DOI: 10.5061/dryad.jm4d5
title: Data from: A rich fossil record yields calibrated phylogeny for Acanthaceae (Lamiales) and evidence for marked biases in timing and directionality of intercontinental disjunctions

description: More than a decade of phylogenetic research has yielded a well-sampled,
 strongly supported hypothesis of relationships within the large (&gt;
 4,000 species) plant family Acanthaceae. This hypothesis points to
 intriguing biogeographic patterns and asymmetries in sister clade
 diversity but, absent a time-calibrated estimate for this evolutionary
 history, these patterns have remained unexplored. Here, we reconstruct
 divergence times within Acanthaceae using fossils as calibration points,
 experimenting both with fossil selection and effects of invoking a maximum
 age prior related to the origin of Eudicots. Contrary to earlier reports
 of a paucity of fossils of Lamiales (an order of ~23,000 species that
 includes Acanthaceae) and to the expectation that a largely herbaceous to
 soft-wooded and tropical lineages would have few fossils, we recovered 51
 reports of fossil Acanthaceae. Rigorous evaluation of these for accurate
 identification, quality of age assessment, and utility in dating yielded
 eight fossils judged to merit inclusion in analyses. With nearly 10
 kilobases of DNA sequence data, we used two sets of fossils as constraints
 to reconstruct divergence times. We demonstrate differences in age
 estimates depending on fossil selection and that enforcement of maximum
 age priors substantially alters estimated clade ages, especially in
 analyses that utilize a smaller rather than larger set of fossils. Our
 results suggest that long-distance dispersal events better explain
 present-day distributions than do Gondwanan or northern land bridge
 hypotheses. This biogeographical conclusion is for the most part robust to
 alternative calibration schemes. Our data support a minimum of 13 Old
 World to New World dispersal events but, intriguingly, only one in the
 reverse direction. Eleven of these 13 were among Acanthaceae s.s., which
 comprises &gt; 90% of species diversity in the family. Remarkably, if
 minimum age estimates approximate true history, these 11 events occurred
 within the last ~20 million years even though Acanthaceae s.s is over
 three times as old. A simulation study confirmed that these dispersal
 events were significantly skewed towards the present and not simply a
 chance occurrence. Finally, we review reports of fossils that have been
 assigned to Acanthaceae that are substantially older than the lower
 Cretaceous estimate for Angiosperms as a whole (i.e., the general
 consensus that has resulted from several recent dating and fossil-based
 studies in plants). This is the first study to reconstruct divergence
 times among clades of Acanthaceae and sets the stage for comparative
 evolutionary research in this and related families that have until now
 been thought to have extremely poor fossil resources.
description: Analysis1A_no max
 ageAnalysis4A_no max
 age.xmlAnalysis1B_max age
 124-126Analysis4B_max age
 124-126.xmlAnalysis 2A_no max
 ageAnalysis
 5A_no max age.xmlAnalysis2B_max age
 124-126Analysis5B_max age
 124-126.xmlcombined_BEASTTesting_Dispersals_R Source CodeTesting_Dispersals_forET.txtFigure S1_Dated Phylogeny with taxon names_accepted