Genomic Sequences of male B.flavifrons specimens for understanding red and black mimicry patterns in the North America
This project provides genomic sequencing data for black and red colored male Bombus flavifrons specimens and one B. centralis male to investigate the genetic basis of abdominal color variation associated with mimicry in North American bumble bees. Across the Pacific Coastal and Rocky Mountain regions, multiple Bombus species converge on distinct mimetic color forms characterized by variation in abdominal pigmentation, particularly transitions between black and red coloration.Previous genome-wide association studies in co-mimetic species (Bombus melanopygus and Bombus vancouverensis) identified independent deletions in a shared cis-regulatory region near the Hox gene Abdominal-B (Abd-B) associated with black pigmentation. In B. flavifrons, which exhibits continuous variation in abdominal coloration shifted posteriorly relative to these species, we examined the genomic basis of similar phenotypic transitions.Genome-wide analyses identified a structural variant located within 50 base pairs of the previously implicated cis-regulatory region that is strongly associated with abdominal color phenotype. Comparative sequencing across populations and closely related taxa revealed a 319 bp tandem duplication at this locus in all red forms of B. flavifrons and in the monomorphic red species Bombus centralis. The duplicated sequence shows evidence of sequence modification relative to the ancestral copy. In contrast, black forms from the Cascade Range retain the duplication without these modifications, while many black forms from the western Rocky Mountains lack the duplication entirely.These data support the role of the Abd-B cis-regulatory region as a recurrent target of genetic variation underlying abdominal coloration in bumble bees and highlight structural variation, including tandem duplication, as a mechanism contributing to phenotypic diversity.