Journal articles on the topic 'Macropus Australia Reproduction'
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1
Schwanz, Lisa E., and Kylie A. Robert. "Reproductive ecology of wild tammar wallabies in natural and developed habitats on Garden Island, Western Australia." Australian Journal of Zoology 60, no. 2 (2012): 111. http://dx.doi.org/10.1071/zo12024.
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Reproduction may be influenced by major environmental changes experienced by an entire population as well as variation within a population in maternal resource availability or quality. We examined relationships between body condition and reproductive traits in two wild populations of the seasonally breeding tammar wallaby (Macropus eugenii) on Garden Island, Western Australia, that differed in access to supplemental food resources. Body condition changed predictably over the year, with females losing condition over the dry summer and gaining condition over the winters, when lactation occurs and most annual precipitation falls. Body condition influenced reproduction, with females of greater body condition more likely to have a pouch young, and to have a larger pouch young, early in the reproductive season. This intrapopulation pattern was opposite to that seen across populations – females in a native bushland were in poorer condition yet were more likely to have pouch young, and had larger pouch young, in March than did females living in a water-supplemented habitat on a naval base. Body condition did not influence the probability of weaning a pouch young in a year, nor did reproductive success influence changes in body condition across seasons. Instead, annual variation in precipitation had a dramatic effect on population weaning success in the native bushland, but not on the naval base. In summary, individual variation in body condition as well as large climatic variation influenced the reproduction of tammar wallabies on Garden Island, but the nature of the effect depended on the different habitats experienced by the two study populations.
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SADLEIR, R. M. F. S. "REPRODUCTION IN TWO SPECIES OF KANGAROO (MACROPUS ROBUSTUS AND MEGALEIA RUFA IN THE ARID PILBARA REGION OF WESTERN AUSTRALIA." Proceedings of the Zoological Society of London 145, no. 2 (August 20, 2009): 239–61. http://dx.doi.org/10.1111/j.1469-7998.1965.tb02016.x.
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MOSS, G. L., and D. B. CROFT. "Body condition of the red kangaroo (Macropus rufus) in arid Australia: The effect of environmental condition, sex and reproduction." Austral Ecology 24, no. 2 (April 1999): 97–109. http://dx.doi.org/10.1046/j.1442-9993.1999.241949.x.
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Shine, Richard, and Gregory P. Brown. "Adapting to the unpredictable: reproductive biology of vertebrates in the Australian wet–dry tropics." Philosophical Transactions of the Royal Society B: Biological Sciences 363, no. 1490 (July 18, 2007): 363–73. http://dx.doi.org/10.1098/rstb.2007.2144.
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In the wet–dry tropics of northern Australia, temperatures are high and stable year-round but monsoonal rainfall is highly seasonal and variable both annually and spatially. Many features of reproduction in vertebrates of this region may be adaptations to dealing with this unpredictable variation in precipitation, notably by (i) using direct proximate (rainfall-affected) cues to synchronize the timing and extent of breeding with rainfall events, (ii) placing the eggs or offspring in conditions where they will be buffered from rainfall extremes, and (iii) evolving developmental plasticity, such that the timing and trajectory of embryonic differentiation flexibly respond to local conditions. For example, organisms as diverse as snakes ( Liasis fuscus , Acrochordus arafurae ), crocodiles ( Crocodylus porosus ), birds ( Anseranas semipalmata ) and wallabies ( Macropus agilis ) show extreme annual variation in reproductive rates, linked to stochastic variation in wet season rainfall. The seasonal timing of initiation and cessation of breeding in snakes ( Tropidonophis mairii ) and rats ( Rattus colletti ) also varies among years, depending upon precipitation. An alternative adaptive route is to buffer the effects of rainfall variability on offspring by parental care (including viviparity) or by judicious selection of nest sites in oviparous taxa without parental care. A third type of adaptive response involves flexible embryonic responses (including embryonic diapause, facultative hatching and temperature-dependent sex determination) to incubation conditions, as seen in squamates, crocodilians and turtles. Such flexibility fine-tunes developmental rates and trajectories to conditions–-especially, rainfall patterns–-that are not predictable at the time of oviposition.
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Cooper, DW. "Should immunocontraception be used for wildlife population management?" Australian Mammalogy 26, no. 1 (2004): 61. http://dx.doi.org/10.1071/am04061.
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Immunocontraception involves eliciting an immune response against eggs, sperm or hormones so that successful reproduction is prevented. Work in Australasia is aimed at European rabbits (Oryctolagus cuniculus), red foxes (Vulpes vulpes), house mice (Mus musculus), common brushtail possums (Trichosurus vulpecula), koalas (Phascolartcos cinereus) and kangaroos (Macropus spp.), with the vaccines involved all containing self antigens or their relatives. Two fundamental problems have been inadequately addressed in this research. The first problem is that it is difficult to obtain strong immune responses against self antigens and so the vaccines may be ineffective. Most published data on the effect of immunocontraceptives on reproduction involve the use of an adjuvant of which there are many kinds. The materials enhance the immune response greatly. The most frequently used is Freund?s adjuvant which can cause chronic suffering. Its use on wildlife will lead to very negative public perceptions. There has been no convincing demonstration that successful immunocontraception is possible with any method of vaccination likely to be used in the field, if success is defined as contraception of a proportion of the population high enough for management requirements. If it is assumed that success can be achieved, the second fundamental problem arises with two potential consequences. Even with adjuvant, a substantial minority of the vaccinated animals remains fertile. The first consequence is that since failure to be contracepted is likely to be in part genetic, there is likely to be rapid selection for these non-responders. The method will become ineffective in a few generations. The second problem is that the offspring of the animals which breed will have altered immune responses. Their capacities to respond to their own pathogens or to harbor pathogens of other species in the same ecosystem are likely to be changed. The presence of chlamydia in P. cinereus and bovine tuberculosis in New Zealand T. vulpecula means that responses to these pathogens would have to be studied in offspring of immunocontracepted parents to ensure that the offspring were not more susceptible to them. New Zealand intentions to put an immunocontraceptive into a T. vulpecula gut worm must be viewed with caution by Australia. The eggs of transgenic worms will be easily transplanted either accidentally or deliberately back into Australia, and so infect T. vulpecula in Australia.
