The genome of the early spider-orchid Ophrys sphegodes provides insights into sexual deception and adaptation to pollinators

Abstract

Abstract Pollinator-driven evolution of floral traits is thought to be a major driver of angiosperm speciation and diversification. The bee orchids (genus Ophrys) mimic their pollinators’ female pheromone, shape and colour to lure male pollinators into pseudocopulation. This strategy, called sexual deception, is highly species-specific, thereby providing strong premating reproductive isolation. Identifying the genomic architecture underlying pollinator adaptation and speciation may shed light on the mechanisms of angiosperm diversification. We report the 5.2 Gb chromosome-scale genome sequence of Ophrys sphegodes and show that chromosomal rearrangements took place in the Ophrys lineage. We find evidence for a transposable element expansion event that preceded the radiation of the O. sphegodes group, and for gene duplication having contributed to the evolution of chemical mimicry. Moreover, one region on chromosome 2 is highly differentiated between O. sphegodes and other Ophrys species, indicating a candidate genomic region for pollinator-mediated evolution.