mardi 22 avril 2008

Speciations observed - but not in mammals.

Talkorigins claims speciation has been observed ... in plants and invertabrates. Exactly not in mammals who are exactly the type of animals where polyploidy is excluded. One event includes a diploid variety having as many chromosomes as a tetraploid would have - but noone observed it becoming diploid. The botanist found the new species among his plants: Evening Primrose (Oenothera gigas)
While studying the genetics of the evening primrose, Oenothera lamarckiana, de Vries (1905) found an unusual variant among his plants. O. lamarckiana has a chromosome number of 2N = 14. The variant had a chromosome number of 2N = 28. He found that he was unable to breed this variant with O. lamarckiana. He named this new species O. gigas.

If he found it, how can he be sure it was offspring of his previously studied plants? Because, you see, if the new chromosome number had been not 2n=28, but 4n=28, it would have been a very simple case of polyploidy. Here the question is: how did the 28 start out as 4*7 and end up as 2*14? Also, it is not specified (ha ha) if he could breed Oenothera gigas at all. There is of course cloning ...

As for diverse chromosome numbers (a k a karyotypes) in mice, they do not make different species, it seems. Do not ask me when and where Mus musculus domesticus with 2n=40 and such with 2n=22 have crossbred, but they count as same species, hence they have the same Latin name. A new chromosomal race of the house mouse, Mus musculus domesticus ...

A want-to-read: creationist Jack Cuozzo's book about Neanderthal man.

Back to Update on Chromosome numbers which forms part of anti-Darwinism series (other issues top links).

1 commentaire:

Hans Georg Lundahl a dit… is the new index post to this series.