Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Allemagne → Mechanisms of three-dimensional (3D) path integration in the desert ant Cataglyphis fortis : odometry and slope detection

Universität Ulm (2006)

Mechanisms of three-dimensional (3D) path integration in the desert ant Cataglyphis fortis : odometry and slope detection

Wittlinger, Matthias

Titre : Mechanisms of three-dimensional (3D) path integration in the desert ant Cataglyphis fortis : odometry and slope detection

Auteur : Wittlinger, Matthias

Université de soutenance : Universität Ulm

Grade : Dr. rer. nat. 2006

Résumé
Desert ants, Cataglyphis fortis, use path integration as a major means of navigation. Path integration in three dimensions requires measurement of three parameters, namely, direction, distance and slope of travelled terrain. Directional information is provided by a celestial compass, while distance measurement is accomplished by a stride integrator, or pedometer. By manipulating leg lengths in foraging desert ants we were also able to change their stride lengths. Ants with elongated legs or shortened legs, take larger or shorter strides, respectively, and misgauge travel distance. Travel distance is overestimated by experimental animals walking on extended legs, and underestimated by animals walking on shortened legs strongly indicative of stride integrator function in distance measurement. High-speed video analysis was used to examine the actual changes in stride length, stride frequency, and walking speed caused by the manipulations of leg length. The predicted changes in homing distance are in quantitative agreement with the experimental data, further supporting the pedometer hypothesis. We also examined a possible role of the hair receptors (established to function in graviception) situated between head, alitrunk, petiole and gaster in for slope detection in 3D-path integration of the desert ant. Cataglyphis judges the ground distance when travelling over hills, allowing correct homing even in uneven terrain. We eliminated the function of these hair sensors either by shaving the hairs, or by immobilizing the joints monitored by the hair plates. With that major component of their sense of graviception eliminated, one would expect the ants to disregard, or at least misgauge, the ascents and descents performed across hills during outbound journey. Surprisingly, neither shaving nor immobilization of the hair sensillae affected correct path integration, across both, uneven terrain and level surface.

Présentation

Version intégrale (2,58 Mb)

Page publiée le 27 mars 2007, mise à jour le 11 janvier 2019