In August 2020, two pioneering papers were published by members from our lab. Rößler et al., employing experimental field and lab work, demonstrated that predators leave DNA on artificial prey (here salamanders dummies made of clay) that help identifying potential predators. This method was already introduced at the 20th Congress of European Society for Evolutionary Biology (ESEB) in 2019 and won the congress poster award (see news entry 01/09/2019 below).

In an ecological modelling study Feldmeier et al. asked whether Alpine salamanders and Common lizards, in response to global warming, would move horizontally from south-exposed to north-exposed slopes (i.e. 'aspect') rather than upward. Apparently, in these species shifts in aspect and elevation are complementary strategies to mitigate climatic warming.

Rößler, D.C., S. Lötters, M. Veith, M. Fugmann, C. Peters, S. Künzel & H. Krehenwinkel (2020): An amplicon sequencing protocol for attacker identification from DNA traces left on artificial prey. — Methods in Ecology & Evolution, in press.

The salamander plague, caused by the Asian invasive chytrid fungus Batrachochytrium salamandrivorans (Bsal), poses a serious threat to the amphibian diversity of Western Europe. Apparently, Germany is a Bsal hotspot with more than half (N = 50) of all known European records to date and massive spreads in recent years.

Recently, a thematic open access issue of the German herpetological journal SALAMANDRA dedicated to Bsal in Germany was published. It contains 11 publications summarizing the current knowledge. Guest editors are Miguel Vences and Stefan Lötters.

Long-distance dispersal (LDD) involves movements outside the standard geographic limits and outside the genetic neighbourhood area of individuals. Although considered ‘rare’, LDD is important to amphibians at the population, species and community levels. To understand how LDD shapes current biogeographic patterns in these tetrapods, Luis F. Marin da Fonte and co-authors, in Frontiers of Biogeography, reviewed the cases reported in the literature.

In 41 studies, we recovered at least 90 LDD events (3 active, 87 passive) involving at least 56 extant species and 38 genera. Most events (73) involved the colonization of islands, with rafting being suggested as the most conceivable means of overwater passive dispersal for these vertebrates.we show that LDD events have played a significant role in shaping current amphibian biogeographic patterns, especially the occurrence of disjunct distributions and the colonization of islands.

The Neotropical toad genus Atelopus, also known as harlequin toads, contains more than 100 species. The majority of them is seriously threatened with extinction, making Atelopus one of the most threatened vertebrate genera. Global Wildlife Conservation, in collaboration with  the  IUCN SSC Amphibian Specialist Group, Amphibian Survival Alliance, Amphibian Ark, Panama Amphibian Rescue and Conservation Project, and others, is spearheading efforts to develop and foster a coordinated harlequin toad conservation network - the Atelopus Survival Initiative (ASI).

The network includes national and international players - conservation groups and zoos, academic institutions and governments - working together to implement substantial, long-term, range-wide conservation measures for these unique amphibians. A kick-off meeting was held in Medellín, Colombia, 4-7 November 2019., including two lab members, Stefan Lötters and Luis F. Marin da Fonte.

Daniela Rößler --- she won the first price of this years' poster award related to the 20th Congress of European Society for Evolutionary Biology (ESEB) in Turku, Finland, 19-24 August 2019. Watch the poster Predator identification from salivary DNA left on artificial prey (by Rößler, D., S. Lötters, M. Fugmann, M. Veith & H. Krehenwinkel) in full size on Research Gate.

What is it about?
Predator-prey interactions are a vast field in ecological research and many mechanisms thereof are crucial to understand natural selection, trait functions, cognition of traits and hence their evolution. However, for many taxa predator-prey interactions are difficult to study because field observations of predation events are rare. Predation is based on perception of stimuli, in many cases visual cues. To understand the effects of different visual cues on predation, such as coloration or patterns of prey animals, many studies use artificial prey to collect information. Although widely deployed, this method largely lacks standardization of attack identification. In a new approach, we tested whether DNA of predators can be isolated from bite and peck marks found on clay models to ultimately allow precise and robust identification of the attacker. In a pilot study, we placed more than 800 models of European fire salamanders (Salamandra salamandra) in the field to collect information on predation. Attack marks on models were first analyzed visually. Subsequently, we successfully isolated and sequenced DNA of more than 6 different species of attackers from the marks left on clay models. Our results not only underline the problem of misidentification of attacks by vision alone, but also offer an intriguing method to gain robust data on predators of artificial prey. Furthermore, the method opens up new possibilities beyond the standard use of clay model studies to date, including a potential use in invasive species monitoring and species inventories.

