Hidden social complexity behind vocal and acoustic communication in non-avian reptiles.

Social interactions are inevitable in the lives of most animals, since most essential behaviours require interaction with conspecifics, such as mating and competing for resources. Non-avian reptiles are typically viewed as solitary animals that predominantly use their vision and olfaction to communicate with conspecifics. Nevertheless, in recent years, evidence is mounting that some reptiles can produce sounds and have the potential for acoustic communication. Reptiles that can produce sound have an additional communicative channel (in addition to visual/olfactory channels), which could suggest they have a higher communicative complexity, the evolution of which is assumed to be driven by the need of social interactions. Thus, acoustic reptiles may provide an opportunity to unveil the true social complexity of reptiles that are usually thought of as solitary. This review aims to reveal the hidden social interactions behind the use of sounds in non-avian reptiles. Our review suggests that the potential of vocal and acoustic communication and the complexity of social interactions may be underestimated in non-avian reptiles, and that acoustic reptiles may provide a great opportunity to uncover the coevolution between sociality and communication in non-avian reptiles. This article is part of the theme issue 'The power of sound: unravelling how acoustic communication shapes group dynamics'.

Building a comprehensive phylogenetic framework in disease ecology.

Disease spillover can have dramatic consequences in multispecies systems, potentially leading to the emergence of zoonoses. To better understand disease emergence patterns, an approach encompassing species relatedness metrics is needed. We show that integrating phylogenetic information in disease ecology is still lagging, and we highlight potential solutions to solve this problem.

When one tail isn't enough: abnormal caudal regeneration in lepidosaurs and its potential ecological impacts.

Abnormal caudal regeneration, the production of additional tails through regeneration events, occurs in lepidosaurs as a result of incomplete autotomy or sufficient caudal wound. Despite being widely known to occur, documented events generally are limited to opportunistic single observations - hindering the understanding of the ecological importance of caudal regeneration. Here we compiled and reviewed a robust global database of both peer-reviewed and non-peer reviewed records of abnormal regeneration events in lepidosaurs published over the last 400 years. Using this database, we qualitatively and quantitatively assessed the occurrence and characteristics of abnormal tail regeneration among individuals, among species, and among populations. We identified 425 observations from 366 records pertaining to 175 species of lepidosaurs across 22 families from 63 different countries. At an individual level, regenerations ranged from bifurcations to hexafurcations; from normal regeneration from the original tail to multiple regenerations arising from a single point; and from growth from the distal third to the proximal third of the tail. Species showing abnormal regenerations included those with intra-vertebral, inter-vertebral or no autotomy planes, indicating that abnormal regenerations evidently occur across lepidosaurs regardless of whether the species demonstrates caudal autotomy or not. Within populations, abnormal regenerations were estimated at a mean ± SD of 2.75 ± 3.41% (range 0.1-16.7%). There is a significant lack of experimental studies to understand the potential ecological impacts of regeneration on the fitness and life history of individuals and populations. We hypothesised that abnormal regeneration may affect lepidosaurs via influencing kinematics of locomotion, restrictions in escape mechanisms, anti-predation tactics, and intra- and inter-specific signalling. Behaviourally testing these hypotheses would be an important future research direction.

Ecto- and endoparasites of the King's skink (Egernia kingii) on Penguin Island.

Wildlife species are often host to a diversity of parasites, but our knowledge of their diversity and ecology is extremely limited, especially for reptiles. Little is known about the host-parasite ecology of the Australian lizard, the King's skink (Egernia kingii). In spring of 2015, we carried out a field-based study of a population of King's skinks on Penguin Island (Western Australia). We documented five species of parasites, including two ectoparasitic mites (an undescribed laelapid mite and Mesolaelaps australiensis), an undescribed coccidia species, and two nematode species (Pharyngodon tiliquae and Capillaria sp.). The laelapid mite was the most abundant parasite, infesting 46.9% of the 113 captured lizards. This mite species increased in prevalence and abundance over the course of the study. Infection patterns of both mites varied with lizard life-stage; sub-adults were more commonly infested with laelapid mites than adults or juveniles, and sub-adults and adults were infested by more laelapid mites than juveniles. By contrast, adults had a higher prevalence of M. australiensis than juveniles or sub-adults. Among the gastrointestinal parasites, P. tiliquae was relatively common among the sampled lizards (35.3%). These results give new important information about reptiles as parasite hosts and what factors influence infection patterns.

The global prevalence of Cryptosporidium infection in dogs: A systematic review and meta-analysis.

