An alternative method for predicting body mass: the case of the Pleistocene marsupial lion

Accurate estimates of body mass in fossil taxa are fundamental to paleobiological reconstruction. Predictive equations derived from correlation with craniodental and body mass data in extant taxa are the most commonly used, but they can be unreliable for species whose morphology departs widely from that of living relatives. Estimates based on proximal limb-bone circumference data are more accurate but are inapplicable where postcranial remains are unknown. In this study we assess the efficacy of predicting body mass in Australian fossil marsupials by using an alternative correlate, endocranial volume. Body mass estimates for a species with highly unusual craniodental anatomy, the Pleistocene marsupial lion (Thylacoleo carnifex), fall within the range determined on the basis of proximal limb-bone circumference data, whereas estimates based on dental data are highly dubious. For all marsupial taxa considered, allometric relationships have small confidence intervals, and percent prediction errors are comparable to those of the best predictors using craniodental data. Although application is limited in some respects, this method may provide a useful means of estimating body mass for species with atypical craniodental or postcranial morphologies and taxa unrepresented by postcranial remains. A trend toward increased encephalization may constrain the method's predictive power with respect to many, but not all, placental clades.

Limited effect of anthropogenic habitat fragmentation on molecular diversity in a rain forest skink, Gnypetoscincus queenslandiae

To examine the effects of recent habitat fragmentation, we assayed genetic diversity in a rain forest endemic lizard, the prickly forest skink (Gnypetoscincus queenslandiae), from seven forest fragments and five sites in continuous forest on the Atherton tableland of northeastern Queensland, Australia. The rain forest in this region was fragmented by logging and clearing for dairy farms in the early 1900s and most forest fragments studied have been isolated for 50-80 years or nine to 12 skink generations. We genotyped 411 individuals at nine microsatellite DNA loci and found fewer alleles per locus in prickly forest skinks from small rain forest fragments and a lower ratio of allele number to allele size range in forest fragments than in continuous forest, indicative of a decrease in effective population size. In contrast, and as expected for populations with small neighbourhood sizes, neither heterozygosity nor variance in allele size differed between fragments and sites in continuous forests. Considering measures of among population differentiation, there was no increase in F-ST among fragments and a significant isolation by distance pattern was identified across all 12 sites. However, the relationship between genetic (F-ST) and geographical distance was significantly stronger for continuous forest sites than for fragments, consistent with disruption of gene flow among the latter. The observed changes in genetic diversity within and among populations are small, but in the direction predicted by the theory of genetic erosion in recently fragmented populations. The results also illustrate the inherent difficulty in detecting genetic consequences of recent habitat fragmentation, even in genetically variable species, and especially when effective population size and dispersal rates are low.

Morphometric and cladistic analyses of the phylogeny of Macropodinium (Ciliophora : Litostomatea : Macropodiniidae)

Phylogenetic studies of the genus Macropodinium were conducted using two methods; phenetics and cladistics. The phenetic study of morphometrics suggested that the genus could be divided into 3 groups attributable mostly to cell size and shape. The cladistic study also split the genus into 3 groups related to cell size but groups were further distinguished by patterns of ornamentation. Reconciliation of both approaches revealed considerable congruence, however, it also suggested the existence of convergences in the phenetic study and a lack of resolution in the cladistic study. The morphological diversity of Macropodinium is probably due to evolutionary trends such as increasing body size, allometry and polymerisation of structures. None of these trends, however, was uniformly directional and differential effects were observed in different regions of the phylogenetic tree. Comparison of the phylogeny of Macropodinium to a consensus phylogeny of the macropodids revealed limited incongruence between the 2 trees. The ciliate groups could be related to 2 host groups; the wallaby genera and the kangaroo and wallaroo subgenera. The association with these host groups may be the result of phyletic codescent, ecological resource tracking or a combination of both. Further studies of both host and ciliate phylogeny are necessary to resolve these effects.

Locomotion and gaits of the northern brown bandicoot, Isoodon macrourus (Marsupalia: Peramelidae)

Gait repertoires of the northern brown bandicoot, Isoodon macrourus, were studied over a wide range of locomotor speeds. At low relative speeds, bandicoots used symmetrical gaits that included pacing, trotting, and lateral sequence strides. Forefoot contact duration was generally shorter than hind foot contact duration at all speeds. At moderate relative speeds bandicoots used half-bounding gaits with either no period of suspension or with a short gathered suspension. At high speeds the predominant gait had both a short extended and a short gathered suspension, although some strides comprised only an extended suspension. Increases in speed were accompanied by increases in spinal extension, presumably leading to the extended suspensions. On a stationary treadmill individuals occasionally used a bipedal gait. Maximum half-bounding speeds appear to be relatively low in this species.

