Late Cenozoic history and the role of Beringia in assembling a Holarctic cestode species complex.

The dynamic climate history that drove sea level fluctuation during past glacial periods mediated the movement of organisms between Asia and North America via the Bering Land Bridge. Investigations of the biogeographic histories of small mammals and their parasites demonstrate facets of a complex history of episodic geographic colonization and refugial isolation that structured diversity across the Holarctic. We use a large multi-locus nuclear DNA sequence dataset to robustly resolve relationships within the cestode genus Arostrilepis (Cyclophyllidea: Hymenolepididae), a widespread parasite of predominantly arvicoline rodents (voles, lemmings). Using this phylogeny, we confirm that several Asian Arostrilepis lineages colonized North America during up to four distinct glacial periods in association with different rodent hosts, consistent with taxon-pulse dynamics. A previously inferred westward dispersal across the land bridge is rejected. We also refine interpretations of past host colonization, providing evidence for several distinct episodes of expanding host range, which probably contributed to diversification by Arostrilepis. Finally, Arostrilepis is shown to be paraphyletic with respect to Hymenandrya thomomyis, a parasite of pocket gophers, confirming that ancient Arostrilepis species colonized new host lineages upon arriving in North America.

MORPHOMETRY OF FIRST-STAGE LARVAE OF ORTHOSTRONGYLUS MACROTIS (NEMATODA: PROTOSTRONGYLIDAE), LUNGWORM OF WILD UNGULATES FROM WESTERN NORTH AMERICA.

Orthostrongylus macrotis (Dikmans, 1931) is a protostrongylid lungworm in wild ungulates from western North America, including mule and Columbia black-tailed deer, pronghorn, and rarely moose and elk. The lack of morphological data for certain developmental stages of O. macrotis and the unresolved taxonomic status of the genus indicate a more detailed morphological characterization of the species is necessary. We provide a detailed description of first-stage larvae (L1) of O. macrotis including morphological, morphometric, and molecular data. Species identity was confirmed based on molecular sequence data from the internal transcribed spacer subunit 2 (ITS-2) and large subunit (28S) rDNA. A fragment of the cytochrome oxidase c subunit 1 (COI) was also sequenced, followed by the determination of genetic distance and phylogenetic analyses. Integrated data describing L1 of O. macrotis contributes to a broader understanding of the parasite fauna of wild ungulates from North America and may be of relevance for a future revision of the genus. Further, we outline information for differentiation among species of North American protostrongylids, with typical spike-tailed L1s, circulating among free-ranging and semi-domestic ungulates.

Ecological super-spreaders drive host-range oscillations: Omicron and risk space for emerging infectious disease.

The unusual genetic diversity of the Omicron strain has led to speculation about its origin. The mathematical modelling platform developed for the Stockholm Paradigm (SP) indicates strongly that it has retro-colonized humans from an unidentified nonhuman mammal, likely originally infected by humans. The relationship between Omicron and all other SARS-CoV-2 variants indicates oscillations among hosts, a core part of the SP. Such oscillations result from the emergence of novel variants following colonization of new hosts, replenishing and expanding the risk space for disease emergence. The SP predicts that pathogens colonize new hosts using pre-existing capacities. Those events are thus predictable to a certain extent. Novel variants emerge after a colonization and are not predictable. This makes it imperative to take proactive measures for anticipating emerging infectious diseases (EID) and mitigating their impact. The SP suggests a policy protocol, DAMA, to accomplish this goal. DAMA comprises: DOCUMENT to detect pathogens before they emerge in new places or colonize new hosts; ASSESS to determine risk; MONITOR to detect changes in pathogen populations that increase the risk of outbreaks and ACT to prevent outbreaks when possible and minimize their impact when they occur.

Food security and emerging infectious disease: risk assessment and risk management.

