The Experts below are selected from a list of 774 Experts worldwide ranked by ideXlab platform
Pieter T J Johnson - One of the best experts on this subject based on the ideXlab platform.
-
SnailShedDataforDryad
2016Co-Authors: Sara H Paull, Thomas R. Raffel, Bryan E. Lafonte, Pieter T J JohnsonAbstract:Laboratory-raised Helisoma trivolvis snails were held at one of 5 acclimation temperatures (13-25 deg C) for 11 days prior to being moved to one of 5 performance temperatures (16-28 deg C) for 7 days. Some snails were exposed in the laboratory to Ribeiroia Ondatrae, and parasite release was measured at several time-points before and after the temperature shift. Please see paper methods for more details
-
development and application of an edna method to detect and quantify a pathogenic parasite in aquatic ecosystems
Ecological Applications, 2015Co-Authors: J R Huver, Pieter T J Johnson, Janet Koprivnikar, S WhyardAbstract:Approaches based on organismal DNA found in the environment (eDNA) have become increasingly utilized for ecological studies and biodiversity inventories as an alternative to traditional field survey methods. Such DNA-based techniques have largely been used to establish the presence of free-living organisms, but have much potential for detecting and quantifying infectious agents in the environment, which is necessary to evaluate disease risk. We developed an eDNA method to examine the distribution and abundance of the trematode Ribeiroia Ondatrae, a pathogenic parasite known to cause malformations in North American amphibians. In addition to comparing this eDNA approach to classical host necropsy, we examined the detectability of R. Ondatrae in water samples subject to different degradation conditions (time and temperature). Our test exhibited high specificity and sensitivity to R. Ondatrae, capable of detecting as little as 14 fg (femtograms) of this parasite's DNA (1/2500th of a single infectious stage) from field water samples. Compared to our results from amphibian host necropsy, quantitative PCR was -90% concordant with respect to R. Ondatrae detection from 15 field sites and was also a significant predictor of host infection abundance. DNA was still detectable in lab samples after 21 days at 25°C, indicating that our method is robust to field conditions. By comparing the advantages and disadvantages of eDNA vs. traditional survey methods for determining pathogen presence and abundance in the field, we found that the lower cost and effort associated with eDNA approaches provide many advantages. The development of alternative tools is critical for disease ecology, as wildlife management and conservation efforts require reliable establishment and monitoring of pathogens.
-
experimental infection dynamics using immunosuppression and in vivo parasite tracking to understand host resistance in an amphibian trematode system
The Journal of Experimental Biology, 2013Co-Authors: Bryan E. Lafonte, Pieter T J JohnsonAbstract:Although naturally occurring hosts often exhibit pronounced differences in infection and pathology, the relative importance of factors associated with host life history and immunity in explaining such patterns often remains speculative. Research in eco-immunology highlights the trade-offs between host physiology and immunity, for which natural variations in disease susceptibility offer a valuable platform to test predictions within this framework. Here, we combined use of a novel, in vivo assay for tracking parasite fate and an experimental manipulation of host immune function ( via chronic corticosterone exposure) to assess the role of host immunity in regulating susceptibility of amphibian hosts to three larval trematodes: Ribeiroia Ondatrae , Echinostoma trivolvis and Alaria sp. 2. Results from the in vivo parasite-tracking assay revealed marked differences in initial parasite penetration and subsequent host clearance. Relative to infections in a highly susceptible species ( Pseudacris regilla ), the virulent trematode R. Ondatrae was ~25% less successful at penetrating larvae of three hylid frog species and was cleared >45× faster, such that all parasites were rapidly cleared from hylid hosts over 72 h following a Weibull distribution. Immune suppression of Hyla versicolor sharply reduced this resistance and increased infection of all three trematodes by 67 to 190%, with particularly strong increases for R. Ondatrae . Diminished resistance correlated with a 62% decrease in circulating eosinophils. Correspondingly, 10 days after corticosterone exposures ended, infections declined dramatically while eosinophil levels returned to normal. In light of ongoing declines and deformities in amphibian populations, these findings have application potential for mitigating disease-driven effects. * AFT : accelerated failure time AICc : corrected Akaike's information criterion Bd : Batrachochytrium dendrobatidis GFP2 : green fluorescent protein 2 k : AFT scale output p : Weibull shape parameter PE : post-exposure Si ( t ) : parasite survival as a function of time within host species i t ½ : median parasite survival time α : AFT regression coefficient for the intercept α i : AFT regression coefficient for host species i γ i : acceleration factor for host species i relative to P. regilla λ i : Weibull scale parameter for host species i
-
experimental exposure of helisoma trivolvis and biomphalaria glabrata gastropoda to ribeiroia Ondatrae trematoda
Journal of Parasitology, 2011Co-Authors: Miranda D Redmond, Richard B Hartson, Jason T Hoverman, Christina N De Jesusvillanueva, Pieter T J JohnsonAbstract:Abstract Experimental infections provide an important foundation for understanding host responses to parasites. While infections with Ribeiroia Ondatrae cause mortality and malformations in a wide range of amphibian second intermediate host species, little is known about how the parasite affects its snail first intermediate hosts or even what species can support infection. In this study, we experimentally exposed Helisoma trivolvis, a commonly reported host of R. Ondatrae, and Biomphalaria glabrata, a confamilial snail known to host Ribeiroia marini, to increasing concentrations of embryonated eggs of R. Ondatrae obtained from surrogate definitive hosts. Over the course of 8 wk, we examined the effect of parasite exposure on infection status, time-to-cercariae release, host size, and mortality of both snail species. Helisoma trivolvis was a highly competent host for R. Ondatrae infection, with over 93% infection in all exposed snails, regardless of egg exposure level. However, no infections were detected ...