Cryptosporidiosis, caused by the protozoan parasite Cryptosporidium spp., is an important zoonotic disease and is considered a global public health concern. Dogs are suggested as one of potential reservoirs for transmitting the Cryptosporidium infection to humans. However, there is a paucity of information about global patterns of occurrence of Cryptosporidium in dogs. A systematic review and meta-analysis were carried out to evaluate the global prevalence of Cryptosporidium infection among dogs. In this study, PubMed, Scopus, Web of Science and Google Scholar databases were systematically searched for relevant studies up until October 30, 2019. Finally, 127 articles (including 160 datasets) were eligible for inclusion in the systematic review and meta-analysis. The overall prevalence of Cryptosporidium infection was estimated at 8% (95 % CI: 5-11 %) using microscopic methods, 7% (95 % CI: 4-10%) using coprogantigenic methods and 6% (95 % CI: 4-9%) using molecular diagnostic methods. Molecular methods revealed that dogs were most frequently infected by C. canis (3.64 %) and C. parvum (1.28 %). The pooled prevalence different of subgroups (WHO regions, geographic and climate parameters, diagnostic methods, type of dog) were analyzed separately. The pooled odds ratio (OR) of Cryptosporidium was significantly higher than one for diarrhea status, with dogs suffering from diarrhea having a higher likelihood of Cryptosporidium infection, compared to dogs without diarrhea (OR; 3.61 95 % CI: 1.89-6.90%). The present study is the first systematic review and meta-analysis providing a comprehensive view of the global prevalence of Cryptosporidium in dogs and its related risk factors. Awareness of Cryptosporidium prevalence, risk factors, and disease complications for the health authorities, physicians, veterinarians and dog's owners is important for developing effective strategies to prevent infection.

Identification of a novel species of Eimeria Schneider, 1875 from the woylie, Bettongia penicillata Gray (Diprotodontia: Potoroidae) and the genetic characterisation of three Eimeria spp. from other potoroid marsupials.

Faecal samples (n = 1,093) collected from the woylie Bettongia penicillata Gray, in south-western Australia were examined for the presence of coccidian parasites. Eimeria sp. oöcysts were detected in 15.2% of samples. Faecal samples obtained from the eastern bettong Bettongia gaimardi (Desmarest) (n = 4) and long-nosed potoroo Potorous tridactylus (Kerr) (n = 12) in Tasmania, were also screened for the presence of Eimeria spp. (prevalence 50% and 41.7%, respectively). Morphological and genetic comparison with other known species of Eimeria indicates that the material identified in woylies is novel. This study aimed to (i) morphologically describe and genetically characterise Eimeria woyliei n. sp. found in woylies; and (ii) genetically characterise Eimeria gaimardi Barker, O'Callaghan & Beveridge, 1988, Eimeria potoroi Barker, O'Callaghan & Beveridge, 1988, and Eimeria mundayi Barker, O'Callaghan & Beveridge, 1988, from other potoroid marsupials. Molecular phylogenetic analyses conducted at the 18S rDNA and mitochondrial cytochrome c oxidase subunit 1 (cox1) loci revealed that E. woyliei n. sp. was most closely related to Eimeria setonicis Barker, O'Callaghan & Beveridge, 1988, at the 18S rDNA locus, and Eimeria trichosuri O'Callaghan & O'Donoghue, 2001, at the cox1 locus. Eimeria woyliei n. sp. is the sixth species of Eimeria to be formally described from potoroid marsupials.

Altered parasite community structure in an endangered marsupial following translocation.

Fauna translocations play an integral role in the management of threatened wildlife, though we are limited by our understanding of how the host-parasite community changes during translocation. During this longitudinal field-based study, we monitored gastrointestinal, blood-borne and ectoparasite taxa infecting woylies (Bettongia penicillata) for up to 12 months following two fauna translocations to supplement existing wild woylie populations in three different sites (Dryandra, Walcott and Warrup East) within the south-west of Western Australia. We aimed to (a) identify changes in parasite community structure of both translocated and resident woylies following translocation; and (b) evaluate the efficacy of ivermectin treatment in translocated hosts. Destination site and time since translocation had the strongest effects on parasite prevalence and mean faecal egg counts following translocation. Ivermectin treatment did not significantly reduce parasite prevalence or mean faecal egg counts in treated hosts. Prior to translocation, parasite community composition differed significantly between woylies selected for translocation and resident woylies within each release site. Following translocation, the parasite communities of translocated and resident hosts converged to become more similar over time, with loss of parasite taxa and novel host-parasite associations emerging. This is the first study to examine changes to the broader parasite community in translocated and resident animals following translocation. The dominant site-specific response of parasites following translocation reinforces the importance of incorporating parasite studies to enhance our fundamental understanding of perturbations in host-parasite systems during translocation, in particular the site-level drivers of parasite dynamics.

