Diversity dynamics in Nymphalidae butterflies: Effect of phylogenetic uncertainty on diversification rate shift estimates

<p>The family Nymphalidae is the largest family within the true butterflies and has been used to<br>develop hypotheses explaining evolutionary interactions between plants and insects. Theories of<br>insect and hostplant dynamics predict accelerated diversification in some scenarios. We<br>investigated whether phylogenetic uncertainty affects a commonly used method (MEDUSA,<br>modelling evolutionary diversity using stepwise AIC) for estimating shifts in diversification rates<br>in lineages of the family Nymphalidae, by extending the method to run across a random sample<br>of phylogenetic trees from the posterior distribution of a Bayesian run. We found that<br>phylogenetic uncertainty greatly affects diversification rate estimates. Different trees from the<br>posterior distribution can give diversification rates ranging from high values to almost zero for<br>the same clade, and for some clades both significant rate increase and decrease were estimated.<br>Only three out of 13 significant shifts found on the maximum credibility tree were consistent<br>across more than 95% of the trees from the posterior: (i) accelerated diversification for<br>Solanaceae feeders in the tribe Ithomiini; (ii) accelerated diversification in the genus Charaxes,<br>and (iii) deceleration in the Danaina. By using the binary speciation and extinction model<br>(BISSE), we found that a hostplant shift to Solanaceae or a codistributed character is responsible<br>for the increase in diversification rate in Ithomiini, and the result is congruent with the diffuse<br>cospeciation hypothesis. A shift to Apocynaceae is not responsible for the slowdown of<br>diversification in Danaina. Our results show that taking phylogenetic uncertainty into account<br>when estimating diversification rate shifts is of great importance, and relying on the maximum<br>credibility tree alone potentially can give erroneous results.</p> <p>