The importance of mating system in translocation programs: reproductive success of released male bridled nailtail wallabies

Translocation is an important tool for the conservation of species that have suffered severe range reductions. The success of a translocation should be measured not only by the survival of released animals, but by the reproductive output of individuals and hence the establishment of a self-sustaining population. The bridled nailtail wallaby is an endangered Australian macropod that suffered an extensive range contraction to a single remaining wild population. A translocated population was established and subsequently monitored over a four year period. The aim of this study was to measure the reproductive success of released males using genetic tools and to determine the factors that predicted reproductive success. Captive-bred and wild-caught animals were released and we found significant variation in male reproductive success among release groups. Variation in reproductive success was best explained by individual male weight, survival and release location rather than origin. Only 26% of candidate males were observed to sire an offspring during the study. The bridled nailtail wallaby is a sexually dimorphic, polygynous macropod and reproductive success is skewed toward large males. Males over 5800 g were six times more likely to sire an offspring than males below this weight. This study highlights the importance of considering mating system when choosing animals for translocation. Translocation programs for polygynous species should release a greater proportion of females, and only release males of high breeding potential. By maximizing the reproductive output of released animals, conservation managers will reduce the costs of translocation and increase the chance of successfully establishing a self-sustaining population. (C) 2004 Elsevier Ltd. All rights reserved.

Gastrointestinal transit in the common brushtail possum measured by gamma scintigraphy

This paper reports an example of the application of pharmaceutical technology to wildlife management, specifically the design of an oral delivery system for the common brushtail possum in New Zealand. Designing an oral delivery system requires a knowledge of the time taken for particulates to reach target sites within the gastrointestinal tract (GIT). The transit time for fluid and indigestible particles of two different size ranges was determined in the common brushtail possum (Trichosurus vulpecula). Technetium-labelled (Tc-99m) anion exchange resin particles (75-125 or 500-700 mu m diameter) or solution (Tc-99m-labelled diethylenetriamine pentaacetic acid, Tc-99m-DTPA) was administered orally. At predetermined times after dosing (3, 6, 12, 24 or 32 h), the distribution of radioactivity throughout excised gastrointestinal tracts was determined by gamma scintigraphy. The transit profile was similar for the three formulations investigated. Unlike other closely related hindgut fermenting marsupials, there was no evidence to support the presence of a colonic separating mechanism in the common brushtail possum. Gastrointestinal transit was independent of body mass, gender and time of day that the dose is given. To target the hindgut for oral delivery of protein and peptide biocontrol agents, the formulation Would need to protect the bioactive for approximately 12 h prior to release. (c) 2005 Elsevier B.V. All rights reserved.

Decreased relatedness between male prickly forest skinks (Gnypetoscincus queenslandiae) in habitat fragments

In species with low levels of dispersal the chance of closely related individuals breeding may be a potential problem; sex-biased dispersal is a mechanism that may decrease the possibility of cosanguineous mating. Fragmentation of the habitat in which a species lives may affect mechanisms such as sex-biased dispersal, which may in turn exacerbate more direct effects of fragmentation such as decreasing population size that may lead to inbreeding depression. Relatedness statistics calculated using microsatellite DNA data showed that rainforest fragmentation has had an effect on the patterns of dispersal in the prickly forest skink (Gnypetoscincus queenslandiae), a rainforest endemic of the Wet Tropics of north eastern Australia. A lower level of relatedness was found in fragments compared to continuous forest sites due to a significantly lower level of pairwise relatedness between males in rainforest fragments. The pattern of genetic relatedness between sexes indicates the presence of male-biased dispersal in this species, with a stronger pattern detected in populations in rainforest fragments. Male prickly forest skinks may have to move further in fragmented habitat in order to find mates or suitable habitat logs.

The prion protein gene: Identifying regulatory signals using marsupial sequence

The function of the prion protein gene (PRNP) and its normal product PrPC is elusive. We used comparative genomics as a strategy to understand the normal function of PRNP. As the reliability of comparisons increases with the number of species and increased evolutionary distance, we isolated and sequenced a 66.5 kb BAC containing the PRNP gene from a distantly related mammal, the model Australian marsupial Macropus eugenii (tammar wallaby). Marsupials are separated from eutherians such as human and mouse by roughly 180 million years of independent evolution. We found that tammar PRNP, like human PRNP, has two exons. Prion proteins encoded by the tammar wallaby and a distantly related marsupial, Monodelphis domestica (Brazilian opossum) PRNP contain proximal PrP repeats with a distinct, marsupial-specific composition and a variable number. Comparisons of tammar wallaby PRNP with PRNPs from human, mouse, bovine and ovine allowed us to identify non-coding gene regions conserved across the marsupial-eutherian evolutionary distance, which are candidates for regulatory regions. In the PRNP 3' UTR we found a conserved signal for nuclear-specific polyadenylation and the putative cytoplasmic polyadenylation element (CPE), indicating that post-transcriptional control of PRNP mRNA activity is important. Phylogenetic footprinting revealed conserved potential binding sites for the MZF-1 transcription factor in both upstream promoter and intron/intron 1, and for the MEF2, MyTI, Oct-1 and NFAT transcription factors in the intron(s). The presence of a conserved NFAT-binding site and CPE indicates involvement of PrPC in signal transduction and synaptic plasticity. (c) 2004 Elsevier B.V. All rights reserved.

