Lab News and Research Highlights

The Meaning of Colors

30/08/2016

One of our key research topics is the evolution and the function of warning colors (aposematism) in toxic prey. We study Neotropical harlequin frogs, Atelopus spumarius and related forms from the Amazon basin and adjacent areas.

Interesting in these frogs is:
(1) They are all toxic and possess the highly potent tetrodotoxin (TTX), a substance known from many animals including puffer fish (for more information on TTX see our recent Quick Guide in Current Biology). The degree of intra- and interspecific variation is subject to ongoing research.

(2) These harlequin frogs highly vary in dorsal color conspicuousness: some are vividly colored while others are virtually non-aposematic.

(3) Some have colorful ventral sides and some even hand/foot soles. These are red and we consider them to represent flash marks to warn potential predators. Actually, we have been able to show that red hand/foot soles can almost only be seen by birds. In contrast, dorsal colors are seen by a variety of potential predators including crabs. See an interesting video on a crab predation attempt here; the frog in the end is apparently too toxic for the crab.

Recent fieldwork by Daniela C. Rössler and Max N. Lorentz, doctorate candidates of the lab, has been very successful and they are currently analyzing relationships between color conspicuousness and toxicty aspects. For more videos from the field, see here.

Harlequin frogs are not the only amphibians with red hand/foot soles. This character is also notable in toads of the toxic genus Melanophryniscus; see here for the extraordinary Melanophryniscus admirabilis, a Critically Endangered species from southern Brazil.

Lorentz, M.N., A.N. Stokes, D.C. Rössler & S. Lötters (2016): Tetrodotoxin in animals. — Current Biology, 26: R870-R872.

 

New Poison Frog Book Out Now

16/05/2016

This new volume with more 500 pages and more than 200 color illustrations (about half of which are detailed scientific drawings) is published in the Conservation International field guide series. It treats all aposematic, i.e. colorful and toxic, species in the poison frog family Dendrobatidae which occur in the Andean countries of South America.

This piece of work is the result of a collaborative work by many contributors. It contains information on species' adult and larval morphology, alkaloid profiles, natural history, calls, reproduction, distribution and threats.

The book can be obtained from Chimaira.

Kahn, T.R., E. La Marca, S. Lötters, J.L. Brown, E. Twomey & A. Amézquita (2016): Aposemtaic poison frogs (Anura; Dendrobatidae) of the Andean countries Bolivia, Colombia, Ecuador, Peru and Venezuela. — Conservation International, Washington D.C. (USA), 582 pp.

Macroecology Meets Biogeography

17/03/2016

We have recently hosted the first joint conference of the "Arbeitskreis Biogeographie" (VGDH) and the "Arbeitskreis Makroökologie" (GfÖ) (15-17 March 2016). Both macroecology and biogeography, besides their own nature, show a large overlap in topics, concepts and methods. The goal of the scientific meeting was to learn more about the other discipline’s scopes and to identify synergies. We had more than 50 participants from seven countries who found the meeting was a successful cometogether. The program included 26 talks and 5 posters. For more information, abstracts etc. see here. We are grateful to all participants and to all people from our own department who helped with the organization.


Disentangling Chemical Communication in Poison Frogs: Cues & Signals

01/07/2015

Poison frogs show a complex parental care behavior. Several species lay eggs on land and later transport the tadpoles on one parent's back singly to small water bodies in plants (phytotelms). For some years now, it is known that Ranitomeya variabilis from the Amazon rainforest of Peru (and maybe other species) only choose phytotelms that are unoccupied by conspecific tadpoles and sometimes by those of other species (such as commonly Hyloxalus azureiventris). First the small water bodies do not provide resources for the development of more than one larva. Second, Ranitomeya larvae are cannibals and would attack each other. In our earlier studies, carried out by Dr. Lisa M. Schulte, we showed that nurse frogs chose the right phytotelm on the basis of chemical recognition (Schulte et al., 2011, Animal Behaviour, 81: 1147-1154). This opened an avenue for further research questions.

We are a remarkable step further now! Combining chemical analyses with in-situ bioassays, we identified the molecular formulas of the chemical compounds triggering the nurse frog's behavior (collaboration was with the Helmholtz Centre for Environmental Research - UFZ; fundig was by the German Research Foundation - DFG). 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 is a very rare communication system between animal species, especially in vertebrates. Read more in the 1st July issue of PLoS ONE (Schulte et al. 2015).

Schulte, L.M. et al. (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.

 

Alarming Research Results: Dramatic Threat by New Salamander Fungus

31/10/2014

A novel skin-eating fungal disease discovered in Europe poses a major threat to native salamanders and newts.
Batrachochytrium salamandrivorans (Bs) was discovered only in 2013 by researchers investigating a remarkable decline in Fire salamander populations in the Netherlands.

New research, involving a global screening of more than 5,000 amphibians (under the lead of An Martel and Frank Pasmans from Gent University, Belgium, involving members from our group), now suggests that the new disease presents a serious threat to many species. Bs is very dangerous to most salamanders and newts, but not to frogs, toads and the snake-like amphibians called caecilians. The fungus was also found in newts from Thailand, Vietnam and Japan as early as 1894, without causing disease, suggesting Bs originates from Southeast Asia. Read more in a press release by Trier University (in German) or watch our movie (in German).

Apparently, Bs has arrived in Europe only recently so far the disease has only been found in the Netherlands and Belgium, but it is likely to reach other European countries soon. In 2014, our group has started a Bs and salamander / newt population monitoring and research program in the area in Germany close to the Belgian and Dutch outbreaks. This will be continued into 2015 and on.

Martel, A. et al. (2014): Recent introduction of a chytrid fungus endangers Western Palearctic salamanders. — Science, 346: 630-631.


Europe Needs a New Vision for a Natura 2020 Network

05/02/2013

Advocating this statement, members of our group have contributed to an important and widely acknowledged policy piece published under the interdisciplinary graduate school 'Cooperation of Science and Jurisprudence in Improving Development and Use of Standards for Environmental Protection – Strategies for Risk Assessment and Management’ at Trier University, funded by the German Science Foundation DFG (GRK 1319). Read more (in German).

Hochkirch, A. et al. (2013): Europe needs a new vision for a Natura 2020 network. — Conservation Letters, 6: 462-476.


'Deutsche Bundesstiftung Umwelt' Book of the Month

01/02/2013

Our group has contributed to a book on the status of amphibians and reptiles under climate change at the national scale. This work, published by the Biodiversität und Klima Forschungszentrum (BiK-F) and Climate Service Center (CSC), was honored as the book of the month in January by the 'Deutsche Bundesstiftung Umwelt', DBU. Read press release by Trier University (in German).

Mosbrugger, V. et al. (2012): Klimawandel und Biodiversität. Folgen für Deutschland. — Darmstadt: WBG, 432 p.

Invited Speaker to 'German Zoological Society'

15/09/2012

On 24 September, Stefan Lötters will be speaking at the 105th annual meeting of the 'Deutsche Zoologische Gesellschaft' (DZG) in Konstanz on "Ecological niches in Amazonian amphibians: linking macroecology and evolution", following a kind invitation by the 'Fachgruppe Ökologie'. 

 

Taylor & Francis Prize 2011 to Lötters et al.

17/02/2012

Our molecular phylogeny on the critically endangered harlequin frogs (Atelopus) published in the journal Systematics and Biodiversity No 9 / 2011, was awarded the 'outstanding paper of the year' by the publisher.

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.