Structural and possible thermoregulatory differences in the ears of grey kangaroos

1. 1. Western Grey Kangaroos generally inhabit more arid and hotter regions than Eastern Greys.

2. 2. Ears from Western Greys are significantly thinner, less furred and have smaller, thinner hairs than those from Eastern Grays.

3. 3. Ears may act as better heat dissipators in the Western Greys than in the Eastern Greys.

In vitro maturation of oocytes from a marsupial,the tammar wallaby (Macropus eugenii)

This study examined the competence of oocytes from the tammar wallaby, Macropus eugeniio mature in vitro. Oocytes were collected from follicles >1 mm diameter 24 h after pregnant mare serum gonadotrophin (PMSG) treatment and incubated in Eagle's minimum essential medium supplemented with 10% fetal calf serum, at 35°C in 5% CO₂ in air for 24, 36, or 48 h. Oocytes were incubated either granulosa cell-intact or granulosa cell-free or in the presence of 10 IU ml^?1 PMSG or 10 μg ml^?1 porcine luteinizing hormone (LH) + 10 μg ml^?1 porcine follicle stimulating hormone (FSH). The ability of oocytes recovered from small (<1.5-mm-diameter) and large (≥1.5-mm-diameter) follicles to mature in vitro was also examined. The nuclear status of oocytes was assessed using the DNA-specific dye Hoechst 33342. Initially, all oocytes examined contained a germinal vesicle. After 24 h of culture, 60% of oocytes had progressed to metaphase I or anaphase I. After 36 h, approximately 20% of oocytes possessed metaphase II chromosomes, and 20% of oocytes were at metaphase I or anaphase I. At the completion of the 48 h culture period, 40% of oocytes had completed maturation to the metaphase II stage. In vitro oocyte maturation after 48 h was not affected by the presence of granulosa cells, PMSG, or LH and FSH. More oocytes from large follicles (55%) completed maturation by 48 h than from small follicles (20%). Approximately 50% of oocytes remained at the GV stage at all times under all conditions. Marsupial oocytes thus undergo spontaneous nuclear maturation once removed from the follicular environment, suggesting a basically similar control system to that in placental mammals. © 1993 Wiley-Liss, Inc.     

致赤大袋鼠皮肤化脓的荚膜血清A型多杀性巴氏杆菌的分离鉴定

正多杀性巴氏杆菌(Pasteurella multocida)是巴氏杆菌属的成员之一,能感染鸡、鸭、兔、猪和牛等多种家养动物和部分野生动物,不同动物感染后的疾病命名不同,如禽霍乱(Eveleth et al.,1949)、猪肺疫和牛出血性败血症(陆承平,2001)。该菌为革兰氏阴性球杆菌或短杆菌,新分离菌株瑞氏染色两极着色明显,有荚膜,人工培养     

Landscape discontinuities influence gene flow and genetic structure in a large, vagile Australian mammal, Macropus fuliginosus

Large vagile mammals typically exhibit little genetic structuring across their range, particularly when their habitat is essentially continuous. We investigated the population genetic structure of a large vagile Australian macropodid, Macropus fuliginosus, which is continuously distributed across most of southern Australia, using nine highly polymorphic nuclear microsatellite loci. Five distinct genetic units were identified across the range, four on the mainland and one on Kangaroo Island. In addition to the predicted historic Nullarbor Plain Barrier, two unexpected mainland barriers to gene flow were identified. Both were associated with landscape discontinuities (Swan River, Flinders Ranges), which appear within the dispersal capabilities of M. fuliginosus. Typical of large vagile mammals, M. fuliginosus displays high genetic diversity (with the exception of an insular population) and weak genetic structuring (within genetic units). However, the expansion of M. fuliginosus from southwestern Australia during the Pleistocene has resulted in significantly reduced genetic diversity in eastern populations. No significant sex-biased dispersal was detected, although differences in habitat, densities and climatic conditions between the eastern and western regions of the range appear to influence dispersal with the effects of isolation by distance only evident in the west. These results suggest that the biogeography of southern Australia is more complex than previously thought and reveal that seemingly minor landscape features can significantly impact genetic structuring in large vagile mammals.     