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Arnold, GW, DE Steven, and JR Weeldenberg. "Comparative ecology of western grey kangaroos (Macropus fulginosus) and euros (M. robustus erubescens) in Durokoppin Nature Reserve, isolated in the central wheatbelt of Western Australia." Wildlife Research 21, no. 3 (1994): 307. http://dx.doi.org/10.1071/wr9940307.
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The populations of western grey kangaroos (Macropus fuliginosus) and euros (M. robustus erubescens) in a 1196-ha area of native vegetation in the central wheatbelt of Western Australia were studied over six years (1985-91). The area was isolated from other remnants of native vegetation by at least 1.4 km. Captures were made periodically throughout each year and the animals weighed and measured. In all, 152 animals were captured (83 euros and 69 western grey kangaroos). The data for each sex and species were assigned to 'seasons' (February-July or August-January) and assessments made of body condition. The weights and tail circumstances, adjusted for individual size by regression on leg length, were higher for western grey kangaroos but not for euros in August-January. Euro males varied significantly in weight from year to year; euro females and grey males and females did not. Too few grey females were captured to analyse seasonality of reproduction. The estimated birth dates of 68 euro pouch young were distributed equally throughout the study period. There were approximately equal numbers of each species in an estimate made in 1988 from a helicopter survey, with a total (� s.e.) of 191�29 kangaroos. The mean faecal pellet counts on 42 Tied transects of 100 m2 did not differ significantly over the period 1985-88. These counts showed that the overall use of the different vegetation types varied by a factor of two. Heaths had the highest pellet counts and open mallee or woodland the least, with Allocasuarina-dominated shrublands being intermediate. Spotlight surveys around the reserve boundary showed a highly significant difference in distribution of the two species. This was confirmed by analysis of the home ranges of 13 radio-collared individuals. Euros showed a strong preference for areas of York gum-wandoo-jam woodland with a herbaceous ground layer and areas with tall Allocasuarina or dense heath. In contrast, the western grey kangaroos preferred the heathlands and open woodlands without a herbaceous ground cover. The sex ratios of the whole populations seen in spotlight searches was 0.72 : 1.00 (males: females) for western grey kangaroos and 0.81 : 1.00 for euros. Both differ significantly from parity. There was a higher proportion of female euros amongst the animals seen in the western part of the reserve than in the eastern part. These populations relied mainly on the resources of the reserve. The average number of kangaroos seen on adjacent farmland on any one night varied from 3.6 in 1986 to 13.5 in 1991. A significantly higher proportion of males of both species were seen on farmland.
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Chambers, Brian, and Roberta Bencini. "Road mortality reduces survival and population growth rates of tammar wallabies on Garden Island, Western Australia." Wildlife Research 37, no. 7 (2010): 588. http://dx.doi.org/10.1071/wr10080.
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Context Although road mortality has the potential to affect the fate of populations, it is often confounded with other forms of environmental change. Therefore determining its impact separately from other factors is difficult because it requires an understanding of how road mortalities affect age- and sex-specific survival rates. Aims We determined the impact of high numbers of road-kills and habitat modification on the growth and survival of the population of tammar wallabies (Macropus eugenii) on Garden Island, off the coast of Western Australia. The increased supply of food from large areas of fertilised and irrigated lawns on a naval base was expected to increase the population growth rate (λ) and the road-kills were expected to offset the population response. Methods We conducted a mark-and-recapture study over three years to estimate rates of survival, reproduction and population growth rates in areas of the island that were either heavily affected by the presence of a naval base that included a network of roads and buildings, close enough to the naval base that animals could be affected by the disturbance there, and completely unaffected and lacking major roads or buildings. All road-kills were collected to estimate the impact of road mortality on the survival and growth rates of the population. Key results The growth rate, λ, for the population on the naval base was 1.02 ± 0.083 (s.e.) per year, which was much higher than in an area of adjacent bushland at 0.92 ± 0.065 per year and in undisturbed bushland at 0.93 ± 0.100 per year. When the impact of road mortality was removed, λ increased to 1.15 ± 0.101 per year on the naval base and 0.96 ± 0.076 per year in the bushland adjacent to the naval base. On the naval base road mortality reduced survival rates of one-year-old and adult animals by 0.14 ± 0.087 and 0.12 ± 0.012 per year (mean ± s.e.). Conclusions Road mortality counteracted the increase in the size of the tammar population caused by the habitat modification on the naval base. The impact of road mortality on the adjacent bushland population may result in its long-term decline, as the population may not be able to recover from the reduction in survival rates. Implications Road mortality has the potential to threaten susceptible populations but its impact should be quantified so that mitigation measures can be implemented where they will achieve the greatest benefits.
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Vernes, Karl, and Lisa Claire Pope. "Reproduction in the northern brown bandicoot (Isoodon macrourus) in the Australian Wet Tropics." Australian Journal of Zoology 57, no. 2 (2009): 105. http://dx.doi.org/10.1071/zo09019.
