Large scale patterns of genetic variation and differentiation in sugar maple from tropical Central America to temperate North America

© 2015 Vargas-Rodriguez et al. Background: Geological events in the latter Cenozoic have influenced the distribution, abundance and genetic structure of tree populations in temperate and tropical North America. The biogeographical history of temperate vegetation that spans large ranges of latitude is complex, involving multiple latitudinal shifts that might have occurred via different migration routes. We determined the regional structuring of genetic variation of sugar maple (Acer saccharum subsp. saccharum) and its only subspecies in tropical America (Acer saccharum subsp. skutchii) using nuclear and chloroplast data. The studied populations span a geographic range from Maine, USA (46°N), to El Progreso, Guatemala (15°N). We examined genetic subdivisions, explored the locations of ancestral haplotypes, analyzed genetic data to explore the presence of a single or multiple glacial refugia, and tested whether genetic lineages are temporally consistent with a Pleistocene or older divergence. Results: Nuclear and chloroplast data indicated that populations in midwestern USA and western Mexico were highly differentiated from populations in the rest of the sites. The time of the most recent common ancestor of the western Mexico haplotype lineage was dated to the Pliocene (5.9 Ma, 95 % HPD: 4.3-7.3 Ma). Splits during the Pleistocene separated the rest of the phylogroups. The most frequent and widespread haplotype occurred in half of the sites (Guatemala, eastern Mexico, southeastern USA, and Ohio). Our data also suggested that multiple Pleistocene refugia (tropics-southeastern USA, midwestern, and northeastern USA), but not western Mexico (Jalisco), contributed to post-glacial northward expansion of ranges. Current southern Mexican and Guatemalan populations have reduced population sizes, genetic bottlenecks and tend toward homozygosity, as indicated using nuclear and chloroplast markers. Conclusions: The divergence of western Mexican populations from the rest of the sugar maples likely resulted from orographic and volcanic barriers to gene flow. Past connectivity among populations in the southeastern USA and eastern Mexico and Guatemala possible occurred through gene flow during the Pleistocene. The time to the most common ancestor values revealed that populations from the Midwest and Northeast USA represented different haplotype lineages, indicating major divergence of haplotypes lineages before the Last Glacial Maximum and suggesting the existence of multiple glacial refugia

Phylogenetics and taxonomy of the N ew W orld leafy spurges, E uphorbia section T ithymalus ( E uphorbiaceae)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/107503/1/boj12167-sup-0002-fs2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/107503/2/boj12167-sup-0003-fs3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/107503/3/boj12167-sup-0004-fs4.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/107503/4/boj12167.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/107503/5/boj12167-sup-0001-fs1.pd

A Floristic Study Of Dawes County, Nebraska

Physical features pertinent to the flora of Dawes County are summarized. A checklist of the known taxa with notes on ecology and origin of each form follows the Literature cited. This study was undertaken because the need for a reasonably complete list of flowering plants and for a plant collection of the Chadron vicinity has been felt in the botany courses taught at Chadron State College. The plants reported in this annotated list were collected from several sites throughout the county by the authors during the 1970 and 1971 growing seasons. However, in order to make the list more complete, plants which were already in the collection at Chadron State College are included, as are those reported from a nearby site in Sioux County. Little floristic research has been published specifically on this area. Tolstead (1947) presented a general survey of the vegetation for the Pine Ridge, and Nixon (1967) did a vegetational study of a site in Sheridan County. Dawes County is located in northwestern Nebraska. It borders South Dakota on the north and only Sioux County separates it from Wyoming on the west

SYSTEMATICS OF THE ERICAMERIA CUNEATA COMPLEX (COMPOSITAE, ASTEREAE)

Volume: 23Start Page: 338End Page: 34

PANAX QUINQUEFOLIUS L. (ARALIACEAE) REDISCOVERED IN LOUISIANA

Volume: 11Start Page: 486End Page: 48

NEW COMBINATIONS IN THE GENUS GUNDLACHIA AND FOUR NEW GENERA OF ASTEREAE (ASTERACEAE) FROM NORTHERN MEXICO AND THE SOUTHERN UNITED STATES

Volume: 21Start Page: 243End Page: 25

GLOCHIDION PUBERUM (EUPHORBIACEAE) NATURALIZED IN SOUTHERN ALABAMA

Volume: 19Start Page: 711End Page: 71

Phylogenetic evaluation of Xylothamia, Gundlachia, and related genera (Asteraceae, Astereae) based on ETS and ITS nrDNA sequence data

Previous molecular investigations of the phylogenetic relationship for Xylothamia employed exemplar taxa and indicated its affiliation is either with the Gutierrezia or the Ericameria alliances. The present 3\u27 ETS and ITS nrDNA gene phylogenies yielded the unexpected result that Xylothamia is polyphyletic. Species within its circumscription are placed into two well-supported evolutionary lineages with other genera of Astereae. Of nine species of Xylothamia, four species plus Gundlachia constitute one clade. The other five species are placed in a sister clade with several other genera including Amphiachyris, Bigelowia, Euthamia, Gutierrezia, and others. Except for X. johnstonii and X. palmeri, these five species of Xylothamia have little affinity for one another or for other genera in the same clade. Morphological similarities in foliar features between certain species in both lineages are possibly from a convergence resulting in adaptation to arid habitats. Such similarities were also the basis, in part, for their taxonomic treatment within Xylothamia or their earlier affiliation with Ericameria, which has similar features. The uncharacteristic leaf form in Xylothamia purpursii has a pattern of adaptation considerably different from its allies. Whether the Xylothamia-containing clades are related to Solidaginineae or represent an independently derived lineage remains equivocal because this outcome rested with the choice of data and optimality criteria