Marmosa constantiae is a species of marsupial restricted to the central portion of South America. In Brazil, it occurs in the northwestern region including five states of the Amazon, Cerrado, and Pantanal biomes. However, there is no study of the helminth fauna or helminth community structure for this marsupial. The aims of this study were to describe the species composition and to analyse the structure of the helminthic community of M. constantiae in an area of the Amazon Arc in Sinop, north of the state of Mato Grosso, Brazil. Parasites were searched in 53 specimens of this marsupial, among which 44 were infected with at least one helminth species. Parasitic helminths were counted and identified. Nine species were collected: seven nematodes, one cestode, and one acanthocephalan. The most abundant species were Gracilioxyuris agilisis, Travassostrongylus scheibelorum, Pterygodermatites sinopiensis, and Subulura eliseae. These species were the only dominant ones in the component community. No significant differences were observed in the abundance and prevalence of helminths between male and female hosts. Host body size significantly influenced helminth abundance in males. The pattern of community structure considering the infracommunities in this locality indicated more species replacement than species loss along the environmental gradient. This is the first study to report the helminth fauna and the helminth community structure of M. constantiae.

One major problem facing wildlife is urbanisation, and the increasing contact between human city dwellers and animals. In this study, we investigated the problems of urban opossums (Didelphis albiventris), through the analysis involving responses to call-outs (n = 500) made by the environmental police of Belo Horizonte, Minas Gerais, Brazil (2002 to 2007). Our objective was to characterise the problems faced by opossums and use this information to suggest how their welfare and urban management could be improved. Two types of call-outs were made: (i) solicitation whereby a person called them to report a problem; and (ii) the report of an injured animal. On average, one call-out was made every four days. There were no ‘time of year’ effects in relation to call-outs, or any effect of gender or age of the person making the call-out. Furthermore, we found no environmental (eg percentage of ‘green area’) or socio-economic variables (eg salary levels) associated with call-out frequency. The majority of call-outs resulted in the attempt to capture opossums, and usually only one animal was captured. Many of these animals were released into city forest fragments at a mean (± SEM) distance of 8,285 (± 727) m; (n = 312) from their point of capture. Injured animals were sent to veterinary clinics or to the Government's wildlife processing centre. From these data we were able to make recommendations regarding the welfare and management of urban opossums.

Didelphis albiventris is the opossum with the largest geographic distribution in Brazil and has a wide spectrum of helminth parasites. This study aimed to describe the species composition and analyse the structure of helminth communities of D. albiventris in two extremes of the Atlantic Forest in Brazil. The influence of host sex, body mass, age, helminth species richness and locality on the abundance and prevalence of the most prevalent helminth species was investigated. Ninety-five per cent of the animals were infected with at least one species. Nine helminth species were found: the nematodes Aspidodera raillieti, Cruzia tentaculata, Trichuris didelphis and Trichuris minuta in the large intestine; Turgida turgida in the stomach; Travassostrongylus orloffi and Viannaia hamata; and the trematodes Brachylaima advena and Rhopalias coronatus in the small intestine. Three helminth morphospecies were also recovered: the nematodes Hoineffia sp. and Viannaia sp. and a cestode in the small intestine. Cruzia tentaculata and V. hamata were the species with the highest mean abundances and intensities, while the most prevalent species were A. raillieti, C. tentaculata, T. turgida and V. hamata, forming the central nucleus of the helminth component community. The analysis of the helminth metacommunity structure indicated a Gleasonian pattern for the total set of infracommunities, corroborating the beta diversity indices, which indicated more species replacement than loss between localities and infracommunities, although at a low level. The results indicated a stronger influence of host attributes than geographical distance on the community structure.

Understanding the role of species traits in mediating ecological interactions and shaping community structure is a key question in ecology. In this sense, parasite population parameters allow us to estimate the functional importance of traits in shaping the strength of interactions among hosts and parasites in a network. The aim of this study was to survey and analyse the small mammal-helminth network in a forest reserve of the Brazilian Atlantic Forest in order to understand (i) how functional traits (type of parasite life cycle, site of infection in their host, host and parasite body length, host diet, host locomotor habit and host activity period) and abundance influence host–parasite interactions, (ii) whether these traits explain species roles, and (iii) if this relationship is consistent across different parasite population parameters (presence and absence, mean abundance and prevalence). Networks were modular and their structural patterns did not vary among the population parameters. Functional traits and abundance shaped the interactions observed between parasites and hosts. Host species abundance, host diet and locomotor habit affected their centrality and/or vulnerability to parasites. For helminths, infection niche was the main trait determining their central roles in the networks.

