Support provided by discrete, but not continuous morphological traits, depends on the estimated age of divergence of the clade.

NICOLAS MONGIARDINO KOCH; EDUARDO M. SOTO; F. SARA CECCARELLI; ANDRÉS A. OJANGUREN AFFILASTRO; MARTIN RAMIREZ

Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina.

Congreso; 35th Annual Meeting of the Willi Henning Society and XII Reunión Argentina de Cladística y Biogeografía.; 2016

Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"

Different sets of characters are useful at different scales of the tree of life, a consequence of factors such as underlying genetic variability, natural selection, evolvability, constraints, and their impact on rate of evolution. Among morphological characters, closely related species generally differ in continuously-varying traits, while showing few discrete dissimilarities. This pattern suggest that continuous characters may be more useful to resolve the divergence of closely related species. At deeper nodes, morphological convergence is thought to override phylogenetic signal, especially when employing traditional morphometric variables. However, this pattern has never been the subject of empirical research. We test this hypothesis with two cases studies: the scorpion genus Brachistosternus and the spider family Anyphaenidae. We build time-calibrated phylogenetic hypothesis for both clades using multilocus molecular datasets, and use these trees as scaffolds to study the support provided by both discrete and continuous morphological partitions. Contrary to expectations, we find in both cases that the support provided by the discrete partition significantly correlates with the age of divergence of the clade. The result is nonetheless opposite in both cases, with support increasing towards the present for the family of spiders, and decreasing for the scorpion genus. No significant relationship is found for the continuous partition, although the overall trend in both cases is the same as with the discrete partition, possibly suggesting that both types of characters are capturing similar patterns of morphological diversification. Finally, congruence with the molecular phylogenetic hypothesis is, in both cases, increased when combining both morphological partitions.