Main Current Projects

Updated in February 2024

Species and range evolution, with a particular focus on Neotropical amphibians 
Since 2002

As for a biodiversity researcher, it is just a super interesting challenge to explain species' biogeographic and evolutionary histories in Amazonia and the adjacent Andean system. 

Our molecular-, field- and model-based research on amphibians contributes to a better understanding of the role of e.g. the various modes of dispersal (such as long distance dispersal), or how secondary contact contributes to evolutionary change within or between species.  

Ameerega trivittata, a fellow
found over most of Amazonia. 
Photo by Denise J. Ellwein

Systematics and taxonomy of harlequin toads (Atelopus
Since 1990

For more than 30 years now, we have continuously contributed to the taxonomy and phylogeny in these Neotropical toads as a baseline for follow-up studies (e.g. on trait evolution, see below) and conservation. 

Atelopus at least is of Eocene origin and contains more than 100 species, making it the largest extant lineage of the entire family Bufonidae. Atelopus species usually have small distributions and are mostly allopatric. On the one hand, we observe highly polytypic species and effects of introgression. On the other hand, there are cryptic taxa shown to be well separated when employing an integrative taxonomic approach. Cryptic diversity even occurs over different clades. All these aspects make harlequin toads an interesting group to generally understand evolutionary and biogeographic aspects. 

Unfortunately, harlequin toads are a sad example and the poster-child of the ongoign global amphibian crisis. Most species of the genus are Cirtically Endangered and many have not been seen for years...  making Atelopus one of the most threatened vertebrate genera. For an update of the situation see our paper in Communications Earth & Environment published in November 2023.

In situ and ex situ conservation is badly needed, which is the goal of the Atelopus Survival Initiative (ASI). Our ongoing work on the systematics of these amphibians provides important ground work for conservation practice.

An undescribed toxic Atelopus 
species from Ecuador. Photo 
by Jos Kielgast

The evoultion and function of traits related to aposematism in brilliant-colored compared to not so colorful amphibians
Since 2012

Many animals are defensive and have signals to warn potential predators. This is generally understood as aposematism, which is a highly complex matter. Generally, warning signals are honest. However, there are sometimes only weak or no signals combined with potent skin toxins in amphibians. This is the case in many South American harlequin toads (Atelopus), but also in European salamanders of the genus Salamandra

In a phylogenetic frame, we study the evolution and function of visual conspicuousness with regard to toxicity. Part of our field experiments use differently colored clay models of amphibians and visual modelling. We also study the DNA that is left on these models  from the attackers. 

A 'battery' of fire salamander clay models 
ready to be place in the field. Photo by 
Stefan Lötters

How do emerging infectious diseases affect amphibian diversity? 
Since 2005

Emerging infectious diseases are one of the main threats to global biodiversity. Amphibians, a group severely declining at the global scale, suffer from spreading fungal diseases, in particular the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd). We have studied this pathogen in the wild in the Alps and in East Africa and have made a risk assessments for all global amphibian species, based on distribution models.

Some years ago, a new amphibian skin fungus, Batrachochytrium salamandrivorans (Bsal), was discovered in western Europe. It is lethal to many salamander and newt species, and our native amphibian fauna is at high risk of extinction. The term 'salamander plague' was termed.

Our studies mainly focus on how the new fungus, which might have originated in Asia, spreads and how it affects populations in the wild. In 2015, we have recorded it for the first time in Germany where it is dramatically spreading, making Germany a Bsal hotspot. Drastic declines in fire salamander (Salamandra salamandra) populations are observed, while newts are also affected in the wild but apparently can cope better with the fungus. A particular risks arises for the Alpine salamander (Salamandra atra) because of its relatively small distribuion restricted to the Alps.

Apart from monitoring, we have ongoing studies on the fungus' biology and on host-parasite interactions both in the wild and in the lab.

The knowledge on Bsal in Germany, as of 2020, was summarized in a thematic issue of Salamandra.

The Alpine salamander is highly 
threatened by the emergence of 
the salamander plague. 
Photo by Ulrich Schulte

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