Research Group Acoustic and Functional Ecology

Research Group Acoustic and Functional Ecology

The Emmy Noether funded research group “Acoustic and Functional Ecology” investigates the functional and ecological principles of sensory processing and associated animal behaviour. We pursue these questions in the ecologically important context of predator-prey interactions, using echolocating bats and eared insects as model systems of auditory information processing and auditory-guided behaviour.

 

Sensory processes are at the centre of an animal’s perception of the world and its actions in this world, including some of the most crucial behaviours for survival such as foraging and predator avoidance. Accordingly, natural selection has not only shaped the morphology of animals, but also their sensory and behavioural properties. Our overall scientific objective is to understand the function of sensory systems and their consequences for ecological and evolutionary processes. In our research, we study bats and moths as two model systems for complex and simple auditory processing and auditory-guided behaviour.

Echolocating bats rely to a large extent on auditory information for orientation, foraging and communication. Bats are thus a great model system to study auditory processing and the adaptation of sensory processes to ecological requirements. In our research, we address questions of sound-based perception of the environment, the use of sound for inter-individual and inter-specific interactions, the importance of dynamic sensory processing for the perception of complex and variable auditory scenes, and effects of the environment, including climate change, on sound-based perception.

In contrast to the flexible sensory-motor system of bats, the ears of noctuoid moths are simple. They consist of only 1-4 auditory neurons and trigger a two-staged evasive flight response, consisting of directional and erratic flight to escape attacking bats. The well-studied neurobiology of the simple moth ear provides an ideal foundation for a systematic study of the evasive behaviour of moths, which is the phenotype selected by bat predation. Moth families differ in the number of auditory receptor cells (1-4 cells) and additional antipredator strategies. This allows to study the function and adaptive value of evasive flight and protean escape mechanisms in a comparative approach and to test biological hypotheses, for example on the risk-dependent evolution of erratic flight, sustained erratic flight without sensory input and phenotypic variability as adaptation to predation pressure.

Echolocating bats and moths with bat-detecting ears are tightly connected in an evolutionary arms race. Their predator-prey-relationship is solely based on acoustic information and auditory-guided behaviour for foraging and for predator avoidance, respectively. They interact with one another in a functional, ecological and evolutionary relationship, adding additional layers of complexity and interdependence. Our research addresses auditory processing and auditory guided behaviours on all these levels, from individuals to populations. They are thus a perfect and highly integrated model system to study auditory-guided flight at two extremes of sensory processing.

Moth species perform evasive flights with species-specific diverse tactics in response to the same simulated bat attack. This variability of evasive flights increases the population-wide unpredictability experienced by bat predators, likely protecting the whole moth community against their predators.

Each moth escapes its own way

Moth species perform evasive flights with species-specific diverse tactics in response to the same simulated bat attack. This variability of evasive flights increases the population-wide unpredictability experienced by bat predators, likely protecting the whole moth community against their predators.
Just published: Our research in the Research Highlights of the Yearbook 2018. Holger Goerlitz’s report about predator-prey-interactions for the Max Planck Yearbook 2018 was chosen as one of the 15 Highlights of the Max Planck Society 2018.

Highlights of the Max Planck Yearbook 2018

Just published: Our research in the Research Highlights of the Yearbook 2018. Holger Goerlitz’s report about predator-prey-interactions for the Max Planck Yearbook 2018 was chosen as one of the 15 Highlights of the Max Planck Society 2018.
Holger R. Goerlitz received a new grant of the Emmy Noether program to continue for another year his research into the sensory strategies underlying predator-prey-interactions.

New Emmy Noether Extension Grant

Holger R. Goerlitz received a new grant of the Emmy Noether program to continue for another year his research into the sensory strategies underlying predator-prey-interactions.
The sonar system of bats exploits spatial information in a way similar to our sense of sight, despite the different anatomy of eyes and ears.

Hearing in 3D

The sonar system of bats exploits spatial information in a way similar to our sense of sight, despite the different anatomy of eyes and ears.
Where do bats go for dinner? Echolocating bats use the social information provided by the echolocation calls of other bats to find food. A large-scale field experiment shows that they integrate species identity, conspecific activity and prey abundance.

Ubiquitous use of social information in bats

Where do bats go for dinner? Echolocating bats use the social information provided by the echolocation calls of other bats to find food. A large-scale field experiment shows that they integrate species identity, conspecific activity and prey abundance.
Microphone arrays are extremely useful to study vocalizing animals. However, we need precise measurements of the position of all microphones, which can be difficult and time consuming, particularly in the field. Here, we present a method for self-calibration based on playbacks from a single loudspeaker.

Robust acoustic self-calibration method for microphone positions

Microphone arrays are extremely useful to study vocalizing animals. However, we need precise measurements of the position of all microphones, which can be difficult and time consuming, particularly in the field. Here, we present a method for self-calibration based on playbacks from a single loudspeaker.
Barbastelle bats trick moths that are able to hear their echolocation calls. These bats are known to counter moth hearing by using quiet, 'stealthy' calls to search for prey in the dark. As they come closer, they sneak up on unsuspecting moths by gradually emitting even fainter calls.

The stealthy hunt of barbastelle bats

Barbastelle bats trick moths that are able to hear their echolocation calls. These bats are known to counter moth hearing by using quiet, 'stealthy' calls to search for prey in the dark. As they come closer, they sneak up on unsuspecting moths by gradually emitting even fainter calls.
An international group of researchers including scientists from Seewiesen used novel miniature tags to study foraging strategies in five bat species. By analyzing high resolution GPS tracks together with the bats' acoustic behaviour, they showed that social foraging is driven by resource distribution: When searching for food that is only available very locally and for a limited time, it pays to fly out in a group and thus increase the chance of finding it.

Resource ephemerality drives social foraging in bats

An international group of researchers including scientists from Seewiesen used novel miniature tags to study foraging strategies in five bat species. By analyzing high resolution GPS tracks together with the bats' acoustic behaviour, they showed that social foraging is driven by resource distribution: When searching for food that is only available very locally and for a limited time, it pays to fly out in a group and thus increase the chance of finding it.
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