Date: Fri, 11 Aug 2000 14:16:30 -0700 From: Ivan Snyder <bioexp@juno.com> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg2472$foo@default> Subject: re: Chromosome Counts
>I guess you are not using the aneuploid material originally examined
>by Prof. Kondo. There are obviously a couple of ploidy levels within
>_D. lanata_, including populations with the regular count of 12
>chromosomes (check out Hoshi & Kondo, Cytologia 63: 203, 1998).
>Kind regards
>Jan
Hi all, Ivan here,
I do not believe that D. lanata and D. falconeri could produce fertile
hybrids, as Sean has shown, with such different counts. My opinion is
that the case of the differing chromosome counts in the petiolaris
complex is a result of error. I have seen other ambiguities amongst
reports. Examples are the counts for the hybrid D. x nagamotoi having 28,
43, and 50 chromosomes. Logic tells me these are not possible. D. x
nagamotoi = D. anglica X D. spatulata. D. anglica has 40, D. spatulata
20, 40. Hybrids get one-half set of chromosomes from both parents. 10 +
20 = 30, 20 + 20 = 40. So, D. x nagamotoi can have either 30 or 40
chromosomes. The reported 28, 43, and 50 can be explained as simply
miscounts. 28 ~ 30, 43 ~ 40. These supposed *aneuploids* are as you can
see, more likely errors. The 50 count seems likely to have not actually
been D. x nagamotoi, but rather D. tokaiensis 60 (previously D. spatulata
var. Kansai) crossed with D. anglica, 30 + 20 = 50. Other than the above
examples of miscounts and misiditifications, I have also been told by one
author that many reports are not actual counts, but instead merely
assumptions. For instance, since D. capillaris and D. esmeraldae are
decidedly closely related, these will both probably have the same count.
As for the miriad of differing counts amongst the Australian pygmy
Drosera, I am confused, it seems there truly are aneuploids in this
group.
Ivan Snyder
Hermosa Beach
California
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