Climate change, emerging infectious diseases (EIDs) and food security create a dangerous nexus. Habitat interfaces, assumed to be efficient buffers, are being disrupted by human activities which in turn accelerate the movement of pathogens. EIDs threaten directly and indirectly availability and access to nutritious food, affecting global security and human health. In the next 70 years, food-secure and food-insecure countries will face EIDs driving increasingly unsustainable costs of production, predicted to exceed national and global gross domestic products. Our modern challenge is to transform this business as usual and embrace an alternative vision of the biosphere formalized in the Stockholm paradigm (SP). First, a pathogen-centric focus shifts our vision of risk space, determining how pathogens circulate in realized and potential fitness space. Risk space and pathogen exchange are always heightened at habitat interfaces. Second, apply the document-assess-monitor-act (DAMA) protocol developing strategic data for EID risk, to be translated, synthesized and broadcast as actionable information. Risk management is realized through targeted interventions focused around information exchanged among a community of scientists, policy practitioners of food and public health security and local populations. Ultimately, SP and DAMA protect human rights, supporting food security, access to nutritious food, health interventions and environmental integrity.

Emerging infectious disease: An underappreciated area of strategic concern for food security.

Emerging infectious diseases (EIDs) increasingly threaten global food security and public health. Despite technological breakthroughs, we are losing the battle with (re)emerging diseases as treatment costs and production losses rise. A horizon scan of diseases of crops, livestock, seafood and food-borne illness suggests these costs are unsustainable. The paradigm of coevolution between pathogens and particular hosts teaches that emerging diseases occur only when pathogens evolve specific capacities that allow them to move to new hosts. EIDs ought to be rare and unpredictable, so crisis response is the best we can do. Alternatively, the Stockholm Paradigm suggests that the world is full of susceptible but unexposed hosts that pathogens could infect, given the opportunity. Global climate change, globalized trade and travel, urbanization and land-use changes (often associated with biodiversity loss) increase those opportunities, making EID frequent. We can, however, anticipate their arrival in new locations and their behaviour once they have arrived. We can 'find them before they find us', mitigating their impacts. The DAMA (Document, Assess, Monitor, Act) protocol alters the current reactive stance and embodies proactive solutions to anticipate and mitigate the impacts of EID, extending human and material resources and buying time for development of new vaccinations, medications and control measures.

Leveraging natural history biorepositories as a global, decentralized, pathogen surveillance network.

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic reveals a major gap in global biosecurity infrastructure: a lack of publicly available biological samples representative across space, time, and taxonomic diversity. The shortfall, in this case for vertebrates, prevents accurate and rapid identification and monitoring of emerging pathogens and their reservoir host(s) and precludes extended investigation of ecological, evolutionary, and environmental associations that lead to human infection or spillover. Natural history museum biorepositories form the backbone of a critically needed, decentralized, global network for zoonotic pathogen surveillance, yet this infrastructure remains marginally developed, underutilized, underfunded, and disconnected from public health initiatives. Proactive detection and mitigation for emerging infectious diseases (EIDs) requires expanded biodiversity infrastructure and training (particularly in biodiverse and lower income countries) and new communication pipelines that connect biorepositories and biomedical communities. To this end, we highlight a novel adaptation of Project ECHO's virtual community of practice model: Museums and Emerging Pathogens in the Americas (MEPA). MEPA is a virtual network aimed at fostering communication, coordination, and collaborative problem-solving among pathogen researchers, public health officials, and biorepositories in the Americas. MEPA now acts as a model of effective international, interdisciplinary collaboration that can and should be replicated in other biodiversity hotspots. We encourage deposition of wildlife specimens and associated data with public biorepositories, regardless of original collection purpose, and urge biorepositories to embrace new specimen sources, types, and uses to maximize strategic growth and utility for EID research. Taxonomically, geographically, and temporally deep biorepository archives serve as the foundation of a proactive and increasingly predictive approach to zoonotic spillover, risk assessment, and threat mitigation.

High prevalence, intensity, and genetic diversity of Trichinella spp. in wolverine (Gulo gulo) from Yukon, Canada.

