A New Scientific Article at Cladistics

A new scientific article on which I’m a co-author is available at the journal Cladistics. Prashant Sharma is the first author, and in the article we examine a recent phylogenetic method used by others.

Hennig’s semaphoront concept and the use of ontogenetic stages in phylogenetic reconstruction

A new practice in systematics, “semaphoront” coding, treats developmental stages as terminals, and it derives from Hennig’s concept of the same name. Semaphoront coding has been implemented recently by Lamsdell and Selden (BMC Evol. Biol., 2013, 13:98) and Wolfe and Hegna (Cladistics, 2014, 30:366) in an effort to understand the relationships of fossil taxa of unknown developmental stage. We submit that this approach is antithetical to cladistic practice and constitutes a gross misunderstanding of Hennig’s original idea. Here we review the concept of the semaphoront and clarify the role of the semaphoront in phylogenetic systematics. We contend that treating ontogenetic stages as terminals both violates tenets of phylogenetic systematics and oversimplifies the complexity of developmental processes. We advocate Hennig’s alternative of including data from as many semaphoronts as possible, but implemented using the superior total evidence framework. Finally, we contend that the application of semaphoront coding to any palaeontological question requires invoking multiple, unjustified assumptions, and ultimately will not yield a possible phylogenetic solution. A total evidence approach can grapple with the placement of fossil developmental stages, if only imperfectly.



Categories: Announcements, articles, Ron Clouse

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