Papillomavirus in healthy skin of Australian animals

Papillomaviruses are a group of ubiquitous viruses that are often found in normal skin of humans, as well as a range of different vertebrates. In this study, swab samples collected from the healthy skin of 225 Australian animals from 54 species were analysed for the presence of papillomavirus DNA with the general skin papillomavirus primer pair FAP59/FAP64. A total of five putative and potential new animal papillomavirus types were identified from three different animal species. The papillomaviruses were detected in one monotreme and two marsupial species: three from koalas, and one each from an Eastern grey kangaroo and an echidna. The papillomavirus prevalence in the three species was 14% (10/72) in koalas, 20% (1/5) in echidnas and 4% (1/23) in Eastern grey kangaroos. Phylogenetic analysis was performed on the putative koala papillomavirus type that could be cloned and it appears in the phylogenetic tree as a novel putative papillomavirus; genus. The data extend the range of species infected by papillomaviruses to the most primitive mammals: the monotremes and the marsupials.

An investigation into the similarities and differences governing the cryopreservation success of koala (Phascolarctos cinereus: goldfuss) and common wombat (Vombatus ursinus: shaw) spermatozoa

The aim of this study was to determine the relative cryopreservation success of koala and wombat spermatozoa and to investigate reasons for their respective post-thaw survival by examining the sperm's response to a range of osmotic media and determining the presence and distribution of F-actin. An hypothesis was proposed that F-actin may be imparting a degree of structural inflexibility to the koala sperm plasma membrane; hence, exposure of spermatozoa to cytochalasin D (5 mu M), a F-actin depolymerisation agent, should result in increased plasticisation of the membrane and greater tolerance of cell volume changes that typically occur during cryopreservation. In experiment 1, koala (n = 4) and wombat (n = 4) spermatozoa packaged in 0.25 mL straws were cryopreserved using two freezing rates (fast-3 cm above liquid N2 interface; slow-6 degrees C/min in a freezing chamber) and two glycerol concentrations (8 and 14% v/v) in a tris-citrate glucose buffer with 15% (v/v) egg yolk. Wombat spermatozoa showed better (P < 0.01) post-thaw survival (% motile, % intact plasma membranes, % decondensed sperm heads) than koala spermatozoa. When exposed to media of varying osmolality, koala spermatozoa were less tolerant (% intact plasma membrane) of hyper-osmotic conditions (920 and 1410mOsmol/kg) than wombat spermatozoa. F-actin was localised using a monoclonal antibody but only found in the wombat sperm head. When koala and wombat spermatozoa were exposed to media of varying osmolality, cytochalasin D had no beneficial effect on sperm survival (% intact plasma membranes). This study has demonstrated that wombat spermatozoa are highly tolerant of cryopreservation when compared to koala sperm but that spermatozoa from both species show greatest post-thaw survival when frozen slowly in 14% glycerol. Koala sperm are also particularly susceptible to hyper-osmotic environments but lack of detectable F-actin in the koala spermatozoan suggests that poor cryopreservation success in this species is unlikely to be associated with F-actin induced plasma membrane inflexibility. (c) 2006 Elsevier Inc. All rights reserved.

Cloning and sequence analysis of pituitary prolactin cDNA from the northern brown bandicoot (Isoodon macrourus)

The nuclectide sequence for pituitary prolactin cDNA from the marsupial bandicoot (Isoodon macrourus) was determined by reverse transcription-polymerase chain reaction and 5'/3' rapid amplification of cDNA ends. The deduced amino acid sequence showed high sequence identity with brushtail possum prolactin (95%) and all of the expected structural features of a quadruped prolactin. A prolactin gene tree was constructed and rates of evolution calculated for bandicoot, possum, opossum and several mammalian and non-mammalian prolactins. Bootstrap analysis provided strong support for marsupials as a sister group with eutherian mammals and weak support for opossum and bandicoot as an independent grouping from the brushtail possum. The rates of molecular evolution for marsupial prolactins were comparable to the slow rate seen in the majority of quadruped prolactins that have been sequenced. (c) 2005 Elsevier Inc. All rights reserved.

