Research

      Main current projects
      Updated in September 2017


Species and range evolution in Amazonian amphibians
Since 2002.
Location: Amazon Basin and beyond.
Taxa: Anura: Atelopus spp.; Ameerega trivittata; others.
Funding: Mohamed bin Zayed, DGHT, Biopat, Stiftung Artenschutz, others. 
Collaboration: Luis A. Coloma, Quito; Raffael Ernst, Dresden; Marcelo Menin,  Manaus; Albertina Lima, Manaus; Marcelo N. Vallinoto, Belém; Youszef Bitar, Belém; and more.

It is challenging to explain amphibian history and diversity in Amazonia. Our molecular-, field- and model-based research contributes towards a better understanding of the role of long distance dispersal, how elevation and secondary contact contribute to evolutionary change within or between species, in particular the identification of cryptic species diversity (and also not forgetting to formally name them). Additionally, we contribute to the neglected question why indeed there are wide-spread species. 

Involved researchers from our lab: Michael Mayer, Luis Fernando Marin da Fonte, Daniela C. Rößler (all are doctorate candidates of Stefan Lötters), Stefan Lötters.
Important publications: Gehara, M. et al. (2014): High levels of diversity uncovered in a widespread nominal taxon: continental phylogeography of the Neotropical tree frog Dendropsophus minutus. — PLoS ONE, 9: e103958. [online]
Lötters, S. et al. (2010): Reinforcing and expanding the predictions of the disturbance vicariance hypothesis in Amazonian harlequin frogs: a molecular phylogenetic and climate envelope modelling approach. — Biodiversity and Conservation, 19: 2125-2146.
[online]

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

Functional aspects and evolution of aposematism
in brilliant-colored and not so colorful toxic toads

Since 2012.
Location: Amazon Basin and adjacent regions.
Taxon: Anura: Atelopus.
Funding: Forschungsfonds of Trier University. 
Collaboration: Pablo J. Venegas, Lima; Heike Pröhl, Hannover; Marcelo Menin, Manaus; Albertina Lima, Manaus; Marcelo N. Vallinoto, Belém; Johanna Mappes, Jyväskylä; and more.

Harlequin toads (Atelopus) greatly vary between cryptic and brilliant colorations and some just have flash marks. All Atelopus are toxic. They contain tetrodotoxin (TTX) which is puzzling, as this highly venomous substance is, other than in amphibians, known from many marine organisms including puffer fish, a delicacy in Japan. In a phylogenetic context, we study the evolution and function of visual conspicuousness with regard to toxicity.

Involved researchers from our lab: Daniela C. Rößler, Max N. Lorentz (both are doctorate candidates of Stefan Lötters), Denise J. Ellwein, Diego Ellis Soto, Stefan Lötters.
Important publications: Lorentz, M.N. et al. (2016): Tetrodotoxin in animals. — Current Biology, 26: R870-R872.
Lötters, S. et al. (2011): Assessing the molecular phylogeny of a near extinct group of vertebrates: the Neotropical harlequin frogs (Bufonidae; Atelopus). — Systematics and Biodiversity, 9: 45-57.

Photo: An undescribed toxic Atelopus species from Ecuador. By Jos Kielgast.

Ecology, evolution and systematics of amphibians in an instable
ecosytem — floating meadows of the Amazon river system
Since 2013.
Location: Amazonia.
Taxon: Anura.
Funding: Stiftung Artenschutz; CAPES.
Collaboration: Pablo J. Venegas, Lima; Marcelo Menin, Manaus; Marcelo Gordo, Manaus; Marcelo N. Vallinoto, Belém; and more.

Floating meadows ('flotantes') on the Amazon river and its tributaries are an interesting but so far largely overlooked habitat to frogs. We explore their diversity and how the high mobility of these instable pieces of vegetation influence species and within-species dispersal and evolution. 

Involved researchers from our lab: Luis Fernando Marin da Fonte (doctorate candidate of Stefan Lötters), Philipp Böning, Stefan Lötters.
Important publication: Böning, P. et al. (2017): Amphibian diversity and its turnover in floating meadows along the Amazon River. — Salamandra, 53: 379-388.

Photos: Dendropsophus triangulum, a typical but otherwise arboreal frog in floating meadows. By Stefan Lötters.