BACKGROUND: Species of Trichinella are globally important foodborne parasites infecting a number of domestic and wild vertebrates, including humans. Free-ranging carnivores can act as sentinel species for detection of Trichinella spp. Knowledge of the epidemiology of these parasites may help prevent Trichinella spp. infections in northern Canadian animals and people. Previous research on Trichinella spp. in wildlife from Yukon did not identify risk factors associated with infection, or the diversity and identity of species of Trichinella in regional circulation, based on geographically extensive sampling with large sample sizes. METHODS: In a cross-sectional study, we determined the prevalence, infection intensity, risk factors, and species or genotypes of Trichinella in wolverine (Gulo gulo) in two regions of Yukon, Canada, from 2013-2017. A double separatory funnel digestion method followed by mutiplex PCR and PCR-RFLP were used to recover and identify species of Trichinella, respectively. RESULTS: We found larvae of Trichinella in the tongues of 78% (95% CI 73-82) of 338 wolverine sampled. The odds of adult (≥ 2 years) and yearling (1 year) wolverine being Trichinella spp.-positive were four and two times higher, respectively, compared to juveniles (<1 year). The odds of Trichinella spp. presence were three times higher in wolverine from southeast than northwest Yukon. The mean intensity of infection was 22.6 ± 39 (SD, range 0.1-295) larvae per gram. Trichinella T6 was the predominant genotype (76%), followed by T. nativa (8%); mixed infections with Trichinella T6 and T. nativa (12%) were observed. In addition, T. spiralis was detected in one wolverine. Out of 22 isolates initially identified as T. nativa in multiplex PCR, 14 were analyzed by PCR-RFLP to distinguish them from T. chanchalensis, a recently discovered cryptic species, which cannot be distinguished from the T. nativa on multiplex PCR. Ten isolates were identified either as T. chanchalensis alone (n = 7), or mixed infection with T. chanchalensis and T. nativa (n = 2) or T. chanchalensis and Trichinella T6 (n = 1)]. CONCLUSIONS: Wolverine hosted high prevalence, high larval intensity, and multiple species of Trichinella, likely due to their scavenging habits, apex position in the food chain, and wide home range. Wolverine (especially adult males) should be considered as a sentinel species for surveys for Trichinella spp. across their distributional range.

When parasites persist: tapeworms survive host extinction and reveal waves of dispersal across Beringia.

Investigations of intercontinental dispersal between Asia and North America reveal complex patterns of geographic expansion, retraction and isolation, yet historical reconstructions are largely limited by the depth of the record that is retained in patterns of extant diversity. Parasites offer a tool for recovering deep historical insights about the biosphere, improving the resolution of past community-level interactions. We explored biogeographic hypotheses regarding the history of dispersal across Beringia, the region intermittently linking Asia and North America, through large-scale multi-locus phylogenetic analyses of the genus Schizorchis, an assemblage of host-specific cestodes in pikas (Lagomorpha: Ochotonidae). Our genetic data support palaeontological evidence for two separate geographic expansions into North America by Ochotona in the late Tertiary, a history that genomic evidence from extant pikas does not record. Pikas descending from the first colonization of Miocene age persisted into the Pliocene, subsequently coming into contact with a second wave of Nearctic colonists from Eurasia before going extinct. Spatial and temporal overlap of historically independent pika populations provided a window for host colonization, allowing persistence of an early parasite lineage in the contemporary fauna following the extinction of its ancestral hosts. Empirical evidence for ancient 'ghost assemblages' of hosts and parasites demonstrates how complex mosaic faunas are assembled in the biosphere through episodes of faunal mixing encompassing parasite lineages across deep and shallow time.

Parasite intensity drives fetal development and sex allocation in a wild ungulate.

