Monday, December 10, 2007 - 9:29 AM

A phylogenetic analysis of pigmentation and mimetic color pattern convergence in bumble bees (Bombus)

Heather M. Hines,, University of Illinois - Urbana/Champaign, Entomology, 320 Morrill Hall, 505 S. Goodwin Ave, Urbana, IL

The aposematic pile coloration of bumble bees (Bombus) includes shades of yellow, red, black, brown, and white that vary in different patterns across body segments. Consistent with Müllerian mimicry, stinging bumble bees have exceptional variation in color pattern across their range, but tend to exhibit similar, phylogenetically-convergent patterns within a geographic region. Color pattern diversity extends to populations of some color-diverse species, which may provide examples of population-level Müllerian mimics similar to Heliconius (Lepidoptera: Nymphalidae). To elucidate the evolutionary means and developmental flexibility in acquiring these diverse mimetic patterns, I pursued two lines of research. First, I performed a cross-phylogeny examination of the pigments that impart colors to bumble bees, testing for both the pigment class (pteridines, ommochromes, carotenoids, or melanins) using extractability in different media and the exact pigments within these classes via TLC, spectrophotometry, and mass spectrometry. These data will be used to build hypotheses on the developmental transitions involved in color change. Second, I compare the pattern of color transition and convergence involved in Müllerian mimicry using population-level phylogenies of three color-diverse species (Bombus trifasciatus, B. haemorroidalis, and B. breviceps) that converge on several mimicry complexes in Southeast Asia. These phylogenies also test alternative published hypotheses of species demarcation.

Species 1: Hymenoptera Apidae Bombus spp (bumblebee, bumble bee)