Jackfruit (Artocarpus heterophyllus Lam.) is an exotic invasive plant species in the Brazilian Atlantic Forest that causes changes in the environment through the release of allelopathic substances and has high fruit production. We aimed to understand the potential effects of the jackfruit on the non-volant small mammal assemblage in an area protected by law, in the municipality of Cariacica – Espírito Santo, south-eastern Brazil. We sampled the small mammals assemblage using live traps in 18 sites, eight with jackfruit and 10 without. We ordinated the assemblage and tested possible differences in species richness and abundance according to the jackfruit density. We recorded 31 species of non-volant small mammals, with 13 species endemic to the Atlantic Forest. Jackfruit species can affect both positively and negatively the studied assemblage of non-volant small mammals. For species with a frugivory habit, jackfruit has a positive effect favouring these species. On the other hand, for insectivorous species, jackfruit represents an impact inhibiting the presence of these species in an area with high jackfruit density. The results presented are the first step in understanding the effect of this invasive species on a small mammals assemblage and initiating a monitoring of these species in areas affected by jackfruits. Furthermore, management of jackfruits in this protected area is required.

Among the Brazilian marsupials, the species of the genus Didelphis are the most parasitized by helminths. This study aimed to describe the species composition and to analyse the helminth communities of the Atlantic Forest common opossum Didelphis aurita at infracommunity and component community levels using the Elements of Metacommunity Structure Analysis, considering peri-urban, sylvatic and rural environments in the state of Rio de Janeiro, Brazil. Seventy-three specimens of D. aurita were captured during the study. Fourteen species of helminths were collected: nine of the phylum Nematoda (Trichuris minuta, Trichuris didelphis, Globocephalus marsupialis, Heterostrongylus heterostrongylus, Travassostrongylus orloffi, Viannaia hamata, Aspidodera raillieti, Cruzia tentaculata and Turgida turgida); four of the phylum Platyhelminthes (three species of Trematoda, Duboisiella proloba, Brachylaima advena and Rhopalias coronatus, and one species of the class Cestoda); and one species of the phylum Acanthocephala (Oligacanthorhynchus microcephalus). More than 95% of the animals were infected with parasites. The most abundant parasite species were V. hamata, T. turgida, C. tentaculata and T. orloffi. The nematodes T. turgida, C. tentaculata and A. raillieti were the most dominant species in the three environments. The analysis of the metacommunity structure indicated a structured pattern as a function of the environmental gradient, but only when all localities were considered together. At the infracommunity and component community levels, quasi-nested and nested structures with stochastic species loss were observed, respectively. The results indicate that the settlement of helminth species in the opossums can be attributed to the heterogeneity among individual hosts in relation to their exposure to parasites and to extrinsic factors, which vary among habitats, considering a regional scale. On a local scale, the characteristics of this host species may promote homogenization among individual hosts in terms of their exposure to the helminths. This study constitutes a new host record for the species G. marsupialis and T. didelphis and represents a pioneering investigation of the helminth metacommunity of a Neotropical marsupial.

The Virginia opossum (Didelphis virginiana) is considered highly adaptable to anthropogenic disturbances; however, the genetic effects of disturbance on this marsupial have not been studied in wild populations in Mexico. Here we evaluated the genetic diversity of D. virginiana at sites with different levels of disturbance within the Highlands and Central Depression regions of Chiapas in southern Mexico. Twelve microsatellite loci were used and the results demonstrated moderate mean heterozygosity (He = 0.60; Ho = 0.50). No significant differences in heterozygosity were found among sites with different levels of disturbance in both regions (range Ho = 0.42–0.57). We observed low but significant levels of genetic differentiation according to disturbance level. The inbreeding coefficient did not differ significantly from zero, suggesting that low genetic differentiation in these environments may be associated with sufficient random mating and gene flow, a result associated with the high dispersal and tolerance characteristics of this marsupial. Our results for D. virginiana in this particular area of Mexico provide a foundation for exploring the impact of human disturbance on the genetic diversity of a common and generalist species.