Increased Trypanosoma spp. richness and prevalence of haemoparasite co-infection following translocation.

BACKGROUND: Understanding how fauna translocation and antiparasitic drug treatment impact parasite community structure within a host is vital for optimising translocation outcomes. Trypanosoma spp. and piroplasms (Babesia and Theileria spp.) are known to infect Australian marsupials, including the woylie (Bettongia penicillata). However relatively little is known about these haemoparasites, or how they respond to management practices such as translocation. We monitored haemoparasites infecting woylies for up to 12 months during two fauna translocations to supplement existing woylie populations in three different sites (Dryandra, Walcott and Warrup East) within south-western Australia between 2014 and 2016, with the aim of investigating (i) how haemoparasite prevalence, Trypanosoma spp. richness and Trypanosoma spp. community composition varied over time and between different sites following translocation; and (ii) whether ivermectin treatment indirectly impacts haemoparasite prevalence. Using molecular methods, 1211 blood samples were screened for the presence of trypanosomes, and a subset of these samples (n = 264) were also tested for piroplasms. RESULTS: Trypanosomes and piroplasms were identified in 55% and 94% of blood samples, respectively. We identified five Trypanosoma species, two Theileria species, a single species of Babesia and a novel Bodo species. Trypanosoma spp. richness and the prevalence of haemoparasite co-infection increased after translocation. Prior to translocation, Trypanosoma spp. community composition differed significantly between translocated and resident woylies within Walcott and Warrup East, but not Dryandra. Six months later, there was a significant difference between translocated and resident woylies within Dryandra, but not Walcott or Warrup East. The response of haemoparasites to translocation was highly site-specific, with predominant changes to the haemoparasite community in translocated woylies occurring within the first few months following translocation. Ivermectin treatment had no significant effect on haemoparasite prevalence. CONCLUSIONS: This study contributes to our understanding of haemoparasite dynamics in woylies following translocation. The highly site-specific and rapid response of haemoparasites to translocation highlights the need to better understand what drives these effects. Given that haemoparasite prevalence and composition of translocated and resident animals changed significantly following translocation, we propose that parasite monitoring should form an essential component of translocation protocols, and such protocols should endeavour to monitor translocated hosts and cohabiting species.

Specific MHC class I supertype associated with parasite infection and color morph in a wild lizard population.

The major histocompatibility complex (MHC) is a large gene family that plays a central role in the immune system of all jawed vertebrates. Nonavian reptiles are underrepresented within the MHC literature and little is understood regarding the mechanisms maintaining MHC diversity in this vertebrate group. Here, we examined the relative roles of parasite-mediated selection and sexual selection in maintaining MHC class I diversity of a color polymorphic lizard. We discovered evidence for parasite-mediated selection acting via rare-allele advantage or fluctuating selection as ectoparasite load was significantly lower in the presence of a specific MHC supertype (functional clustering of alleles): supertype four. Based on comparisons between ectoparasite prevalence and load, and assessment of the impact of ectoparasite load on host fitness, we suggest that supertype four confers quantitative resistance to ticks or an intracellular tickborne parasite. We found no evidence for MHC-associated mating in terms of pair genetic distance, number of alleles, or specific supertypes. An association was uncovered between supertype four and male throat color morph. However, it is unlikely that male throat coloration acts as a signal of MHC genotype to conspecifics because we found no evidence to suggest that male throat coloration predicts male mating status. Overall, our results suggest that parasite-mediated selection plays a role in maintaining MHC diversity in this population via rare-allele advantage and/or fluctuating selection. Further work is required to determine whether sexual selection also plays a role in maintaining MHC diversity in agamid lizards.

Debilitating disease in a polyparasitised woylie (Bettongia penicillata): A diagnostic investigation.