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We investigated timing of reproduction in a wild population of northern brown bandicoots (Isoodon macrourus) in the Australian Wet Tropics. Almost all births occurred during the late dry season and early wet season, and most adult females (78–96%) were carrying pouch young during those times. Litter sizes ranged from 1 to 6 pouch young (mean = 3.1) and was not influenced by season. Adult males had significantly larger testes in the late dry and early wet seasons, corresponding with the peak in births. Daylength was the only environmental factor that predicted the presence of a litter; when daylength exceeded 12 h, more than 70% of captured females were carrying pouch young, and most (94%) births were estimated to have occurred on days with >12 h of daylight. Various environmental factors have been proposed as a cue for breeding in I. macrourus, with daylength though to be the primary cue initiating breeding in temperate Australia, but temperature and rainfall thought to be more important in the tropics. Our data suggest that in the Australian Wet Tropics, increasing daylength in the late dry season acts as the primary cue for breeding.
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Attard, S. M., and S. C. Mckillup. "Reproduction and Growth of The Bandicoot Isoodon macrourus At Four Sites in Rockhampton, Queensland." Australian Mammalogy 20, no. 3 (1998): 411. http://dx.doi.org/10.1071/am98411.
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Within Australia the northern short-nosed bandicoot, Isoodon macrourus, occurs in coastal areas from the Kimberleys to the monsoonal tropics of the Northern Territory and from Cape York Peninsula to the Hawkesbury River, New South Wales (Gordon 1983). The reproductive ecology of I. macrourus has been studied in two captive (Hall 1983; Gemmell 1988) and five natural populations (Gordon 1971, 1974; Gemmell 1982; Hall 1983; Friend 1990; Kem- per et al. 1990; Budiawan 1993). Three of the latter (Darwin, the Mitchell Plateau and Townsville) were in the tropics; breeding at these sites occurred dur- ing the wetter months of the year but not during the summer of 1982/3 in Darwin when the monsoon failed (Friend 1990) or during the relatively dry winter/spring of 1991 in Townsville (Budiawan 1993), suggesting a dependence on rainfall (Friend 1990; Budiawan 1993). We report on differences in the reproduction, growth and development of I. macrourus in Rockhampton, Queensland, from March - October 1993 at four adjacent sites which received different amounts of artificial watering.
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Sunnucks, Paul, and Andrea C. Taylor. "Sex of Pouch Young Related to Maternal Weight in Macropus eugenii and M. parma (Marsupialia: Macropodidae)." Australian Journal of Zoology 45, no. 6 (1997): 573. http://dx.doi.org/10.1071/zo97038.
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Competing theories of sex allocation in mammals may best be reconciled in the light of data from diverse species. The tammar wallaby (Macropus eugenii) is potentially a particularly interesting study animal because females wean only one young per year, and exhibit extreme synchronicity in the annual onset of breeding. By contrast, reproduction in the closely related parma wallaby (M. parma) is almost asynchronous. These two Australian species are found sympatrically only on Kawau Island, New Zealand, where they were introduced in about 1870. We sampled wallabies on Kawau Island in April of 1996, when both species were breeding. Although the sex ratios in both species were not significantly different from unity, offspring of M. eugenii were very significantly more likely to be male with increasing maternal weight (logistic regression χ2 = 16.8, P < 0.0001), and the fewer M. parma data showed a non-significant trend in the same direction (χ2 = 1.9, P= 0.16). These data, at least for M. eugenii, are consistent with the Trivers–Willard hypothesis, and warrant further investigation in wild and captive populations under different measured or manipulated ecological conditions. We suggest an approach utilising the characteristics of M. eugenii which might help determine whether the sex bias is determined close to conception, or is effected later in the reproductive cycle by differential survival of the sexes.
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Renfree, Marilyn B., Anthony T. Papenfuss, Janine E. Deakin, James Lindsay, Thomas Heider, Katherine Belov, Willem Rens, et al. "Genome sequence of an Australian kangaroo, Macropus eugenii, provides insight into the evolution of mammalian reproduction and development." Genome Biology 12, no. 12 (2011): 414. http://dx.doi.org/10.1186/gb-2011-12-12-414.
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Renfree, Marilyn B., Anthony T. Papenfuss, Janine E. Deakin, James Lindsay, Thomas Heider, Katherine Belov, Willem Rens, et al. "Genome sequence of an Australian kangaroo, Macropus eugenii, provides insight into the evolution of mammalian reproduction and development." Genome Biology 12, no. 8 (2011): R81. http://dx.doi.org/10.1186/gb-2011-12-8-r81.
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Coulson, Graeme, Christopher D. Nave, Geoff Shaw, and Marilyn B. Renfree. "Long-term efficacy of levonorgestrel implants for fertility control of eastern grey kangaroos (Macropus giganteus)." Wildlife Research 35, no. 6 (2008): 520. http://dx.doi.org/10.1071/wr07133.