Use of road underpasses by mammals and a monitor lizard in eastern Australia and consideration of the prey‐trap hypothesis

Road networks continue to expand globally with predictable effects on ecological systems. Research into the effectiveness of road underpasses and overpasses for wildlife has been concentrated in North America and Europe. In Australia, most studies of underpasses have been of relatively short duration and without reference sites to give context to the measured rates of use. We studied 5–7 road underpasses at two locations in eastern Australia over 2–3 years, comparing camera trap detections of animals in underpasses with those at nearby forest sites. Three species of large macropod (wallabies and kangaroos) were frequently detected in the underpasses, with some underpasses traversed 1–4 times per week, and in many cases exceeded detections in the forest. The lace monitor (Varanus varius) was detected in all underpasses, often once per week during spring and summer, and infrequently in the forest. At each location, a different small macropod species, including one regionally threatened, showed a higher probability of detection in one underpass compared with several of the forest sites. The vulnerable koala (Phascolarctos cinereus) was detected infrequently in underpasses and in the adjoining forest. The short‐beaked echidna (Tachyglossus aculeatus) had a high probability of detection in a single underpass. The “prey‐trap hypothesis” postulates that predators will exhibit increased activity at underpasses as a consequence of prey being funneled. We found the red fox (Vulpes vulpes) had high activity in some underpasses. However, its activity coincided less than expected with the activity of the mammals most at risk to it. Our results provide no consistent support for the “prey‐trap hypothesis.” Instead, our study confirms the generic value of underpasses for a range of medium‐large mammals as well as one large reptile. Habitat adjoining underpasses exert a strong influence on their use and require greater consideration to maximize underpass use.     

Differing impact of a major biogeographic barrier on genetic structure in two large kangaroos from the monsoon tropics of Northern Australia

Tropical savannas cover 20–30% of the world's land surface and exhibit high levels of regional endemism, but the evolutionary histories of their biota remain poorly studied. The most extensive and unmodified tropical savannas occur in Northern Australia, and recent studies suggest this region supports high levels of previously undetected genetic diversity. To examine the importance of barriers to gene flow and the environmental history of Northern Australia in influencing patterns of diversity, we investigated the phylogeography of two closely related, large, vagile macropodid marsupials, the antilopine wallaroo (Macropus antilopinus; n = 78), and the common wallaroo (Macropus robustus; n = 21). Both species are widespread across the tropical savannas of Australia except across the Carpentarian Barrier (CB) where there is a break in the distribution of M. antilopinus. We determined sequence variation in the hypervariable Domain I of the mitochondrial DNA control region and genotyped individuals at 12 polymorphic microsatellite loci to assess the historical and contemporary influence of the CB on these species. Surprisingly, we detected only limited differentiation between the disjunct Northern Territory and Queensland M. antilopinus populations. In contrast, the continuously distributed M. robustus was highly divergent across the CB. Although unexpected, these contrasting responses appear related to minor differences in species biology. Our results suggest that vicariance may not explain well the phylogeographic patterns in Australia's dynamic monsoonal environments. This is because Quaternary environmental changes in this region have been complex, and diverse individual species’ biologies have resulted in less predictable and idiosyncratic responses.     

Isolation from mammalian predators differentially affects two congeners

Evolutionary isolation from predators can profoundly influencethe morphology, physiology, and behavior of prey, but littleis known about how species respond to the loss of only someof their predators. We studied antipredator behavior of tammarwallabies (Macropus eugenii) and western gray kangaroos (Macropusfuliginosus) on Kangaroo Island (KI), South Australia, andat Tutanning Nature Reserve on the mainland of western Australia.Both species on KI have been isolated from native mammalian predators for several thousand years. On KI, wallabies (becauseof their size) are vulnerable to diurnal aerial predators.In contrast, on the mainland both species have been exposedcontinuously to native and introduced mammalian and avian predators.At both locations, wallabies modified the amount of time they allocated to vigilance and foraging in response to group size,whereas kangaroos did so only at the higher risk Tutanningsite. Both species modified overall time budgets (they werewarier at the higher risk site), and both species modifiedspace-use patterns as a function of risk. At the higher risk site, tammars were closer to cover, whereas kangaroos were,on average, farther from cover. We hypothesize that the presenceof a single predator, even if it is active at a different timeof day, may profoundly affect the way a species responds tothe loss of other predators by maintaining certain antipredatorbehaviors. Such an effect of ancestral predators may be expected as long as species encounter some predators.     

