Robert D. Owen

COMPOSITION AND STRUCTURE OF BAT ASSEMBLAGES IN PARAGUAY: A SUBTROPICAL–TEMPERATE INTERFACE

Abstract Little is known about geographic variation in the local composition of South American assemblages of mammals or the factors that may produce such variation. This is particularly unfortunate in Paraguay because it occurs at the interface of a number of phytogeographic regions (e.g., Cerrado, Chaco, Interior Atlantic Rainforest, and Pantanal) and is the point at which many temperate species reach their northern limits or at which tropical species reach their southern limits. Based on 2 years of intensive fieldwork, we documented the species and familial composition of bat assemblages at 25 sites throughout the country. We also estimated similarity among sites based on indices sensitive to presence or absence of species (Ochiais index), to rank abundance of species (rank correlation index), or to relative abundance of species (Euclidean index). Geographic distance between sites accounted for little variation in composition based on presence–absence or rank abundances of species but accounted significantly for variation related to both identity and relative frequency of species. Distinct assemblages of species do not correspond to the 7 distinct biomes of the country; rather, strong differences exist between sites east (mesic) and west (xeric) of the Río Paraguay. For the most part, these differences are related to dominance by molossids (e.g., Eumops patagonicus, Molossops temminckii, and Molossus molossus) and vespertilionids (e.g., Lasiurus ega, Myotis albescens, and M. nigricans) in dry regions versus phyllostomids (e.g., Artibeus fimbriatus, A. lituratus, and Sturnira lilium) in mesic regions. As a consequence, classification of sites into 2 broad biogeographic regions based on bat familial composition generally is concordant with that based on plants.

TAXONOMIC STATUS OF MYOTIS (CHIROPTERA: VESPERTILIONIDAE) IN PARAGUAY

Abstract Qualitative and quantitative variation in morphology was assessed for 6 species of Myotis from South America to determine which taxa occur in Paraguay, characteristics that allow for their discrimination, and the degree of geographic and secondary sexual variation that occurs in Paraguayan forms. Secondary sexual dimorphism and geographic variation were evaluated from univariate and multivariate perspectives. Multivariate morphometric differences in cranial morphology among taxa, independent of size, and mensural characters that best separate species were determined using principal components analysis followed by size-adjusted discriminant function analysis. Five species, M. albescens, M. nigricans, M. riparius, M. ruber, and M. simus, occur in Paraguay and can be distinguished using combinations of cranial and external characteristics. No significant sexual dimorphism or geographic variation was detected in these taxa of Myotis in Paraguay. M. levis has not been recorded for Paraguay as previously reported, but it may occur in the country. M. simus, a species previously considered to be restricted to the Amazon Basin, occurs as far south as Paraguay and northern Argentina. Although M. simus varies significantly in size across its range, highly differentiated cranial and external morphology allows for recognition of this species across its range.

Sympatry of 2 Hantavirus Strains, Paraguay, 2003-2007

To explore geographic and host-taxonomic patterns of hantaviruses in Paraguay, we established sampling sites in the Mbaracayú Biosphere Reserve. We detected Jaborá virus and Itapúa37/Juquitiba–related virus in locations ≈20 m apart in different years, which suggested sympatry of 2 distinct hantaviruses.

Androlaelaps rotundus Fonseca (Acari: Laelapidae) associated with akodontine rodents in Paraguay: a morphometric examination of a pleioxenous ectoparasite

A multivariate analysis of morphometric data suggests that the nominally pleioxenous ectoparasite, Androlaelaps rotundus, includes at least three distinct host-associated populations in Paraguay. Where multiple akodontine hosts occur sympatrically, each host species is accompanied by a morphologically distinct mite population. These host-mite associations were consistent across all localities, implying that A. rotundus is a complex of unrecognized species.

Spatiotemporal variation in Akodon montensis (Cricetidae: Sigmodontinae) and hantaviral seroprevalence in a subtropical forest ecosystem

Abstract Relatively little information is available concerning the natural history or population ecology of the montane akodont, Akodon montensis, a sigmodontine species that harbors Jaborá and Ape Aime hantaviruses. On the basis of mark-recapture sampling of 3 locales during 2 years, this report provides comparative data on populational and other characteristics of the species near its distributional limit, in the Upper Paraná Atlantic Forest in Paraguay. We found A. montensis to be almost exclusively terrestrial (nonarboreal) and to vary in population density among locales and between years, findings consistent with earlier studies. Population density was not related either to neotropical seasonality or to most precipitation variables, but sex ratio varied seasonally, which has not been reported previously. We evaluated the seroprevalence of hantavirus in A. montensis, in association with external, populational, and individual variables. As in most previous studies of rodent–hantavirus systems, seroprevalence varied among sampling locales and was higher among males. However, unlike previous reports, especially those from North America, we did not find a correspondence between seroprevalence and population density, seasonal variation, or most precipitation variables. Simple and direct associations between seroprevalence levels and either seasonality or precipitation may be less characteristic of humid neotropical or subtropical systems. Our analyses revealed that seropositive animals exhibit several noteworthy behavioral and life-history modifications, in particular that they have larger home ranges than do seronegatives; exhibit greater maximum distance moved; have greater home range displacement between sampling sessions, particularly those individuals that are seroconverting during the same period; and have greater longevity, especially among males. In general, these characteristics could be postulated as favorable to the capacity of the virus to be transmitted horizontally to other hosts.

