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Bandicoots and bilbies (order Peramelemorphia) represent the principal group of omnivorous marsupials from a range of habitats across Australia and New Guinea. Bandicoots and bilbies most commonly use quadrupedal, asymmetrical half-bounding or bounding gaits and present an unusual combination of hind limb morphological features, including an ossified patella, a modified tibiofibular joint, and syndactylous morphology of the pes. We performed comparative dissections of the hind limb of the southern brown bandicoot (Isoodon obesulus fusciventer) (n = 13) and greater bilby (Macrotis lagotis) (n = 4), providing detailed descriptions of the muscular anatomy. These species displayed significant modification of the hind limb muscular anatomy and associated connective tissues, including emphasis on multiarticular muscles, such as the hamstrings, and extreme development of fascial structures. These patterns were more extreme in I. obesulus than in M. lagotis. Differences between the hind limb anatomy of I. obesulus and M. lagotis reflect the different ecological and environmental pressures on their locomotion and digging behaviours.
Parasite infection is increasingly recognised as a factor shaping the population dynamics, life history and behaviour of hosts. However, before the impacts of parasites on wildlife hosts can be investigated, seasonal patterns in host exposure to parasitic agents must be determined. We examined infection patterns at three sites in Victoria, and combined field experiments and observations to construct a generalised life cycle of the helminth community in eastern grey kangaroos (Macropus giganteus). Kangaroo populations in Victoria had very similar helminth communities, with 20–25 species detected at each site. Despite examining relatively few hosts in this study, at least 87% of all gastrointestinal helminths were recovered according to bootstrap estimates. The prepatent period of infection in eastern grey kangaroo nematodes was at least 3 months, and faecal egg output showed a distinct seasonal pattern, with a peak in egg counts from October through to January each year. Data from one site indicated that faecal egg counts were influenced predominantly by the abundance of a single nematode species (Pharyngostrongylus kappa), despite adults accounting for only 7% of the total nematode burden. This highlights the problems associated with using faecal egg counts to estimate nematode burdens in this host. Contamination of pasture plots showed that nematode eggs take ∼14 days to larvate once deposited, and that autumn rains likely triggered emergence from faecal pellets. The abundance of infective larvae in the environment therefore appears to be closely tied to environmental conditions, with a peak in infection of hosts in the winter months.
At least three species of New Guinean tree frogs (Litoria) are sexually dimorphic in that the snout of the male is projected into a proboscis, which is poorly developed or absent in females. In this paper the anatomy of the proboscis in the male Litoria pronimia is described and compared with the structure of the smaller proboscis of Litoria havina, described previously. We note that it appears to be erectile, speculate on the possible method of erection and suggest directions for future research.
Captive breeding of the short-beaked echidna (Tachyglossus aculeatus) has proven a difficult challenge; as recently as 2009, there were fewer than 10 echidnas born in captivity. We present observations of captive reproductive behaviour following video surveillance and measurements of body temperature collected from six captive female echidnas over a six-year period. In the first series of observations (2009–10) we examined the efficacy of artificial burrow boxes as possible aids for reproductive success. Females with access to burrow boxes had significantly higher levels of reproductive activity (P = 0.001), there was coincidental improvement in the production of eggs or pouch young (two eggs, one unhatched and one offspring). During 2009–10, a range of reproductive behaviours (courtship, copulation and postcopulation) were documented and analysed, as were new observations of oestrous cycle activity. Female body temperature was characteristically stable during egg incubation during this study and has the potential to be used as a tool for the assessment of reproductive status. Following initial observations, burrow boxes and infrared lamps were implemented as standard husbandry in our echidna breeding facility and the effects on reproductive success were monitored, albeit less intensively, for a further four years (2011–14). Although no direct causal effect could be ascribed, the use of burrow boxes and heat lamps coincided with a total of 13 young being born to four females in the last four years (2011–14). These female echidnas were found to be receptive at intervals throughout the breeding season, both before and after presumed incubation phases, suggesting that captive animals exhibit polyoestry. In 2012 and 2014, the same female showed evidence of producing two young from one breeding event.