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Overabundant populations of kangaroos pose substantial management problems in small parks on the fringe of urban areas in Australia. Translocation is impractical and culling is often not publicly acceptable, but fertility control offers an acceptable alternative. One potential contraceptive is levonorgestrel, which provides effective long-term contraception in women, and prevents births in some marsupials for up to five years. We evaluated the long-term efficacy of levonorgestrel in free-ranging eastern grey kangaroos (M. giganteus) at two sites in Victoria, Australia. We trapped 25 adult females at one site (Portland Aluminium), treating 18 with two subcutaneous 70-mg levonorgestrel implants and seven with control (inert) implants. We darted 25 adult females at the other site (Woodlands Historic Park), treating all with two 70-mg levonorgestrel implants. We monitored the reproductive status of the kangaroos, as indicated by the obvious presence of a pouch young, in spring each year for up to seven years. In the first three years at Portland, 81–86% of levonorgestrel-treated females were infertile, compared with 12–29% in the control group, but the effectiveness of fertility control declined over time. At this site, the proportions of treated females breeding in the fourth, fifth, sixth and seventh years of the trial were 36%, 50%, 67% and 100% respectively. Fecundity at Woodlands was similar. Although this protocol achieved fertility control for several years, it was likely that more than one treatment or a higher dose rate would be required for effective fertility control in this long-lived species.
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Berris, Karleah K., Steven J. B. Cooper, William G. Breed, and Susan M. Carthew. "Timing of breeding and female fecundity of the greater bilby (Macrotis lagotis) in the temperate zone of South Australia: implications for translocations of a previously widespread species." Wildlife Research 46, no. 5 (2019): 444. http://dx.doi.org/10.1071/wr18159.
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Context Many of Australia’s threatened mammals were once widespread across the continent and present in both arid, semiarid and temperate habitats. However, data on breeding biology can be lacking for some climatic regions due to local extinctions of populations. The breeding biology of the greater bilby (Macrotis lagotis) has previously only been studied in captive colonies or free-ranging arid zone populations. Between 1997 and 2005, captive-bred bilbies were released at two sites in temperate South Australia. These populations provided an opportunity to determine whether bilbies adopt a seasonal reproductive strategy in the temperate zone, where this species has not been present since the early 1900s. Aims To determine the season of births, litter size and female reproductive potential in two free-ranging populations of the bilby in the temperate zone of South Australia. Methods Bilbies were regularly cage-trapped at Venus Bay Conservation Park and Thistle Island between August 2007 and April 2010 to obtain data on reproductive activity in both populations. Key results Births of pouch young in both populations occurred in winter (June–August), spring and early summer, but not between February and mid-May. Males had a significantly smaller mean testes size relative to head length in late summer, when breeding activity ceased. Average litter size at pouch emergence was between 1.00 and 1.47 pouch young, with females producing up to three litters per annum. The mean head length of females that successfully raised twins was significantly larger than that of females who raised a single pouch young. Conclusions The seasonal breeding pattern observed in the present study differs from that of year-round reproductive activity in captivity and the arid zone. The present study suggests that female body size influences fecundity, and that releasing large females at the start of the breeding season in temperate areas may maximise the initial rate of increase of a translocated bilby population. Implications The present study suggests previously widespread species such as the bilby can adapt their reproductive strategy to suit local conditions. Cessation of breeding in autumn, as observed in this study, has also been observed in other bandicoot species in southern Australia.
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Arnold, GW, A. Grassia, DE Steven, and JR Weeldenburg. "Population ecology of western grey kangaroos in a remnant of wandoo woodland at Baker's Hill, southern Western Australia." Wildlife Research 18, no. 5 (1991): 561. http://dx.doi.org/10.1071/wr9910561.
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A subpopulation of western grey kangaroos (Macropus fuliginosus) living in a 305-ha remnant of wandoo woodland in the mediterranean climate of the south-west of Western Australia was studied for 10 years. Measurements and estimates were made of a wide range of population characteristics including population size, composition, reproductive rate, emigration and immigration rates and death rates. Growth rates of males and females were established and yearly differences in nutritional status assessed. The population increased over four years from 146 � 22 to a plateau of around 200 before being culled to 95. The numbers then increased slowly over another six years to 158 individuals. The population had an average of 46 adult males per 100 adult females. Subadults plus juveniles made up 10-36% of the population, depending on the year. Breeding was seasonal, being earlier in years with early autumn rain. Reproductive rate was higher, overall, in these years. Females became sexually mature at about 16 kg, their reproductive rate increased with weight until they reached 24 kg; 91% of adult females over 24 kg had pouch young annually. Mortality of young appeared to be high, and to be the factor regulating the population. On average, only 27% of young survived the first year after leaving the pouch. Emigration rate was estimated to exceed immigration by 5% per annum. The estimated mortality rate of adults was 5% per annum. The nutritional status of individuals varied from year to year; within a year, only females were heavier in early summer than in later summer. It was concluded from faecal nitrogen levels that nitrogen was not a major factor influencing nutritional status in summer. Fifteen years after this remnant woodland was established by clearing, the subpopulation of kangaroos living in it appeared to be relatively stable in numbers, and certainly was not showing the marked fluctuations known to occur in semi-arid areas of Australia.
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Pharo, Elizabeth A. "Marsupial milk: a fluid source of nutrition and immune factors for the developing pouch young." Reproduction, Fertility and Development 31, no. 7 (2019): 1252. http://dx.doi.org/10.1071/rd18197.
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Marsupials have a very different reproductive strategy to eutherians. An Australian marsupial, the tammar wallaby (Macropus eugenii) has a very short pregnancy of about 26.5 days, with a comparatively long lactation of 300–350 days. The tammar mother gives birth to an altricial, approximately 400 mg young that spends the first 200 days postpartum (p.p.) in its mother’s pouch, permanently (0–100 days p.p.; Phase 2A) and then intermittently (100–200 days p.p.; Phase 2B) attached to the teat. The beginning of Phase 3 marks the first exit from the pouch (akin to the birth of a precocious eutherian neonate) and the supplementation of milk with herbage. The marsupial mother progressively alters milk composition (proteins, fats and carbohydrates) and individual milk constituents throughout the lactation cycle to provide nutrients and immunological factors that are appropriate for the considerable physiological development and growth of her pouch young. This review explores the changes in tammar milk components that occur during the lactation cycle in conjunction with the development of the young.