Diet of four rock‐dwelling macropods in the Australian monsoon tropics

Abstract An unusually high diversity of macropods inhabit the rocky areas in the monsoon tropics of the Northern Territory, Australia, yet the mechanisms that allow their niche separation are not clear. Previous studies suggest that the nabarlek, Petrogale concinna, may have a more grazing diet than the short‐eared rock‐wallaby, Petrogale brachyotis, with whom it coexists. Thus, diet may be an important mechanism of niche separation between these species. We examined the diet of the four sympatric species (the black wallaroo Macropus bernardus, common wallaroo Macropus robustus, P. brachyotis and P. concinna) to determine whether there are differences in the dominant plant groups eaten by the species across the landscape and with season. Diets were determined with a macroscopic analysis of the seed and fruit content of scats and an analysis of the ¹²C to ¹³C isotope ratios of scats using mass spectrometry. In the dry season the rock‐wallaby species predominantly consumed browse and/or forbs, and the larger wallaroos predominantly consumed grass. However, there was large variation across the landscape in the dry season diets of P. brachyotis, M. bernardus and M. robustus; including high proportions of grass eaten at some sites and high proportions of browse at other sites. In the wet season, greater proportions of grass were eaten by P. brachyotis and M. bernardus than in the dry season. Generally, there was little evidence to support the previous suggestion that P. concinna is more of a grazer than P. brachyotis, but there was some evidence than M. bernardus consumes greater amounts of browse and/or forbs than M. robustus.     

The habitat requirements of four sympatric rock‐dwelling macropods of the Australian monsoon tropics

A high diversity of rock‐dwelling macropod species inhabit the tropics of the Northern Territory, Australia. Within this region, individual species have varied distributions, with ranges variously being widespread, restricted, or geographically disjunct with variable levels of sympatry between them. The cause of these patterns is unknown and little is known of the ecology of these rock‐dwelling macropods. We hypothesized that differences in the habitat requirements is the key to understanding the biogeography and sympatry of the species. We examined this hypothesis at both regional and local scales. We analysed records of occurence of Petrogale brachyotis, P. concinna, Macropus bernardus and M. robustus and environmental correlates (such as geology type, vegetation type, distance to drainage and distance to ‘rugged’ terrain) throughout the monsoon tropics using geographic information systems and generalized linear modelling. We surveyed 80 sites across the tropics of the Northern Territory and collected presence‐absence data using scats and environmental correlates to examine fine‐scale habitat requirements. From the regional scale analysis, it was clear that distance to rugged terrain strongly influences presence of all four species. Responses to this variable suggest M. bernardus and P. concinna have greater requirements for rugged terrain, whereas M. robustus and P. brachyotis are found across a broader range of habitats. The local scale analysis suggested presence of M. robustus is primarily driven by vegetation type, M. bernardus by the cover of outcrops, boulders and large rocks, and P. brachyotis by the density of caves. Although these species overlap in their use of habitats, there are also differences in their habitat requirements that are likely to play a role in their niche separation and in some cases their biogeography. However, it is apparent that the distributions of the species have also been influenced by historical factors given the absence of these species from some apparently suitable sites.     

Body condition of the red kangaroo (Macropus rufus) in arid Australia: The effect of environmental condition,sex and reproduction

The body condition of live-caught male and female red kangaroos (Macropus rufus Desmarest 1842) was assessed in environmental conditions described by a period of high (two years) followed by low (one year) rainfall. Changes in pasture biomass and quality closely followed rainfall fluctuations in these years. Fluctuations in standardized body mass, in turn, lagged behind changes in pasture biomass with a delay of three months. Male and female body condition was best predicted by green grass biomass. Kangaroos caught during the high rainfall period reached an above average plane of condition. In the low rainfall period that followed, the condition of kangaroos declined, and was greater for small males (14–41 kg), large males (45–89 kg), and females (18–36 kg) with small or no pouch young than for female subadults (< 22 kg) and females with large pouch young (20–34 kg). Female subadults were also significantly older and the ratio of females:females with young-at-foot was higher in the low rainfall period. This suggests a mechanism for age/sex class differences in survivorship. The lagged synchrony of body condition with pasture biomass can be explained by body-size related digestive constraints, reflecting sex differences in adaptation to a stochastic environment.     

New Zealand cicadas of the genus Maoricicada (Homoptera: Tibicinidae)

Abstract

The genus Maoricicada Dugdale, 1972 includes 19 taxa, of which 15 are described here. Ten from the South Island mountains are described as new: M. alticola, M. clamitans, M. mangu gourlayi, M. m. multicostata, M. m. celer, M. nigra frigida, M. otagoensis otagoensis, M. o. maceweni, M. phaeoptera, and M. tenuis. The distributions of most taxa are mapped, their songs are represented by sonograms, and their known periods of emergence are recorded. Evidence of hybridisation is unknown. Most species are characteristic of open, unforested sites; M. nigra nigra and M. oromelaena occur close to the summer snowline, a zone not known to be inhabited by cicadas elsewhere in the world.     

