kinman2 at YAHOO.COM
Wed Apr 28 22:19:34 CDT 2004
The "anthophyte hypothesis" (Gnetales as sister group to angiosperms) has been under repeated attack in recent years. Various lines of molecular data have been used to argue that Gnetales are only convergently similar to angiosperms, and that gnetophytes are closer to conifers. Some say Gnetales is sister group to Family Pinaceae ("gnepine" hypothesis), and others say Gnetales is sister group to all conifers (which I presume is what is called the "gnetifer" hypothesis). Actually, if Pinaceae is sister group to all other conifers, then it would seem to me that the gnepine hypothesis is really only slightly different from the gnetifer hypothesis. The really big question is whether we should abandon the anthophyte hypothesis.
But if Gnetales are not the immediate relatives of angiosperms, then which gymnosperms are? Caytoniales? Or perhaps Bennettitales? And if the latter, are Bennettitales themselves also convergent to Gnetales? Are there any other candidates for sister group to angiosperms? Darwin's big "mystery" remains unsolved and I just wonder how long it will remain so.
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