An understanding of the mechanisms influencing prenatal characteristics is fundamental to comprehend the role of ecological and evolutionary processes behind survival and reproductive success in animals. Although the negative influence of parasites on host fitness is undisputable, we know very little about how parasitic infection in reproductive females might influence prenatal factors such as fetal development and sex allocation. Using an archival collection of Dall's sheep (Ovis dalli dalli), a capital breeder that depends on its body reserves to overcome the arctic winter, we investigated the direct and indirect impacts of the parasite community on fetal development and sex allocation. Using partial least squares modelling, we observed a negative effect of parasite community on fetal development, driven primarily by the nematode Marshallagia marshalli. Principal component analysis demonstrated that mothers with low parasite burden and in good body condition were more likely to have female versus male fetuses. This association was primarily driven by the indirect effect of M. marshalli on ewe body condition. Refining our knowledge of the direct and indirect impact that parasite communities can have on reproduction in mammals is critical for understanding the effects of infectious diseases on wildlife populations. This can be particularly relevant for species living in ecosystems sensitive to the effects of global climate change.

Wild ruminants as reservoirs of domestic livestock gastrointestinal nematodes.

Gastrointestinal nematode (GIN) infections in cattle cause appetite suppression which leads to poor feed conversion, reduced weight gain and reduced milk production. Overuse and exclusive reliance on anthelmintic drugs has resulted in widespread resistance in many parasitic nematode species infecting livestock making control increasingly difficult. Wild ruminants are competent hosts of a number of nematode species that typically infect and are best adapted for cattle, sheep, and goats. Thus, the potential exists for wild ruminants to act as reservoirs in the translocation of domestic GIN, including those carrying anthelmintic resistance mutations as well as susceptible genotypes. The potential for parasite exchange is heightened by interfaces or ecotones between managed and wild rangelands, and by perturbations linked to climate warming that can increasingly alter the distributions of wild ungulates and their interactions with domestic and free-ranging ruminants. To investigate the extent to which wild ruminants harbour parasites capable of infecting domestic ruminants we first performed an epidemiological study of feces from wildlife hosts that spanned 16 states and included white-tailed deer (85 % of the samples), pronghorn, elk, mule deer, bighorn sheep, moose, cattle, and caribou across the United States. All samples were cultured to third stage larvae and nematode DNA was isolated and PCR amplified. Among the 548 wild ruminant samples received, 33 % (181 samples) were positive for nematode DNA, among which half (84 samples) contained DNA from GIN species commonly found in cattle. DNA from cattle GIN species was detected in 46 % of samples from the Northeast, 42 % from the Southeast, 10 % from the Midwest, 0 % from the Southwest and 11 % from the West. Deep amplicon sequencing of the ITS-2 rDNA indicated that Ostertagia and Trichostrongylus were present in 90 % and 69 % of the nematode DNA positive samples, respectively, whereas Haemonchus, Cooperia and Oesophagostomum were present in 26 %, 2 % and 10 % of the samples, respectively. These data clearly show that wild ruminants commonly harbour multiple parasite species whose primary hosts are domestic cattle, and suggest that further work is warranted to investigate their specific roles in the management of anthelmintic resistance.

Hiding in plain sight: discovery and phylogeography of a cryptic species of Trichinella (Nematoda: Trichinellidae) in wolverine (Gulo gulo).

Understanding parasite diversity and distribution is essential in managing the potential impact of parasitic diseases in animals and people. Imperfect diagnostic methods, however, may conceal cryptic species. Here, we report the discovery and phylogeography of a previously unrecognized species of Trichinella in wolverine (Gulo gulo) from northwestern Canada that was indistinguishable from T. nativa using the standard multiplex PCR assay based on the expansion segment 5 (ESV) of ribosomal DNA. The novel genotype, designated as T13, was discovered when sequencing the mitochondrial genome. Phylogenetic analyses of the mitochondrial genome and of 15 concatenated single copy orthologs of nuclear DNA indicated a common ancestor for the encapsulated clade is shared by a subclade containing Trichinella spiralis and Trichinella nelsoni, and a subclade containing T13 and remaining taxa: T12 + (T2 + T6) + [(T5 + T9) + (T3 + T8)]. Of 95 individual hosts from 12 species of mammalian carnivores from northwestern Canada from which larvae were identified as T. nativa on multiplex PCR, only wolverines were infected with T13 (14 of 42 individuals). These infections were single or mixed with T. nativa and/or T6. Visual examination and motility testing confirmed that T13 is encapsulated and likely freeze-tolerant. We developed a new Polymerase Chain Reaction-Restriction Fragment Length Polymorphism which unequivocally distinguishes between T13 and T. nativa. We propose Trichinella chanchalensis n. sp. for T13, based on significant genetic divergence from other species of Trichinella and broad-based sampling of the Trichinella genome. Exploration of Alaskan and Siberian isolates may contribute to further resolution of a phylogeographically complex history for species of Trichinella across Beringia, including Trichinella chanchalensis n. sp. (T13).