-
high temperature enhances host pathology in a snail trematode system possible consequences of climate change for the emergence of disease
Freshwater Biology, 2011Co-Authors: Sara H Paull, Pieter T J JohnsonAbstract:Summary 1. Disease severity may be altered by the differential responses of hosts and parasites to rising temperatures leading to an increase or reduction in disease. The net effect of climate change on emerging diseases will reflect the effects of temperature on all life history stages of both hosts and parasites. 2. To explore how climate change differentially influences hosts and parasites, we studied the effect of increasing temperatures on different life stages of the multi-host trematode parasite Ribeiroia Ondatrae, which has been linked to the emerging phenomenon of amphibian limb malformations, and its snail intermediate host Planorbella trivolvis. We determined the effects of temperature on the development of R. Ondatrae eggs and redia larvae and the effects of parasite exposure (exposed and sham-exposed), temperature (13, 20, and 26 °C) and their interaction on snail host vital rates, including growth, mortality and reproduction. 3. Ribeiroia eggs developed four times faster at 26 °C than at 17 °C and did not develop at 12 °C. Higher temperatures increased snail growth, egg production and mortality. Infection interacted with temperature to enhance the growth of infected snails while reducing their fecundity at 26 °C. These results suggest that pathology associated with infection is amplified at higher temperatures. 4. The timing of interactions between R. Ondatrae and P. trivolvis may be influenced by their physiological responses to temperature. Temperature-driven increases in the growth of infected snails coupled with the cessation of parasite development at lower temperatures suggest that warming temperatures will change host–parasite dynamics. Taken together, these results indicate that future climate change could alter parasite abundance and pathology by creating a ‘phenological mismatch’ between snail hosts and parasites, potentially leading to infection of both snail and amphibian hosts in earlier and, in the case of amphibians, more vulnerable stages of development.
Paulauskas Algimantas - One of the best experts on this subject based on the ideXlab platform.