Erythroblastic islands are multicellular clusters in which a central macrophage supports the development and maturation of red blood cell (erythroid) progenitors. These clusters play crucial roles in the pathogenesis observed in animal models of hematological disorders. The precise structure and function of erythroblastic islands is poorly understood. Here, we have combined scanning electron microscopy and immuno-gold labeling of surface proteins to develop a better understanding of the ultrastructure of these multicellular clusters. The erythroid-specific surface antigen Ter-119 and the transferrin receptor CD71 exhibited distinct patterns of protein sorting during erythroid cell maturation as detected by immuno-gold labeling. During electron microscopy analysis we observed two distinct classes of erythroblastic islands. The islands varied in size and morphology, and the number and type of erythroid cells interacting with the central macrophage. Assessment of femoral marrow isolated from a cavid rodent species (guinea pig, Cavis porcellus) and a marsupial carnivore species (fat-tailed dunnarts, Sminthopsis crassicaudata) showed that while the morphology of the central macrophage varied, two different types of erythroblastic islands were consistently identifiable. Our findings suggest that these two classes of erythroblastic islands are conserved in mammalian evolution and may play distinct roles in red blood cell production.

The activity of the water opossum Chironectes minimus was studied in Atlantic forest rivers in south-eastern Brazil using radiotracking, from October 2004 to October 2008. There were 439 nocturnal fixes of 11 males and four females. Activity patterns of the water opossum were compared among sexes and seasons, using linear and generalized linear mixed models. The water opossum is active mostly at night, showing a unimodal pattern, with activity increasing after sunset and decreasing thereafter along the night. Females were more active in the first quarter of the night and males in the second one. The activity period of males was longer in the dry season, while for females it was longer in the wet season. Sex and season were important determinants of the water opossum activity patterns, mainly because of different sex strategies in a promiscuous/polygynous mating system. However, despite those influences the overall distribution of activity along the night was similar to most Neotropical marsupials. Therefore, similarities in the activity patterns are probably due to phylogenetic constraints and to the absence or weakness of selective pressures modifying the activity of the water opossum.

Cryptosporidium is an important enteric parasite that is transmitted via the fecal-oral route, water and food. Humans, wildlife and domestic livestock all potentially contribute Cryptosporidium to surface waters. Most species of Cryptosporidium are morphologically indistinguishable and can only be identified using molecular tools. Over 24 species have been identified and of these, 7 Cryptosporidium species/genotypes are responsible for most human cryptosporidiosis cases. In Australia, relatively few genotyping studies have been conducted. Six Cryptosporidium species (C. hominis, C. parvum, C. meleagridis, C. fayeri, C. andersoni and C. bovis) have been identified in humans in Australia. However, little is known about the contribution of animal hosts to human pathogenic strains of Cryptosporidium in drinking water catchments. In this review, we focus on the available genotyping data for native, feral and domestic animals inhabiting drinking water catchments in Australia to provide an improved understanding of the public health implications and to identify key research gaps.

Spatial organization within animal populations is often thought to reflect the outcome of strategies implemented by each individual to enhance its reproductive success and survival (Clutton-Brock 1989). Thus, while females usually focus on the acquisition of food and breeding sites, male dispersion is more often determined by the distribution and availability of females (Clutton-Brock 1989). Due to these factors, intraspecific competition for space could lead to the adoption of a territorial strategy, whenever the benefits of territorial defence are higher than the costs (Brown & Orians 1970). Among small mammals, two main hypotheses have been proposed to explain the occurrence of territoriality in females. Ostfeld (1990) proposed that females should defend food resources, so the distribution and availability of food items should determine the cost–benefit relationship of adopting a territorial strategy. However, Wolff (1993) developed a hypothesis, based on small rodents, that females should defend nest sites in order to avoid infanticide, the so-called pup-defence hypothesis.

During the course of a population study of small mammals in a Brazilian coastal shrubland we calculated the movements between successive captures, the residence time, the indices of aggregation and the kinds of movements of the five most common species of small mammal. A capture-mark-recapture study was undertaken over two years, quarterly. Philander opossum, Akodon cursor and Proechimys iheringi presented low mobility, with a high proportion of restricted movements, long residence time and larger coefficients of aggregation. Didelphis aurita and Metachirus nudicaudatus presented higher mobility and exploratory movements, short residence time and small coefficients of aggregation. The species with lower mobility had permanent populations within our sampling grid, while the species with higher mobility used areas outside the grid, presenting no local populations but occupying portions of regional metapopulations.