Phenotypic plasticity and local adaptation in freeze tolerance: Implications for parasite dynamics in a changing world.

Marshallagia marshalli is a multi-host gastrointestinal nematode that infects a variety of artiodactyl species from temperate to Arctic latitudes. Eggs of Marshallagia are passed in host faeces and develop through three larval stages (L1, L2, and L3) in the environment. Although eggs normally hatch as L1s, they can also hatch as L3s. We hypothesised that this phenotypic plasticity in hatching behaviour may improve fitness in subzero and highly variable environments, and this may constitute an evolutionary advantage under current climate change scenarios. To test this, we first determined if the freeze tolerance of different free-living stages varied at different temperatures (-9 °C, -20 °C and -35 °C). We then investigated if there were differences in freeze tolerance of M. marshalli eggs sourced from three discrete, semi-isolated, populations of wild bighorn and thinhorn sheep living in western North America (latitudes: 40°N, 50°N, 64°N). The survival rates of eggs and L3s were significantly higher than L1s at -9 °C and -20 °C, and survival of all three stages decreased significantly with increasing freeze duration and decreasing temperature. The survival of unhatched L1s was significantly higher than the survival of hatched L1s. There was no evidence of local thermal adaptation in freeze tolerance among eggs from different locations. We conclude that developing to the L3 in the egg may result in a fitness advantage for M. marshalli, with the egg protecting the more vulnerable L1 under freezing conditions. This phenotypic plasticity in life-history traits of M. marshalli might be an important capacity, a potential exaptation capable of enhancing parasite fitness under temperature extremes.

The biogeography of the caribou lungworm, Varestrongylus eleguneniensis (Nematoda: Protostrongylidae) across northern North America.

Varestrongylus eleguneniensis (Nematoda; Protostrongylidae) is a recently described species of lungworm that infects caribou (Rangifer tarandus), muskoxen (Ovibos moschatus) and moose (Alces americanus) across northern North America. Herein we explore the geographic distribution of V. eleguneniensis through geographically extensive sampling and discuss the biogeography of this multi-host parasite. We analyzed fecal samples of three caribou subspecies (n = 1485), two muskox subspecies (n = 159), and two moose subspecies (n = 264) from across northern North America. Protostrongylid dorsal-spined larvae (DSL) were found in 23.8%, 73.6%, and 4.2% of these ungulates, respectively. A portion of recovered DSL were identified by genetic analyses of the ITS-2 region of the nuclear rDNA or the cytochrome oxidase c subunit I (COI) region of the mtDNA. We found V. eleguneniensis widely distributed among caribou and muskox populations across most of their geographic prange in North America but it was rare in moose. Parelaphostrongylus andersoni was present in caribou and moose and we provide new geographic records for this species. This study provides a substantial expansion of the knowledge defining the current distribution and biogeography of protostrongylid nematodes in northern ungulates. Insights about the host and geographic range of V. eleguneniensis can serve as a geographically extensive baseline for monitoring current distribution and in anticipating future biogeographic scenarios under a regime of accelerating climate and anthropogenic perturbation.

Discovery of Arostrilepis tapeworms (Cyclophyllidea: Hymenolepididae) and new insights for parasite species diversity from Eastern North America.