-
New data on the helminths of the muskrat (Ondatra zibethicus) in Lithuania
2016Co-Authors: Mažeika Vytautas, Kontenytė Rima, Paulauskas AlgimantasAbstract:Thirty-four muskrats, hunted in 2006 2007 on Rusnė Island, Lithuania, were examined for helminths. Eight helminth species were found: five trematodes (Echinostoma sp., Plagiorchis elegans, Skrjabinoplagiorchis Ondatrae, Psilotrema spiculigerum, Psilotrema simillimum) and three cestodes (Hydatigera taeniaeformis, Tetratirotaenia polyacantha, Echinococcus multilocularis). All the species found are widely spread or are indigenous to Europe. The helminth fauna in the muskrat consisted of helminths hosted by a wide range of waterfowl and mammals. This was only the second time the cestode E. multilocularis, the causative agent of the serious zoonosis alveolar echinococcosis, was found in the muskrat in LithuaniaBiologijos katedraGamtos mokslų fakultetasKlaipėdos universitetasVytauto Didžiojo universiteta
-
Ondatros (Ondatra zibethicus) invazinis paplitimas ir poveikis ekosistemai
2016Co-Authors: Skyrienė Gintarė, Paulauskas AlgimantasAbstract:Ondatros (Ondatra zibethicus) greitai paplito naujuose biotopuose po to, kai buvo introdukuotos į Europą ir užėmė jos šiaurinę, rytinę ir vidurinę dalis. Viena sėkmingos invazijos priežasčių – greita reprodukcija ir sėkmingas savarankiškas plitimas naujose vietose. Ondatros yra pusiau vandens graužikai, neigiamai veikiantys ekosistemas. Ši rūšis, ženkliai veikianti aplinką, gali būti pakankamai svarbi ekonomikos požiūriu. Šiuo metu ondatrų labai sumažėjo, ypač Lietuvoje, Lenkijoje, ir tai gali būti ekologinių veiksnių, tokių kaip maisto prieinamumas, ligos, parazitai, plėšrūnai, poveikis. Be to, ondatrų mirtingumą nemažai lemia ir žmogaus veikla: jos intensyviai gaudomos dėl kailio, kurio ekonominė vertė yra išaugusi visame pasaulyje. Straipsnyje apžvelgiama ondatros (Ondatra zibethicus) introdukcijos į Europą istorija, paplitimas visoje Eurazijoje, veiksniai, nulėmę populiacijos didėjimą, o vėliau ir mažėjimą, genetiniai tyrimai ir šios invazinės rūšies poveikis ekosistemaiThe muskrat (Ondatra zibethicus L.) after being introduced to Europe quickly colonized new areas. They occupied Northern, Eastern and Central Europe. One of the reasons for their successful invasion into new areas was the release of animals in numerous places and their subsequent successful self-spreading from these places. However, this semi-aquatic rodent negatively impacts the ecosystem (causes damages of watercourse embankment through burrowing, consumes crops). The species possesses a high potential for both environmental and economic impact. Nowadays, following the successful widespread of this species, abundance of its population is reduced in some countries, e. g. Lithuania and Poland. The reasons for that can be ecological factors: availability of food, diseases, parasites and carnivore predators. Moreover, humans cause significant mortality of muskrats. The rodents are extensively trapped for fur, which is of increasing economic value around the world. The paper presents a review of the muskrat introduction history into Europe and whole Eurasia, distribution of the species, the factors important for population abundance increase and reduction, on genetics as well as muskrat invasion impact on non-native ecosystems for this speciesBiologijos katedraGamtos mokslų fakultetasVytauto Didžiojo universiteta
-
The microsatellite markers for genetic structure of muskrat (Ondatra zibethicus)
2015Co-Authors: Skyrienė Gintarė, Paulauskas Algimantas, Belkin Vladimir, Fyodorov FyodorAbstract:The muskrat (Ondatra zibethicus) is one of the semi-aquatic mammals which were introduced from North America in various regions around the world (Danell, 1996; Musser ir Carleton, 2005). The microsatellites markers were used only for the Canadian muskrat populations (Laurence et al. 2009) and there are no genetics studies (using microsatellite) of muskrat in Europe or Russia. The aim of this study was to evaluate genetic structure (using microsatellite markers) of muskrat populations in Lithuania and South Karelia, Russia. A total of 179 samples of muskrat were investigated genetically: 71 muskrat from Lithuania and 108 – Russia. The genetic variability was compared using 7 polymorphic microsatellite loci (Oz08, Oz17, Oz22, Oz30, Oz41, Oz43, Oz44). Population analysis revealed moderate to high levels of genetic variability (in Lithuania: He = 0.35- 0.88, Ho = 0.29-0.94; In Russia: He = 0.74-0.90, Ho = 0.44-0.80). The numbers of polymorphic loci were 100 % and size ranged from 183 to 272 base pairs in Lithuania and Russia. The numbers of alleles per locus ranging from 5 to 15 in Lithuania (in a total of 67 alleles) and from 8 to 19 – Russia (in a total of 91 alleles). Each locus was tested for departure from Hardy-Weinberg equilibrium (HWE) and all loci exhibited significant in Russia populations and 6 loci in Lithuania. The results of principal coordinate analysis (PCA) by genetic similarity showed that the two populations separated and formed two different groups – Lithuanian and Russian. The results showed that the genetic diversity was higher in Russia population of muskrat than in Lithuania, but lower if to compare with muskrat population from Canada (Laurence et al. 2009; Laurence et el., 2013). The study was supported by the Research Council of Lithuania (grant No. LEK-14/2012)Biologijos katedraGamtos mokslų fakultetasVytauto Didžiojo universiteta