Pentapedal locomotion is the use of the tail as a fifth leg during the slow gait of kangaroos. Although previous studies have informally noted that some smaller species of macropodines do not engage in pentapedal locomotion, a systematic comparative analysis of tail use during slow gait across a wide range of species in this group has not been done. Analysis of relative movement of the pelvis, tail, and joint angles of the lower limbs during slow gait, using 2D landmark techniques on video recordings, was carried out on 16 species of Macropodinae. We also compared the relative lengthening of the tibia using crural index (CI) to test whether hindlimb morphology was associated with pentapedal locomotion. Pentapedal locomotion was characterised by three features: the presence of the ‘tail repositioning phase’, the constant height of the pelvis and the stationary placement of the distal tail on the ground during the hindlimb swing phase. The mean CI of pentapedal species was significantly greater than that of non-pentapedal species (1.71 versus 1.36; P < 0.001). This lends support to the hypothesis that the use of pentapedal locomotion is associated with the relative lengthening of the hindlimb, which in turn is associated with body size and habitat preference within the Macropodinae.
We describe the isolation and development of 14 polymorphic microsatellite loci for the critically endangered plant-louse Trioza barrettae (Hemiptera : Triozidae). The loci were tested in 25 individuals from a single population situated in the south-west of Western Australia. No evidence of linkage disequilibrium was detected between any pair of loci. However, eight loci showed significant departures from Hardy–Weinberg expectations. The number of alleles per locus ranged from 2 to 27.
In eastern Australia, small ephemeral soft-sediment pools are common on sheltered sand- and mudflats, and are occupied by the juveniles of fishes of economic and ecological importance. To address the question of whether these pools are merely refugia or whether they constitute a hitherto unrecognised nursery feeding habitat for small obligate meiobenthivorous fishes, we surveyed the meiofaunal communities of ephemeral soft-sediment pools within three intertidal shores of Moreton Bay, Australia. Highest mean meiofaunal abundances occurred at Godwin Beach and differed significantly throughout the year. Nematodes and copepods were the most abundant taxa while all other taxa contributed to <10% of the total meiofaunal abundance. Pool characteristics (i.e. volume and surface area) did not correlate with the abundance of benthic faunal assemblages. Overall, ephemeral soft-sediment pools of Moreton Bay support meiofaunal communities that are likely to provide prey resources for juvenile and small fish that use them as nurseries at low tide.
In the wake of the global decline in amphibians there is a need for long-term population monitoring. Previous research suggested that the endangered Fleay’s barred frog (Mixophyes fleayi) had recovered after a severe decline. We aimed to determine whether this recovery has been sustained and to test an example of a monitoring program that could be employed at intervals of five or more years to assess long-term population stability. We conducted capture–mark–recapture five years after the last detailed census at Brindle Creek in Border Ranges National Park, New South Wales. Frogs were captured along a 200 m creek transect between September 2013 and February 2014. We used program Mark to estimate demographic parameters of adult male frogs using two modelling approaches: robust design (RD) and the POPAN formulation of the Jolly–Seber model. Abundance was estimated at 38.2 ± 0.5 (s.e.) (RD) and 46.0 ± 2.7 (POPAN). Abundance in 2008 was estimated at 53.2 ± 10.0 (POPAN) male frogs. Estimates of apparent monthly survival over our five-month-long study were very high (RD: 1.0 ± 0.0; POPAN: 1.0 ± 0.02). Recapture estimates were also high (RD: 0.40 ± 0.07 to 0.72 ± 0.05 per session; POPAN: 0.84 ± 0.05 per month). These data suggest that the Brindle Creek population has remained relatively stable over a period of ∼10 years.
Control of maturation in all-female salmonid stock can be achieved by manipulating photoperiod. This initially requires an assessment of the annual reproductive cycle under ambient photoperiod. This study therefore describes the seasonal variations in ovarian development and plasma profiles of oestradiol-17β and testosterone during the second year of a population of female brook trout. It was found that fish recruited for maturation following the summer solstice in December. Shortening of photoperiod likely stimulated the brain–pituitary–gonadal axis for vigorous progress of ovarian development, as indicated by increasing levels of oestradiol-17β and gonadosomatic index values. The highest gonadosomatic index value (18.26 ± 1.1%) was observed in June. During July, eggs were released from mature females by manual stripping. Total fecundity was observed as 4266 ± 341 oocytes per mature fish. Profiles of sex steroids observed here were found to be finely entrained within the succession of seasonal photoperiod. This finding indicates that maturation suppression by photoperiod manipulation should be instigated before initiation of oocyte recruitment that commenced during December.
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