The diversity of strategies by animals to avoid predation is fascinating. We studied diurnal, toxic harlequin toads, Atelopus spumarius sensu lato, from the Amazon basin. In this species complex, some populations have striking red soles of the hands and feet, visible only when walking (see video). When stationary, the toads are hard to detect. Consequently, these toads switch between high and low conspicuousness. Interestingly, some populations lack the extra colour display of the soles.

In a recent study, lead by Daniela Rößler and published in Scientific Reports, we found comprehensive support that the red coloration can act as an warning signal directed towards potential predators: red soles are significantly more conspicuous than soles lacking red coloration to bird predators and the presence of the red signal significantly increases detection. In line with this, toads with red soles show bolder behaviour by using higher sites in the vegetation than those lacking this signal. Field experiments hint at a lower attack risk for painted frog clay models with red soles than for those lacking the signal, in a population where the red soles naturally occur.

If advantageous, why red soles are absent in some Atelopus populations? Signal lack (evolutionary loss?) may be explained by a higher overall attack risk or potential differences of predator community structure between populations.

Emerging fungal diseases are increasingly contributing to the global biodiversity crises. Among the most blatant is chytridiomycosis in amphibians. It can be caused by 2 species of chytrid skin fungi, Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal). We for the first time ever found that both fungi can parasite on the same host individual. Of 22 fire salamanders (Salamandra salamandra) found dead at the "Belgenbach", Eifel (Germany), 21 had Bsal and 16 of them additionally Bd. 

This is alarming news! In a recent paper we discuss that multi-parasitism can have effects on host susceptibility, infection duration, transmission risk and clinical symptoms. Moreover, 'horizontal gene transfer', already known from Bd and other fungi, may increase pathogen virulence. 

On the other hand, pathogen interaction can also be antagonistic. Moreover, among nearly another 500 fire salamanders from all over Germany Bd - besides its wide geographic spread of Europe - was almost entirely absent. Bsal was confirmed in about 70 of them. Bd/Bsal co-infection definitvely is one of the many research fields in amphibian conservation which urgently need attention!    

Predator-prey interactions can be addressed using clay models of prey animals. These are placed in the field to test the predator’s behavior: attack, avoid or whatever?

Our lab uses clay models to learn more about the function of warning signals in toxic amphibians. For instance we test if attack rates change if a novel signal is involved, such as when in real yellow-black fires salamanders are suddenly blue and black ('fake news' so to say). For various reasons clay model studies are really tricky. In a recent BMC Zoology paper, Rößler et al. comment on such studies in the future including the use of proper (non-toxic) clay materials, standardization and next generation clay model studies. 

Rößler, D.C., H. Pröhl & S. Lötters (2018): Commentary: the future of clay model studies. — BMC Zoology, 3: 6.

The license to kill - are we allowed to drive species to extinction that are transmitters of serious diseases? At least we do so: In the “Pan African Tsetse and Trypanosomiasis Eradication Campaign,” we aim at eradicating the pathogen Trypanosoma via eradication of its vector: tsetse flies. Is this justified, can we decide a species is 'good' or 'bad'? How does this meet with our general goal to globally safeguard biodiversity? We come to the conclusion that disease eradication programs may not be in line with the Convention on Biological Diversity (CBD), which we discuss in a recent policy perspective by Hochkirch et al. in Conservation Letters. The 'License to Kill' might be exclusive to Mr. James Bond in another mission.

This week, our group was involved in a policy forum article in Science. People from the Department of Biogeography and the Institute of Environmental  and Technology Law of Trier University contributed to this paper by  Norman Wagner and colleagues. 

Our policy piece deals with de-extinction of animal species which no longer exist on our planet, such as mammoths species. New techniques  -  back-breeding, cloning, and genomic engineering  -  now provide the opportunity to attempt to resurrect extinct species. We discuss implications for conservation laws, which largely depend on zoological nomenclature, and laws regarding the release of genetically engineered species, which do not, and argue for unique naming of de-extinct species.

Wagner, N., A. Hochkirch, H. Martin, D. Matenaar, K. Rohde, F. Wacht, C. Wesch, S. Wirtz, R. Klein, S. Lötters, A. Proelss & M. Veith (2017): De-extinction, nomenclature, and the law. — Science, 356: 1016-1017.