Species of the genus Arostrilepis were discovered and definitively identified for the first time in rodents from geographically disparate localities along the Appalachian Mountain range of eastern North America (West Virginia, Virginia, and Maine). These are the first confirmed records for species of Arostrilepis occurring east of the Rocky Mountains and the Mississippi River in North America. Arostrilepis gardneri n. sp. is described on the basis of specimens obtained from two phylogenetically divergent rodent hosts: Southern Red-Backed Vole Myodes gapperi (Cricetidae: Arvicolinae) (from West Virginia) and the Woodland Jumping Mouse Napaeozapus insignis (Dipodidae: Zapodinae) (West Virginia, Virginia, and Maine). Additionally, in a mixed infection, specimens of Arostrilepis insperata n. sp. were also found in a Southern Red-Backed Vole from West Virginia. These previously unknown species are primarily distinguished from congeners based on shape, dimensions, and spination (pattern, shape, and size of spines) of the cirrus. Specimens of A. gardneri n. sp. are further characterized by the relative position and length of the cirrus-sac, arrangement of the testes, and relative size of the external seminal vesicle and seminal receptacle. Specimens of A. insperata n. sp. are structurally most similar to A. macrocirrosa from the western Nearctic and Palearctic but with consistently greater dimensions for the cirrus-sac, testes, and seminal receptacle. Phylogenetic analysis of Arostrilepis spp. using partial sequences of the mitochondrial cytochrome b gene and the nuclear second ribosomal internal transcribed spacer strongly supported the status of A. gardneri n. sp. and A. insperata n. sp. within an unresolved clade of congeners in Red-Backed Voles (Myodini and species of Myodes). Our observations extend the known geographic distribution for species of Arostrilepis to the Appalachian Mountains in either a disjunct or possibly continuous but patchy range across North America. Prior observations, summarizing field and museum collections, had suggested that geographic ranges for a diverse assemblage of Arostrilepis in North America were largely restricted to the north-western region of the continent, with historical connections to Beringia and Eurasia. Recognition of a more extensive distribution is consistent with a history of episodic biotic expansion and isolation under a dynamic of taxon pulses for arvicoline rodents and an associated parasite fauna in the Nearctic during the Quaternary. Occurrence in a dipodid rodent represents an event of host colonization from an arvicoline source.

Conservation Genomics in a Changing Arctic.

Although logistically challenging to study, the Arctic is a bellwether for global change and is becoming a model for questions pertinent to the persistence of biodiversity. Disruption of Arctic ecosystems is accelerating, with impacts ranging from mixing of biotic communities to individual behavioral responses. Understanding these changes is crucial for conservation and sustainable economic development. Genomic approaches are providing transformative insights into biotic responses to environmental change, but have seen limited application in the Arctic due to a series of limitations. To meet the promise of genome analyses, we urge rigorous development of biorepositories from high latitudes to provide essential libraries to improve the conservation, monitoring, and management of Arctic ecosystems through genomic approaches.

Adaptations and phenotypic plasticity in developmental traits of Marshallagia marshalli.

Despite the economic, social and ecological importance of the ostertagiine abomasal nematode Marshallagia marshalli, little is known about its life history traits and its adaptations to cope with environmental extremes. Conserved species-specific traits can act as exaptations that may enhance parasite fitness in changing environments. Using a series of experiments, we revealed several unique adaptations of the free-living stages of M. marshalli that differ from other ostertagiines. Eggs were isolated from the feces of bighorn sheep (Ovis canadensis) from the Canadian Rocky Mountains and were cultured at different temperatures and with different media. Hatching occurred primarily as L1s in an advanced stage of development, morphologically very similar to a L2. When cultured at 20 °C, however, 2.86% of eggs hatched as L3, with this phenomenon being significantly more common at higher temperatures, peaking at 30 °C with 28.95% of eggs hatching as L3s. After hatching, free-living larvae of M. marshalli did not feed nor grow as they matured from L1 to infective L3. These life history traits seem to be adaptations to cope with the extreme environmental conditions that Marshallagia faces across its extensive latitudinal distribution in North America and Eurasia. In order to refine the predictions of parasite dynamics under scenarios of a changing climate, basic life history traits and temperature-dependent phenotypic behaviour should be incorporated into models for parasite biology.

