Parazitáltság, fajösszetétel és ploiditás vizsgálata a Pelophylax esculentus komplexen

Doktori értekezésemben egy összetett gazda-parazita rendszert vizsgáltam a Kelet-Magyarországon található Hortobágyi Nemzeti Park (HNP) területén. Emellett egy újfajta parazitagyűjtési protokollt (DAMA) is alkalmaztam ezen a rendszeren. Az elmúlt évtizedekben egyre inkább növekvő figyelem irányult a parazita szervezetek felé és ezáltal nyilvánvalóvá vált, hogy ezen organizmusok a földi élet sokféleségének a jelentős részét alkotják, illetve kapocsként szolgálhatnak a klímaváltozás, biodiverzitás és az előretörő fertőző betegségek közötti kapcsolat feltárásában. Disszertációmban dokumentáltam és értékelésnek vettetem alá a Pelophylax esculentus komplex endoparazita helminth élősködőit, melyeknek faji identitását morfológiai módszerekkel azonosítottam, emellett pedig genetikai mintát is gyűjtöttem ezekből a helminth fajokból, annak érdekében, hogy a jövőben a DNS vonalkód alapú azonosításukat megvalósítsam. A DNS vonalkódok alkalmazása egy gyors és költséghatékony módja az organizmusok faji azonosításának. Emellett remek lehetőséget nyújt ahhoz, hogy a gazdák szempontjából nem-invazív módon monitorozhassuk a belső élősködőiket. Ezáltal szakíthatunk a korábbi gyakorlattal, amely sokszor kihívásokkal teli terepi gyűjtést, boncolást és a morfológiai azonosítást takart és csupán néhány gazdaszervezet felmérésére korlátozódott. Ezen módszer sikeres alkalmazásával viszont földrajzilag nagyobb léptékű, intenzív és szisztematikus mintagyűjtés válik lehetővé. Mindemellett dolgozatomban a HNP területén lévő három különböző típusú vizes élőhelyen vizsgáltam a P. esculentus komplex populációk fajösszetételét, amelyet a két szülői faj, a Pelophylax ridibundus és a Pelophylax lessonae, illetve ezek interspecifikus hibridje a Pelophylax esculentus alkot. Mikroszatellita markerek alkalmazásával megállapítottam a hibrid egyedek genotípusát. Végül, populáció genetikai indexek számításával következtettem a zöldbékák szaporodási rendszerére. The studies of this thesis examined a host-parasite system in Hortobágy National Park, in eastern Hungary. In addition, new approach of parasite inventory (DAMA) protocol was proposed and also applied on that system. The growing focus on parasites in the past few decades revealed that parasitic organisms cover a great majority of known biodiversity and they started to recognize them as significant linkage components between climate change, biodiversity dynamics, and emerging infectious diseases. We documented and assessed the macroparasite fauna of Pelophylax esculentus complex and collected helminth material not just for classical morphology-based taxonomic identification, but the majority of the samples were preserved for the development of DNA barcodes. DNA barcoding emerged as a cost-effective method for rapid species identification. Additionally, it offers an unique way to perform non-destructive monitoring of hosts for parasites. This creates the potential to shift from logistically challenging field collections, necropsy, and morphological characterization based on assessments of a few hosts to more geographically extensive, site-intensive, and near-simultaneous sampling across ecosystems, thus linking landscape to regional scales for assemblages of host species and populations. We investigated the taxonomic composition and ploidy level of P. esculentus complex which consists of two sexual species, Pelophylax ridibundus and Pelophylax lessonae and their hybridogenetic hybrid, Pelophylax esculentus sampled in three different types of wetland habitats in eastern Hungary at HNP. We applied population genetic approach to determine the type of gametes produced by hybrids and to infer the breeding system of water frogs.N

Taxonomic composition and ploidy level among European water frogs (Anura: Ranidae: Pelophylax) in eastern Hungary

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First detection of Ranavirus infection in amphibians in Hungary

