3-D Raum-Orientierung bei Wüstenameisen I

How does a 0.1-mg brain solve a complex computational task? This is the question we investigate in a collaboration project between Prof. Rüdiger Wehner (Univ. Zurich) Prof. Reinhard Blickhan (Jena), Prof. Harald Wolf (Ulm) and Prof. Bernhard Ronacher (HU Berlin), by using the Saharan desert ant Cataglyphis as a model system for studying navigation within 3-D space. Earlier experiments (Wohlgemuth et al. 2001, 2002) have shown that, when walking over hills, Cataglyphis ants measure the base line distances, i.e. the projections of the ascent and descent slopes onto the horizontal plane a quite unexpected capacity of these elegant animals. We try to unravel the algorithms underlying the ant s 3-D path integration by combining neurophysiological, behavioural, and computational approaches. From previous studies on two-dimensional path integration we know that Cataglyphis does not employ a perfect vector-summation mechanism but rather uses a rule-of-thumb strategy well adapted to its particular navigational needs. As this approximation rule has been deduced experimentally from systematic navigational errors displayed by the ants within particular test paradigms that do not readily occur under natural conditions, a similar experimental approach is pursued in our recent studies on 3-D behaviour. It is a likely hypothesis that we shall arrive again at a robust special-purpose solution that has evolved in Cataglyphis through particular selection pressures and, hence, is evolution proof . These fascinating animals may thus offer an experimental approach to the general problems of brain functioning: how complex computational tasks can be boiled down to simpler approximative solutions, and how the accumulation of errors can be avoided.

A first central question was whether ants do completely reduce a 3-D orientation task to a 2-D problem the answer is a clear no . However, it is also unlikely that the ants compute a true 3-D vector (Grah et al. 2005, and in prep). A second question was how different kinds of sensory input interact to enable error-tolerant orientation. Interestingly, the ants seem to ignore the odometric information about travelling distances, if there is no simultaneous input from the sky-view based compass available (Ronacher et al., submitted).

Ronacher, Bernhard Prof. Dr. rer. nat. (Details) (Verhaltensphysiologie)

Volkswagen-Stiftung (VW)

Projektstart: 10/2002
Projektende: 05/2008


Wohlgemuth S, Ronacher B, Wehner R (2001) Ant odometry in the third dimension. Nature 411, 795-798

Wohlgemuth S, Ronacher B, Wehner R (2002). Distance estimation in the third dimension in desert ants. J Comp Physiol A 188, 273-281

Ronacher B (2005) Wegfindung ohne Wegmarken der Himmelskompass der Wüsten-ameisen. Pp. 27-46 in Elsner N, & Luer G (eds.) Sind eben alles Menschen Verhalten zwischen Zwang, Freiheit und Verantwortung. Wallstein, Göttingen

Grah G, Wehner R, Ronacher B (2005) Path integration in a three-dimensional maze: ground distance estimation keeps desert ants (Cataglyphis fortis) on course. J Exp Biol 208, 4005-4011

Ronacher B, Westwig E, Wehner R (2006) Integrating two-diemnsional paths: do desert ants process distance information inb the absence of celestial compass cues? (submitted)

Zuletzt aktualisiert 2020-10-03 um 16:31