Building an integrated infrastructure for exploring biodiversity: field collections and archives of mammals and parasites.

Museum specimens play an increasingly important role in predicting the outcomes and revealing the consequences of anthropogenically driven disruption of the biosphere. As ecological communities respond to ongoing environmental change, host-parasite interactions are also altered. This shifting landscape of host-parasite associations creates opportunities for colonization of different hosts and emergence of new pathogens, with implications for wildlife conservation and management, public health, and other societal concerns. Integrated archives that document and preserve mammal specimens along with their communities of associated parasites and ancillary data provide a powerful resource for investigating, anticipating, and mitigating the epidemiological, ecological, and evolutionary impacts of environmental perturbation. Mammalogists who collect and archive mammal specimens have a unique opportunity to expand the scope and impact of their field work by collecting the parasites that are associated with their study organisms. We encourage mammalogists to embrace an integrated and holistic sampling paradigm and advocate for this to become standard practice for museum-based collecting. To this end, we provide a detailed, field-tested protocol to give mammalogists the tools to collect and preserve host and parasite materials that are of high quality and suitable for a range of potential downstream analyses (e.g., genetic, morphological). Finally, we also encourage increased global cooperation across taxonomic disciplines to build an integrated series of baselines and snapshots of the changing biosphere. Los especímenes de museo desempeñan un papel cada vez más importante tanto en la descripción de los resultados de la alteración antropogénica de la biosfera como en la predicción de sus consecuencias. Dado que las comunidades ecológicas responden al cambio ambiental, también se alteran las interacciones hospedador-parásito. Este panorama cambiante de asociaciones hospedador-parásito crea oportunidades para la colonización de diferentes hospedadores y para la aparición de nuevos patógenos, con implicancias en la conservación y manejo de la vida silvestre, la salud pública y otras preocupaciones de importancia para la sociedad. Archivos integrados que documentan y preservan especímenes de mamíferos junto con sus comunidades de parásitos y datos asociados, proporcionan un fuerte recurso para investigar, anticipar y mitigar los impactos epidemiológicos, ecológicos y evolutivos de las perturbaciones ambientales. Los mastozoólogos que recolectan y archivan muestras de mamíferos, tienen una oportunidad única de ampliar el alcance e impacto de su trabajo de campo mediante la recolección de los parásitos que están asociados con los organismos que estudian. Alentamos a los mastozoólogos a adoptar un paradigma de muestreo integrado y holístico y abogamos para que esto se convierta en una práctica estándarizada de la obtención de muestras para museos. Con este objetivo, proporcionamos un protocolo detallado y probado en el campo para brindar a los mastozoólogos las herramientas para recolectar y preservar materiales de parásitos y hospedadores de alta calidad y adecuados para una gran variedad de análisis subsecuentes (e.g., genéticos, morfológicos, etc.). Finalmente, también abogamos por una mayor cooperación global entre las diversas disciplinas taxonómicas para construir una serie integrada de líneas de base y registros actuales de nuestra cambiante biosfera.

Museum metabarcoding: A novel method revealing gut helminth communities of small mammals across space and time.