During monitoring of critically endangered woylie (Bettongia penicillata) populations within the south-west of Western Australia, an adult female woylie was euthanased after being found in extremely poor body condition with diffuse alopecia, debilitating skin lesions and severe ectoparasite infestation. Trypanosoma copemani G2 and Sarcocystis sp. were detected molecularly within tissue samples collected post-mortem. Potorostrongylus woyliei and Paraustrostrongylus sp. nematodes were present within the stomach and small intestine, respectively. Blood collected ante-mortem revealed the presence of moderate hypomagnesaemia, mild hypokalaemia, mild hyperglobulinaemia and mild hypoalbuminaemia. Diffuse megakaryocytic hypoplasia was evident within the bone marrow. We propose various hypotheses that may explain the presence of severe ectoparasite infection, skin disease and poor body condition in this woylie. Given the potential deleterious effects of parasite infection, the importance of monitoring parasites cannot be over-emphasised.

Trypanosome co-infections increase in a declining marsupial population.

Understanding the impacts of parasites on wildlife is growing in importance as diseases pose a threat to wildlife populations. Woylie (syn. brush-tailed bettong, Bettongia penicillata) populations have undergone enigmatic declines in south-western Western Australia over the past decade. Trypanosomes have been suggested as a possible factor contributing towards these declines because of their high prevalence in the declining population. We asked whether temporal patterns of infection with Trypanosoma spp. were associated with the decline patterns of the host, or if other factors (host sex, body condition, co-infection or rainfall) were more influential in predicting infection patterns. Species-specific nested PCRs were used to detect the two most common trypanosomes (T. copemani and T. vegrandis) from 444 woylie blood samples collected between 2006 and 2012. Time relative to the decline (year) and an interaction with co-infection by the other trypanosome best explained patterns of infection for both trypanosomes. The prevalence of single species infections for both T. copemani and T. vegrandis was lower after the population crash, however, the occurrence of co-infections increased after the crash compared to before the crash. Our results suggest an interaction between the two parasites with the decline of their host, leading to a higher level of co-infection after the decline. We discuss the possible mechanisms that may have led to a higher level of co-infection after the population crash, and highlight the importance of considering co-infection when investigating the role of parasites in species declines.

Parasites at Risk - Insights from an Endangered Marsupial.

Parasites are the most abundant form of life on earth and are vital components of ecosystem health. Yet, it is only relatively recently that attention has been given to the risks of extinction that parasites face when their hosts, particularly wildlife, are endangered. In such circumstances, parasites that are host-specific with complicated life cycles are most at risk. Such extinction/coextinction events have been poorly documented, principally because of the difficulties of following such extinction processes in nature. Fortunately, we were presented with the rare opportunity to catalogue an endangered Australian marsupial's parasites; we present our near-complete catalogue here. We incorporate this catalogue into a predictive framework to understand which parasites might be most vulnerable to coextinction, which we hope will serve as a model for endangered hosts and their parasites elsewhere.

Lizards, ticks and contributions to Australian parasitology: C. Michael Bull (1947-2016).

Professor C. Michael Bull was a great scientist and mentor, and an Associate Editor of this journal. While his research career spanned the fields of behavioural ecology, conservation biology and herpetology, in this article, we pay tribute to his major contribution to Australian parasitology. Mike authored more than eighty articles on host-parasite ecology, and revealed major insights into the biology and ecology of ticks from his long term study of the parapatric boundary of two tick species (Amblyomma limbatum and Bothriocroton hydrosauri) on the sleepy lizard (Tiliqua rugosa). In this article, we provide an overview of how this research journey developed to become one of the longest-running studies of lizards and their ticks, totalling 35 years of continuous surveys of ticks on lizards, and the insights and knowledge that he generated along that journey.

Genes and Group Membership Predict Gidgee Skink (Egernia stokesii) Reproductive Pairs.

Due to their role in mate choice, disease resistance and kin recognition, genes of the major histocompatibility complex (MHC) are good candidates for investigating genetic-based mate choice. MHC-based mate choice is context dependent and influenced by many factors including social structure. Social structure diversity makes the Egernia group of lizards suitable for comparative studies of MHC-based mate choice. We investigated mate choice in the gidgee skink (Egernia stokesii), a lizard that exhibits high levels of social group and spatial stability. Group membership was incorporated into tests of the good genes as heterozygosity and compatible genes hypotheses for adaptive (MHC) and neutral (microsatellite) genetic diversity (n = 47 individuals genotyped). Females were more likely to pair with a male with higher MHC diversity and with whom they had a lower degree of microsatellite relatedness. Males were more likely to pair with a female with higher microsatellite heterozygosity and with whom they shared a lower proportion of MHC alleles. Lizards were more likely to mate with an individual from within, rather than outside, their social group, which confirmed earlier findings for this species and indicated mate choice had already largely occurred prior to either social group formation or acceptance of an individual into an existing group. Thus, a combination of genes and group membership, rather than group membership alone, predicted mate choice in this species. This work will contribute to an enhanced understanding of squamate group formation and a deeper understanding of the evolution of sociality within all vertebrates.