Male reproductive tactics and female choice in the solitary, promiscuous bridled nailtail wallaby (Onychogalea fraenata)

Several behavioral studies of large, gregarious, and sexually dimorphic macropods have shown that males form dominance hierarchies and large males have the highest reproductive success. The bridled nailtail wallaby (Onychogalea fraenata) is a smaller and strongly sexually dimorphic macropod, but is also highly solitary and males do not form dominance hierarchies that are maintained temporally or spatially. Genetic studies of paternity have shown that large males are the most reproductively successful and only one-quarter of males sire offspring at any one time. The aim of this study was to investigate the tactics that males adopt to secure access to females at the time of estrus and to investigate whether females can influence which males have access to them. This study was conducted using 2 wild, free-ranging populations of bridled nailtail wallabies. Females in estrus were located and observed. and the total number of males present, the relative weight rank of each mate, and interactions between individuals were recorded. Females showed a preference for large males and incited male-male competition when the group of males present was large. Unlike other dimorphic macropods, fights among males were rare and were restricted to males of similar size. Large males gained access to females by guarding and following them closely and threatening other males who attempted to gain access. Smaller males spent less time with females, suggesting that small males may leave multimale groups in an attempt to locate unguarded females. Given the solitary nature of this species and the lack of a stable dominance hierarchy to influence male reproductive success. mate searching and mate guarding may be important male reproductive tactics in this species.

Reduced genetic diversity and significant genetic differentiation after translocation: Comparison of the remnant and translocated populations of bridled nailtail wallabies (Onychogalea fraenata)

Loss of genetic diversity and increased population differentiation from source populations are common problems associated with translocation programmes established from captive-bred stock or a small number of founders. The bridled nailtail wallaby is one of the most endangered macropods in Australia, having been reduced to a single remnant population in the last 100 years. A translocated population of bridled nailtail wallabies was established using animals sourced directly from the remnant population (wild-released) as well as the progeny of animals collected for a captive breeding programme (captive-bred). The aims of this study were to compare genetic diversity among released animals and their wild-born progeny to genetic diversity observed in the remnant population, and to monitor changes in genetic diversity over time as more animals were released into the population. Heterozygosity did not differ between the translocated and remnant population; however, allelic diversity was significantly reduced across all released animals and their wild-born progeny. Animals bred in captivity and their wild-born progeny were also significantly differentiated from the source population after just four generations. Wild-released animals, however, were representative of the source population and several alleles were unique to this group. Both heterozygosity and allelic diversity among translocated animals decreased over time with the additional release of captive-bred animals, as no new genetic stock was added to the population. Captive breeding programmes can provide large numbers of animals for release, but this study highlights the importance of sourcing animals directly from remnant populations in order to maintain genetic diversity and minimise genetic drift.

Comparison of growth and development of the red-tailed phascogale (Phascogale calura) in three captive colonies

The red-tailed phascogale ( Phascogale calura) is an endangered dasyurid species that has recently been brought into captivity in an effort to increase numbers before release back into the wild. As part of investigations into the reproductive biology of the species, information on the growth and development of young was collected throughout lactation from litters raised in three separate colonies. Growth curves for aging young throughout lactation and a timetable of developmental changes were constructed. While two colonies, with fourth- and fifth-generation captive animals, showed no significant difference in growth, animals from a third colony that had been wild caught before breeding displayed a slower rate of growth from 34 days of age. The pattern of development resembled that of other dasyurids, with young left in the nest from 44 days of age, fully furred by 78 days and weaned between 90 and 110 days. Captive phascogales invest heavily in their young, with litters weighing 380 +/- 67% of maternal bodyweight at weaning.

The importance of forest area and configuration relative to local habitat factors for conserving forest mammals: A case study of koalas in Queensland, Australia

The loss and fragmentation of forest habitats by human land use are recognised as important factors influencing the decline of forest-dependent fauna. Mammal species that are dependent upon forest habitats are particularly sensitive to habitat loss and fragmentation because they have highly specific habitat requirements, and in many cases have limited ability to move through and utilise the land use matrix. We addressed this problem using a case study of the koala (Phascolarctos cinereus) surveyed in a fragmented rural-urban landscape in southeast Queensland, Australia. We applied a logistic modelling and hierarchical partitioning analysis to determine the importance of forest area and its configuration relative to site (local) and patch-level habitat variables. After taking into account spatial auto-correlation and the year of survey, we found koala occurrence increased with the area of all forest habitats, habitat patch size and the proportion of primary Eucalyptus tree species; and decreased with mean nearest neighbour distance between forest patches, the density of forest patches, and the density of sealed roads. The difference between the effect of habitat area and configuration was not as strong as theory predicts, with the configuration of remnant forest becoming increasingly important as the area of forest habitat declines. We conclude that the area of forest, its configuration across the landscape, as well as the land use matrix, are important determinants of koala occurrence, and that habitat configuration should not be overlooked in the conservation of forest-dependent mammals, such as the koala. We highlight the implications of these findings for koala conservation. (c) 2006 Elsevier Ltd. All rights reserved.