Paul S. Manos

Comparative phylogeography of unglaciated eastern North America

Regional phylogeographical studies involving co‐distributed animal and plant species have been conducted for several areas, most notably for Europe and the Pacific Northwest of North America. Until recently, phylogeographical studies in unglaciated eastern North America have been largely limited to animals. As more studies emerge for diverse lineages (including plants), it seems timely to assess the phylogeography across this region: (i) comparing and contrasting the patterns seen in plants and animals; (ii) assessing the extent of pseudocongruence; and (iii) discussing the potential applications of regional phylogeography to issues in ecology, such as response to climatic change. Unglaciated eastern North America is a large, geologically and topographically complex area with the species examined having diverse distributions. Nonetheless, some recurrent patterns emerge: (i) maritime — Atlantic vs. Gulf Coast; (ii) Apalachicola River discontinuity; (iii) Tombigbee River discontinuity; (iv) the Appalachian Mountain discontinuity; (v) the Mississippi River discontinuity; and (vi) the Apalachicola River and Mississippi River discontinuities. Although initially documented in animals, most of these patterns are also apparent in plants, providing support for phylogeographical generalizations. These patterns may generally be attributable to isolation and differentiation during Pleistocene glaciation, but in some cases may be older (Pliocene). Molecular studies sometimes agree with longstanding hypotheses of glacial refugia, but also suggest additional possible refugia, such as the southern Appalachian Mountains and areas close to the Laurentide Ice Sheet. Many species exhibit distinct patterns that reflect the unique, rather than the shared, aspects of species’ phylogeographical histories. Furthermore, similar modern phylogeographical patterns can result from different underlying causal factors operating at different times (i.e. pseudocongruence). One underemphasized component of pseudocongruence may result from the efforts of researchers to categorize patterns visually — similar patterns may, in fact, not fully coincide, and inferring agreement may obscure the actual patterns and lead to erroneous conclusions. Our modelling analyses indicate no clear spatial patterning and support the hypothesis that phylogeographical structure in diverse temperate taxa is complex and was not shaped by just a few barriers.

MOLECULAR INDICATORS OF TREE MIGRATION CAPACITY UNDER RAPID CLIMATE CHANGE

Recent models and analyses of paleoecological records suggest that tree populations are capable of rapid migration when climate warms. Fossil pollen is commonly interpreted as suggesting that the range of many temperate tree species expanded at rates of 100–1000 m/yr during the early Holocene. We used chloroplast DNA surveys to show that the geography of postglacial range expansion in two eastern North American tree species differs from that expected from pollen-based reconstructions and from patterns emerging from European molecular studies. Molecular evidence suggests that American beech (Fagus grandifolia) and red maple (Acer rubrum) persisted during the late glaciation as low-density populations, perhaps within 500 km of the Laurentide Ice Sheet. Because populations were closer to modern range limits than previously thought, postglacial migration rates may have been slower than those inferred from fossil pollen. Our estimated rates of <100 m/yr are consistent with model predictions based on life histo...

Systematics of Fagaceae: Phylogenetic Tests of Reproductive Trait Evolution

The family Fagaceae includes nine currently recognized genera and ca. 1000 species, making it one of the largest and most economically important groups within the order Fagales. In addition to wide variation in cupule and fruit morphology, polymorphism in pollination syndrome (wind vs. generalistic insect) also contributes to the uniqueness of the family. Phylogenetic relationships were examined using 179 accessions spanning the taxonomic breadth of the family, emphasizing tropical, subtropical, and relictual taxa. Nuclear ribosomal DNA sequences encoding the 5.8S rRNA gene and two flanking internal transcribed spacers (ITS) were used to evaluate phylogenetic hypotheses based on previous morphological cladistic analysis and intuitive schemes. Parsimony analyses rooted with Fagus supported two clades within the family, Trigonobalanus sensu lato and a large clade comprising Quercus and the castaneoid genera ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape

Systematics of Nothofagus (Nothofagaceae) based on rDNA spacer sequences (ITS): taxonomic congruence with morphology and plastid sequences

Castanea+Castanopsis

IS FLORAL SPECIALIZATION AN EVOLUTIONARY DEAD‐END? POLLINATION SYSTEM TRANSITIONS IN RUELLIA (ACANTHACEAE)

\end{document} , Chrysolepis, Lithocarpus). Three DNA sequence data sets, 179‐taxon ITS, 60‐taxon ITS, and a 14‐taxon combined nuclear and chloroplast (matK), were used to test a priori hypotheses of reproductive character state evolution. We used Templeton’s (1983) test to assess alternative scenarios of single and multiple origins of derived and seemingly irreversible traits such as wind pollination, hypogeal cotyledons, and flower cupules. On the basis of previous exemplar‐based and current in‐depth analyses of Fagaceae, we suggest that wind pollination evolved at least three times and hypogeal cotyledons once. Although we could not reject the hypothesis that the acorn fruit type of Quercus is derived from a dichasium cupule, combined analysis provided some evidence for a relationship of Quercus to Lithocarpus and Chrysolepis, taxa with dichasially arranged pistillate flowers, where each flower is surrounded by cupular tissue. This indicates that a more broadly defined flower cupule, in which individual pistillate flowers seated within a separate cupule, may have a single origin.

A Framework Phylogeny of the American Oak Clade Based on Sequenced RAD Data

The angiosperm family Fagaceae is a central element of several distinct community types throughout the Northern Hemisphere and a prime candidate for modern biogeographic analysis. The rich fossil record for the family provides an unparalleled source to compare with modern distributions and evaluate hypotheses of origin, migration, and vicariance. We conducted separate phylogenetic analyses on genera with intercontinentally disjunct distributions using various noncoding regions of chloroplast and nuclear ribosomal DNA sequences. Analyses generally supported the (North \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape

PHYLOGENETIC RELATIONSHIPS IN FAGALES BASED ON DNA SEQUENCES FROM THREE GENOMES

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