Vasyl Tkach

Vasyl Tkach
University of North Dakota | UND · Department of Biology

Ph.D., D.Sc.,

About

485
Publications
75,857
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6,160
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Introduction
Vasyl Tkach currently works at the Department of Biology, University of North Dakota. Vasyl does research in Zoology, Systematics (Taxonomy) and Evolutionary Biology.
Additional affiliations
January 2003 - present
University of North Dakota
Position
  • Professor (Full)

Publications

Publications (485)
Article
Full-text available
Schistosomatidae Stiles and Hassall 1898 is a medically significant family of digenetic trematodes (Trematoda: Digenea), members of which infect mammals or birds as definitive hosts and aquatic or amphibious gastropods as intermediate hosts. Currently, there are 17 named genera, for many of which evolutionary interrelationships remain unresolved. T...
Article
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Renschetrematidae is a very small family of digeneans parasitic in bats in southern and Southeast Asia. According to the original descriptions and the latest revision, its representatives are characterized by the presence of several unusual characters. Among them are the dorsal position of the genital pores, separate male and female genital pores,...
Article
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Avian haemosporidians from the genera Plasmodium and Haemoproteus are vector transmitted parasites. A growing body of evidence suggests that variation in their prevalence within avian communities is correlated with a variety of avian ecological traits. Here, we examine the relationship between infection probability and diversity of haemosporidian l...
Article
The Proterodiplostomidae Dubois, 1936 is a family of digeneans within the superfamily Diplostomoidea Poirier, 1886. Members of the family are distributed mostly in the tropics and subtropics, primarily in crocodilians, although some species are known from other reptiles. Despite their broad geographical distribution, the knowledge of proterodiplost...
Article
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Philophthalmus is a cosmopolitan genus of digeneans that includes ocular parasites of birds and mammals. Despite broad distribution and veterinary importance of these digeneans, there are still gaps in knowledge about their diversity and biology , especially in South America. Herein, we conducted morphological, life cycle, and molecular studies of...
Article
Ochoterenatrema is a small genus of lecithodendriid digeneans that includes 6 species parasitic in Neotropical bats in North and South America. Members of this genus are characterized by the presence of a pseudogonotyl formed by thickened tegument on the left side of the ventral sucker. We examined morphology of specimens belonging to five species...
Article
Fibricola and Neodiplostomum are diplostomid genera with extremely similar morphology that are currently separated based on their definitive hosts, i.e., Fibricola spp. are normally found in mammals, while Neodiplostomum spp. typically parasitize birds. Prior to our study, no DNA sequence data was available for any member of Fibricola. We generated...
Article
The Diplostomidae Poirier, 1886 is a large, globally distributed family of digeneans parasitic in intestines of their definitive hosts. Diplostomum and Tylodelphys spp. are broadly distributed, commonly reported, and the most often sequenced diplostomid genera. The majority of published DNA sequences from these genera originated from larval stages...
Article
Pharyngostomoides, Alaria and Didelphodiplostomum are among genera of diplostomid digeneans known to parasitize mammalian definitive hosts. Despite numerous recent molecular phylogenetic studies of diplostomids, limited DNA sequence data is available from diplostomids parasitic in mammals. Herein, we provide the first 28S rDNA and cox1 mtDNA sequen...
Preprint
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Multi-host helminth systems are difficult to study at a population level due to inherent spatial and temporal sampling challenges. Consequently, our understanding of the factors affecting gene flow, genetic drift and effective population size is limited. Population genetic parameters (Ne, Θ, π) are necessary in understanding fundamental processes i...
Article
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Aim: Macroecological analyses provide valuable insights into factors that influence how parasites are distributed across space and among hosts. Amid large uncertainties that arise when generalizing from local and regional findings, hierarchical approaches applied to global datasets are required to determine whether drivers of parasite infection pat...
Article
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Crassiphialinae Sudarikov, 1960 is a large subfamily of the Diplostomidae Poirier, 1886 with a complex taxonomic history. It includes a diversity of species parasitic in the intestines of avian and mammalian definitive hosts worldwide. Posthodiplostomum Dubois, 1936 is a large and broadly distributed crassiphialine genus notorious for its associati...