Effects of environmental contaminants in amphibians and reptiles
Since 2010.
Location: Germany.
Taxa: Anura, Caudata; Squamata.
Funding: German Science Foundation (DFG) Graduiertenkolleg; Federal Agency for Nature Conservation (BfN), Germany.
Collaboration: Bruno Viertel, Michael Veith, Norman Wagner, Trier.

Changing land use practices in agriculture may increase the contamination risk to amphibians and reptiles with pesticides. For instance, this may simply be related to the expansion of previously uncultivated areas due to the demand for energy crops, but also the cultivation of genetically manipulated crops. We investigate direct and indirect effects of environmentally (and legally) pesticide concentrations on the survival of individuals, populations and species. (i) We perform lab experiments on an amphibian standard model organism (Clawed frogs, Xenopus), with a strong focus on potential effects from glyphosate-based herbicides. (ii) Wild frogs, newts, lizards and snakes are investigated in the field. Here, we aim at studying at e.g. avoidance of differently contaminated water bodies and the detection of unusual deformation rates in larvae or individual degrees of contamination, for instance, via arthropod food sources. We also use GIS-based approaches in risk analyses.

Involved researchers from our lab: Norman Wagner, Valentin Mingo (former and current doctorate candidates of Stefan Lötters), Stefan Lötters.
Important publications: Mingo, V., S. Lötters & N. Wagner (2017): The use of buccal swabs as a minimal-invasive method for detecting effects of pesticide exposure on enzymatic activity in common wall lizards. — Environmental Pollution, 220: 53-62.
Mingo, V. et al.
(2016): Risk of pesticide exposure for reptile species in the European Union. Environmental Pollution, 215: 164-169.
Lötters, S. et al. (2014): Hypothesizing if responses to climate change affect herbicide exposure risk for amphibians. — Environmental Sciences Europe, 26: 31. [online]
Wagner, N. et al. (2013): Questions concenring the potential impact of glyphosate-based herbicides on amphibians. — Environmental Toxicology and Chemistry, 32: 1688-1700.

Photo: The Wall lizard (Podarcis muralis), a reptile species common in vineyards and to which pesticide contamination is relevant. By Ulrich Schulte.

 

How do emerging infectious diseases affect amphibian diversity?
Special focus: The salamander-eating fungus in Western Europe
Since 2008.
Location: Worldwide.
Taxon: Amphibians.
Funding: Stiftung Artenschutz, Nikolaus-Koch-Stiftung, DGHT, European Commission, Bundesamt für Naturschutz.
Collaboration: Biostationen Aachen & Düren, Frank Pasmans & An Martel, Ghent; Miguel Vences & Sebastian Steinfartz, Braunschweig; Jos Kielgast, Copenhagen; and others.

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. We have studied this pathogen in the wild in the Alps and in East Africa and have made a risk assessment for all global amphibian species, based on distribution models.
Some years ago, a new amphibian skin fungus, Batrachochytrium salamandrivorans, was discovered in western Europe. It is lethal to many salamander and newt species (not to frogs and toads or caecilians), and our native amphibian fauna is at high risk of extinction. Our studies mainly focus on how the new fungus, which might have originated in Asia (where immune species have been found), spreads and how it affects populations in the wild. In 2015, we have recorded it for the first time in Germany (see below: Spitzen-van der Sluijs et al. 2016). For more information see the informative webpage of RAVON and a film made by students from Trier University.

Involved researchers from our lab: Michael Veith, Norman Wagner, Jos Kielgast, Dennis Rödder (past), Stefan Lötters.
Important publications: Feldmeier et al. (2016): Present and future high risk zones for the spreading lethal salamander chytrid fungus in its invasive range in Europe using bioclimate and weather extremes. — PLoS ONE, 11: e0165682 [online]
Spitzen-van der Sluijs, A. et al. (2016):
Expanding distribution of lethal amphibian fungus Batrachochytrium salamandrivorans in Europe. — Emerging Infectious Diseases, 22: 1286-1288. [online]
Martel, A. et al.
(2014): Recent introduction of a chytrid fungus endangers Western Palearctic salamanders. — Science, 346: 630-631.
[online]
Lötters, S. et al. (2012): Absence of infection with the amphibian chytrid fungus in the terrestrial Alpine salamander, Salamandra atra. — Salamandra, 48: 58-62
.
Rödder, D. et al. (2009): Global amphibian extinction risk assessment for the panzootic chytrid fungus. — Diversity, 1: 52-66.[online]


Photo: Fire salamander (Salamandra salamandra):
Still common, but soon severly threatened? By SIVAE.

