Fig.22 in A taxonomic revision of the Palaearctic members of the Formica rufa group (Hymenoptera: Formicidae) - the famous mound-building red wood ants

Fig.22: Classification by the exploratory data analyses NC-Ward (dendrogram shown), NC-part.hclust and NC-part.kmeans and final species hypothesis formed by a controlling linear discriminant function (for details, see Material and Methods). Shown are 169 samples of workers of Formica rufa (red bars), Formica polyctena × rufa and backcrosses (green bars), and F. polyctena (black bars). White bars indicate outliers in NC- part.clust. The mean error of three analyses is 3.7% for K = 2 (presence of hybrids ignored) but 13.2% for K = 3 (presence of hybrids accepted), with 19% of the hybrid samples classified as either parental species. Accordingly, a hypothesis forma- tion based on NC-clustering alone, neglecting any accessory information, would suggest two sufficiently separable species. Twelve phenotypic characters were considered.