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Hinds, LA, TP Fletcher, and JC Rodger. "Hormones of oestrus and ovulation and their manipulation in marsupials." Reproduction, Fertility and Development 8, no. 4 (1996): 661. http://dx.doi.org/10.1071/rd9960661.
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Oestrus and ovulation occur spontaneously in the majority of marsupials, with behavioural oestrus usually occurring 1-2 days before ovulation. The hormone changes that occur at this time have been described in the most detail for the monovular tammar wallaby Macropus eugenii. The respective roles of the Graafian follicle, corpus luteum and the pituitary in the events leading up to oestrus and ovulation in this species are also reviewed. Recently, various protocols have been developed for superovulation of marsupials, including Australian species, such as the brush-tailed possum, fat-tailed dunnart, brush-tailed bettong and tammar wallaby, and the American laboratory opossum, Monodelphis domestica. These protocols provide an opportunity for studying the regulation of ovarian activity and for the collection of larger quantities of material for the study of gamete maturation, in vitro fertilization and embryonic development.
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Wilson, Michelle E., Graeme Coulson, Geoff Shaw, and Marilyn B. Renfree. "Deslorelin implants in free-ranging female eastern grey kangaroos (Macropus giganteus): mechanism of action and contraceptive efficacy." Wildlife Research 40, no. 5 (2013): 403. http://dx.doi.org/10.1071/wr13050.
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Context Fertility control offers a non-lethal management technique for iconic yet overabundant wildlife. Slow-release hormonal implants containing deslorelin show promise for managing free-ranging populations, particularly in peri-urban reserves, but most studies have been limited to captivity. Aims We investigated the efficacy and mechanism of deslorelin implants in free-ranging female eastern grey kangaroos (Macropus giganteus) under realistic management conditions. Methods We assigned females to a deslorelin (9.4 mg, n = 53) or placebo (n = 56) group at three peri-urban sites in Victoria, Australia, and monitored reproductive success for 3 years by observing young in the pouch. We tested the plasma LH response of control and treated females to exogenous GnRH, and compared the size of ovarian follicles between the two groups. Key results Deslorelin implants reduced fertility at all three sites. No deslorelin-treated females bred in Year 1 at Anglesea and Serendip versus 42% and 44% of control females respectively. At Plenty Gorge, 60% of deslorelin-treated females bred in Year 1 versus 100% of control females. In Year 2, between 11% and 39% of the treated females bred versus between 82% and 100% of control females at all sites. The contraceptive efficacy reduced by Year 3 when between 43% and 57% of the treated females bred versus between 85% and 100% of controls. A GnRH challenge elicited higher plasma LH concentrations in control than in treated females, and unlike untreated females, treated females lacked ovarian follicles >2 mm. Conclusions Deslorelin implants reduced fertility in free-ranging female eastern grey kangaroos over three successive breeding seasons. Chronic exposure to deslorelin desensitised the pituitary gland to GnRH and suppressed follicular development, but did not inhibit the development of a blastocyst, pregnancy or lactation in at least some females that had conceived before treatment. Implications Effective population management using deslorelin implants will require females to be re-treated on multiple occasions because the contraceptive effect lasts only a portion of their reproductive life. This would be practical only at sites where kangaroos are relatively easy to capture. The timing of treatment is also important in a species that undergoes embryonic diapause, particularly at sites providing high-quality habitat.
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Moseby, K. E., and E. O'Donnell. "Reintroduction of the greater bilby, Macrotis lagotis (Reid) (Marsupialia : Thylacomyidae), to northern South Australia: survival, ecology and notes on reintroduction protocols." Wildlife Research 30, no. 1 (2003): 15. http://dx.doi.org/10.1071/wr02012.
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Nine bilbies were reintroduced to a 14-km2 reserve free of rabbits, cats and foxes in South Australia in April 2000. The survival, growth and ecology of the population were studied for 17 months after release by means of radio-tracking and trapping. Reproduction was continuous over the study period, with juveniles successfully recruited into the population. Home-range size of female bilbies averaged 0.18 km2 and was significantly smaller than home ranges of males, which averaged 3.16 km2. Wild-born subadults had smaller home ranges than adults. While male home ranges, and male and female home ranges overlapped considerably, females appeared to maintain areas discrete from other adult females. Bilbies showed a significant preference for dune habitat. As swale habitat appears too hard for burrow construction and males moved greater distances from diurnal burrows than females, males are likely to access food reserves that are under-used by females. Both males and females reused at least 30% of their burrows, and females displayed long-term site fidelity. The release was considered successful and suggests that despite historical damage from rabbits and stock, bilbies are able to successfully recolonise parts of their former range in arid South Australia once rabbits, cats and foxes are removed.
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Coulson, G., A. M. MacFarlane, S. E. Parsons, and J. Cutter. "Evolution of sexual segregation in mammalian herbivores: kangaroos as marsupial models." Australian Journal of Zoology 54, no. 3 (2006): 217. http://dx.doi.org/10.1071/zo05062.