Community structure, macrohabitat selection, and patterns of species co-occurrence were examined during a 14-month study of small mammals in the Cerrado Province of central Brazil. Data were collected from mark-recapture grids in brejo and gallery forest, and from live-trapping and specimen collection in all habitat types within cerrado (campo limpo, campo sujo, cerrado [s.s.], cerradão, brejo, valley-side wet campo, and gallery forest). Gallery forest supported the highest species richness, most complex vertical distribution of species, highest level of trophic diversity, and highest macroniche diversity. Degree of habitat selection varied widely. All habitat types supported both rodents and marsupials, although marsupials tended to be much less common in the grasslands (campos) than in woodlands (cerrado) and forests (cerradão, gallery forest). Some species, such as Didelphis albiventris, occurred in all habitat types, while others were much more restricted. Oryzomys bicolor, for example, ocur-red only in gallery forest. No habitat type had a completely distinct fauna: overlap in species composition always occurred with at least one other habitat type. Because of the great variability of habitats, and the fact that subsets of the mammal fauna were frequently habitat specific, the overall species richness of any portion of mixed cerrado vegetation is remarkably high.

We have determined the sequence and genomic organization of the genes encoding the cone visual pigment of the platypus (Ornithorhynchus anatinus) and the echidna (Tachyglossus aculeatus), and inferred their spectral properties and evolutionary pathways. We prepared platypus and echidna retinal RNA and used primers of the middle-wave-sensitive (MWS), long-wave-sensitive (LWS), and short-wave sensitive (SWS1) pigments corresponding to coding sequences that are highly conserved among mammals; to PCR amplify the corresponding pigment sequences. Amplification from the retinal RNA revealed the expression of LWS pigment mRNA that is homologous in sequence and spectral properties to the primate LWS visual pigments. However, we were unable to amplify the mammalian SWS1 pigment from these two species, indicating this gene was lost prior to the echidna-platypus divergence (∼21 MYA). Subsequently, when the platypus genome sequence became available, we found an LWS pigment gene in a conserved genomic arrangement that resembles the primate pigment, but, surprisingly we found an adjacent (∼20 kb) SWS2 pigment gene within this conserved genomic arrangement. We obtained the same result after sequencing the echidna genes. The encoded SWS2 pigment is predicted to have a wavelength of maximal absorption of about 440 nm, and is paralogous to SWS pigments typically found in reptiles, birds, and fish but not in mammals. This study suggests the locus control region (LCR) has played an important role in the conservation of photo receptor gene arrays and the control of their spatial and temporal expression in the retina in all mammals. In conclusion, a duplication event of an ancestral cone visual pigment gene, followed by sequence divergence and selection gave rise to the LWS and SWS2 visual pigments. So far, the echidna and platypus are the only mammals that share the gene structure of the LWS-SWS2 pigment gene complex with reptiles, birds and fishes.

Spatial patterns presented by the opossums Caluromys philander, Philander frenata and Micoureus demerarae were studied, through radio-tracking, in a landscape composed of eight small (1.3–13.3 ha) forest fragments surrounded by a matrix of open vegetation in south-eastern Brazil. Sixteen individuals were fitted with radio-collar transmitters and monitored for 2–8 mo. Fixes were obtained by the ‘homing-in on the animal’ technique. Numbers of locations of each individual varied from 6 to 117. Home ranges sizes ranged from 2.5–7.0 ha for C. philander, 0.6–7.4 ha for P. frenata and 0.8–1.7 ha for M. demerarae. Fragments, both edges and interiors, were used more often than the matrix; they are the primary habitat for these marsupials in the landscape. The matrix was used for foraging by P. frenata and C. philander, and traversed in five movements between fragments by P. frenata. Ability to use fragment edges and the matrix is important in explaining how these marsupials are able to persist in the landscape.

Neotropical species richness is often estimated using accumulation or rarefaction curves and extrapolations based on various methods, but the efficacy of these methods is rarely tested. We used both a time-limited trapping session and previous knowledge of the mammal fauna from a site in French Guiana to validate these different methods. Three currently used extrapolation models were tested on our data. In a 2.5-mo trapping period we caught 75 individuals representing 18 small non-volant mammal species in three different habitats. We found that for comparable trapping efforts, village edges presented a higher abundance and species richness than primary and secondary forests. Species richness extrapolations using current models demonstrated that the exponential dependence model fits the known diversity of the site better, although this model is usually applied to large geographic areas and to relatively poorly documented taxa. Both Clench equation and linear dependence models underestimate small-mammal species richness in our study. We finally emphasize the interest of sampling in such edges surrounded by either primary or secondary forest, to maximize the probability of trapping rare species.

