Guido wrote; > Nick, I am afraid you are mistaken. It is only 50/50 if and when you > postulate a single gene and if and when there are no dominances > involved and if there is no crossover etc. etc. etc.
Nope, You're wrong on this one, Guido. Bert's original comment was on the genetic makeup of the F1 generation of a cross between species A and species B. They are indeed 50%A/50%B. Dominance is not relevant, because we are discussing inheritance of genes, not their phenotypic effect. Crossovers have no effect in this situation: A crossover during meiosis in species A will still produce gametes that are 100% species A. Species A cannot produce anything but gametes that are 100% species A. The same goes for species B, so the offspring of that cross will inherit one copy of each chromosome from each parent. Now, unless the two parent species are 100% inbred, the offspring will not be genetically identical. But, that does not alter the fact that their genetic makeup is 50% species A and 50% species B as Bert wrote. It is in the later generations of the cross that Mendel's principles start to have an effect and it is no longer possible to define exactly the contribution from the original parent species. In the F2 generation, the offspring will average 50% contribution from the original species, but each individual plant can vary widely due to recombination in the F1 and independent assortment of chromosomes (Mendel's second law). But, Bert's description of the F1 generation was correct. > Just check Mendel's laws .... there is plenty avout that on the internet. When I'm not posting to OGD or messing around in my greenhouse, I'm a research geneticist. Nick -- Nicholas Plummer [EMAIL PROTECTED] _______________________________________________ the OrchidGuide Digest (OGD) orchids@orchidguide.com http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
