tag:blogger.com,1999:blog-2028565150475419281.post666497480691154310..comments2024-01-23T15:18:52.111-05:00Comments on Trichopterology: The hollow curve, lumpers versus splitters, and arbitrary (yet useful) ranks.Kaihttp://www.blogger.com/profile/15709111344826156855noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-2028565150475419281.post-35649226388386184082012-03-15T14:38:19.287-04:002012-03-15T14:38:19.287-04:00I would not be surprised at all if "the hollo...I would not be surprised at all if "the hollow curve" does represent the results of evolutionary process. <br /> <br />As you hint, and others discuss, evolutionary theory is rife with the concepts of adaptive radiation, punctuated equilibrium, concurrent with gradual 'simplification' by extinction.BioBobnoreply@blogger.comtag:blogger.com,1999:blog-2028565150475419281.post-82187544718635794852012-01-03T19:57:21.499-05:002012-01-03T19:57:21.499-05:00Ted-
That's a good point. When I was writing...Ted-<br /><br /> That's a good point. When I was writing this post, I was referring to the hollow curve, but so much of Ferris' explanation seemed to be anecdotal evidence. I've experienced what you've described with several large caddisfly genera like Hydropsyche and Cheumatopsyche. Their characters show them to be obviously monophyletic, yet there aren't any obvious characters to separate out the subgenera. Indeed, when some people have tried to separate Hydropsyche into several genera, more evidence has come back to suggest that wasn't a good idea after all.<br /><br />What it seems to me is that, in many cases, the authors of old described fewer, larger genera, and that these genera are being split down into smaller groups. Some of the large genera are left, nearly unsplitable, and so we get a hollow curve. <br /><br />But it could very well be that large genera are hints of recent diversifications; if they are hard to separate out, maybe they diverged only recently. The oldest Cheumatopsyche fossils are 25 million years, and there are more than 300 species in that genus, new ones described every year.<br /><br />And I don't mean to say that there are these guilds of lumpers and splitters, but that there are distinct philosophies on larger versus smaller groupings that have been at odds, and that this often shapes the taxonomy of various groups. And perhaps I'm wrong about that as well.<br /><br />Thanks for your comment, and your interest.Kaihttps://www.blogger.com/profile/15709111344826156855noreply@blogger.comtag:blogger.com,1999:blog-2028565150475419281.post-78097941133986180002012-01-03T19:42:11.447-05:002012-01-03T19:42:11.447-05:00Thanks for the correction, Christopher. I agree th...Thanks for the correction, Christopher. I agree that the raising and lowering of taxa and the disagreements between authors causes a great deal of these orphans, /despite/ the rules of coordination and priority in the ICZN. Perhaps I am too comfortable in insects, where the higher classification doesn't jump around as much these days as it does in other groups. At least, by a single author (and in many cases between authors), the ranking system can be used to communicate hierarchy better than a non-ranked system can. Thanks again for your criticism.Kaihttps://www.blogger.com/profile/15709111344826156855noreply@blogger.comtag:blogger.com,1999:blog-2028565150475419281.post-67901513782095468612012-01-03T19:21:27.876-05:002012-01-03T19:21:27.876-05:00It is unambiguous that a tribe belongs to a family...<i>It is unambiguous that a tribe belongs to a family, that a subgenus belongs to a genus.</i><br /><br />Wrong. <i>Very</i> wrong, and for the same reasons that you talked about in this very post. There is absolutely no reason (and it has happened regularly) that someone could split a 'family' to the point that it is more exclusive than another author's 'tribe'. 'Family Hominidae' as used to include <i>Homo sapiens</i> and its direct fossil relatives only is a smaller group than 'subfamily Homininae' used to include both humans and the African great apes. Among tanaids, the 'families' Anarthruridae and Agathotanaididae of Larsen & Wilson (2002) included species that had all previously been placed together in the 'subfamily' Anarthrurinae. Perhaps most extreme of all, the annelid 'family' Siboglinidae of recent authors includes taxa that some had previously treated as separate 'phyla' Pogonophora and Vestimentifera.<br /><br />So no, you cannot simply assume that one author's 'subfamily' is a subgroup of another author's 'family'. You can't even really assume this when comparing publications by the <i>same</i> author, because authorities have been known to change their preferred taxonomies. The only place where you can generally take this line for granted is within a single publication. Where it is usually redundant because you will already have the explicit context of the publication itself to provide the relative status of the taxa.Christopher Taylorhttps://www.blogger.com/profile/11075565866351612441noreply@blogger.comtag:blogger.com,1999:blog-2028565150475419281.post-25501472224993057862012-01-03T19:09:07.839-05:002012-01-03T19:09:07.839-05:00I didn't read through all 71 (and counting) co...I didn't read through all 71 (and counting) comments on Ed Yong's thread, but I agree in principle with your summary here. I will say, however, that I have a little bit of difficulty with the idea that a superdiverse genus like <i>Agrilus</i> is a completely subjective result of the battle between 'lumpers' and 'splitters'. Many people have tried to split it up but failed because, unlike the genus itself, which nobody doubts is monophyletic, it has proven impossible to define monophyletic units within the genus. It's pretty easy to recognize something an undescribed <i>Agrilus</i> as belonging to that genus, and of the many, many species awaiting description there is no other genus to which they can be assigned when described. They are placed there not to show allegiance to lumpers and shun splitters, but because that is the smallest unambiguously monophyletic unit that can be discerned. <br /><br />Obviously I don't mean to suggest that there are no monophyletic subunits within the genus (as with any genus), and it is the degree of difference between those units that determines (subjectively rather than arbitrarily) whether they rise to the rank of genus or not. How much difference is required to consititute a genus tends not to bounce around from one genus to another, especially within a family since specialists tend to focus on family-level units and reach consensus with other specialists in the same family.<br /><br />I guess this is a long-winded way of saying that I think there actually is an element of reality to the "holow curve."<br /><br />regards--tedAnonymousnoreply@blogger.com