus domesticus) on agricultural fields in southern Queensland to measure movements and to determine social organisation. During the breeding season most individuals were site-attached and home ranges of both sexes overlapped extensively. There was no sign of exclusive space use for breeding individuals. Breeding males had home ranges that were larger than those of breeding females (0.035 ha v. 0.015 ha), and moved about more. After breeding ended, home ranges increased over tenfold in area, and most mice became nomadic and not site-attached.