DH was supported by the National Research, Development and Innovation Office (NKFIH) of Hungary (grant no. K-124375) and the Young Investigators Programme (FiKut) of the Hungarian Academy of Sciences (MTA). TP was supported by the Bolyai Research Fellowship of the Hungarian Academy of Sciences (BO/00569/15)

A füstölgő meddőhányóktól a globális közlekedésig : Beszélgetés Erdősi Ferenccel

Erdősi Ferenc 1934. április 19-én született Pécsett. Elsőként a Szegedi Tudományegyetem földrajz– geológia szakán diplomázott, majd az ELTE Bölcsészettudományi Karán szerzett történelemtanári oklevelet. 1976-ban kandidált, 1989-ben lett a földrajztudomány doktora, 1993-ban egyetemi tanári kinevezést kapott. Az utóbbi két évtizedben közlekedésföldrajzzal, valamint a telematika területi hatásainak vizsgálatával foglalkozott. 2004-ben Baross Gábor-díjjal és a Magyar Köztársasági Érdemrend lovagkeresztjével, 2010-ben tisztikereszttel tüntették ki. Az itt olvasható, utólagosan strukturált interjú 2021 szeptemberében, otthonában készült. A jelen beszélgetés célja, hogy jobban megismertesse a professzor életének fontos mozzanatait, azt a miliőt, amely szerepet játszott szakmai életútjának alakulásában. Célunk továbbá, hogy ezen keresztül érzékeltessük a hazai földrajz erényeit, kihívásait és feladatait

Distinctive site preference of the fish parasite Myxobolus cerebralis (Cnidaria, Myxozoa) during host invasion

Here, we experimentally studied the site preference of Myxobolus cerebralis, one of the most pathogenic myxozoan (Cnidaria, Myxozoa) fish parasites, which causes whirling disease in salmonids. Parasite invasion was examined in three fish species with various susceptibility levels: the type host brown trout, the highly susceptible rainbow trout, and the non-susceptible gibel carp, in which parasite spores do not develop. We investigated the first two hours of fish invasion, and measured the site preference of triactinomyxons (TAMs) during attachment and penetration of fish in three body parts (gills, fins, skin). Infection prevalence and intensity were estimated using a species-specific nested PCR, optimised in the present study. The highest infection prevalence was detected in the most susceptible fish species, rainbow trout. Interestingly, higher prevalence was observed in gibel carp than in the type host, brown trout (95.2% vs. 85.7%). Considering body locations, remarkable differences were detected in infection intensities. The highest intensity was observed in fins, whereas skin was the least infected body part in every fish species examined. Infection prevalence and intensity did not differ significantly among fish species. Thus, we confirmed that M. cerebralis TAMs cannot discern fish species. Furthermore, we proved experimentally that fish fin is significantly more attractive to fish-invading parasite TAMs than gills or skin

Batrachochytrium dendrobatidis in Hungary: an overview of recent and historical occurrence

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Chytridiomycosis and climate change: exposure to Batrachochytrium dendrobatidis and mild winter conditions do not increase mortality in juvenile agile frogs during hibernation

Hibernation is often associated with high mortality, especially during early life stages, and losses can be exacerbated by unusual winter conditions or if animals enter hibernation carrying a disease. Here, we examined how overwintering amphibians may be affected by the combined effects of mild winters, which are projected to increase in frequency due to climate change, and of chytridiomycosis, a disease that has contributed to the decline of hundreds of species worldwide. We exposed juvenile agile frogs Rana dalmatina to Batrachochytrium dendrobatidis (Bd), the causative agent of chytridiomycosis, and subsequently subjected them to either a long, cold winter (1.5°C for 91 days) or a short, mild winter (4.5°C for 61 days) under laboratory conditions. Agile frogs proved to be highly resistant to Bd as only 37% of Bd-exposed individuals became infected as determined before hibernation, and prevalence further decreased to 8% by the end of hibernation, with individuals showing very low infection intensity values. We observed lack of mortality in control and Bd-exposed groups also, in both types of winter. The two types of winter we simulated did not result in differing body mass loss either alone or in combination with experimental infection. In the Bd-exposed group, the two types of winter also did not cause differences in prevalence and infection intensity. However, among Bd-exposed frogs, individuals that were Bd negative when entering hibernation lost more body mass than their conspecifics that carried the fungus at the onset of overwintering. Based on our results, warming winter climate conditions, with or without Bd infection, do not decrease body mass and survival rate of hibernating agile frogs, and do not increase susceptibility of individuals to chytridiomycosis. It remains to be seen to what extent the relatively weak effects of milder winters can be generalized to other amphibians of the temperate climate zone