Article
Neopsilotrema is a small genus of psilostomid digeneans parasitic in the intestine of birds in the Palearctic and Nearctic. At present, the genus includes 4 species: Neopsilotrema lisitsynae from the Palearctic and Neopsilotrema affine, Neopsilotrema lakotae, and Neopsilotrema marilae from the Nearctic. Herein, we describe a new species, Neopsilotr...
Article
As presently recognized, Herpetodiplostomum is a small genus of proterodiplostomid digeneans parasitic in crocodilians. Most members of Cheloniodiplostomum, a genus of proterodiplostomids that parasitize chelonians, were originally placed within Herpetodiplostomum. The 2 genera were distinguished based on the presence/absence of papillae on the hol...
Article
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Anenterotrema is a small genus of dicrocoeliids (Digenea: Dicrocoeliidae) containing 6 species found in Neotropical bats. Members of this genus are characterized by the lack of digestive system organs and, unlike the majority of dicrocoeliids, parasitize the intestine of their definitive hosts. In this study, we have morphologically examined newly...
Article
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We synthesize the historical biogeography of non-marine fauna (mammals, birds, fish, non-parasitic and parasitic invertebrates) occurring across Bering Sea islands, considering endemism, species with origins in both North America and Far East Asia, and the impacts of introduced species through the Bering region. Insular communities often constitute...
Article
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A recent paper in this journal concerning parasites of rock pigeons (Columba livia) published by Ali and colleagues exemplifies a growing trend of misidentified parasites in the literature, despite increased online resources that should help facilitate accurate identification. In the Ali et al. paper, a pigeon louse in the genus Columbicola (Phthir...
Article
Sphincterodiplostomum is a monotypic genus of diplostomid digeneans that parasitize fish-eating birds in the neotropics. The type species Sphincterodiplostomum musculosum has a unique, dorsal, tubular invagination in the opisthosoma with a muscular sphincter. Whereas larvae of S. musculosum are relatively commonly reported in Neotropical fish helmi...
Article
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Background The Eucotylidae Cohn, 1904 (Superfamily: Microphalloidea), is a family of digeneans parasitic in kidneys of birds as adults. The group is characterized by the high level of morphological similarities among genera and unclear systematic value of morphological characters traditionally used for their differentiation. In the present study, w...
Article
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Classical theory suggests that parasites will exhibit higher fitness in sympatric relative to allopatric host populations (local adaptation). However, evidence for local adaptation in natural host‐parasite systems is often equivocal, emphasizing the need for infection experiments conducted over realistic geographic scales and comparisons among spec...
Article
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Southernmost South America provides significant wintering habitats for migrant shorebirds, most of which breed in the High Arctic tundra. Helminth species parasitizing these migratory birds have been well studied in North America; however, in South America they are poorly known. As part of an ongoing research on the helminth fauna from Patagonian b...
Article
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The Proterodiplostomidae Dubois, 1936 is a relatively small family of diplostomoidean digeneans parasitising the intestines of reptilian hosts associated with freshwater environments in tropical and subtropical regions. The greatest diversity of proterodiplostomids is found in crocodilians, although some parasitise snakes and turtles. According to...
Article
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Ticks are ectoparasites that feed on blood of a broad taxonomic range of terrestrial and flying vertebrates and are distributed across a wide range of environmental conditions. Here, we explore the biotic and abiotic factors on infestation probability of ticks of the genus Amblyomma and assess the degree of host specificity based on analysis of 102...
Article
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Biogeography is known to have shaped the diversity and evolutionary history of avian haemosporidian parasites across the Neotropics. However, a paucity of information exists for the temperate Neotropics and especially from nonpasserine hosts. To understand the effect of biogeography in the temperate Neotropics on haemosporidians of nonpasserine hos...
Article
We used odds ratios and a hurdle model to analyze parasite co-infections over 25 years on >20,000 young-of-the year of endangered Shortnose and Lost River Suckers. Host ecologies differed as did parasite infections. Shortnose Suckers were more likely to be caught inshore and 3 – 5 times more likely to have Bolbophorus spp. and Contracaecum sp. infe...