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Sexual segregation is best known in sexually dimorphic ungulates. Many hypotheses have been proposed to explain the evolution of sexual segregation in ungulates, but all are reducible to the influence of two factors: body size and sex-specific reproductive strategy. Definitive tests of these hypotheses are lacking in ungulates because these factors are confounded, all males being somewhat larger than females. Kangaroos represent a parallel radiation of terrestrial herbivores, but their populations are composed of a spectrum of adult body sizes, ranging from small males the same size as females to large males more than twice the size. We exploited this heteromorphism to assess the independent influences of size and sex in these ungulate analogues. We conducted a preliminary study of western grey kangaroos (Macropus fuliginosus) in north-western Victoria, Australia. Adult males predominately occupied grassland habitat, whereas females occurred mostly in lakebed, woodland and shrubland. Single-sex groups occurred more often than expected during the non-mating season. The diet of large males had the highest proportion of grass, and females had the least. These initial results indicate that both size and sex influence segregation in this species, confirming the worth of kangaroos as marsupial models for research into the evolution of sexual segregation.
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Wilson, Michelle E., and Graeme Coulson. "Comparative efficacy of levonorgestrel and deslorelin contraceptive implants in free-ranging eastern grey kangaroos (Macropus giganteus)." Wildlife Research 43, no. 3 (2016): 212. http://dx.doi.org/10.1071/wr15176.
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Context Fertility control of females with levonorgestrel or deslorelin implants shows promise for managing populations of overabundant eastern grey kangaroos (Macropus giganteus). Although these implants have been tested separately in captive and free-ranging kangaroos, there has been no direct comparison under equivalent field conditions. Aims We investigated the long-term efficacy of levonorgestrel and deslorelin implants, together with the cost of treatment, ease of administration, and the welfare of the animals, in a side-by-side trial under realistic management conditions. Methods We captured 65 adult female kangaroos over 11 days at a golf course in Anglesea, Victoria, Australia. We assigned each female to one of the following three experimental groups: levonorgestrel (210 mg, n = 18), deslorelin (9.4 mg, n = 24) or procedural control (n = 23). We monitored reproductive success for 8 years, by observing young in the pouch in winter and spring. Key results Natural fertility was high; in most years, less than 20% of control females failed to reproduce. For deslorelin-treated females, the odds of failing to reproduce were four times higher than for the control group; for levonorgestrel-treated females, these odds were 74 times higher. Deslorelin was ineffective after 3 years, whereas levonorgestrel was effective for at least 5 years. Conclusions Levonorgestrel was markedly superior in efficacy, as shown by a stronger contraceptive effect persisting for longer. In other respects, the two implants were comparable, being similar in cost and ease of delivery, and equally safe. Implications Only levonorgestrel implants fulfill their promise for non-lethal, long-term control of kangaroo populations. Deslorelin implants cannot be recommended for this purpose.
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Fatima, Anam, Jessica K. Holien, Chandni Tiwari, Michael W. Parker, Raymond J. Rodgers, and Lisandra L. Martin. "Sequence comparisons of cytochrome P450 aromatases from Australian animals predict differences in enzymatic activity and/or efficiency†." Biology of Reproduction 102, no. 6 (March 17, 2020): 1261–69. http://dx.doi.org/10.1093/biolre/ioaa028.
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Abstract Aromatase (P450arom, CYP19A1) is the terminal enzyme in the synthesis of the steroid hormone family of estrogens. Not surprisingly, this enzyme has structural similarities between the limited number of species studied thus far. This study examined the structure of aromatases from four diverse Australian species including a marsupial (tammar wallaby; Macropus eugenii), monotreme (platypus; Ornithorhynchus anatinus), ratite (emu; Dromaius novaehollandiae) and lizard (bearded dragon; Pogona vitticeps). We successfully built homology models for each species, using the only crystallographically determined structure available, human aromatase. The amino acid sequences showed high amino acid sequence identity to the human aromatase: wallaby 81%, platypus 73%, emu 75% and bearded dragon at 74%. The overall structure was highly conserved among the five species, although there were non-secondary structures (loops and bends) that were variable and flexible that may result in some differences in catalytic activity. At the N-terminal regions, there were deletions and variations that suggest that functional distinctions may be found. We found that the active sites of all these proteins were identical, except for a slight variation in the emu. The electrostatic potential across the surfaces of these aromatases highlighted likely variations to the protein-protein interactions of these enzymes with both redox partner cytochrome P450 reductase and possibly homodimerization in the case of the platypus, which has been postulated for the human aromatase enzyme. Given the high natural selection pressures on reproductive strategies, the relatively high degree of conservation of aromatase sequence and structure across species suggests that there is biochemically very little scope for changes to have evolved without the loss of enzyme activity.
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Miller, Emily J., Mark D. B. Eldridge, Neil Thomas, Nicola Marlow, and Catherine A. Herbert. "The genetic mating system, male reproductive success and lack of selection on male traits in the greater bilby." Australian Journal of Zoology 58, no. 2 (2010): 113. http://dx.doi.org/10.1071/zo09092.
Full textAbstract:
The greater bilby (Macrotis lagotis) is the sole remaining species of desert bandicoot on the Australian mainland. The mating system of this species remains poorly understood, due to the bilby’s cryptic nature. We investigated the genetic mating system of the greater bilby in a five-year study of a semi-free-ranging captive population that simulated their wild environment. Morphological traits were examined to determine whether these influenced patterns of male reproductive success and whether selection was acting on them. In any given year more than half the males (59.2 ± 9.3%) failed to sire any offspring. Approximately 70% of sires fathered one offspring, and 30% two or three offspring. Since paternity was not dominated by few males, and given the species’ solitary nature, lack of territoriality and large home ranges, it is likely that males adopt a roving strategy to find receptive females. These results are consistent with an overlap promiscuous mating system. Sires and non-sires could not be distinguished by their morphological traits, and there was no evidence for strong linear or non-linear selection on male traits. These data increase our understanding of bandicoot life-history traits and will assist conservation and management efforts.