-
Assessment of invasive muskrat Ondatra zibethicus distribution and impacts on ecosystems in Lithuania
2015Co-Authors: Butautytė-skyrienė Gintarė, Paulauskas Algimantas, Ulevičius AliusAbstract:After acclimatization muskrats spread over almost all Lithuania and increased to about 40 000 individuals in the 1980s. But since then the number of muskrats has decreased to about 2000 individuals. We used BINPAS (Bioinvasion Impact/Biopollution Assessment System) for terrestrial ecosystems, which is usually using for water ecosystems, to assess the impact of Ondatra zibethicus on native species and communities, on habitats, on ecosystems and the biopollution level (BPL). The impact of muskrats varied between different regions of Lithuania. Widespread and high numbers of muskrats, and strong biopollution of ecosystem functioning were identified in four regions of Lithuania – Nevėžis and Nemunas Rivers, Šalčia River, Varėnė river, Vištytis Regional ParkBiologijos katedraGamtos mokslų fakultetasVytauto Didžiojo universiteta
-
Population structure of muskrat (Ondatra zibethicus) in Lithuania
2014Co-Authors: Skyrienė Gintarė, Paulauskas AlgimantasAbstract:The muskrat (Ondatra zibethicus) is a semi-aquatic rodent and it is listed as the most successfully acclimatized alien species in Europe with a wide distribution, fast increase of abundance, short colonisation time, massive spread into various ecosystems and significant ecological impact. Lithuania is no exception; after introducing, the muskrat rapidly inhabited a wide spectrum of waters throughout the whole country. The analysis of the variation in body dimensions and other characteristics of muskrats is important for assessing the effect of environmental factors on muskrat populations. The aim of this reasearch was to examine invasive species muskrat population demographic status, sex structure and ratio, weight and to count the embryons and placental scars. Population structure of muskrat were studied using muskrat population (n꞊129) hunted during 2001 – 2012 throughout Lithuania. Males predominant over females in catch numbers – 67% of all hunted males and 33 % of all hunted females. Male dominance in numbers has been attributed either to different mortality of the sexes or the differences in activity resulting in a greater proportion of males being hunted (Pankakoski, 1983). The biggest differences of caught muskrat in different years were in 2006 and 2007 (65% males and 35% females, 77% and 23%, respectively). The male and female ratio of the muskrat population was 2:1 and effective population size (Ne) 113 and it is being less than an absolute population size (N) 129. The literature on the sex ratios in muskrat populations is extensive and usually there is a clear prepoderance of males in spring (Pankakoski, 1983). Mean weight of muskrat was 936 g. Males showed slighlty higher weight in comparison to females (980 g and 900g, respectively) because of intraspecific competition. There was significant difference between weight of females and males (t = 1.682, p = 0.031). [...]Biologijos katedraVytauto Didžiojo universiteta
Andrew R Blaustein - One of the best experts on this subject based on the ideXlab platform.
-
induces severe limb malformations in western toads (Bufo boreas)
2015Co-Authors: Kevin B. Lunde, Jay Bowerman, Ryan W. Haight, Andrew R BlausteinAbstract:Abstract: Widespread reports of malformed amphibians in North America have prompted investigations into the cause(s) and implications of the phenomenon. Recently, a trematode parasite (Ribeiroia Ondatrae) was identified as the probable cause of hind-limb malformations in Pacific treefrogs (Hyla regilla) from California. We exposed a second anuran species, the western toad (Bufo boreas), to specific levels of R. Ondatrae infection. In a dose-dependent manner, R. Ondatrae infection induced high frequencies (40–85%) of severe limb malformations in surviving toads. Survivorship declined significantly with increasing parasite exposure, falling to 42 % in the heaviest treatment. Larvae in control treatments exhibited normal development and low mortality levels. In contrast to previous experiments with R. Ondatrae infection in treefrogs, cutaneous fusion was the predominant malformation among infected toads in all treatments. In-fection also caused polymely (extra limbs; fore and hind), ectromely (missing limbs), polydactyly (extra digits), and a variety of additional limb malformations. Taken together, these results demonstrate that (i) the teratogenic effects of R. Ondatrae are not limited to treefrogs, (ii) the spectrum of R. Ondatrae-induced malformations is not confined to the hind limbs, and (iii) the frequency and composition of malformations resulting from infection may vary among am-phibian species. Finally, we review historical reports of limb abnormalities in the genus Bufo and discuss established and proposed causative agents, with emphasis on trematode infection and predation. Résumé: Les malformations chez les amphibiens sont de plus en plus signalées en Amérique du Nord; nous avon
