The chromosomes of Diprion pini and D. similis (Hymenoptera: Diprionidae): implications for karyotype evolution.
This study showed that Diprion pini and D. similis have 14 acrocentric chromosomes (n = 14 for haploid males and 2n = 28 for diploid females). In D. pini, ribosomal RNA genes are located on the satellite and the round short arm of the chromosome carrying this segment. Six populations with no evidence of chromosomal polymorphism at the species level were studied. The results disagreed with those published previously and reopen the question of karyotype evolution. Chromosome morphology, ISH and C-banding results supported the hypothesis of chromosome number doubling by centric fission and not by polyploidization, followed by the growth of short arms by means of pericentromeric DNA amplification.