PUB - Publikationen an der Universität Bielefeld

We are in the midst of a global biodiversity crisis, and many species experience drastic population declines or local extinction events. Amphibians are by far the most threatened taxon. They are highly affected by habitat loss, climate change, pollution and emerging infectious diseases such as chytridiomycosis caused by the chytrid fungus *Batrachochytrium salamandrivorans* (*Bsal*). In the European fire salamander (*Salamandra salamandra*), this fungus has led to numerous population collapses and thus, conservation efforts have increased during the last years. However, to guide conservation efforts, we need to gather more population data and more knowledge about how amphibians cope with environmental changes. Amphibians might shift to different habitats or niches (niche choice), adjust their phenotype to match the given habitat (niche conformance) or change the environment to match their phenotype (niche construction). This research aims to investigate niche choice and niche conformance in the European fire salamander as a model species for the taxon of amphibians. In particular, I studied the effects of the mother’s choice of a larval habitat on their offspring and whether the larvae can conform to their specific niche.
I investigated these questions by combining a systematic literature review, population monitoring in the field, population analyses using a new automatic photographic identification software (Amphibian and Reptile Wildbook) and behavioural experiments in the field and in the laboratory. First, I introduce the mechanisms of niche choice, niche conformance and niche construction, give some general background on amphibian declines and provide information on the study species, the European fire salamander (Chapter I). Chapter II comprises a literature review on reciprocal transfer experiments and a case study on fire salamanders. In Chapter III, I used a photographic mark-recapture approach with the Amphibians and Reptile Wildbook for population analyses with open population Jolly-Seber models. The behavioural experiments included larval risk-taking behaviour (Chapter IV) and anti-predator responses of larvae towards chemical stimuli of a predator (Chapter V). Furthermore, I tested the risk-taking behaviour from the larval stage across metamorphosis to the postmetamorphic stage (Chapter VI). In Chapter VII, I introduced a new tool for individual identification of fire salamander larvae and adults, the Amphibian and Reptile Wildbook. I discussed a potential pathway of disease transmission, the interspecific amplexus (Chapter VIII), and contributed valuable information to the biology of the European fire salamander and recommendations for captive breeding programs (Chapter IX). In the last chapter (Chapter X), I summarised the key results, put them into a larger context and discussed the implications for future research.
This work revealed that there is no clear evidence for local adaptation in amphibians indicating that phenotypic plasticity might play a larger role than genetic adaptation. I could show that fire salamander larvae conform to their habitat and that the larval habitat can affect the phenotype (e.g., risk-taking behaviour) even across metamorphosis. Furthermore, this study is the first to provide valid larval population size data and survival estimates for a population of fire salamanders in western Germany (Kottenforst forest). It also includes the first report of interspecific amplexus of a common toad and a rare amplexus of a common frog with fire salamanders. These findings stress the need for further studies investigating the underlying mechanisms of niche choice and niche conformance in salamanders and amphibians in general. It also emphasizes the importance of population monitoring in the face of global amphibian declines and the spread of *Bsal*.
In summary, this research contributes to the growing body of literature about fire salamanders, expands the basic knowledge about this species and its behaviour, establishes a new tool for population analyses and gives recommendations for captive breeding programs. Thus, this work provides new substantial information that builds the base for further research and is crucial for future conservation of the European fire salamander and other amphibian species.