Article
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Background: The Dicrocoeliidae are digenetic trematodes mostly parasitic in the bile ducts and gall bladder of various avian and mammalian hosts. Until recently their systematics was based on morphological data only. Due to the high morphological uniformity across multiple dicrocoeliid taxa and insufficient knowledge of relative systematic value o...
Article
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1.Geographic variation in environmental conditions as well as host traits that promote parasite transmission may impact infection rates and community assembly of vector transmitted parasites. 2.Identifying the ecological, environmental, and historical determinants of parasite distributions and diversity is therefore necessary to understand disease...
Article
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An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
Purpose: Cardiocephaloides is a small genus of strigeid digeneans with an essentially cosmopolitan distribution. Most members of Cardiocephaloides are found in larid birds, however, Cardiocephaloides physalis is an exception and parasitizes penguins in some coastal regions of South America and South Africa. No prior molecular phylogenetic studies...
Article
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Despite the use of Hymenolepis diminuta as a model organism in experimental parasitology, a full genome description has not yet been published. Here we present a hybrid de novo genome assembly based on complementary sequencing technologies and methods. The combination of Illumina paired-end, Illumina mate-pair and Oxford Nanopore Technology reads g...
Article
Codonocephalus is a monotypic genus of diplostomid digeneans and is the only genus in the subfamily Codonocephalinae. The type-species Codonocephalus urniger has an unusual progenetic metacercaria that uses frogs as intermediate hosts and can use snakes as paratenic hosts. Adult C. urniger parasitize ardeid wading birds in the Palearctic. Despite t...
Article
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Despite the evidence that diseases have increased in marine taxa, parasites remain underrepresented in studies of marine ecology. Recently, observations of black-spot syndrome (BSS) in Caribbean fishes, especially ocean surgeonfishes, Acanthurus tractus (Poey, 1860), have been reported, although its cause(s) has remained conjectural. We investigate...
Article
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Crassiphiala is a monotypic genus of diplostomid digeneans, and is the type-genus of the subfamily Crassiphialinae. The type-species Crassiphiala bulboglossa parasitizes kingfishers in the Nearctic and has a Neascus-type metacercaria that encysts on fish intermediate hosts, often causing black spot disease. While recent molecular phylogenetic studi...
Article
Codonocephalus is a monotypic genus of diplostomid digeneans and is the only genus in the sub-family Codonocephalinae. The type-species Codonocephalus urniger has an unusual progenetic metacercaria that uses frogs as intermediate hosts and can use snakes as paratenic hosts. Adult C. urniger parasitize ardeid wading birds in the Palearctic. Despite...
Article
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Speciation among many animals has been rapid through Quaternary climate cycling and periodic isolation-reconnection dynamics. As such, species limits among often morphologically cryptic lineages may remain unresolved despite clear genetic partitioning within the mitogenome. Accumulating evidence from phylogeographic studies is also revealing congru...
Article
Uvulifer Yamaguti, 1934 is a genus of diplostomoidean digeneans that parasitizes kingfishers worldwide. Species have a Neascus-type metacercaria that encysts in or on fish intermediate hosts, often causing black spot disease. Only 3 prior studies published DNA sequence data for Uvulifer species with only 1 including a single named species (Uvulifer...
Conference Paper
Full-text available
Biogeography is known to have shaped the evolutionary history of avian haemosporidian parasites across the Neotropics. However, a paucity of information exists for the temperate Neotropics and especially from non-passerine hosts. To understand the effect of biogeography in the temperate Neotropics on haemosporidians and their non-passerine hosts we...
Article
Two new genera and species of freshwater turtle blood flukes (TBFs) are described herein based on specimens infecting the nephritic and mesenteric blood vessels of "matamatas" (a side-necked turtle, Chelus fimbriata [Schneider, 1783] [Pleurodira: Chelidae]) from the Amazon River Basin, Peru. These taxa comprise the first-named species and the first...
Article
Ecotones can increase free‐living species richness, but little is known about how parasites respond to ecotones. Here we use parasite communities in raccoons (Procyon lotor) to test the hypothesis that parasite communities can be divided into core and satellite species, each with fundamentally different responses to ecotones. We used published para...