-
ribeiroia Ondatrae trematoda digenea infection induces severe limb malformations in western toads bufo boreas
Canadian Journal of Zoology, 2001Co-Authors: Kevin B. Lunde, Jay Bowerman, Ryan W. Haight, Andrew R BlausteinAbstract:Widespread reports of malformed amphibians in North America have prompted investigations into the cause(s) and implications of the phenomenon. Recently, a trematode parasite (Ribeiroia Ondatrae) was identified as the probable cause of hind-limb malformations in Pacific treefrogs (Hyla regilla) from California. We exposed a second anuran species, the western toad (Bufo boreas), to specific levels of R. Ondatrae infection. In a dose-dependent manner, R. Ondatrae infection induced high frequencies (40-85%) of severe limb malformations in surviving toads. Survivorship declined significantly with increasing parasite exposure, falling to 42% in the heaviest treatment. Larvae in control treatments exhibited normal development and low mortality levels. In contrast to previous experiments with R. Ondatrae infection in treefrogs, cutaneous fusion was the predominant malformation among infected toads in all treatments. In - fection also caused polymely (extra limbs; fore and hind), ectromely (missing limbs), polydactyly (extra digits), and a variety of additional limb malformations. Taken together, these results demonstrate that ( i) the teratogenic effects of R. Ondatrae are not limited to treefrogs, (ii) the spectrum of R. Ondatrae-induced malformations is not confined to the hind limbs, and (iii) the frequency and composition of malformations resulting from infection may vary among am- phibian species. Finally, we review historical reports of limb abnormalities in the genus Bufo and discuss established and proposed causative agents, with emphasis on trematode infection and predation. Resume : Les malformations chez les amphibiens sont de plus en plus signalees en Amerique du Nord; nous avons cherche a determiner les causes et les consequences de ce phenomene. Recemment, le trematode parasite (Ribeiroia on- datrae) a ete reconnu comme la cause probable des malformations des membres posterieurs chez la Rainette du Paci- fique (Hyla regilla) en Californie. Nous avons soumis une seconde espece d'anoure, le Crapaud de l'ouest (Bufo boreas), a des infections de gravites diverses de R. Ondatrae. Les infections de R. Ondatrae entrainent des frequences elevees (40-85 %) de malformations serieuses des membres en fonction de la dose administree chez les crapauds survi- vants. La survie diminue significativement a mesure qu'augmente l'exposition aux parasites, jusqu'a 4 2%al asuite des traitements les plus severes. Chez les larves des groupes temoins, le developpement est normal et la mortalite est faible. Contrairement aux resultats d'experiences anterieures sur les rainettes, ici c'est la fusion cutanee qui constitue la principale malformation chez les crapauds infectes, a la suite de tous les traitements. Les infections sont aussi a l'origine de polymelies (membres surnumeraires, anterieurs et posterieurs), d'ectromelies (membres manquants), de po- lydactilies (doigts surnumeraires) et d'autres malformations des membres. Consideres dans leur ensemble, ces resultats demontrent que (i) les effets teratogenes de R. Ondatrae ne sont pas restreints aux rainettes, ( ii) l'eventail des malfor- mations attribuables a R. Ondatrae n'affecte pas que les membres posterieurs et (iii) la frequence et la nature des mal- formations dues aux infections peuvent varier chez les differentes especes d'amphibiens. Nous avons passe en revue tous les rapports historiques sur les malformations des membres chez Bufo et nous examinons ici les agents putatifs reconnus et supposes, en insistant sur les infections causees par les trematodes et sur la predation. (Traduit par la Redaction) 379
Jane E. Huffman - One of the best experts on this subject based on the ideXlab platform.
-
histopathological effects of the intramolluscan stages of zygocotyle lunata echinostoma trivolvis and ribeiroia Ondatrae on helisoma trivolvis and observations on keratin in the trematode larvae
Parasitology Research, 2009Co-Authors: Jane E. Huffman, Jennifer Klockars, Shamus P. Keeler, Bernard FriedAbstract:The histopathological effects of Zygocotyle lunata, Echinostoma trivolvis, and Ribeiroia Ondatrae in naturally infected Helisoma trivolvis were studied in hematoxylin and eosin sections of infected digestive glands fixed in 10% neutral buffered formalin. The larval stages of all three trematodes damaged the snail digestive gland. Most notable histopathology included disrupted digestive gland tubules, lysed cells, compressed tubules, and edematous spaces between tubules. Considerable damage was done by rediae ingesting digestive cells. There was a detectable hemocytic response by H. trivolvis in response to the rediae and cercariae of Z. lunata. Histochemical studies on sectioned material stained with the Ayoub-Shklar method for keratin detected the presence of this protein in the rediae and cercariae of Z. lunata and R. Ondatrae. The presence of keratin is probably related to its role in cercarial encystment.
