Steve, I think I've been interpreting Yukawa's words differently to you. He said:
"The number of base differences and sequence divergences within the ITS region were as follows: D. suzukii-D.formosanum: 38, 0,0801; D. suzukii-D.cruentum: 28, 0,0592; D. suzukii-D.tobaense: 38, 0.0803. Based on these molecular characters, D. suzukii is distinct from closely related species by its unique base substitutions in the ITS region and appears to have a sister group relationship with D. cruentum." My understanding of these words is that D. suzukii is different from both D.cruentum and D.tobaense because it has 28 bases not found in D. cruentum, and 38 bases not found in D. tobaense. Yukawa has not said that D. suzukii has any base substitutions that are unique in the sense that they are not found in either of the other two species. I hope he will reply to your email and clear this up. As for a hybrid exhibiting half the sequence changes from each parent, yes, that would be expected as long as: a) the two specimens tested are the parents of the hybrid. If the plants tested are not the parents, you would have to take into account the genetic variability (in the sequence being tested) between different plants of the same species. Do you have any idea what the normal variation is in the ITS region different plants of any one of these species ? I don't. b) nuclear ribosomes (the part of the cell that Yukawa tested) result in their entirety from material created as a consequence of the fusion of male and female gametes, and that none of the nuclear ribosomal DNA originates from other sources in the egg cell. I've been unable to get confirmation that this is the case. Cheers, Peter O'Byrne in Singapore _______________________________________________ the OrchidGuide Digest (OGD) [email protected] http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