Right hand side is a global model of the potential
distribution of the amphibian chytrid fungus.
Warmer colors suggest higher suitability to the
pathogen and therefore higher risk to amphibians.

Species, time and space — Biogeography of the Congo Basin
Since 2004.
Location: Congo Basin and adjacent regions.
Taxa: Anura: Hylarana, Hymenochirus, Hyperolius; others.
Funding: Lab resources.
Collaboration: Rayna Bell, Washington DC; Jos Kielgast, Copenhagen; Zoltan T. Nagy, Brussels; Václav Gvozdík, Prague; Breda M. Zimkus, Havard; Marius Burger, Cape Town; Alan Channing, Bellville; and more.

Africa's 'green heart' is among the least explored rainforests, remarkably huge in size. We are interested in understanding past and on-going distributional patterns and processes. Our key groups comprise different anurans that can be attributed to distinct 'functional guilds' and show variable adaptabilities. Apart from the collection of basics (including the description of new species), we study dispersal, vicariance and identify potential refuges, making use of molecular phylogenetic data as well as species distribution models.

Involved researchers from our lab: Daniela C. Rößler, Stefan Lötters.
Important publications: Bell, R.C. et al. (2017): Idiosyncratic responses to climate-driven forest fragmentation and marine incursions in reed frogs from Central Africa and the Gulf of Guinea Islands. — Molecular Ecology, in press.
Zimkus, B.M. et al. (2017): Leapfrogging into new territory: How Mascarene ridged frogs diversified across Africa and Madagascar to maintain their ecological niche. — Molecular Phylogenetics and Evolution, 106: 254-269.
Bell, R.C. et al. (2015): Over-seas dispersal of Hyperolius reedfrogs from Central Africa to the oceanic islands of São Tomé and Príncipe. — Journal of Biogeography, 42: 65-75.

Photo: Beautiful rainforests in DRC. By Jos Kielgast.

Evolution and systematics of Afrotropical reed frogs
Since 2003.
Location:
Sub-Saharan Africa.
Taxon: Anura: Hyperoliidae.
Funding: BIOLOG; lab resources.
Collaboration: Daniel Portik, Berkeley; Alan Channing, Bellville; Rayna Bell, Ithaca; Jos Kielgast, Copenhagen; Zoltan T. Nagy, Brussels; Václav Gvoždík, Prague; Michael Veith, Trier;
Mark-Oliver Rödel, Berlin; Max Dehling, Koblenz; and more.

Hyperoliid frogs comprise several hundred species with exclusively sub-Saharan African and Madagascan distributions. These so called Reed frogs are highly sexually dichromatic. Using ancestral character reconstructions on phylogenies, we found that this trait has independently developed multiple times even within one genus. In the course of the on-going research, we intend to contribute to a more complete picture of (i) the phlogeny and taxonomy and (ii) trait evolution in these mainly arboricol frogs. This generally gives some insight how plesimorphic, synapomorphic and convergent adaptations evolve within large clades.

Involved researcher from our lab: Stefan Lötters.
Important publications: Bell, R.C. et al. (2017): Idiosyncratic responses to climate-driven forest fragmentation and marine incursions in reed frogs from Central Africa and the Gulf of Guinea Islands. — Molecular Ecology, in press.
Channing, A. et al.(2013): Taxonomy of the super-cryptic Hyperolius nasutus group of long reed frogs of Africa (Anura: Hyperoliidae), with descriptions of six new species. — Zootaxa, 3620: 301-350.
Schick, S., et al. (2010): New species of reed frog from the Congo basin with discussion of paraphyly in Cinnamon-belly reed frogs. — Zootaxa, 2501: 23-36.
Veith, M. et al. (2009): Multiple evolution of sexual dichromatism in African reed frogs. — Molecular Phylogenetics and Evolution, 51: 388-393.

Photos: Sexual dichromatism in Hyperolius viridiflavus from Kenya: females are green-yellow, males have the same color or are brownish. By Stefan Lötters.

 

Main past projects

Intra- and interspecific signalling in poison frogs
2009-2014.
Location: Amazonian Peru.
Taxon: Anura: Ranitomeya variablis.
Funding: German Research Foundation - DFG.
Collaboration: Werner Brack, Leipzig; Michael Veith, Trier.