Evaluating Stress Physiology and Parasite Infection Parameters in the Translocation of Critically Endangered Woylies (Bettongia penicillata).

Translocation can be stressful for wildlife. Stress may be important in fauna translocation because it has been suggested that it can exacerbate the impact of infectious disease on translocated wildlife. However, few studies explore this hypothesis by measuring stress physiology and infection indices in parallel during wildlife translocations. We analysed faecal cortisol metabolite (FCM) concentration and endoparasite parameters (nematodes, coccidians and haemoparasites) in a critically endangered marsupial, the woylie (Bettongia penicillata), 1-3 months prior to translocation, at translocation, and 6 months later. FCM for both translocated and resident woylies was significantly higher after translocation compared to before or at translocation. In addition, body condition decreased with increasing FCM after translocation. These patterns in host condition and physiology may be indicative of translocation stress or stress associated with factors independent of the translocation. Parasite factors also influenced FCM in translocated woylies. When haemoparasites were detected, there was a significant negative relationship between strongyle egg count and FCM. This may reflect the influence of glucocorticoids on the immune response to micro- and macro-parasites. Our results indicate that host physiology and infection patterns can change significantly during translocation, but further investigation is required to determine how these patterns influence translocation success.

Evaluating the Effects of Ivermectin Treatment on Communities of Gastrointestinal Parasites in Translocated Woylies (Bettongia penicillata).

Wildlife species are often treated with anti-parasitic drugs prior to translocation, despite the effects of this treatment being relatively unknown. Disruption of normal host-parasite relationships is inevitable during translocation, and targeted anti-parasitic drug treatment may exacerbate this phenomenon with inadvertent impacts on both target and non-target parasite species. Here, we investigate the effects of ivermectin treatment on communities of gastrointestinal parasites in translocated woylies (Bettongia penicillata). Faecal samples were collected at three time points (at the time of translocation, and 1 and 3 months post-translocation) and examined for nematode eggs and coccidian oocysts. Parasite prevalence and (for nematodes) abundance were estimated in both treated and untreated hosts. In our study, a single subcutaneous injection of ivermectin significantly reduced Strongyloides-like egg counts 1 month post-translocation. Strongyle egg counts and coccidia prevalence were not reduced by ivermectin treatment, but were strongly influenced by site. Likewise, month of sampling rather than ivermectin treatment positively influenced body condition in woylies post-translocation. Our results demonstrate the efficacy of ivermectin in temporarily reducing Strongyloides-like nematode abundance in woylies. We also highlight the possibility that translocation-induced changes to host density may influence coinfecting parasite abundance and host body condition post-translocation.

Host stress physiology and Trypanosoma haemoparasite infection influence innate immunity in the woylie (Bettongia penicillata).

Understanding immune function is critical to conserving wildlife in view of infectious disease threats, particularly in threatened species vulnerable to stress, immunocompromise and infection. However, few studies examine stress, immune function and infection in wildlife. We used a flow cytometry protocol developed for human infants to assess phagocytosis, a key component of innate immunity, in a critically endangered marsupial, the woylie (Bettongia penicillata). The effects of stress physiology and Trypanosoma infection on phagocytosis were investigated. Blood and faecal samples were collected from woylies in a captive facility over three months. Trypanosoma status was determined using PCR. Faecal cortisol metabolites (FCM) were quantified by enzyme-immunoassay. Mean phagocytosis measured was >90%. An interaction between sex and FCM influenced the percentage of phagocytosing leukocytes, possibly reflecting the influence of sex hormones and glucocorticoids. An interaction between Trypanosoma status and FCM influenced phagocytosis index, suggesting that stress physiology and infection status influence innate immunity.

When the going gets tough: behavioural type-dependent space use in the sleepy lizard changes as the season dries.

