The isotopic niche of Atlantic, biting marine mammals and its relationship to skull morphology and body size.

Understanding the trophic niches of marine apex predators is necessary to understand interactions between species and to achieve sustainable, ecosystem-based fisheries management. Here, we review the stable carbon and nitrogen isotope ratios for biting marine mammals inhabiting the Atlantic Ocean to test the hypothesis that the relative position of each species within the isospace is rather invariant and that common and predictable patterns of resource partitioning exists because of constrains imposed by body size and skull morphology. Furthermore, we analyze in detail two species-rich communities to test the hypotheses that marine mammals are gape limited and that trophic position increases with gape size. The isotopic niches of species were highly consistent across regions and the topology of the community within the isospace was well conserved across the Atlantic Ocean. Furthermore, pinnipeds exhibited a much lower diversity of isotopic niches than odontocetes. Results also revealed body size as a poor predictor of the isotopic niche, a modest role of skull morphology in determining it, no evidence of gape limitation and little overlap in the isotopic niche of sympatric species. The overall evidence suggests limited trophic flexibility for most species and low ecological redundancy, which should be considered for ecosystem-based fisheries management.

Long-term assessment of trace elements in franciscana dolphins from the Río de la Plata estuary and adjacent Atlantic waters.

The estuary of Río de la Plata, in the eastern coast of South America, is a highly anthropized area that brings a high load of contaminants to the surrounding waters, which may have detrimental effects on the local marine fauna. The franciscana dolphin (Pontoporia blainvillei) is a small cetacean species endemic of the southwestern Atlantic Ocean listed as Vulnerable in the IUCN red list. In this study, we assessed the concentrations of 13 trace elements in bone samples from 100 franciscana dolphins that were found stranded dead or incidentally bycaught in the Río de la Plata and adjacent coast between 1953 and 2015. Elements were, in decreasing order of mean concentrations: Zn > Sr > Fe > Al > Mn > Cu > Pb > Cr > Ni > As > Hg > Cd > Se. The concentrations of Al, Cr and Fe were slightly higher in females than in males. The concentrations of As, Ni, and Pb significantly decreased with body length. Throughout the study period, the concentrations of Al, Cr, Cu, Fe, Mn and Ni significantly increased, while the concentrations of As, Pb and Sr significantly decreased. The increasing trends may be due to increased inputs from river discharges, the leather industry and petroleum refineries, while the decrease in Pb may be due to the ban in the use of this element as an additive in gasoline and as component of car batteries. This investigation supports the validity of analysing trace element in bone, a tissue available in scientific collections and museums, to retrospectively examine variation over long temporal scales and thus assess long-term trends in pollution.

Multiple forms of hotspots of tetrapod biodiversity and the challenges of open-access data scarcity.

The uneven spatial distribution of biodiversity is a defining feature of nature. In fact, the implementation of conservation actions both locally and globally has progressively been guided by the identification of biodiversity 'hotspots' (areas with exceptional biodiversity). However, different regions of the world differ drastically in the availability of fine-scale data on the diversity and distribution of species, thus limiting the potential to assess their local environmental priorities. Within South America-a megadiverse continent-Uruguay represents a peculiar area where multiple tropical and non-tropical eco-regions converge, creating highly heterogeneous ecosystems, but where the systematic quantification of biodiversity remains largely anecdotal. To investigate the constraints posed by the limited access to biodiversity data, we employ the most comprehensive database for tetrapod vertebrates in Uruguay (spanning 664 species) assembled to date, to identify hotspots of species-richness, endemism and threatened species for the first time. Our results reveal negligible spatial congruence among biodiversity hotspots, and that tetrapod sampling has historically concentrated in only a few areas. Collectively, our study provides a detailed account of the areas where urgent biodiversity monitoring efforts are needed to develop more accurate knowledge on biodiversity patterns, offering government and environmental bodies a critical scientific resource for future planning.

Borrelia burgdorferi sensu lato infecting Ixodes auritulus ticks in Uruguay.

In the southern cone of South America different haplotypes of Borrelia burgdorferi sensu lato (Bbsl) have been detected in Ixodes spp. from Argentina, southern Brazil, Chile, and Uruguay. So far, Lyme borreliosis has not been diagnosed in Uruguay and the medical relevance of the genus Ixodes in South America is uncertain. However, the growing number of new genospecies of Bbsl in the southern cone region and the scarce information about its pathogenicity, reservoirs and vectors, highlights the importance of further studies about spirochetes present in Uruguay and the region. The aim of this study was to determine the presence of Bbsl in Ixodes auritulus ticks collected from birds and vegetation in two localities of southeastern Uruguay. In total 306 I. auritulus were collected from 392 passerine birds sampled and 1110 ticks were collected by flagging in vegetation. Nymphs and females were analyzed for Borrelia spp. by PCR targeting the flagellin (fla) gene and the rrfA-rrlB intergenic spacer region (IGS). The phylogenetic analysis of Borrelia spp. positive samples from passerine birds and vegetation revealed the presence of four fla haplotypes that form a clade within the Bbsl complex. They were closely related to isolates of Borrelia sp. detected in I. auritulus from Argentina and Canada.