This species lays eggs on land and transports its larvae singly into water pools in leaf axils (phytotelms). We found that nurse frogs do avoid pools occupied by conspecific tadpoels on the basis of chemical recognition. Phytotelms do provide limited resources only and tadpoles are cannibalistic. We have been able to show that sometimes tadpoels of other frog species are avoided, too (e.g. Hyloxalus azureiventris), but that occasionally pools with (chemical compounds of) tadpoles of heterospecifics are 'preferred'. The latter especially applies to non-cannibalistic tadpoles (e.g. Rhinella poeppigii). Interestingly, nurse frogs are unable to detect insect predators in phytotelms on the basis on chemical compounds.

Combining chemical analyses with in-situ bioassays, we identified the molecular formulas of the chemical compounds triggering the nurse frog's behavior. Ranitomeya variabilis and Hyloxalus azureiventris both produce distinct chemical compound combinations. This leads us to conclude that two separate communication systems are at work. In an ecological context, we classify the conspecific R. variabilis compounds as chemical cues - that is, they are only advantageous to the receiver (nurse frog), not the emitters (tadpoles). The heterospecific compounds, we suggest are chemical signals. These are advantageous to the emitters (heterospecific tadpoles) and likely also to the receivers (nurse frog). Due to these assumed receiver benefits, the heterospecific compounds are possibly synomones which are advantageous to both emitter and receiver. This would be a very rare communication system between animal species, especially vertebrates. 

Involved researchers from our lab: Lisa M. Schulte (former doctorate cnadidate of Stefan Lötters), Stefan Lötters.
Important publications: Schulte, L.M., M. Krauss, S. Lötters, T. Schulze & W. Brack (2015): Decoding and discrimination of chemical cues and signals: Avoidance of predation and competition during parental care behavior in sympatric poison frogs. — PLoS ONE, 10: e0129929. [online
Schulte, L.M. & S. Lötters (2013): The power of the seasons: rainfall triggers parental care in poison frogs. — Evolutionary Ecology, 27: 711-723.
Schulte, L.M. et al. (2011): The smell of success: choice : choice of larval rearing sites by means of chemical cues in a Peruvian poison frog. — Animal Behaviour, 81: 1147-1154.

Photo: Male Ranitomeya variabilis carrying a tadpole on its back. By Lisa M. Schulte.

Contact zones in the parapatric Alpine and Fire salamanders
2010-2014.
Location: Swiss Alps.
Taxa: Caudata: Salamandra atra, S. salamandra.
Funding: DGHT.
Collaboration: Benedikt R. Schmidt, KARCH, Neuchâtel.

Parapatric species which meet in small contact zones pose interesting questions. With the aim to to identify the determinants
for contact zones in these two land salamanders, our research combines (i) new methodical approaches in ecological modelling at various spatial scales and (ii) life history field studies.

Involved researchers from our lab: Philine Werner (former doctorate candidate of Stefan Lötters), Stefan Lötters.
Important publications:  Werner, P. et al. (2017): Microhabitat use within a contact zone of parapatric land salamanders in the Swiss Alps. — Amphibia-Reptilia, 38: 307-314.
Werner, P. et al. (2014): Analysis of habitat determinants in a contact zone of parapatric European salamanders. — Journal of Zoology, 292: 31-38.
Werner, P. et al. (2013): The role of climate for the range limits of parapatric European land salamanders. — Ecography, 36: 1127-1137
.

Photo: Amazing Alpine salamander portrait. By Ulrich Schulte.

 

Modelling range shifts in Foraminifera
2009-2013.
Location: Worldwide.
Taxon: Foraminifera.
Funding: German Research Foundation - DFG.
Collaboration: Martin Langer, Bonn; Anna Weinmann, Bonn; Dennis Rödder, Bonn.

Involved researcher from our lab: Stefan Lötters.
Important publications: Weinmann, A.E. et al. (2013): Heading for new shores: Projecting marine distribution ranges of selected larger foraminifera. — PLoS ONE, 8: e2182. [online]
Langer, M.R. et al. (2013): Climate-driven range extension of Amphistegina (Protista, Foraminiferida): models of current and predicted future ranges. — PLoS ONE, 8: e54443. [online]
Langer, M.R. et al. (2012): “Strangers” in paradise: modeling the biogeographic range expansion of the foraminifera Amphistegina in the Mediterranean Sea. — Foraminiferal Research, 42: 234-244.

Above is shown the potential New World distribution of Amphistegina spp. under current and future climatic conditions (for the year 2050, right). Warmer colors suggest higher suitability; that is a trend to decrease with anthropogenic warming.