Genetic variation was examined in the anoplocephalid cestode Progamotaenia festiva, from Australian marsupials, in order to test the hypothesis that P. festiva, is a complex of sibling species and to assess the extent of host switching reported previously based on multilocus enzyme electrophoresis (MEE). Polymerase chain reaction (PCR)-based single-strand conformational polymorphism (SSCP) was used for the analysis of sequence variation in the cytochrome c oxidase subunit 1 (cox1) gene among 179 specimens of P. festiva (identified based on morphology and predilection site in the host) from 13 different host species, followed by selective DNA sequencing. Fifty-three distinct sequence types (haplotypes) representing all specimens were defined. Phylogenetic analyses of these sequence data (utilizing maximum parsimony and neighbour-joining methods) revealed 12 distinct clades. Other heterologous species, P. ewersi and P. macropodis, were used as outgroups and the remaining bile-duct inhabiting species, P. diaphana and P. effigia, were included in the analysis for comparative purposes. The latter 2 species were nested within the clades representing P. festiva. Most clades of P. festiva identified were restricted to a single host species; one clade primarily in Macropus robustus was also found in the related host species M. antilopinus in an area of host sympatry; another clade occurring primarily in M. robustus occurred also in additional kangaroo species, M. rufus and M. dorsalis. High levels of genetic divergence, the existence of distinct clades and their occurrence in sympatry provide support for the hypothesis that P. festiva represents a complex of numerous species, most of which, but not all, are host specific. Three distinct clades of cestodes were found within a single host, M. robustus, but there was no evidence of within-host speciation.

Studies of color vision in marsupial mammals have been very limited. Two photoreceptor genes have been characterized from the tammar wallaby, but a third cone pigment was suggested by microspectrophotometric measurements on cone photoreceptors in two other species, including the fat-tailed dunnart, Sminthopsis crassicaudata. To determine the sequence and infer absorption maxima of the cone photoreceptor pigments of S. crassicaudata and the related stripe-faced dunnart (Sminthopsis macroura), we have used evolutionarily conserved sequences of the cone pigments of other species, including the tammar wallaby, to design primers to amplify the S. macroura and S. crassicaudata pigment sequences by the polymerase chain reaction (PCR) using genomic DNA or retinal cDNA as a template. These primers will be useful for amplifying cone opsin coding sequences from a variety of vertebrates. Amplified products were directly sequenced to determine gene structure and coding sequences. The inferred amino acid sequences of the cone visual pigments indicated that both species have middle-wave-sensitive (MWS) pigments with a predicted absorption maximum (λmax) at 530 nm, and ultraviolet-sensitive (UVS) pigments with a predicted λmax at 360 nm. The MWS pigments of the two species differ by two, and UVS by three amino acid positions. No evidence was obtained for a third cone pigment in either species.

The gametes of man and some other Eutheria have been manipulated successfully for practical reasons, but many gaps remain in our basic understanding of the way that they function. This situation stems not least from a failure to recognize the extent to which eutherian spermatozoa and eggs, and elements related to their operation, have come to differ from those of other groups. Novel features in the male that reflect this include a radical design of the sperm head with the acrosome seeming to function primarily in egg-coat binding rather than its lysis, a multifaceted post-testicular sperm maturation and an androgen/low-temperature-regulated system of sperm storage – both tied to the epididymis, a variable male accessory sex gland complex, and descent of the testis and epididymis to a scrotum. In the female, such novelties are represented in a need for sperm capacitation, in an unusual regulation of sperm transport within the oviduct, in the cumulus oophorus and character of the zona pellucida around the small egg, and in a unique configuration of gamete fusion.

The collective evidence now suggests that many of these features reflect a new fertilisation strategy or its consequences, with most being causally linked. One initial ‘domino’ in this regard appears to be the small yolkless state of the egg and its intolerance for polyspermy, as determinants of the unusual mode of oviductal sperm transport and possibly the existence and form of the cumulus oophorus. However, a particularly influential first ‘domino’ appears to be the physical character of the eutherian zona pellucida. This differs from the egg coats of other animal groups by virtue of a resilient elasticity and thickness. These qualities allow this primary and often only coat to stretch and so persist during later expansion of the blastocyst, usually until close to implantation. At the same time, the dimensions, physical character, and particularly the relative protease-insensitivity of the zona appear to have had profound effects on sperm form and function and, more indirectly, on sperm-related events in the male and the female tract. Marsupials display some similarities and also some strikingly different features, against which the enigmas of the eutherian situation can be evaluated.