Biodiversidata: An Open-Access Biodiversity Database for Uruguay.

BACKGROUND: The continental and marine territories of Uruguay are characterised by a rich convergence of multiple biogeographic ecoregions of the Neotropics, making this country a peculiar biodiversity spot. However, despite the biological significance of Uruguay for the South American subcontinent, the distribution of biodiversity patterns in this country remain poorly understood, given the severe gaps in available records of geographic species distributions. Currently, national biodiversity datasets are not openly available and, thus, a dominant proportion of the primary biodiversity data produced by researchers and institutions across Uruguay remains highly dispersed and difficult to access for the wider scientific and environmental community. In this paper, we aim to fill this gap by developing the first comprehensive, open-access database of biodiversity records for Uruguay (Biodiversidata), which is the result of a large-scale collaboration involving experts working across the entire range of taxonomic diversity found in the country. NEW INFORMATION: As part of the first phase of Biodiversidata, we here present a comprehensive database of tetrapod occurrence records native from Uruguay, with the latest taxonomic updates. The database provides primary biodiversity data on extant Amphibia, Reptilia, Aves and Mammalia species recorded within the country. The total number of records collated is 69,380, spanning 673 species and it is available at the Zenodo repository: https://doi.org/10.5281/zenodo.2650169. This is the largest and most geographically and taxonomically comprehensive database of Uruguayan tetrapod species available to date and it represents the first open repository for the country.

Mouth gape determines the response of marine top predators to long-term fishery-induced changes in food web structure.

Here, we analyse changes throughout time in the isotopic niche of the Franciscana dolphin (Pontoporia blainvillei), the South American fur seal (Arctocephalus australis) and the South American sea lion (Otaria flavescens) from the Río de la Plata estuary and adjacent Atlantic Ocean to test the hypothesis that fishing may modify the diet of small-gape predators by reducing the average size of prey. The overall evidence, from stable isotope and stomach contents analyses, reveals major changes in resource partitioning between the three predators considered, mainly because of an increased access of Franciscana dolphins to juvenile demersal fishes. These results are consistent with the changes in the length distribution of demersal fish species resulting from fishing and suggest that Franciscana dolphin has been the most benefited species of the three marine mammal species considered because of its intermediate mouth gape. In conclusion, the impact of fishing on marine mammals goes beyond the simple reduction in prey biomass and is highly dependent on the mouth gape of the species involved.

DNA barcoding of sigmodontine rodents: identifying wildlife reservoirs of zoonoses.

Species identification through DNA barcoding is a tool to be added to taxonomic procedures, once it has been validated. Applying barcoding techniques in public health would aid in the identification and correct delimitation of the distribution of rodents from the subfamily Sigmodontinae. These rodents are reservoirs of etiological agents of zoonoses including arenaviruses, hantaviruses, Chagas disease and leishmaniasis. In this study we compared distance-based and probabilistic phylogenetic inference methods to evaluate the performance of cytochrome c oxidase subunit I (COI) in sigmodontine identification. A total of 130 sequences from 21 field-trapped species (13 genera), mainly from southern Brazil, were generated and analyzed, together with 58 GenBank sequences (24 species; 10 genera). Preliminary analysis revealed a 9.5% rate of misidentifications in the field, mainly of juveniles, which were reclassified after examination of external morphological characters and chromosome numbers. Distance and model-based methods of tree reconstruction retrieved similar topologies and monophyly for most species. Kernel density estimation of the distance distribution showed a clear barcoding gap with overlapping of intraspecific and interspecific densities < 1% and 21 species with mean intraspecific distance < 2%. Five species that are reservoirs of hantaviruses could be identified through DNA barcodes. Additionally, we provide information for the description of a putative new species, as well as the first COI sequence of the recently described genus Drymoreomys. The data also indicated an expansion of the distribution of Calomys tener. We emphasize that DNA barcoding should be used in combination with other taxonomic and systematic procedures in an integrative framework and based on properly identified museum collections, to improve identification procedures, especially in epidemiological surveillance and ecological assessments.

Borrelia burgdorferi sensu lato infecting ticks of the Ixodes ricinus complex in Uruguay: first report for the Southern Hemisphere.

