Ökologie, Artenschutz und Populationsgenetik einheimischer Amphibien und Laubfrösche

Drittmittelprojekt: DBU, CULT-Stiftung, 81.550 EUR

Kliniken/Institute:
Institut für Zoologie
Institut für Terrestrische und Aquatische Wildtierforschung (Hannover)

Projektdetails:
This project serves the long-term purpose of protecting the species of the yellow-bellied toad, Bombina variegata, which is highly endangered in Germany and Central Europe. In many areas, the yellow-bellied toad only occurs in secondary, i.e. anthropogenically modified, habitats such as quarries. The populations are often isolated, too small, and suffer from inbreeding and genetic impoverishment. Previous studies have also shown that yellow-bellied toads use different life cycle strategies in different habitats. These differences suggest that the species has adapted to local ecological conditions, and these adaptations are potentially manifested in the genome. The project aims to improve the genetic and ecological information available about the species in order to make practical conservation more effective. For this purpose, DNA samples from German, French and Swiss yellow-bellied toad populations, which have already been sampled in previous projects, are examined using genomic methods (RADSeq). In addition, toads in Germany will be sampled in the few natural habitats where they still occur. The genomic results are then correlated with ecological data (habitat type, local climate). The results provide evidence as to whether yellow-bellied toads are adapted to their local habitat (anthropogenic vs. natural) or to their local climate at the molecular level. The aim is to identify specific candidate genes that mediate this local adaptation. Furthermore, species distribution models based on climatic data should show where suitable habitats are for the yellow-bellied toad today and in the future - also with a view on climate change. The results obtained will be discussed with scientists and species protection specialists in a workshop. In follow-up projects, so-called genetic rescue will be used for small, isolated occurrences to stabilize them, and larger populations will be genetically upgraded. Genetic rescue projects based on genomic information are innovative since so far they have been successfully implemented in species protection in only a few countries.

Kooperationspartner:

Prof. Jean-Paul Léna, Dr. Hugo Cayuela, Benjamin Monod-Broca, University of Lyon;

Dr. Mirjam Nadjafzadeh, NABU Niedersachsen; Fabian Droppelmann, Chance 7

Kliniken/Institute:
Institut für Zoologie

Projektdetails:
Many animals use colorations in antipredator strategies. Cryptic coloration conceals the animal on its natural substrate while bright aposematic coloration is paired with unpalatability, for example conveyed by toxins, and functions as warning signal. Geographic variation in coloration shades or patterns have been interpreted as local adaptations to the prevailing local substrates and predator classes. Yellow bellied toads are particularly exciting study objects since they present a cryptic grey-brown coloration in their dorsum, but a highly contrasting yellow-black pattern on their bellies. The toads also possess highly poisonous bombinatoxins in their skin and use a deimatic display, the so-called Unkenreflex, when a predator is close. We studied variation in the cryptic and aposematic coloration in three local populations in Southern Lower Saxony. We found the toads to be most cryptic dorsally on their local substrates, while the internal aposematic contrast on the belly remained constant. Furthermore we investigate whether the toads are able to change their dorsal coloration when placed on substrates of different colorations (darker and brighter substrates). In the next steps, we will analyze whether toads from different localities and substrates differ in their capacities of coloration plasticity and which genes show differential expression (e.g. genes involved in the production of melanin) while the animals adapt their cryptic coloration to their current substrate. Finally we will carry out predation experiments with clay model toads in the field to find out whether the adaptation of cryptic coloration to the local substrate helps to decrease the attack risk by predators.

Resultate:

Preißler KP, Rodríguez A, Pröhl H (2021) Evidence for coloration plasticity in the yellow-bellied toad, Bombina variegata. Ecology and Evolution, 11: 17557-17567. https://doi.org/10.1002/ece3.8391

Kooperationspartner:

Kathleen Preißler, TU Braunschweig

Drittmittelprojekt: NABU DBU, 22.564 EUR

Kliniken/Institute:
Institut für Biochemie
Research Center for Emerging Infections and Zoonoses
Institut für Zoologie

Projektdetails:
Infectious diseases are a worldwide problem, sometimes causing declines and extinctions in wild populations and species. An alarming situation is the infestation of amphibians by a chytrid fungus: Batrachochytrium dendrobatidis (Bd) has infected over 520 species worldwide. This fungus grows in the skin surface of amphibians and keratinizes cells; this difficults the transport of ions, and therefore osmoregulation, which in many cases leads to death by cardiac arrest and massive mortalities. Habitat fragmentation, within other factors including diseases, has lead amphibians to be the most threatened vertebrate group. In Europe, the yellow bellied toad (Bombina variegata) is classified as endangered, and is one of the few anurans with a high Bd infection prevalence. In Germany, yellow bellied toads have been recorded to have a Bd infection rate around 14%, however no Bd massive mortalities due to chytridiomycosis have been reported. In spite of that, Bd infection could entail a fitness reduction. Currently the yellow bellied toad is listed at the German red list as endangered and within some regions of Germany as threatened with extinction. For this reason the NABU started a native habitat management and connection project, which includes reintroductions. As Bd is present in Germany, this project aims to understand better the threat Bd is posing to yellow bellied toad populations. At the northernmost distribution of the yellow bellied toad, NABU is monitoring 16 populations and in four of them toads have been reintroduced. These populations were sampled three times in spring and summer 2016 (May, July and September) to determine the difference in infection rate in relation to temperature, population size and genetic diversity. The quantification of Bd infection rate is determined by real-time qPCR. The technique was established at RIZ-TiHo by Dr. Bourke together with de Buhr, PhD. Up to now, 593 DNA samples have been extracted, the qPCR technique set up and Bd infection quantified.