Phylogeny of Plecotine Bats: Reevaluation of Morphological and Chromosomal Data

Recent systematic studies of the tribe Plecotini have generated two alternative phylogenetic hierarchies: ( Barbastella ( Corynorhinus ( Plecotus ( Idionycteris Euderma )))); and ( Euderma \[including Idionycteris \] ( Barbastella ( Plecotus Corynorhinus ))). To test these hypotheses we examined 44–45 morphological and 11 karyological characters of 10 plecotine species, including Otonycteris hemprichii . Character states for the hypothetical ancestor were inferred by evaluation of selected outgroup taxa: Rhogeessa tumida, Nycticeius humeralis, Eptesicus fuscus, Myotis lucifugus, M. ciliolabrum , and Miniopterus schreibersi . The most parsimonious trees, identical in topology but different in character-state optimization, were congruent with the systematic hierarchy of Plecotini suggested by the first hypothesis. Otonycteris branched off before Corynorhinus . These results strongly support separation of Corynorhinus as an independent genus and limitation of Plecotus to Palaearctic species. The two highly derived taxa, Idionycteris phyllotis and Euderma maculatum , seem to be sufficiently different from each other to be regarded as genetically distinct. It is proposed that the tribe Plecotini originated in the eastern hemisphere.

Microhabitat characteristics of Akodon montensis, a reservoir for hantavirus, and hantaviral seroprevalence in an Atlantic forest site in eastern Paraguay

ABSTRACT: Hantaviruses may cause serious disease when transmitted to humans by their rodent hosts. Since their emergence in the Americas in 1993, there have been extensive efforts to understand the role of environmental factors on the presence of these viruses in their host rodent populations. HPS outbreaks have been linked to precipitation, but climatic factors alone have not been sufficient to predict the spatial-temporal dynamics of the environment-reservoir-virus system. Using a series of mark-recapture sampling sites located at the Mbaracayú Biosphere Reserve, an Atlantic Forest site in eastern Paraguay, we investigated the hypothesis that microhabitat might also influence the prevalence of Jaborá hantavirus within populations of its reservoir species, Akodon montensis. Seven trapping sessions were conducted during 2005–2006 at four sites chosen to capture variable microhabitat conditions within the study site. Analysis of microhabitat preferences showed that A. montensis preferred areas with little forest overstory and denser vegetation cover on and near the ground. Moreover, there was a significant difference in the microhabitat occupied by antibody-positive vs antibody-negative rodents, indicating that microhabitats with greater overstory cover may promote transmission and maintenance of hantavirus in A. montensis.

A habitat-based model for the spread of hantavirus between reservoir and spillover species

Abstract New habitat-based models for spread of hantavirus are developed which account for interspecies interaction. Existing habitat-based models do not consider interspecies pathogen transmission, a primary route for emergence of new infectious diseases and reservoirs in wildlife and man. The modeling of interspecies transmission has the potential to provide more accurate predictions of disease persistence and emergence dynamics. The new models are motivated by our recent work on hantavirus in rodent communities in Paraguay. Our Paraguayan data illustrate the spatial and temporal overlaps among rodent species, one of which is the reservoir species for Jabora virus and others which are spillover species. Disease transmission occurs when their habitats overlap. Two mathematical models, a system of ordinary differential equations (ODE) and a continuous-time Markov chain (CTMC) model, are developed for spread of hantavirus between a reservoir and a spillover species. Analysis of a special case of the ODE model provides an explicit expression for the basic reproduction number, R 0 , such that if R 0 < 1 , then the pathogen does not persist in either population but if R 0 > 1 , pathogen outbreaks or persistence may occur. Numerical simulations of the CTMC model display sporadic disease incidence, a new behavior of our habitat-based model, not present in other models, but which is a prominent feature of the seroprevalence data from Paraguay. Environmental changes that result in greater habitat overlap result in more encounters among various species that may lead to pathogen outbreaks and pathogen establishment in a new host.

Phylogenetic exploration of hantaviruses in paraguay reveals reassortment and host switching in South America

BackgroundLongitudinal mark-recapture studies of rodents in two sites in the Mbaracayú Biosphere Reserve in the Interior Atlantic Forest of eastern Paraguay have revealed a complex and intriguing pattern of hantaviruses harbored by rodents in this area. Full-length sequencing and phylogenetic analyses were conducted for several rodents from Akodon montensis and Oligoryzomys fornesi. The phylogenetic relationships of these viruses were analyzed in the context of hantaviruses in South America with published S- and M-segment sequences.FindingsPhylogenetic analyses of hantaviruses identified in the Mbaracayú Biosphere Reserve in Paraguay revealed Jabora and Juquitiba viruses are harbored by Akodon montensis and Oligoryzomys fornesi, respectively. These analyses revealed that in general the constituents of the major subclade for the S- and M-segments differ for the South American hantaviruses. Further, the two major groups within subclade C for the M-segment reflect in general the lethality associated with the viruses within each group.ConclusionsPhylogenetic studies of Jabora and Juquitiba viruses and other Paraguayan viruses in the context of American hantaviruses revealed reassortment and host-switching in the evolution of South American hantaviruses.

Fluctuating asymmetry in the cheetah: methodological and interpretive concerns

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