tag:blogger.com,1999:blog-3342041114052632712.post8703351010588068640..comments2024-01-20T16:39:42.179+11:00Comments on PhyloBotanist: So why is incomplete lineage sorting not an issue at higher taxonomic levels?Alex SLhttp://www.blogger.com/profile/00801894164903608204noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-3342041114052632712.post-52277028510500965762013-03-19T10:14:12.613+11:002013-03-19T10:14:12.613+11:00It is clear that all supra-specific ranks are arbi...It is clear that all supra-specific ranks are arbitrary. I merely wrote of genera etc because not everybody reading this can be expected to have the frame of mind to understand what I mean if I constantly write about older and younger clades.<br /><br />You raise a very good point with the testability. Admittedly, this is more on the level of "it stands to reason" - but some conclusions do follow from certain observations. I cannot interbreed with an oak tree or a rat, for example. That means that _somewhere_ the distance between two clades becomes too big for gene flow to happen. It is now an empirical matter whether the crown groups of extant clades whose stem group ages are ca xyz million years were usually far enough apart that they were already completely isolated from each other genetically.<br /><br />Personally, I think people exaggerate the problems. They see a few spectacular cases of really young, closely related species, not least because those are the most interesting to study, and extrapolate from that over all the plant kingdom. At least in the groups that I know well interbreeding just doesn't happen over large distances. Mentha section Mentha is a mess - but you cannot cross a true mint with thyme or oregano, probably not even section Mentha with the other sections. Prunella with its four species is a mess but you certainly cannot cross it with Lamium. And so on.Alex SLhttps://www.blogger.com/profile/00801894164903608204noreply@blogger.comtag:blogger.com,1999:blog-3342041114052632712.post-50668618362177765762013-03-19T06:50:52.610+11:002013-03-19T06:50:52.610+11:00I think the principle components of macroevolution...I think the principle components of macroevolution are speciation and extinction. I have never seen a reference to genusization or familyization. It is sometimes argued that higher categories are arbitrary and largely meaningless. I agree that they are human artifacts, but reflect our best understanding of the groups involved. There is also the argument at any monophyletic group is just as real as species are. <br /><br />I wonder how much differentiation, both morphological and genetic, can occur in a speciation event. Is there any meaningful idea of average differentiation in speciation events?<br />Is there any way to estimate how many hidden by extinction speciation events there are in a linage?<br /><br />Anyway, your discussion is interesting, but how to test the hypothesis? <br />Jim Thomersonnoreply@blogger.comtag:blogger.com,1999:blog-3342041114052632712.post-13122667033374069962013-03-18T08:20:46.230+11:002013-03-18T08:20:46.230+11:00Thanks, I think I hadn't seen that although I ...Thanks, I think I hadn't seen that although I remember discussing a similar paper in journal club once. The figure at the website you linked to is very nice indeed.<br /><br />What we should remember is that it appears to work in many cases nonetheless. In the gorilla case, most of the genome gives the answer that is congruent with what was inferred from fossils and morphological analysis. And I am just now conducting a phylogenetic analysis of certain paper daisies where the often maligned ribosomal DNA gives us groups that make a lot of sense from a morphological perspective.Alex SLhttps://www.blogger.com/profile/00801894164903608204noreply@blogger.comtag:blogger.com,1999:blog-3342041114052632712.post-68821323446324380392013-03-18T02:53:04.950+11:002013-03-18T02:53:04.950+11:00Have you seen this, about alfalfa phylogeny?
http:...Have you seen this, about alfalfa phylogeny?<br />http://nothinginbiology.org/2013/03/12/how-many-phylogenies-are-there-in-a-genome-lots/Jim Thomersonnoreply@blogger.com