Image via WikipediaI have been comparing the different phylogenetic hypotheses for the Strepsiptera. As always, it has been hell to get the trees from images back into a suitable format for topology comparison. I have used the program METATREE for comparing multiple trees. The tree of trees essentially shows the two main hypotheses "Strepsiptera sister to Diptera" supported by the studies of Whiting and Wheeler using 18S and 28S rDNA, and at the other end of the metatree the "Strepsiptera sister to Coleoptera" supported by morphological studies and recent molecular studies using nuclear genes. Other differences in the Holometabola topologies are also illustrated in the metatree such as the variable position of the Hymenoptera. Anyway, to me, it looks like the research community is reaching a consensus on the "Strepsiptera problem": Strepsiptera sister to Coleoptera. What do you think?
4 comments:
As I understand it, "consensus" cannot resolve the Strepsiptera problem. The problem is that even the oldest/most plesiomorphic fossils are still too derived to glean anything much of their origins. So, until better "missing link" fossils are found, the problem cannot be solved. The fly and beetle theories are just the most common ones historically,but both could be wrong ...
As I understand it, "consensus" cannot resolve the Strepsiptera problem. The problem is that even the oldest/most plesiomorphic fossils are still too derived to glean anything much of their origins. So, until better "missing link" fossils are found, the problem cannot be solved. The fly and beetle theories are just the most common ones historically,but both could be wrong ...
Sure, the phylogenetic hypotheses put forward are only as good as the data we use but if a number of studies using independent data suggest the same story, we can start to be pretty confident about our hypothesis. The 'Strepsiptera sister to Coleoptera' is currently supported by a number of studies using different data sets. Obviously, if the "missing link" fossils could be found, it would provide additional evidence for or against the latte hypothesis.
Thanks for commenting.
Not convinced ... there aren't that many lines of evidence to examine, and if they point in different directions, then so what if 4 out of 6 (or whatever) point in the same direction? It could still be random chance. One of the main things linking streps to beetles was posteromotorism (using only hindwings for active flight), which I always found rather unconvincing to say the least! I would be surprised if streps are the sister group to any big order like Coleoptera ... I think it more likely that they are just a highly derived group within such a big order. The late/great coleopterist Roy Crowson thought that they were just a derived family of Tenebrionoidea! His reasons weren't too convincing, but it could be ...
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