Skyrienė Gintarė - One of the best experts on this subject based on the ideXlab platform.
-
Ondatros (Ondatra zibethicus) invazinis paplitimas ir poveikis ekosistemai
2016Co-Authors: Skyrienė Gintarė, Paulauskas AlgimantasAbstract:Ondatros (Ondatra zibethicus) greitai paplito naujuose biotopuose po to, kai buvo introdukuotos į Europą ir užėmė jos šiaurinę, rytinę ir vidurinę dalis. Viena sėkmingos invazijos priežasčių – greita reprodukcija ir sėkmingas savarankiškas plitimas naujose vietose. Ondatros yra pusiau vandens graužikai, neigiamai veikiantys ekosistemas. Ši rūšis, ženkliai veikianti aplinką, gali būti pakankamai svarbi ekonomikos požiūriu. Šiuo metu ondatrų labai sumažėjo, ypač Lietuvoje, Lenkijoje, ir tai gali būti ekologinių veiksnių, tokių kaip maisto prieinamumas, ligos, parazitai, plėšrūnai, poveikis. Be to, ondatrų mirtingumą nemažai lemia ir žmogaus veikla: jos intensyviai gaudomos dėl kailio, kurio ekonominė vertė yra išaugusi visame pasaulyje. Straipsnyje apžvelgiama ondatros (Ondatra zibethicus) introdukcijos į Europą istorija, paplitimas visoje Eurazijoje, veiksniai, nulėmę populiacijos didėjimą, o vėliau ir mažėjimą, genetiniai tyrimai ir šios invazinės rūšies poveikis ekosistemaiThe muskrat (Ondatra zibethicus L.) after being introduced to Europe quickly colonized new areas. They occupied Northern, Eastern and Central Europe. One of the reasons for their successful invasion into new areas was the release of animals in numerous places and their subsequent successful self-spreading from these places. However, this semi-aquatic rodent negatively impacts the ecosystem (causes damages of watercourse embankment through burrowing, consumes crops). The species possesses a high potential for both environmental and economic impact. Nowadays, following the successful widespread of this species, abundance of its population is reduced in some countries, e. g. Lithuania and Poland. The reasons for that can be ecological factors: availability of food, diseases, parasites and carnivore predators. Moreover, humans cause significant mortality of muskrats. The rodents are extensively trapped for fur, which is of increasing economic value around the world. The paper presents a review of the muskrat introduction history into Europe and whole Eurasia, distribution of the species, the factors important for population abundance increase and reduction, on genetics as well as muskrat invasion impact on non-native ecosystems for this speciesBiologijos katedraGamtos mokslų fakultetasVytauto Didžiojo universiteta
-
The microsatellite markers for genetic structure of muskrat (Ondatra zibethicus)
2015Co-Authors: Skyrienė Gintarė, Paulauskas Algimantas, Belkin Vladimir, Fyodorov FyodorAbstract:The muskrat (Ondatra zibethicus) is one of the semi-aquatic mammals which were introduced from North America in various regions around the world (Danell, 1996; Musser ir Carleton, 2005). The microsatellites markers were used only for the Canadian muskrat populations (Laurence et al. 2009) and there are no genetics studies (using microsatellite) of muskrat in Europe or Russia. The aim of this study was to evaluate genetic structure (using microsatellite markers) of muskrat populations in Lithuania and South Karelia, Russia. A total of 179 samples of muskrat were investigated genetically: 71 muskrat from Lithuania and 108 – Russia. The genetic variability was compared using 7 polymorphic microsatellite loci (Oz08, Oz17, Oz22, Oz30, Oz41, Oz43, Oz44). Population analysis revealed moderate to high levels of genetic variability (in Lithuania: He = 0.35- 0.88, Ho = 0.29-0.94; In Russia: He = 0.74-0.90, Ho = 0.44-0.80). The numbers of polymorphic loci were 100 % and size ranged from 183 to 272 base pairs in Lithuania and Russia. The numbers of alleles per locus ranging from 5 to 15 in Lithuania (in a total of 67 alleles) and from 8 to 19 – Russia (in a total of 91 alleles). Each locus was tested for departure from Hardy-Weinberg equilibrium (HWE) and all loci exhibited significant in Russia populations and 6 loci in Lithuania. The results of principal coordinate analysis (PCA) by genetic similarity showed that the two populations separated and formed two different groups – Lithuanian and Russian. The results showed that the genetic diversity was higher in Russia population of muskrat than in Lithuania, but lower if to compare with muskrat population from Canada (Laurence et al. 2009; Laurence et el., 2013). The study was supported by the Research Council of Lithuania (grant No. LEK-14/2012)Biologijos katedraGamtos mokslų fakultetasVytauto Didžiojo universiteta