The Borrelia burgdorferi sensu lato (s.l.) group comprises genetically related spirochetes, mostly associated with tick species belonging to the Ixodes ricinus complex in the Northern Hemisphere. The present study evaluated borrelial infection in the tick Ixodes pararicinus, which is the only representative species of the I. ricinus complex in Uruguay. A total of 137 I. pararicinus ticks were collected from deer, cattle, or vegetation in 2 Uruguayan Departments. A part of these ticks was tested directly by PCR targeting the borrelial gene flagellin (fla), whereas another part of the ticks was inoculated into Barbour-Stoenner-Kelly (BSK)-H medium in an attempt to isolate Borrelia. Overall, Borrelia infection was detected in 9 males and 1 nymphal tick pool. These ticks were found to be infected by unique fla haplotypes, which were shown through phylogenetic analysis to represent possibly 2 new B. burgdorferi s.l. genospecies, 1 associated with B. bissettii, the other phylogenetically closest to B. americana. These results were reinforced by PCR and DNA sequencing analyses of portions of 2 additional borrelial genes, rrfA-rrlB intergenic spacer region (IGS) and 16S rDNA (rrs). Weekly examinations of BSK cultures by dark-field microscopy failed to demonstrate live Borrelia through a 100-day incubation period. However, Borrelia DNA was detected by fla-PCR in culture media from 2 vials up to 90 days after inoculation. To the best of our knowledge, this is the first report of B. burgdorferi s.l. infecting ticks in South America.

Hosts, distribution and genetic divergence (16S rDNA) of Amblyomma dubitatum (Acari: Ixodidae).

We supply information about hosts and distribution of Amblyomma dubitatum. In addition, we carry out an analysis of genetic divergence among specimens of A. dubitatum from different localities and with respect to other Neotropical Amblyomma species, using sequences of 16S rDNA gene. Although specimens of A. dubitatum were collected on several mammal species as cattle horse, Tapirus terrestris, Mazama gouazoubira, Tayassu pecari, Sus scrofa, Cerdocyon thous, Myocastor coypus, Allouata caraya, Glossophaga soricina and man, most records of immature and adult stages of A. dubitatum were made on Hydrochoerus hydrochaeris, making this rodent the principal host for all parasitic stages of this ticks. Cricetidae rodents (Lundomys molitor, Scapteromys tumidus), opossums (Didelphis albiventris) and vizcacha (Lagostomus maximus) also were recorded as hosts for immature stages. All findings of A. dubitatum correspond to localities of Argentina, Brazil, Paraguay and Uruguay, and they were concentrated in the Biogeographical provinces of Pampa, Chaco, Cerrado, Brazilian Atlantic Forest, Parana Forest and Araucaria angustifolia Forest. The distribution of A. dubitatum is narrower than that of its principal host, therefore environmental variables rather than hosts determine the distributional ranges of this tick. The intraspecific genetic divergence among 16S rDNA sequences of A. dubitatum ticks collected in different localities from Argentina, Brazil and Uruguay was in all cases lower than 0.8%, whereas the differences with the remaining Amblyomma species included in the analysis were always bigger than 6.8%. Thus, the taxonomic status of A. dubitatum along its distribution appears to be certain at the specific level.

First report of mites (Gamasida: Laelapidae) parasitic on wild rodents in Uruguay, with new host records.

Information is presented for the first time on laelapid mites associated with wild rodents in Uruguay. Specimens of the following species were identified: Laelapinae: Androlaelaps fahrenholzi (Berlese), Androlaelaps rotundus (Fonseca), Gigantolaelaps wolffsohni (Oudemans), Laelaps paulistanensis (Fonseca), Laelaps manguinhosi (Fonseca) and Mysolaelaps microspinosus Fonseca; Haemogamasinae: Eulaelaps stabularis (Koch). Most of the ectoparasite-host associations are reported for the first time. New host and locality records presented in this study are in accordance with previous findings on the same and/or related host species in nearby South American localities.

First report of mites (Gamasida: Laelapidae) parasitic on wild rodents in Uruguay, with new host records

Information is presented for the first time on laelapid mites associated with wild rodents in Uruguay. Specimens of the following species were identified: Laelapinae: Androlaelaps fahrenholzi (Berlese), Androlaelaps rotundus (Fonseca), Gigantolaelaps wolffsohni (Oudemans), Laelaps paulistanensis (Fonseca), Laelaps manguinhosi (Fonseca) and Mysolaelaps microspinosus Fonseca; Haemogamasinae: Eulaelaps stabularis (Koch). Most of the ectoparasite-host associations are reported for the first time. New host and locality records presented in this study are in accordance with previous findings on the same and/or related host species in nearby South American localities.

Se presenta por primera vez información sobre ácaros lelápidos asociados a roedores silvestres en Uruguay. Se identificaron especímenes de las siguientes especies: Laelapinae: Androlaelaps fahrenholzi (Berlese), Androlaelaps rotundus (Fonseca), Gigantolaelaps wolffsohni (Oudemans), Laelaps paulistanensis Fonseca, Laelaps manguinhosi Fonseca y Mysolaelaps microspinosus Fonseca; Haemogamasinae: Eulaelaps stabularis (Koch). La mayoría de las asociaciones ectoparásito-hospedador se registran por primera vez. Los nuevos registros de hospedador y localidad que se presentan en este estudio coinciden con hallazgos previos en las mismas, o estrechamente relacionadas, especies hospedadoras en localidades cercanas de Sud América.