Insular tammar wallabies (Macropus eugenii) respond to visual but not acoustic cues from predators

We studied the way in which a population of tammar wallabies(Macropus eugenii), which have been isolated from mammalianpredators since the last ice age, responded to the sight andsound of historical and ontogenetically and evolutionarilynovel predators. Tammars were shown a range of visual stimuli,including taxidermic mounts of two evolutionarily novel predators,a red fox (Vulpes vulpes) and a cat (Felis catus), and a modelof an extinct predator, the thylacine (Thylacinus cynocephalus).Controls were a conspecific, the cart on which all mounts werepresented, and blank trials in which spontaneous change in behaviorwas measured. We played back recorded sounds to characterizeresponses to acoustic cues from predators and to a putativeconspecific antipredator signal. Treatments included the howlsof dingoes (Canis lupus dingo), an evolutionarily novel predator;calls of a wedge-tailed eagle (Aquila audax), a historicaland current predator; and wallaby foot thumps. Controls werethe song of an Australian magpie (Gymnorhina tibicen) and ablank trial. After seeing a fox, wallabies thumped their hindfeet in alarm, suppressed foraging, and increased looking.The sight of a cat similarly suppressed foraging and increasedlooking. The sounds of predators did not influence responsiveness,but wallabies foraged less and looked more after thump playbacks.Our results suggest that tammars respond to the sight, butnot the sounds, of predators. In contrast, the response to footthumps demonstrates that this particular sound functions asan antipredator signal. We suggest that responsiveness to visualcues has been preserved under relaxed selection because predatormorphology is convergent, but vocalizations are not.     

Sexual conflict in action: An antagonistic relationship between maternal and paternal sex allocation in the tammar wallaby,Notamacropus eugenii

Sex ratio biases are often inconsistent, both among and within species and populations. While some of these inconsistencies may be due to experimental design, much of the variation remains inexplicable. Recent research suggests that an exclusive focus on mothers may account for some of the inconsistency, with an increasing number of studies showing variation in sperm sex ratios and seminal fluids. Using fluorescent in‐situ hybridization, we show a significant population‐level Y‐chromosome bias in the spermatozoa of wild tammar wallabies, but with significant intraindividual variation between males. We also show a population‐level birth sex ratio trend in the same direction toward male offspring, but a weaning sex ratio that is significantly female‐biased, indicating that males are disproportionately lost during lactation. We hypothesize that sexual conflict between parents may cause mothers to adjust offspring sex ratios after birth, through abandonment of male pouch young and reactivation of diapaused embryos. Further research is required in a captive, controlled setting to understand what is driving and mechanistically controlling sperm sex ratio and offspring sex ratio biases and to understand the sexually antagonistic relationship between mothers and fathers over offspring sex. These results extend beyond sex allocation, as they question studies of population processes that assume equal input of sex chromosomes from fathers, and will also assist with future reproduction studies for management and conservation of marsupials.     

Exsheathment of the infective larva of Labiostrongylus eugenii, a nematode parasite of the Kangaroo Island wallaby Macropus eugenii.

The infective larva of L. eugenii is enveloped in two cuticles which are discarded when the larva exsheaths in the sacculated portion of the wallaby's stomach. In vitro larvae exsheathed in a 0·85% solution of sodium chloride at 37°C, buffered to pH 7 with bicarbonate ion and 40% carbon dioxide. Survival was enhanced if the liquid phase contained medium 199 and serum, and exsheathment was quicker if exposure to carbon dioxide was 1 h rather than 1 day or 7 days. As larvae exsheathed, contractions of the pharynx commenced, and medium was ingested, even when larvae were enveloped in both cuticles. The stimuli for exsheathment and the subsequent pattern of events are like those already recognised in some trichostrongyles.     

Cutaneous leishmaniasis in red kangaroos: isolation and characterisation of the causative organisms

This is the first report of cutaneous leishmaniasis in kangaroos where infection was acquired within Australia. The diagnosis is based on the clinical criteria used for humans, the lesion histopathology, the detection and isolation of parasites from the lesions, and the analysis of the small subunit ribosomal RNA genes using the polymerase chain reaction. Despite a clear indication that the parasites belong to the genus Leishmania, no assignation to a known Leishmania species could be made using these or other less conserved genetic loci such as the non-transcribed spacer of the mini-exon repeat. As is the case in humans, some but not all animals harbouring lesions had antibodies to the isolated parasites or to several other Leishmania species. The isolated parasites displayed two well characterised Leishmania glycoconjugates, the lipophosphoglycan and proteophosphoglycan. They were infectious for mouse macrophages in vitro and established long-term infection at 33 degrees C but not at 37 degrees C. Our findings raise the possibility of transmission to humans, which may be unrecognised and suggest the possibility that imported species of Leishmania could become endemic in Australia.