Figure 3
Comparison of odour similarity in ants, bees and rats. A) Dendrogram (Ward's classification) showing similarity relationships among the 11 aliphatic odours in ants, honeybees Apis mellifera (data from [48]) and rats Rattus norvegicus (9 odours, data from [22]). Three main clusters are found in each species, with one cluster containing mainly alcohols (cluster ant #1, bee #1 and rat #2), and another containing the three aldehydes (cluster ant #2, bee #3, rat #1). B) Inter-odour Euclidian distances in ants as a function of the same measure in honeybees, with either maximized number of odour pairs (Left, 55 odour pairs, 3-5 ants, r = 0.43, Mantel test, p = 0.036) or maximized number of ants (Right, 15 odour pairs, 5 ants, r = 0.76, Mantel test, p = 0.018). C) Inter-odour distances in ants as a function of the same measure in rats (36 odour pairs, 3-5 ants, r = 0.75, Mantel test, p < 0.001). D) Running correlation between instantaneous Euclidian distances in ants (maximizing ant number, as in B, right panel) and fixed-point distances in honeybees [48]. The quality of the correlation (r2 in red) is plotted along with the inter-odour distance (in blue, taken from Figure 2B) showing the separation power of the ant olfactory system throughout a recording. Maximum correlation is obtained very shortly after odour application (~200 ms), and remains high throughout odour presentation. After odour offset, correlation decreases but oscillations are observed, with high correlation epochs as late as 5 sec after odour application, when activity and the separation powerof the ant system are low. Orange bars below the graph indicate significance in running Mantel tests 1) between ant data at each 200 ms time bin and the fixed-point bee data or 2) between ant data at each 200 ms bin and fixed-point ant data 200 ms after odour onset (frame termed 'ref' in the figure). Significant correlation rebounds (see text) are marked with orange arrows. Circles correspond to plots between ant and bee data on the upper right, showing instantaneous Euclidian distances in the ant as a function of distances in the bee.