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Ballantyne, K., P. Matson, N. Noakes, V. Nicolson, and S. D. Johnston. "Reproductive physiology of the female greater bilby (Macrotis lagotis Thylacomyidae): evidence for a male-induced luteal phase." Reproduction, Fertility and Development 21, no. 2 (2009): 274. http://dx.doi.org/10.1071/rd08134.
Full textAbstract:
Endocrinology of the oestrous cycle, pregnancy and early lactation was investigated in captive Western Australian greater bilbies (Macrotis lagotis). Initially, six females were monitored for changes in urogenital cytology, plasma progestogen, pericloacal and pouch morphology in the absence of a male. This was followed by the introduction of a male and a reproductive assessment through mating, gestation and early lactation. In the absence of a male, there was no cyclical pattern of urogenital cytology, pericloacal or pouch development, and progestogen concentrations remained basal. Within 5 days of the introduction of a male, all females had a karyopycnotic index of 100%. Spermatozoa were present in the urogenital smear within 3 days of male introduction in all five females that gave birth. Five to 9 days after the introduction of a male, there was an increase in plasma progestogen concentration that remained elevated for 14–19 days. Six of the seven females gave birth approximately 3 days after reaching peak plasma progestogen concentrations. Gestation length ranged between 14 and 17 days. Plasma progestogen concentrations of the postpartum and early lactation period were lower (P < 0.0001) than during gestation, but greater (P < 0.0001) than those recorded before the introduction of a male. One female that gave birth early in the study that was examined until weaning of the pouch young showed a cyclical pattern of plasma progestogen secretion that ended at weaning. This study provides evidence that the luteal phase in the greater bilby is induced by the presence of a male. Similar to female reproductive physiology in the Peramelidae, elevated progestogen concentration in the greater bilby was extended into lactation.
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Paris, D. B. B. P., D. A. Taggart, M. C. J. Paris, P. D. Temple-Smith, and M. B. Renfree. "198 DISTRIBUTION OF SPERMATOZOA AND COPULATORY PLUG IN RELATION TO THE TIME OF MATING AND OVULATION IN THE FEMALE TAMMAR WALLABY (MACROPUS EUGENII)." Reproduction, Fertility and Development 17, no. 2 (2005): 249. http://dx.doi.org/10.1071/rdv17n2ab198.
Full textAbstract:
In the monovular macropodid marsupial, the tammar wallaby (Macropus eugenii), the cervices are the primary selective barrier to spermatozoa, resulting in differential transport to the non-gravid uterus where a sperm reservoir is established (Tyndale-Biscoe CH and Rodger JC 1978 J. Reprod. Fertil. 52, 37–43). However, due to limited sample size, the dynamics of sperm transport could not be thoroughly examined. In this study, the distribution of spermatozoa, the size of the copulatory plug in the reproductive tract at various times after mating, and the timing of ovulation were characterized in 28 naturally mated female tammars. After the first postpartum (p.p.) mating, adult females were isolated and their reproductive tracts dissected at 0.5, 6, 18, 36, and 40 h post-coitum (p.c.). Each tract was ligated into 13 major anatomical sections, and spermatozoa and eggs were recovered by flushing. Mating occurred 21.7 ± 2.5 h p.p. (mean ± SEM; n = 20) in these animals that were checked frequently and lasted 7.8 ± 0.7 min (n = 15). Within 0.5 h after a single mating (n = 5) the tract contained 2.6 ± 1.0 × 107 spermatozoa and 21.6 ± 8.8 g of copulatory plug, 96 and 70% of which was lost within 6 h p.c., respectively. Spermatozoa reached the uterus, isthmus, and ampulla of the oviduct ipsilateral to the developing follicle within 0.5, 6, and 18 h p.c. respectively, and a uterine population of 2.6 ± 1.2 × 104 spermatozoa (n = 24) was maintained for over 40 h (ANOVA, P > 0.05). Sperm numbers were reduced at the cervix (up to 57-fold) and utero-tubule junction (8-fold), and only 1 in ∼7600 ejaculated spermatozoa (3.4 ± 0.9 × 103; n = 14) reached the oviduct on the side of ovulation. Although sperm numbers were reduced in the gravid uterus (n = 24), differential transport of spermatozoa was not observed (ANOVA, P > 0.05). Ovulation and recovery of sperm-covered eggs from the isthmus of the oviduct occurred 36–41 h p.c. (49–72 h p.p.) (n = 8). Like many eutherian mammals, but in contrast to polyovular dasyurid and didelphid marsupials, the tammar ejaculates large numbers of spermatozoa, but transport is relatively inefficient and sperm storage in the tract before ovulation is limited. Research was supported by the Australian Research Council (grant No. C09930004) and the University of Melbourne.
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Marks, Clive A. "Bait-delivered cabergoline for the reproductive control of the red fox (Vulpes vulpes): estimating mammalian non-target risk in south-eastern Australia." Reproduction, Fertility and Development 13, no. 8 (2001): 499. http://dx.doi.org/10.1071/rd01076.
