Poster

1. Promoters and constraints of
morphological change in
Polyxenida (Miriapoda: Diplopoda).
López-Estrada E.K.*¹,2 & Rodríguez-Flores P.C.1,3
1. Museo Nacional de Ciencias Naturales Naturales-Consejo Superior de Investigaciones Científicas (MNCN-CSIC),
Madrid, Spain.
2. Real Jardín Botánico de Madrid-Consejo Superior de Investigaciones Científicas (MNCN-CSIC), Madrid, Spain.
3. Centre d'Estudis Avançats de Blanes – CEAB-CSIC
*lokaren21@gmail.com

2. The order Polyxenida encompasses less than 200
extinct and extant species, displaying a highly
conserved general body plan, with the first fossils of
these millipedes being from the Lower Cretaceous and
already displaying a body plan comparable to extant
species. Nonetheless, some characters and structures
greatly vary among taxa and clades. For instance, the
evolution of the number of segments and pair of
legs, seems to be under a more relaxed process with
multiple changes within subclades. Here we aimed to
identify the mode of evolution of these characters,
integrating fossil information to the analysis, to
identify if the variation follows an evolutionary trend or
if it is a random process.
INTRODUCTION

3. For bayesian phylogenetic reconstruction, we used all the sequences
available in Genbank for the order Polyxenida (cox1, 16S, 18S). We
estimated divergences times using fossil records to calibrate the
molecular clock (BEAST). We statistically evaluated the fit of two
models of morphological evolution to the tree (Brownian Motion
and Trends) using fossil character states in certain nodes
(GEIGER). Finally, we estimate rates of morphological evolution
(BAMM).
MATERIALS AND METHODS

4. • Results in the selection of model, support an evolutionary trend toward the the loss of pair
legs and the number of segments in Polyxenida.
• Rates of morphological evolution, pinpoint, as previously discussed, a severe
morphological stasis, with extremely low rates of phenotypic evolution.
• We need to cover a higher taxon sampling (extant and fossil species) and generate more
molecular data, to accurately reconstruct a phylogenetic hypothesis and test our
preliminary results
RESULTS AND DISCUSSION

5. Referencias:
Drummond A.J., Suchard M.A., Xie D. & Rambaut A., 2012. Bayesian phylogenetics with
BEAUti and the BEAST 1.7. Mol. Biol. Evol. 29(8):1969–1973.
Harmon L. J., Weir J. T., Brock C. D., Glor R. E. y Challenger W. 2008. GEIGER: investigating evolutionary radiations. Bioinformatics, 24(1): 129-131.
Rabosky D. L. 2014. Automatic Detection of Key Innovations, Rate Shifts, and Diversity-Dependence on Phylogenetic Trees. PLoS ONE, 9(2): e89543. doi:10.1371/journal.pone.0089543