Resultate:

Oswald P, Rodríguez A, Bourke J, Wagner N, de Buhr N, Buschmann H, Köckritz-Blickwede M, Pröhl H (2020) Locality, time and heterozygosity affect chytrid infection in yellow-bellied toads. Diseases of Aquatic Organisms 142: 225-237

Kooperationspartner:

M.Sc. Pia Oswald, Universität Bielefeld

Dr. Holger Buschmann, NABU

Dr. Norman Wagner, Universität Trier

Drittmittelprojekt: NABU DBU, 22.564 EUR

Kliniken/Institute:
Institut für Biochemie
Research Center for Emerging Infections and Zoonoses
Institut für Zoologie

Projektdetails:
Infectious diseases are a worldwide problem, sometimes causing declines and extinctions in wild populations and species. An alarming situation is the infestation of amphibians by a chytrid fungus: Batrachochytrium dendrobatidis (Bd) has infected over 520 species worldwide. This fungus grows in the skin surface of amphibians and keratinizes cells; this difficults the transport of ions, and therefore osmoregulation, which in many cases leads to death by cardiac arrest and massive mortalities. Habitat fragmentation, within other factors including diseases, has lead amphibians to be the most threatened vertebrate group. In Europe, the yellow bellied toad (Bombina variegata) is classified as endangered, and is one of the few anurans with a high Bd infection prevalence. In Germany, yellow bellied toads have been recorded to have a Bd infection rate around 14%, however no Bd massive mortalities due to chytridiomycosis have been reported. In spite of that, Bd infection could entail a fitness reduction. Currently the yellow bellied toad is listed at the German red list as endangered and within some regions of Germany as threatened with extinction. For this reason the NABU started a native habitat management and connection project, which includes reintroductions. As Bd is present in Germany, this project aims to understand better the threat Bd is posing to yellow bellied toad populations. At the northernmost distribution of the yellow bellied toad, NABU is monitoring 16 populations and in four of them toads have been reintroduced. These populations were sampled three times in spring and summer 2016 (May, July and September) to determine the difference in infection rate in relation to temperature, population size and genetic diversity. The quantification of Bd infection rate is determined by real-time qPCR. The technique was established at RIZ-TiHo by Dr. Bourke together with de Buhr, PhD. Up to now, 593 DNA samples have been extracted, the qPCR technique set up and Bd infection quantified.

Kooperationspartner:

M.Sc. Pia Oswald, Universität Bielefeld

Dr. Holger Buschmann, NABU

Dr. Norman Wagner, Universität Trier

Drittmittelprojekt: DBU, NABU, 100.000 EUR

Kliniken/Institute:
Institut für Zoologie

Projektdetails:
Amphibien gehören zu den am stärksten bedrohten Tiergruppen. Sie sind weltweit von Populationsrückgängen betroffen, viele Arten gelten schon als ausgestorben. Gründe für die Populationsrückgänge sind insbesondere Habitatfragmentierung, Ausbreitung von Krankheiten und Kontamination von Laichgewässern. Für niedersächsische Amphibien gilt, dass früher große kontinuierliche Populationen heute durch Straßenbau und Habitatzerstörung stark fragmentiert sind. Mit Hilfe von molekularen Markern (Mikrosatelliten, mt Gene) soll am Beispiel der Gelbbauchunke untersucht werden wie groß die verbleibenden Populationen sind (effektive Populationsgröße), wie stark die Populationen sich genetisch unterscheiden und wie hoch der Genfluss zwischen ihnen ist; wie groß die die genetische Diversität innerhalb von Populationen ist und ob alle Populationen als authochton angesehen werden können. Landscape-Ecology-Analysen sollen potentielle Verbreitungsbarrieren (z.B. Straßen) identifizieren und in wie weit sie Genfluß verhindern und die genetische Diversität beeinflussen. Weiterhin soll geklärt werden, ob in Niedersachsen oder anderswo in Deutschland unterschiedliche genetische Linien vorliegen, die durch postglaziale Einwanderung oder andere Vorgänge zustande gekommen sein könnten. Diese müssten dann als unterschiedliche Conservation Units gemanagt werden. Schließlich soll geklärt werden, ob sich die genetische Diversität innerhalb von Populationen auf die Fitness der Individuen auswirkt. Wiederansiedlungsprojekte können mit molekular-genetischen Daten gezielt unterstützt werden.

Resultate:

Kleißen J, Balkenhol N, Pröhl H (2021) Landscape Genetics of the Yellow-Bellied Toad (Bombina variegata) in the Northern Weser Hills of Germany. Diversity 13: 623 https://doi.org/10.3390/d13120623

 

Pröhl H, Auffarth J, Bergmann T, Buschmann H, Balkenhol N (2021) Conservation genetics of the yellow-bellied toad (Bombina variegata): population structure, genetic diversity and landscape effects in an endangered amphibian. Conserv Genetics 22: 513-529

 

Hantzschmann AL, Sinsch U, Göttlicher C, Pröhl H (2020) Conservation genetics of yellow-bellied toads (Bombina variegata): a matter of geographical scale and isolation. Conserv Genetics 22: 83-96

 

Riaño GM, Rodriguez A, Kirst K, Pröhl H (2020) Population genetics of the yellow-bellied toads (Bombina variegata) in the area of Stolberg (Germany). Mertensiella 29: 59-65.

 

 

Auffarth J, Pollmann D, Buschmann H, Pröhl H (2020) Conservation genetics of yellow-bellied toads (Bombina variegata) in the Northern Rhineland. Mertensiella 29: 50-58

Kooperationspartner:

Dr. Holger Buschmann, NABU

Dr. Jana Kirchhoff

Prof. Dr. Nico Balkenhol, Universität Göttingen