Full textAbstract:
Cabergoline (CAB) is a potent dopamine agonist and an inhibitor of prolactin (PRL). In red foxes (Vulpes vulpes), a single oral dose of 100 g kg–1 CAB can cause abortions and postnatal cub mortality from at least Day 21 of the 52-day pregnancy. The abortifacient activity of CAB is owing to the suppression of PRL, which is essential for luteotrophic support in some eutherian species. Postnatal cub mortality probably results from a reduction in the development of the mammary ductile system, which is also partially dependant on PRL during pregnancy. This paper investigates the potential risks faced by non-target mammalian species that may consume CAB baits intended for fox control. Baiting with CAB is proposed from 1 August until 1 October each year, to correspond with the time that most vixens are pregnant in south-eastern Australia. Thirty-four endemic mammals in south-eastern Australia (9 eutherians and 25 marsupials) are considered to be potentially bait-consuming (PBC) species. The percentage overlap of pregnancy and birth periods for each PBC species was compared with the duration of the proposed CAB baiting period. Only Antechinus (3 species) and Sminthopsis leucopushave greater than 40% overlap, whereas overlap in endemic rodents ranges from 0% to 22%. Overall, most PBC rodent populations appear to face little risk from CAB baiting, as their period of pregnancy does not overlap significantly with the proposed CAB baiting period. The Antechinus species, Phascogale tapoatafa and Dasyurus maculatus are the only PBC mammals that are seasonally mono-oestrous and are thus probably more susceptible to disruption of breeding compared with polyoestrous species that may breed many times a year. At a baiting density of 8 baits km–2, theoretical bait availability for small dasyurids, rodents and peramelids is low. This suggests a low potential for affecting these populations if CAB was indiscriminate in affecting reproductive success in all mammal groups. Presently, studies in a limited range of marsupials suggest that, unlike eutherians, the marsupial corpus luteum is independent of pituitary control and thus suppression of PRL is not likely to cause abortions in marsupials. As yet, CAB has not been shown to be orally active in any PBC species other than rodents and carnivores. Oral doses of CAB given post partum have not been found to affect lactation in Sminthopsis crassicaudata,Trichosurus vulpecula, Macropus eugenii andSetonix brachyurus. Further studies are required in order to assess the potential for high doses of oral CAB to affect pre-partum mammary development and early lactation post partum, especially in peramelids and larger dasyurids. Highly target-specific baiting techniques, may eliminate most PBC species from being exposed to CAB and these are briefly discussed.
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Kingsley, Lisa, Anne Goldizen, and Diana O. Fisher. "Establishment of an Endangered species on a private nature refuge: what can we learn from reintroductions of the bridled nailtail wallaby Onychogalea fraenata?" Oryx 46, no. 2 (April 2012): 240–48. http://dx.doi.org/10.1017/s0030605311000652.
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AbstractTranslocation and reintroduction are used to reduce extinction risk associated with a small population and range size in threatened mammal species. We evaluated the outcome of a reintroduction of the bridled nailtail wallaby Onychogalea fraenata to Avocet Nature Refuge, a private refuge in central Queensland, Australia. This macropod was also reintroduced to Idalia National Park in western Queensland in 1996 and occurs in one natural population in central Queensland. We estimated population growth, adult and juvenile survival, and distribution changes since the last release of O. fraenata to Avocet in 2005, and evaluated female reproductive success and health. Although animals were in good condition, population size was a tenth of that of the 1996 Idalia reintroduction reported after 3 years and, unlike at Idalia, juvenile survival at Avocet was low. The likely causes are consistent with predictors of translocation and reintroduction failures in mammals. These are predation, the small number of individuals in each release, the likely suboptimal health status of reintroduced individuals, drought, and possibly lack of dispersal from the small area of preferred habitat. The lessons of this reintroduction are that future attempts are likely to have the best chance of success if they occur in non-drought years, at sites with large, non-fragmented areas of brigalow forest, involve the release of large groups of animals together, and are accompanied by intensive, long-term baiting to control introduced predators.
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Ladd, P. G., X. Zhao, and N. J. Enright. "Fire regime and climate determine spatial variation in level of serotiny and population structure in a fire-killed conifer." Plant Ecology, May 26, 2022. http://dx.doi.org/10.1007/s11258-022-01243-8.
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AbstractFire-killed serotinous trees are often dominant species in fire-prone regions with contrasting wet and dry seasons. We studied a serotinous fire-killed conifer (Callitris preissii, Cupressaceae) to identify the influence of fire regime and climate on geographic variation in level of serotiny, recruitment and population structure. We measured population size distributions, seedling recruitment and level of serotiny for sample stands across a climatic gradient from mesic coastal (including two islands) to semi-arid inland sites in SW Australia. Trees on islands were mostly non-serotinous and were only weakly serotinous on the adjacent mainland in the higher rainfall West coast region. In the semi-arid Goldfields and South inland, and the higher rainfall South coast region, trees were more strongly serotinous with up to six cohorts of closed cones retained on trees. Level of serotiny was stronger at the drier end of the climatic gradient where severe to extreme fire danger weather occurs most frequently, and where vegetation type (e.g., shrublands) supports frequent crown-type, stand-replacing fires. Recruitment was most abundant post-fire in all regions, but seedlings also established inter-fire where there was regular seed fall due to low level of serotiny or spontaneous release of seeds from old cones on trees with a high cone load. Population structures for mainland stands shifted from approximately reverse-J (indicating continuous recruitment) in mesic regions to mainly unimodal (establishment mostly after fire) in drier, inland regions, although some long-unburned inland stands showed occasional inter-fire recruitment, likely linked to high rainfall years. Unimodal population structures characterized islands, where previous studies have identified herbivory on seedlings by refugial populations of native macropods as a limiting factor on inter-fire establishment. Understanding landscape context, response to disturbance, biotic interactions and reproductive traits of dominant species is essential in conservation planning in a rapidly changing global environment.