tag:blogger.com,1999:blog-5460788270738656369.post5472091004075081040..comments2023-12-24T07:02:43.274+08:00Comments on Catalogue of Organisms: Where Do You Put Your Camels?Christopher Taylorhttp://www.blogger.com/profile/11075565866351612441noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-5460788270738656369.post-47286652805941525372017-02-09T11:08:22.796+11:002017-02-09T11:08:22.796+11:00Most weighted phylogenetic studies these days use ...Most weighted phylogenetic studies these days use some variant on implied weighting, which calculates the weighting based on the distribution of character states within the data set itself (so, for instance, characters that show a fair degree of correlation in their state distribution to others may be weighted higher than characters that seem to be distributed fairly randomly). This avoids any <i>a priori</i> biases about what one might expect to be important, but does depend on your data-set not being somehow inherently biased itself. For instance, to use the post as an example, I've wondered if 'chambered stomach' and 'crescentic molars' might end up weighted highly because they correlate with each other, even if they only correlate because they're induced by the same selective pressures.<br /><br />There's also the question of just how much of a weighting gradient one should introduce, and as far as I know there's no really objective way as yet of doing that. A common work-around is to run the analysis at a number of different weighting settings and see how that changes the results.Christopher Taylorhttps://www.blogger.com/profile/11075565866351612441noreply@blogger.comtag:blogger.com,1999:blog-5460788270738656369.post-78071494004634146002017-02-07T17:04:36.525+11:002017-02-07T17:04:36.525+11:00Is there any principled way to weight molecular ve...Is there any principled way to weight molecular versus morphological characters? Saying that one change in morphological state is counts as as much change as a SNP sounds the height of arbitrarinesss, but what wouldn't?Andreas Johanssonhttps://www.blogger.com/profile/08802392912541974977noreply@blogger.comtag:blogger.com,1999:blog-5460788270738656369.post-50975276043075365342017-02-05T18:13:37.653+11:002017-02-05T18:13:37.653+11:00Vote of thanks from the mammal enthusiasts for thi...Vote of thanks from the mammal enthusiasts for this post!<br />Worth noting that Darren Naish had several posts, back in 2009, on Andrewsarchus and what the state of play about its relationships was at that time (typing "Andrewsarchus" into Firefox's search engine generated 4 references).<br />Protoceratids are, I think, only one of the extinct Artidactyl groups whose affinities, as between Camels and Ruminants, have been... problematic.Allen Hazenhttps://www.blogger.com/profile/05223023647802175202noreply@blogger.com