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5 de junio de 2017

El artículo en Cladistics que no leerán los que hacen verosimilitud y probs Bayesianas

"Is there any reason, other than esprit de corps, to explain why, in many journals, it became almost impossible to publish a paper using parsimony as the only method?"

Pablo A. Goloboff, Ambrosio Torres and J. Salvador Arias. 2017. Weighted parsimony outperforms other methods of phylogenetic inference under models appropriate for morphology. Cladistics

Aqui esta el resumen.

Abstract One of the lasting controversies in phylogenetic inference is the degree to which specific evolutionary models should influence the choice of methods. Model-based approaches to phylogenetic inference (likelihood, Bayesian) are defended on the premise that without explicit statistical models there is no science, and parsimony is defended on the grounds that it provides the best rationalization of the data, while refraining from assigning specific probabilities to trees or character-state reconstructions. Authors who favour model-based approaches often focus on the statistical properties of the methods and models themselves, but this is of only limited use in deciding the best method for phylogenetic inference—such decision also requires considering the conditions of evolution that prevail in nature. Another approach is to compare the performance of parsimony and model- based methods in simulations, which traditionally have been used to defend the use of models of evolution for DNA sequences. Some recent papers, however, have promoted the use of model-based approaches to phylogenetic inference for discrete morpho- logical data as well. These papers simulated data under models already known to be unfavourable to parsimony, and modelled morphological evolution as if it evolved just like DNA, with probabilities of change for all characters changing in concert along tree branches. The present paper discusses these issues, showing that under reasonable and less restrictive models of evolution for discrete characters, equally weighted parsimony performs as well or better than model-based methods, and that parsimony under implied weights clearly outperforms all other methods. © The Willi Hennig Society 2017.

12 de abril de 2017

Que buen sentido de humor tenemos los taxónomos

Neopalpa donaldtrumpi, named for the distinctive wave of yellowish-white scales that cascades forward from the moth’s head.
Un entomólogo canadiense recién nombró una nueva especie con dedicatoria especial a Donald Trump.
El artículo fue publicado en  ZooKeys y Vazrick Nazariel, el autor,  explica "The specific epithet is selected because of the resemblance of the scales on the frons (head) of the moth to Mr. Trump’s hairstyle."
Información general esta aqui:
Pero hay más ... no solo es por la melena al frente .....

23 de marzo de 2017

Morfología y un nuevo análisis de la filogenia de los dinosaurios

The proposed new family tree of dinosaurs. The group to the left is for close relatives but not true dinosaurs. The old tree grouped the theropods, purple, with the Saurischia, green, and viewed the Saurischia and the Ornithischia as the two major branches of the tree. The scale to the left shows the placement of the tree in geological time. A is the branchpoint that includes all the dinosaurs, B represents the joint ancestor of Ornithischia and the theropods, and C is the joint ancestor of Saurischia and an early group known as herrerasaurs. Credit Baron et al./Nature 

Hay una nota interesante en NYTimes aqui: >

El resumen del articulo original esta aqui:

A new hypothesis of dinosaur relationships and early dinosaur evolution. 2017.
Matthew G. Baron, David B. Norman & Paul M. Barrett.
Nature 543, 501–506 (23 March 2017) doi:10.1038/nature21700

Abstract. For 130 years, dinosaurs have been divided into two distinct clades—Ornithischia and Saurischia. Here we present a hypothesis for the phylogenetic relationships of the major dinosaurian groups that challenges the current consensus concerning early dinosaur evolution and highlights problematic aspects of current cladistic definitions. Our study has found a sister-group relationship between Ornithischia and Theropoda (united in the new clade Ornithoscelida), with Sauropodomorpha and Herrerasauridae (as the redefined Saurischia) forming its monophyletic outgroup. This new tree topology requires redefinition and rediagnosis of Dinosauria and the subsidiary dinosaurian clades. In addition, it forces re-evaluations of early dinosaur cladogenesis and character evolution, suggests that hypercarnivory was acquired independently in herrerasaurids and theropods, and offers an explanation for many of the anatomical features previously regarded as notable convergences between theropods and early ornithischians.

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