02526nas a2200133   4500008004100000245008700041210006900128300001400197490000800211520210000219100001502319700001402334856004402348       2016                        eng d00aDisentangling the phylogeny of Isoetes (Isoetales), using nuclear and plastid data0 aDisentangling the phylogeny of Isoetes Isoetales using nuclear a  a157–1740 v1773 aPremise of research. The heterosporous lycopsids of Isoetes show limited morphological and genetic variation despite a worldwide distribution and the ancient origin of the lineage. Here major relationships within the genus are clarified, using a substantially larger sampling of species than in previous studies. A first assessment of divergence times of clades is made, and the implications for dispersal mechanisms and biogeographic distribution patterns are discussed. Methodology. On the basis of sequences from three gene regions and 109 specimens representing 74 species of Isoetes, phylogeny and node ages were estimated using parsimony and Bayesian inference. Pivotal results. Three rooting approaches (outgroup analysis, midpoint rooting, and clock rooting) coherently resolved a diverse clade containing species from South Africa, India, Australia, and South America (clade A) as sister to remaining Isoetes. Analysis of divergence times of clades yielded a median age of the crown group of 147 million years ago (mya) using a birth-death tree prior and 165 mya using a Yule tree prior. Clade A was dated to 111 or 125 mya, respectively. While the earliest divergences in Isoetes appear readily explained by ancient vicariance, patterns in younger clades are consistent with dispersal processes, sometimes over long distances. Isoetes andicola (Amstutz) L.D. Gómez, once hypothesized to represent a separate lineage and assigned to the genus Stylites, is here included in a phylogenetic study for the first time. It is closely related to some other South American species, despite its peculiar morphology with a dichotomizing stem. Conclusions. Despite limited intrageneric variation at the molecular and morphological levels, node ages as well as species composition (phylogeny) indicate a Mesozoic origin of the extant clade. Biogeographic patterns appear complicated and intriguing but need more research. Tuberculate megaspore ornamentation (sensu Pfeiffer) is ancestral in the genus, as indicated by current knowledge. Other megaspore patterns appear restricted to two subclades.1 aLarsen, E.1 aRydin, C.  uhttps://isoetes.myspecies.info/node/23001649nas a2200193   4500008004100000245009000041210007000131260001200201300001200213490000700225520102500232653001501257653001201272653001401284653000901298100001401307700001801321856011601339       2002                        eng d00aPhylogeny of Isoëtes (Lycopsida): Resolving basal relationships using rbcL sequences0 aPhylogeny of Isoëtes Lycopsida Resolving basal relationships usi  c2002///  a83 - 890 v513 aThe phylogenetic relationships of Isoëtes (Isoëtaceae) were investigated by means of a cladistic analysis using plastid rbcL sequences and a representative sample of 18 species. The analysis supports a basal split in Isoëtes separating two main groups, one including aquatic species from South America (I. bradei and I. amazonica) and West Africa (I. kersii and I. schweinfurthii), and the other including aquatic, amphibious and terrestrial species representing all major continents. Higher level relationships remain unresolved, but supported groups do conflict with previous morphology-based hypotheses. Comparatively low levels of sequence divergence indicate that the use of more rapidly evolving regions will be required to resolve higher level relationships. The phylogenetically isolated nature of Isoëtes will in such analyses make standard outgroup comparisons problematic, and results presented here will in this respect prove important by providing support for choosing among alternative rooting options.10aIsoetaceae10aIsoetes10aPhylogeny10arbcL1 aRydin, C.1 aWikström, N.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0036254372&partnerID=40&md5=f4c2dc2699e8c72b00c4dccdb1f20c1f