Mitigating Disease Impacts in Amphibian Populations: Capitalizing on the Thermal Optimum Mismatch Between a Pathogen and Its Host

Understanding how animal behavior can influence the susceptibility of endangered hosts to emerging pathogens and using this knowledge to ameliorate negative effects of infectious wildlife diseases is a promising avenue in conservation biology. Chytridiomycosis, an emerging infectious disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) in amphibians has led to the most spectacular disease-borne loss of vertebrate biodiversity ever recorded in history. Unfortunately, the methods of mitigation that are available today are only practical in captive populations, and an effective method that could be applied in natural habitats without inflicting vast collateral damage is lacking. We suggest here that the thermal tolerance mismatch between Bd and its ectothermic hosts coupled with the thermoregulatory behavior of amphibians could be exploited in mitigation interventions combating Bd infection in situ. If microhabitats with elevated temperatures are made available in their natural environment, individuals taking advantage of the possibility to reach their preferred body temperature could critically lower their infection intensity or even clear the pathogen. We provide a basis for studying this approach by reviewing the evidence that supports the idea, describing how technical difficulties may be overcome, pointing out gaps in our knowledge that need to be filled by future studies, and listing presumable bene fits and probable limitations of localized heating. The proposed approach has good potential to become an effective in situ mitigation method that can be easily employed in a wide taxonomic range of amphibians, especially in species that are warm-adapted, while causing less collateral damage than any other method that is currently available. If so, it may quickly become a widely applicable tool of biodiversity conservation and may contribute to saving many amphibian populations and species from extinction in the next few decades

Host–multiparasite interactions in amphibians: a review

Parasites, including viruses, bacteria, fungi, protists, helminths, and arthropods, are ubiquitous in the animal kingdom. Consequently, hosts are frequently infected with more than one parasite species simultaneously. The assessment of such co-infections is of fundamental importance for disease ecology, but relevant studies involving non-domesticated animals have remained scarce. Many amphibians are in decline, and they generally have a highly diverse parasitic fauna. Here we review the literature reporting on field surveys, veterinary case studies, and laboratory experiments on co-infections in amphibians, and we summarize what is known about within-host interactions among parasites, which environmental and intrinsic factors influence the outcomes of these interactions, and what effects co-infections have on hosts. The available literature is piecemeal, and patterns are highly diverse, so that identifying general trends that would fit most host–multiparasite systems in amphibians is difficult. Several examples of additive, antagonistic, neutral, and synergistic effects among different parasites are known, but whether members of some higher taxa usually outcompete and override the effects of others remains unclear. The arrival order of different parasites and the time lag between exposures appear in many cases to fundamentally shape competition and disease progression. The first parasite to arrive can gain a marked reproductive advantage or induce cross-reaction immunity, but by disrupting the skin and associated defences (i.e., skin secretions, skin microbiome) and by immunosuppression, it can also pave the way for subsequent infections. Although there are exceptions, detrimental effects to the host are generally aggravated with increasing numbers of co-infecting parasite species. Finally, because amphibians are ectothermic animals, temperature appears to be the most critical environmental factor that affects co-infections, partly via its influence on amphibian immune function, partly due to its direct effect on the survival and growth of parasites. Besides their importance for our understanding of ecological patterns and processes, detailed knowledge about co-infections is also crucial for the design and implementation of effective wildlife disease management, so that studies concentrating on the identified gaps in our understanding represent rewarding research avenues. [Image: see text