Figure 4. Fly antennae resolve yeast volatile headspace into discrete odor space.

Principal Component Analysis (PCA) resolved antennal responses to each yeast into discrete species clusters for D. suzukii (A) and D. melanogaster (B). The 25 most intense responses induced by each yeast from both fly species were extracted. Since these responses were not the same for each profile, extracting the top 25 responses and retrieving those in the other profiles yielded a list of 53 responses overall that were subjected to PCA. Insets are as described in Fig. 2. (C) A heat map based on the hypothesis tests between PCA clusters indicates highly significant differences in the fly odor space. Note the inter-species difference in the resolution: while C. zemplinina and S. cerevisiae are least resolved in D. suzukii, the reverse is true for D. melanogaster. (D) Odor space in two fly species can be resolved by PCA.