Historical perspective and the interpretation of ecological patterns: defensive compounds of tiger beetles (Coleoptera: Cicindelidae)

The defensive compounds produced by pygidial glands of adult tiger beetles were analyzed for 83 species from North America, India, and Peru. Benzaldehyde, the most common defensive compound detected, was found in 39 species. Presence of this compound, which has evolved independently in only a few other arthropod groups, indicates a cyanogenic precursor. Each species occurred primarily in 1 of 7 distinct habitats. Species were also grouped according to genitalic similarities into distinct systematic taxa that represent closely related species. In systematic groups with ≥4 species analyzed, 34 of 39 pooled species were consisent within a group for the presence or absence of benzaldehyde, regardless of habitat type, but for only 1 of the 7 habitats (sandy water edge) was benzaldehyde present nonrandomly regardless of geographical location and systematic relationship. Historical (phylogenetic) factors are thus likely to be generally important in interpreting ecological data. -from Authors