Analysis of the Blackbeard locus. (A) Schematic representation of the primer pairs used to perform PCR at the Blackbeard locus. Primer pairs are embedded within ovals and dashed lines indicate the projection of the Bkb locus found in haplotype b to its native target site on haplotype a. (B) Haplotype analysis by PCR to assess the presence/absence of the Blackbeard insertion in ten P. tricornutum accessions. Haplotypes a and b respectively refer to the absence and presence of the Blackbeard insertion.