Natural history collections spanning multiple decades provide fundamental historical baselines to measure and understand changing biodiversity. New technologies such as next generation DNA sequencing have considerably increased the potential of museum specimens to address significant questions regarding the impact of environmental changes on host and parasite/pathogen dynamics. We developed a new technique to identify intestinal helminth parasites and applied it to shrews (Eulipotyphla: Soricidae) because they are ubiquitous, occupy diverse habitats, and host a diverse and abundant parasite fauna. Notably, we included museum specimens preserved in various ways to explore the efficacy of using metabarcoding analyses that may enable identification of helminth symbiont communities from historical archives. We successfully sequenced the parasite communities (using 12S mtDNA, 16S mtDNA, 28S rDNA) of 23 whole gastrointestinal tracts. All gastrointestinal tracts were obtained from the Museum of Southwestern Biology, USA, and from recent field collections, varying both in time since fixation (ranging from 4 months to 16 years) and preservation method (70% or 95% ethanol stored at room temperature, or flash frozen in liquid nitrogen and stored at -80 °C). Our proof of concept demonstrates the feasibility of applying next generation DNA sequencing techniques to authoritatively identify the parasite/pathogen communities within whole gastrointestinal tracts from museum specimens of varying age and fixation, and the value of future preservation of host-associated whole gastrointestinal tracts in public research archives. This powerful approach facilitates future comparative examinations of the distributions and interactions among multiple associated groups of organisms through time and space.

A cryptic species of Onchocerca (Nematoda: Onchocercidae) in blackflies (Simulium spp.) from southern California, USA.

BACKGROUND: Entomological surveillance for pathogens based on molecular screening of putative arthropod vectors such as blackflies (Diptera: Simuliidae) is becoming increasingly important. Surveillance provides a means to understand host and geographical patterns of underestimated biodiversity among North American species of Onchocerca and a pathway to identify and track expanding emergence of the zoonotic Onchocerca lupi. Herein, we have screened two blackfly species, Simulium tescorum and Simulium vittatum (s.l.), from Los Angeles County, southern California, USA for DNA of filarioid nematodes to better understand species richness and limits within the genus Onchocerca. METHODS: A total of 1056 and 378 female blackflies was collected using CO2-baited mosquito traps from March to November of 2015 and 2016, respectively. All blackflies during 2015 were individually processed for DNA extraction and PCR targeting of the cytochrome c oxidase subunit 1 (cox1) of the mitochondrial DNA (mtDNA). Specimens of S. tescorum collected in 2016 were processed individually with heads and bodies extracted separately, whereas those of S. vittatum (s.l.) were processed in pooled samples with heads and bodies extracted separately. A subset of filarioid-positive samples from 2015 and all samples from 2016 were screened using a PCR targeting the NADH dehydrogenase subunit 5 (nad5) gene (mtDNA). RESULTS: In 2015, 356 S. tescorum (33.7%) and 683 S. vittatum (s.l.) (64.7%) were collected, and an additional 17 specimens were not assessed morphologically. In 2016, a total of 378 blackflies was collected. Of these, 43 (11.6%) were S. tescorum and 327 (88.4%) were S. vittatum (s.l.), and an additional 8 specimens were not assessed morphologically. In 2015, Onchocerca sequences were detected in 4.8% (n = 17) of S. tescorum samples, and only one S. vittatum (0.15%). In 2016, only a single S. vittatum pool was positive for the same cryptic Onchocerca species. In phylogenetic comparisons based on nad5, the Onchocerca sequences from California formed a clade with those isolates in white-tailed deer from upstate New York, suggesting these belong to a single widespread cryptic species. CONCLUSIONS: An uncharacterized species of Onchocerca associated with cervid hosts was found in blackflies from southern California. Sequence data demonstrated it is likely conspecific with an unnamed species of Onchocerca previously found in white-tailed deer from upstate New York. Current data support recognition of a broad geographical distribution across North America for an apparently cryptic species of Onchocerca that is discrete from O. cervipedis, considered to be a typical filarioid among cervids. Our data suggest that this cryptic species of Onchocerca may infect subspecies of white-tailed deer (Odocoileus virginianus), and mule and black-tailed deer (Odocoileus hemionus) at temporal latitudes. The blackflies Simulium tescorum and S. vittatum (s.l.) (presumably, S. tribulatum) are putative vectors. Discovery of a cryptic complex indicates that species diversity and putative associations for definitive hosts and vectors of Onchocerca species in North America must be reassessed.