J. Mark Porter

Tribal delimitation and phylogenetic relationships of Loteae and Coronilleae (Faboideae: Fabaceae) with special reference to Lotus: evidence from nuclear ribosomal ITS sequences

The temperate herbaceous tribes Loteae and Coronilleae have traditionally been regarded as taxonomically distinct entities. More recent morphological assessments, however, have challenged this view and suggest combining the two tribes under Loteae. Two key features used to distinguish the Coronilleae from Loteae include jointed fruits and branched root nodules. We evaluate the taxonomic utility of these characters using information derived from phylogenetic analyses of the internal transcribed spacers ITS1 + 2, and the intervening 5.8S region of nuclear ribosomal DNA. Results from this study show that neither the Loteae nor Coronilleae form individual monophyletic groups, and that key fruit and root nodule characters used to distinguish the Coronilleae are homoplastic. Given these data, we support the recognition of a single tribe, Loteae. We also find that Lotus, the largest and most morphologically complex genus in either tribe, is not monophyletic. Rather, it consists of two geographically distinct lineages, Old and New World, each of which are more closely related to other Loteae genera: Old World Lotus are more closely related to Old World Anthyllis, while New World Lotus show closer affinities to Old World Coronilla. These data also have important implications for the biogeography of New World Lotus: equally most parsimonious reconstructions suggest a complex scenario of intercontinental dispersals that involve not only Old World Lotus but Coronilla as well.

ECOLOGICAL SPECIATION IN THE EAST MAUI-ENDEMIC DUBAUTIA (ASTERACEAE) SPECIES

Abstract Adaptive diversification can be viewed as a balance between the conservative force of interpopulation gene flow and selection for differential environments. In this paper, we examine ecological, morphological, and genetic differentiation in a small clade consisting of four East Maui‐endemic species of Dubautia: D. menziesii, D. platyphylla, D. reticulata, and D. waianapanapaensis, in the Hawaiian silversword alliance (Asteraceae). The East Maui clade is apparently recently derived (less than 1 million years ago) and is geographically restricted yet displays significant ecological and morphological differences. We used geographic data from historical herbarium specimens, measurements of plant architecture and leaf morphometrics, and measures of genetic differentiation in both microsatellite and nuclear coding loci to examine the correlation of different forms of divergence in this small species flock. We found overlap in large‐scale geographic distributions, significant differentiation in most habitat factors, significant micro‐satellite differentiation, and many shared alleles at nuclear coding loci suggesting on‐going lineage sorting. Despite the presence of apparent hybrids in some populations, microsatellite variation is consistent with isolation among species. Using Mantel tests, we compared the direction and extent of diversification among different datasets, to determine whether ecological/morphological divergence was correlated with genetic divergence. Correlations among different datasets showed that habitat was strongly correlated with plant architecture but not leaf morphology. Taken together, these results indicate that ecological and morphological diversification has driven genetic divergence at rapidly evolving microsatellite loci, whereas there is continuing lineage sorting at neutral sites in nuclear coding loci.

Back to the basics: a simple method of DNA extraction for mucilaginous cacti

Zusammenfassung: Wir betrachten und diskutieren eine Anzahl von DNA-Extraktionsprotokollen, die für schleimhaltige Pflanzen erarbeitet wurden. In der Folge werden zwei verhältnismässig einfache Methoden vorgestellt, die zuverlässig die Isolation molekularer Daten aus schleimhaltigen Kakteen erlauben. Wir sind der Ansicht, dass die hier vorgeschlagenen Methoden mit einem Minimum an Zeitund Geldaufwand brauchbare Resultate liefern können.

Fates of angiosperm species following long-distance dispersal: Examples from American amphitropical Polemoniaceae

PREMISE OF THE STUDY Following establishment after long-distance dispersal, species may experience stasis, accumulate changes leading to new species identity, diversify into multiple species, interact with related species to form novel species, and even become extirpated. We examined each species of temperate Polemoniaceae in South America via the literature and new analyses to better understand the fates of species in this family after their dispersal from North America. METHODS We reviewed literature for the 15 species of Polemoniaceae in South America amphitropically disjunct from their relatives in North America. We conducted DNA sequence analyses to infer relationships, timing of dispersal, and processes involved since dispersal in Microsteris gracilis, three Gilia, two Giliastrum, and three Collomia. Analyses included construction of haplotype networks and phylogenetic trees using maximum likelihood and Bayesian inference. KEY RESULTS For all species examined in detail, origins in South America are compatible with dispersal via epizoochory from ca. 0.092-19.46 million years ago. Most species in South America are unique relative to their North American congeners, yet few have radiated into two or more species. Relative stasis, divergence, and hybridization with, and without, allopolyploid formation have occurred postdispersal in Polemoniaceae, as well as extirpation following at least brief establishment. CONCLUSIONS Polemoniaceae that have established in South America share many features likely inherited from their North American progenitors, but some traits may have arisen in situ in specific taxa, such as cleistogamy, self-incompatibility, and the annual habit, evidencing the rich nature of diversification processes.

Species Status of Sclerocactus brevispinus, S. wetlandicus, and S. glaucus: Inferences from Morphology, Chloroplast DNA Sequences, and AFLP Markers

We examine patterns of variation in 12 continuous morphological traits, chloroplast DNA sequences from 10 intergenic spacer regions (petA-psbJ, psbk-trnS, psbM-trnD, rpob-trnC, trnC-trnD, trnGCUtrnG2S, trnFM-trnUGA, atpF-atpH, trnT-trnD, trnQ-psbk), atpF, and rpl16, and Amplified Fragment Length Polymorphism (AFLP) genetic markers in Sclerocactus glaucus sensu lato (5S. brevispinus, S. glaucus, and S. wetlandicus), a complex that historically has been considered conspecific and afforded protection under the Endangered Species Act. This complex is considered to represent three different species by some authors. We describe the expected patterns of morphological, DNA, and AFLP variation under the conditions that (a) the complex is a single species, and (b) that there are three antonymous species. We show that morphological evidence is consistent with the presence of three significantly different morphological species. Chloroplast DNA sequences provide evidence that the populations of S. glaucus (restricted to Colorado) are a lineage distinct from the populations of S. brevispinus and S. wetlandicus (restricted to Utah). AFLP genetic markers reveal significant genetic divergence among S. brevispinus, S. glaucus, and S. wetlandicus. Equally important, there is greater divergence among species than among populations within the species. The three sources of evidence all support the presence of three species and not a single species. These results indicate that protection of S. glaucus as a threatened species under the Endangered Species Act, as historically prescribed, includes populations of three species, two in Utah (S. brevispinus and S. wetlandicus) and one in Colorado (S. glaucus).