Article
Local and global measurements of parasite prevalence and abundance are critical for understanding the dynamics that underlie the diversity, distribution, and evolution of infectious diseases. Here we present a dataset of gut helminths found in 1) raccoons throughout their range, based on primary literature from 1925‐ 2017 and 2) raccoons in Santa B...
Article
The Cyathocotylidae is a globally distributed family of digeneans parasitic as adults in fish, reptiles, birds, and mammals in both freshwater and marine environments. Molecular phylogenetic analysis of interrelationships among cyathocotylids is lacking with only a few species included in previous studies. We used sequences of the nuclear 28S rRNA...
Article
Serpentirhabdias mussuranae n. sp. is described from the lungs of the mussurana, Clelia clelia (Daudin, 1803), from vicinities of Lábrea, Amazonas State, Brazil. The species is characterized by the triangular oral opening, the presence of teeth (onchia) in the oesophastome, the excretory glands longer than the oesophagus and the tail abruptly narro...
Article
The genus Rhabdias Stiles & Hassal, 1905 includes about 83 species of nematodes parasitic in amphibians and reptiles worldwide. Herein, we describe Rhabdias glaurungi sp. nov. from the hylid frog Scinax gr. ruber (Laurenti, 1768) in the Gunma Ecological Park, Santa Bárbara municipality, state of Pará, Brazil. This species has six small lips, an inf...
Article
We analyze the phylogenetic relationships and taxonomic status of hymenolepidid cestodes with rudimentary rostellum parasitic in Holarctic shrews of the genus Sorex. These cestodes were previously termed as a “Ditestolepis clade" and encompass 8 genera: Ditestolepis, Spasskylepis, Mathevolepis, Ecrinolepis, Spalania, Diorchilepis, Gulyaevilepis, No...
Article
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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 opportun...
Article
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Identifying the ecological factors that shape parasite distributions remains a central goal in disease ecology. These factors include dispersal capability, environmental filters, and geographic distance. Using 520 haemosporidian parasite genetic lineages recovered from 7,534 birds sampled across tropical and temperate South America we tested 1) the...
Article
Background We describe a new dicrocoeliid collected from the Eurasian water shrew Neomys fodiens in Bulgaria based on the combination of morphological characteristics and molecular data. Results Pojmanskatrema balcanica n. sp., n. gen. is distinguished from all other species of family Dicrocoeliidae Looss, 1900 in having a postovarian vitellarium...
Article
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Digenetic trematodes of the genus Clinostomum are cosmopolitan parasites infecting fishes, amphibians, reptiles, and snails as intermediate hosts. Despite the broad geographical distribution of this genus, debate about the number of species and how they vary in host use has persisted. To better understand patterns of infection among host species an...
Article
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Parasites with low host specificity (e.g. infecting a large diversity of host species) are of special interest in disease ecology, as they are likely more capable of circumventing ecological or evolutionary barriers to infect new hosts than are specialist parasites. Yet for many parasites, host specificity is not fixed and can vary in response to e...
Article
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Lyperosomum Looss, 1899 is one of the largest genera of the Dicrocoeliidae and is one of the best examples of the systematic complexity and taxonomic instability within this family. We present the molecular analyses based on novel sequences of nuclear and mitochondrial genes obtained from 56 isolates of adult flukes and larval stages of dicrocoelii...
Article
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Background Despite being a significant element of biodiversity and playing an important role in their hosts’ physiology, ecology and evolution, parasites remain understudied and are often neglected during biotic surveys and other collection efforts. More often than not, it is due to the perception that parasitological examination requires specializ...
Article
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The systematic position of Urotrema Braun, 1900 and the family Urotrematidae Poche, 1926 have always been controversial. Due to its unusual morphological characteristics, lack of knowledge of the life cycle or details of its excretory system, this family was placed within different higher taxonomic groups of digeneans. Despite being one of the most...
Article
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Corynosoma obtuscens Lincicome, 1943 (Acanthocephala: Polymorphidae) is synonymised with Corynosoma australe Johnston, 1937 based on combined morphological and molecular evidence. Morphological comparison of C. obtuscens (24 males and 27 females) collected from a California sea lion Zalophus californianus (Lesson) in California, USA, with the type-...