INVESTIGADORES
RAMIREZ Martin Javier
congresos y reuniones científicas
Título:
Problems in accumulation of phylogenetic data: An example case of a morphology based analysis of dionychan spiders
Autor/es:
RAMÍREZ, M. J.
Lugar:
Paris, Francia
Reunión:
Congreso; Simposio “Treatments and samplings”, Hennig XXIII, 23rd Annual Meeting of the Willi Hennig Society ‘‘Phylogenetics and Evolutionary Biology’’; 2004
Institución organizadora:
Willy Hennig Society
Resumen:
As phylogenetic analyses accumulate, there is moreand more overlapping in characters and terminalsamong different studies. Taking the example of spiders,this accumulation of phylogenetic analyses did notimply much of an accumulation in knowledge. Fusingdatasets (i.e., combining two or more datasets in abroader analysis) is at best laborious, and most oftenimpossible. Differences in character state definitions,and in representative taxa are the obvious limitations,but the ways in which phylogenetic data are recorded,documented, and disseminated impose importantrestrictions as well. These problems are exemplified withthe construction of a cladistic dataset of Dionycha, aninformal group of 17 families of two-clawed spiders.Sometimes regarded as the crown group of spiders,Dionycha comprises about 2000 genera and more than13 000 species, 35% of the spider species known to date,including the charismatic jumping spiders, and crabspiders. I reviewed most morphological systems andpreviously proposed characters, and built a unifiedhomology system spanning much of the spectrum ofvariation within spiders. The dataset comprises about400 characters scored for about 140 taxa, and isdocumented with 4800 original SEM images. I discussthe issues of documentation, scoring of noninformativecharacters, and the priority of databases over cladisticdatasets. The construction of character states is not anaive procedure, and in general must be done after thedata is collected. Storing observations in the mostunprocessed form increases the possibilities for datagrowing and accumulation. I discuss possibilities for alayered structure of phylogenetic data.