-
The distribution, genetic diversity and helminths of alien mammal muskrat (Ondatra zibethicus)
2014Co-Authors: Skyrienė GintarėAbstract:Ondatra yra svetimkraštis pusiau-vandens žinduolis, kuris buvo introdukuotas iš Šiaurės Amerikos į įvairius regionus visame pasaulyje. Šio darbo tikslas – ištirti svetimkraščio žinduolio ondatros (Ondatra zibethicus) paplitimą, genetinę įvairovę ir helmintus. Šiame moksliniame darbe įvertintas ondatros paplitimas ir gausumas Lietuvoje parodė, kad jie skirtinguose Lietuvos regionuose yra nevienodi, skirtingais metais svyruoja, įvairiuose vandens telkiniuose ženkliai krenta. Todėl ondatros poveikis vietinėms rūšims ir bendrijai, buveinių ir ekosistemų funkcionavimui yra nežymus ir lokalus. Iki šiol invazinio gyvūno genetinei struktūrai dėmesio buvo skirta labai mažai, todėl panaudojant DNR mikrosatelitinius žymenis ištirta genetinė įvairovė. Pirmą kartą įvertinta Lietuvos ondatrų populiacijų genetinė analizė ir genetinė įvairovė, kuri buvo mažesnė antrinėje (Lietuvos) introdukcijos vietovėje, nei pirminėje (Karelijos (Rusijos)), ar aborigeninėse Kanados populiacijose. Ondatrų helmintų ištirtumas, leido įvertinti, kad veikiant aklimatizacijai Ondatra neteko amerikinės kilmės parazitų. O palyginus helmintų fauną ir helmintų užsikrėtimo rodiklius buvo nustatyta, kad jie didesni didžiausio ondatros skaitlingumo metais (1973-1975 m.) negu smarkiai sumažėjusio (2001-2014 m.). Ištirtas ondatrų skaičius leidžia daryti prielaidą, kad jos helmintologinis poveikis žmonėms ir aplinkai yra mažas.The muskrat is an alien semi-aquatic mammal which was introduced to various regions around the world from North America. The aim of the study – to investigate the distribution, genetic diversity and helminths of alien mammal muskrat (Ondatra zibethicus). The evaluated distribution and the abundance of muskrats showed that it are not the same, very varying in different years and falling significantly in the various water bodies in Lithuania. Therefore, the impact of muskrats on native species and communities, habitats and ecosystems are insignificant and localized. Until now, the attention to the genetic structure of this invasive animal was very little. The genetic analysis and genetic diversity of the population of muskrats was assessed for the first time in Lithuania. The genetic diversity was studied using the microsatellite DNA markers. This allowed for the evaluation that the genetic diversity was lower in Lithuania than Karelia (Russia) or native Canadian populations of muskrat. After the evaluation of helminthological analysis were determined that the muskrat has lost American origin parasites after the period of acclimatization. The comparison of the helminth community structure and infection rates of muskrat were determined that it were higher in the highest numerosity of muskrat’s abundance (in 1973-1975) to comparing the period than it significantly reduced (in 2001-2014). Investigated number of muskrats suggests that the helminthological impact of muskrat to humans and the environment is low.Vytauto Didžiojo universiteta
-
Svetimkraščio žinduolio ondatros (Ondatra zibethicus) paplitimas, genetinė įvairovė ir helmintai
2014Co-Authors: Skyrienė GintarėAbstract:The muskrat is an alien semi-aquatic mammal which was introduced to various regions around the world from North America. The aim of the study – to investigate the distribution, genetic diversity and helminths of alien mammal muskrat (Ondatra zibethicus). The evaluated distribution and the abundance of muskrats showed that it are not the same, very varying in different years and falling significantly in the various water bodies in Lithuania. Therefore, the impact of muskrats on native species and communities, habitats and ecosystems are insignificant and localized. Until now, the attention to the genetic structure of this invasive animal was very little. The genetic analysis and genetic diversity of the population of muskrats was assessed for