TY  - JOUR
A1  - Grafe, T. Ulmar
A1  - Preininger, Doris
A1  - Sztatecsny, Marc
A1  - Kasah, Rosli
A1  - Dehling, J. Maximilian
A1  - Proksch, Sebastian
A1  - Hödl, Walter
T1  - Multimodal Communication in a Noisy Environment: A Case Study of the Bornean Rock Frog Staurois parvus
JF  - PLoS One
N2  - High background noise is an impediment to signal detection and perception. We report the use of multiple solutions to improve signal perception in the acoustic and visual modality by the Bornean rock frog, Staurois parvus. We discovered that vocal communication was not impaired by continuous abiotic background noise characterised by fast-flowing water. Males modified amplitude, pitch, repetition rate and duration of notes within their advertisement call. The difference in sound pressure between advertisement calls and background noise at the call dominant frequency of 5578 Hz was 8 dB, a difference sufficient for receiver detection. In addition, males used several visual signals to communicate with conspecifics with foot flagging and foot flashing being the most common and conspicuous visual displays, followed by arm waving, upright posture, crouching, and an open-mouth display. We used acoustic playback experiments to test the efficacy-based alerting signal hypothesis of multimodal communication. In support of the alerting hypothesis, we found that acoustic signals and foot flagging are functionally linked with advertisement calling preceding foot flagging. We conclude that S. parvus has solved the problem of continuous broadband low-frequency noise by both modifying its advertisement call in multiple ways and by using numerous visual signals. This is the first example of a frog using multiple acoustic and visual solutions to communicate in an environment characterised by continuous noise.
KW  - call
KW  - dart-poison frog
KW  - animal communication
KW  - auditory masking
KW  - acoustic communication
KW  - anthropogenic noise
KW  - courtship displays
KW  - traffic noise
KW  - higher pitch
KW  - signals
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-133718
VL  - 7
IS  - 5
ER  - 
TY  - JOUR
A1  - Scharmann, Mathias
A1  - Thornham, Daniel G.
A1  - Grafe, T. Ulmar
A1  - Federle, Walter
T1  - A Novel Type of Nutritional Ant-Plant Interaction: Ant Partners of Carnivorous Pitcher Plants Prevent Nutrient Export by Dipteran Pitcher Infauna
JF  - PLoS ONE
N2  - Many plants combat herbivore and pathogen attack indirectly by attracting predators of their herbivores. Here we describe a novel type of insect-plant interaction where a carnivorous plant uses such an indirect defence to prevent nutrient loss to kleptoparasites. The ant Camponotus schmitzi is an obligate inhabitant of the carnivorous pitcher plant Nepenthes bicalcarata in Borneo. It has recently been suggested that this ant-plant interaction is a nutritional mutualism, but the detailed mechanisms and the origin of the ant-derived nutrient supply have remained unexplained. We confirm that N. bicalcarata host plant leaves naturally have an elevated \(^{15}N/^{14}N\) stable isotope abundance ratio (\(\delta ^{15}N\)) when colonised by C. schmitzi. This indicates that a higher proportion of the plants' nitrogen is insect-derived when C. schmitzi ants are present (ca. 100%, vs. 77% in uncolonised plants) and that more nitrogen is available to them. We demonstrated direct flux of nutrients from the ants to the host plant in a \(^{15}N\) pulse-chase experiment. As C. schmitzi ants only feed on nectar and pitcher contents of their host, the elevated foliar \(\delta ^{15}N\) cannot be explained by classic ant-feeding (myrmecotrophy) but must originate from a higher efficiency of the pitcher traps. We discovered that C. schmitzi ants not only increase the pitchers' capture efficiency by keeping the pitchers' trapping surfaces clean, but they also reduce nutrient loss from the pitchers by predating dipteran pitcher inhabitants (infauna). Consequently, nutrients the pitchers would have otherwise lost via emerging flies become available as ant colony waste. The plants' prey is therefore conserved by the ants. The interaction between C. schmitzi, N. bicalcarata and dipteran pitcher infauna represents a new type of mutualism where animals mitigate the damage by nutrient thieves to a plant.
KW  - community
KW  - alternative trapping strategies
KW  - leaf-litter utilization
KW  - nepenthes bicalcarata
KW  - camponotus schmitzi
KW  - food web
KW  - epiphytic fern
KW  - nitrogen
KW  - prey
KW  - rafflesiana
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-130952
VL  - 8
IS  - 5
ER  - 
TY  - JOUR
A1  - Grafe, T. Ulmar
A1  - Schmuck, Richard
A1  - Linsenmair, Karl Eduard
T1  - Reproductive energetics of the African Reed Frogs, Hyperolius viridiflavus and Hyperolius marmoratus
N2  - No abstract available
Y1  - 1992
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-31187
ER  -