Understanding space use remains a major challenge for animal ecology, with implications for species interactions, disease spread, and conservation. Behavioural type (BT) may shape the space use of individuals within animal populations. Bolder or more aggressive individuals tend to be more exploratory and disperse further. Yet, to date we have limited knowledge on how space use other than dispersal depends on BT. To address this question we studied BT-dependent space-use patterns of sleepy lizards (Tiliqua rugosa) in southern Australia. We combined high-resolution global positioning system (GPS) tracking of 72 free-ranging lizards with repeated behavioural assays, and with a survey of the spatial distributions of their food and refuge resources. Bayesian generalized linear mixed models (GLMM) showed that lizards responded to the spatial distribution of resources at the neighbourhood scale and to the intensity of space use by other conspecifics (showing apparent conspecific avoidance). BT (especially aggressiveness) affected space use by lizards and their response to ecological and social factors, in a seasonally dependent manner. Many of these effects and interactions were stronger later in the season when food became scarce and environmental conditions got tougher. For example, refuge and food availability became more important later in the season and unaggressive lizards were more responsive to these predictors. These findings highlight a commonly overlooked source of heterogeneity in animal space use and improve our mechanistic understanding of processes leading to behaviourally driven disease dynamics and social structure.

Trypanosomes of Australian mammals: A review.

Approximately 306 species of terrestrial and arboreal mammals are known to have inhabited the mainland and coastal islands of Australia at the time of European settlement in 1788. The exotic Trypanosoma lewisi was the first mammalian trypanosome identified in Australia in 1888, while the first native species, Trypanosoma pteropi, was taxonomically described in 1913. Since these discoveries, about 22% of the indigenous mammalian fauna have been examined during the surveillance of trypanosome biodiversity in Australia, including 46 species of marsupials, 9 rodents, 9 bats and both monotremes. Of those mammals examined, trypanosomes have been identified from 28 host species, with eight native species of Trypanosoma taxonomically described. These native trypanosomes include T. pteropi, Trypanosoma thylacis, Trypanosoma hipposideri, Trypanosoma binneyi, Trypanosoma irwini, Trypanosoma copemani, Trypanosoma gilletti and Trypanosoma vegrandis. Exotic trypanosomes have also been identified from the introduced mammalian fauna of Australia, and include T. lewisi, Trypanosoma melophagium, Trypanosoma theileri, Trypanosoma nabiasi and Trypanosoma evansi. Fortunately, T. evansi was eradicated soon after its introduction and did not establish in Australia. Of these exotic trypanosomes, T. lewisi is the sole representative that has been reported from indigenous Australian mammals; morphological forms were recorded from two indigenous species of rodents (Hydromys chrysogaster and Rattus fuscipes). Numerous Australian marsupial species are potentially at risk from the native T. copemani, which may be chronically pathogenic, while marsupials, rodents and monotremes appear at risk from exotic species, including T. lewisi, Trypanosoma cruzi and T. evansi. This comprehensive review of trypanosome biodiversity in Australia highlights the negative impact of these parasites upon their mammalian hosts, as well as the threatening biosecurity concerns.

Temporal and spatial dynamics of trypanosomes infecting the brush-tailed bettong (Bettongia penicillata): a cautionary note of disease-induced population decline.

BACKGROUND: The brush-tailed bettong or woylie (Bettongia penicillata) is on the brink of extinction. Its numbers have declined by 90% since 1999, with their current distribution occupying less than 1% of their former Australian range. Woylies are known to be infected with three different trypanosomes (Trypanosoma vegrandis, Trypanosoma copemani and Trypanosoma sp. H25) and two different strains of T. copemani that vary in virulence. However, the role that these haemoparasites have played during the recent decline of their host is unclear and is part of ongoing investigation. METHODS: Woylies were sampled from five locations in southern Western Australia, including two neighbouring indigenous populations, two enclosed (fenced) populations and a captive colony. PCR was used to individually identify the three different trypanosomes from blood and tissues of the host, and to investigate the temporal and spatial dynamics of trypanosome infections. RESULTS: The spatial pattern of trypanosome infection varied among the five study sites, with a greater proportion of woylies from the Perup indigenous population being infected with T. copemani than from the neighbouring Kingston indigenous population. For an established infection, T. copemani detection was temporally inconsistent. The more virulent strain of T. copemani appeared to regress at a faster rate than the less virulent strain, with the infection possibly transitioning from the acute to chronic phase. Interspecific competition may also exist between T. copemani and T. vegrandis, where an existing T. vegrandis infection may moderate the sequential establishment of the more virulent T. copemani. CONCLUSION: In this study, we provide a possible temporal connection implicating T. copemani as the disease agent linked with the recent decline of the Kingston indigenous woylie population within the Upper Warren region of Western Australia. The chronic association of trypanosomes with the internal organs of its host may be potentially pathogenic and adversely affect their long term fitness and coordination, making the woylie more susceptible to predation.