the first time in Lithuania. The genetic diversity was studied using the microsatellite DNA markers. This allowed for the evaluation that the genetic diversity was lower in Lithuania than Karelia (Russia) or native Canadian populations of muskrat. After the evaluation of helminthological analysis were determined that the muskrat has lost American origin parasites after the period of acclimatization. The comparison of the helminth community structure and infection rates of muskrat were determined that it were higher in the highest numerosity of muskrat’s abundance (in 1973-1975) to comparing the period than it significantly reduced (in 2001-2014). Investigated number of muskrats suggests that the helminthological impact of muskrat to humans and the environment is low.Ondatra yra svetimkraštis pusiau-vandens žinduolis, kuris buvo introdukuotas iš Šiaurės Amerikos į įvairius regionus visame pasaulyje. Šio darbo tikslas – ištirti svetimkraščio žinduolio ondatros (Ondatra zibethicus) paplitimą, genetinę įvairovę ir helmintus. Šiame moksliniame darbe įvertintas ondatros paplitimas ir gausumas Lietuvoje parodė, kad jie skirtinguose Lietuvos regionuose yra nevienodi, skirtingais metais svyruoja, įvairiuose vandens telkiniuose ženkliai krenta. Todėl ondatros poveikis vietinėms rūšims ir bendrijai, buveinių ir ekosistemų funkcionavimui yra nežymus ir lokalus. Iki šiol invazinio gyvūno genetinei struktūrai dėmesio buvo skirta labai mažai, todėl panaudojant DNR mikrosatelitinius žymenis ištirta genetinė įvairovė. Pirmą kartą įvertinta Lietuvos ondatrų populiacijų genetinė analizė ir genetinė įvairovė, kuri buvo mažesnė antrinėje (Lietuvos) introdukcijos vietovėje, nei pirminėje (Karelijos (Rusijos)), ar aborigeninėse Kanados populiacijose. Ondatrų helmintų ištirtumas, leido įvertinti, kad veikiant aklimatizacijai Ondatra neteko amerikinės kilmės parazitų. O palyginus helmintų fauną ir helmintų užsikrėtimo rodiklius buvo nustatyta, kad jie didesni didžiausio ondatros skaitlingumo metais (1973-1975 m.) negu smarkiai sumažėjusio (2001-2014 m.). Ištirtas ondatrų skaičius leidžia daryti prielaidą, kad jos helmintologinis poveikis žmonėms ir aplinkai yra mažas.Vytauto Didžiojo universiteta
-
Population structure of muskrat (Ondatra zibethicus) in Lithuania
2014Co-Authors: Skyrienė Gintarė, Paulauskas AlgimantasAbstract:The muskrat (Ondatra zibethicus) is a semi-aquatic rodent and it is listed as the most successfully acclimatized alien species in Europe with a wide distribution, fast increase of abundance, short colonisation time, massive spread into various ecosystems and significant ecological impact. Lithuania is no exception; after introducing, the muskrat rapidly inhabited a wide spectrum of waters throughout the whole country. The analysis of the variation in body dimensions and other characteristics of muskrats is important for assessing the effect of environmental factors on muskrat populations. The aim of this reasearch was to examine invasive species muskrat population demographic status, sex structure and ratio, weight and to count the embryons and placental scars. Population structure of muskrat were studied using muskrat population (n꞊129) hunted during 2001 – 2012 throughout Lithuania. Males predominant over females in catch numbers – 67% of all hunted males and 33 % of all hunted females. Male dominance in numbers has been attributed either to different mortality of the sexes or the differences in activity resulting in a greater proportion of males being hunted (Pankakoski, 1983). The biggest differences of caught muskrat in different years were in 2006 and 2007 (65% males and 35% females, 77% and 23%, respectively). The male and female ratio of the muskrat population was 2:1 and effective population size (Ne) 113 and it is being less than an absolute population size (N) 129. The literature on the sex ratios in muskrat populations is extensive and usually there is a clear prepoderance of males in spring (Pankakoski, 1983). Mean weight of muskrat was 936 g. Males showed slighlty higher weight in comparison to females (980 g and 900g, respectively) because of intraspecific competition. There was significant difference between weight of females and males (t = 1.682, p = 0.031). [...]Biologijos katedraVytauto Didžiojo universiteta
