02785nas a2200277 4500008004100000022001300041245010500054210006900159260001600228300001400244490000700258520198100265653000902246653001402255653001702269653002302286653001902309653001402328653001402342653001302356653001402369653002002383653001502403100002302418856006602441 2008 eng d a1055790300aUnraveling the evolutionary history of the hyperdiverse ant genus Pheidole (Hymenoptera: Formicidae)0 aUnraveling the evolutionary history of the hyperdiverse ant genu cJan-07-2008 a224 - 2390 v483 a

Pheidole is currently the most species rich genus of ants in the world, with many taxa still awaiting description. In this study, I reconstruct the phylogeny of Pheidole using molecular characters from three mitochondrial genes and two nuclear genes for ∼140 species. The phylogenetic relationships of Pheidole are investigated with special interest in understanding factors that may have led to their remarkable diversity. The results presented here establish a framework for understanding the explosive radiation of this group by providing (1) a phylogenetic estimate, and (2) a comparative analysis of life history traits that are likely to have been important in the diversification of the group. In all analyses, Pheidole is recovered as a monophyletic lineage, and molecular clock estimates infer an age of 58.4–61.2 million years ago (Ma) for crown group members of the genus. Using an estimate of diversification rate, it appears that Pheidole has undergone 0.108–0.103 speciation events per million years. Previous hypotheses of species groups were largely not upheld in the analyses presented here. Workers of the genus Pheidole are dimorphic with a minor and major (soldier) subcaste. A third subcaste of super majors is known in eight species of Pheidole and this trait was found to have arisen multiple times throughout the phylogeny. Seed harvesting is common among species of the genus and is thought to be one of the factors leading to the diversification of the group, but additional data will be required to further test this hypothesis. To address biogeographic questions on the origin of the genus, both New and Old World species were included in these analyses, and the results suggest that Pheidole is New World in origin with a possible single introduction into the Old World.

10aAnts10aDimorphic10aHyperdiverse10aHypothesis testing10aKey innovation10aNew World10aOld World10aPheidole10aPhylogeny10aSeed harvesting10aTrimorphic1 aMoreau, Corrie, S. uhttp://linkinghub.elsevier.com/retrieve/pii/S1055790308000602