Najas flexilis (Hydrocharitaceae) in Alaska : a reassessment

Author Posting. © New England Botanical Club, 2015. This article is posted here by permission of New England Botanical Club for personal use, not for redistribution. The definitive version was published in Rhorora 117 (2015): 354-370, doi:10.3119/15-03.Fifteen Najas flexilis collections were made in Alaska during the summer of 2012, with 13 of the stations representing either new or formerly undocumented localities for this imperiled Alaskan species. These field collections characterize the Alaskan habitats of N. flexilis as shallow water sites (<1.5 m) with sand-dominated substrates (71% of sites) and have documented an additional 28 species associates (a 300% increase). However, the additional collections have not extended the elevational, latitudinal, or longitudinal extent of N. flexilis from the limits indicated by previous Alaskan collections. Najas flexilis remains rare in Alaska as evidenced by a low specimen recovery rate (10%) from potentially suitable sites, and a total of only 12 geographically distinct localities known across the entire state. The new collections have furnished valuable study material for morphological and genetic analyses, which have confirmed the identity of Alaskan populations as N. flexilis, rather than N. canadensis, a recently identified, cryptic, allotetraploid derivative. A synthesis of information indicates that N. flexilis is indigenous to Alaska, where it originated via past (versus recent) migrations from other North American rather than Old World populations.Portions of this work were funded by National Science Foundation grant DEB-0841658 to D.H.L

Phylogenetic relationships in Nuphar (Nymphaeaceae): Evidence from morphology, chloroplast DNA, and nuclear ribosomal DNA

The genus Nuphar consists of yellow-flowered waterlilies and is widely distributed in north-temperate bodies of water. Despite regular taxonomic evaluation of these plants, no explicit phylogenetic hypotheses have been proposed for the genus. We investigated phylogenetic relationships in Nuphar using morphology and sequences of the chloroplast gene matK and of the internal transcribed spacer (ITS) regions of nuclear ribosomal DNA. Two major lineages within Nuphar are consistently resolved with the morphological and molecular data sets. One lineage comprises New World taxa and the other represents a primarily Old World lineage. Relationships within the major lineages were poorly resolved by morphology and ITS, yet certain relationships were elucidated by all analyses. Most notable is the strong support for a monophyletic lineage of dwarf taxa and the alliance of the North American N. microphylla with the Eurasian taxa. Minor discordance between the independent cladograms is accounted for by hybridization. The common taxonomic practice of uniting all North American and Eurasian taxa under one species is not supported phylogenetically

Distribution and habitats of forked aster (Aster furcatus), a threatened Wisconsin plant

We describe the locations and habitat characteristics of 10 of the 14 known populations of Aster furcatus in Wisconsin. We were unable to identify any particularly unusual features of A. furcatus habitats which could be related to its rarity. The rarity of forked aster is probably not related to specialized habitats, but is most likely the result of requirements for moderate disturbance, inability to withstand competition, poor reproduction from seed, and low genetic variance

A Reappraisal of Phylogentic Relationships in the Monocotyledon Family Hydrocharitaceae (Alismatidae)

The diverse, aquatic Hydrocharitaceae have defied stable classification for nearly two centuries. Anatomical and morphological convergence characterize many aquatic plants and undoubtedly have hindered the ability of researchers to ascertain accurately those features representing reliable phylogenetic markers within Hydrocharitaceae. Most prior classifications of the family have emphasized few characters to define major taxonomic subdivisions (i.e., they were highly artificial). Previous studies using molecular data have shown that DNA sequences provide novel indications of phylogeny not indicated previously by morphologically based classifications; however, they have not yet recommended alterations to the classification for the family. We conducted a more comprehensive phylogenetic study of Hydrocharitaceae to better elucidate evolutionary relationships among the genera that in turn could be used to provide insight for improvements in classification. We analyzed different data sets (55 morphological characters; chloroplast rbcL, matK, trnK intron sequences; nuclear ribosomal ITS region sequences) singly and in various combinations using maximum parsimony and maximum likelihood methods of phylogenetic reconstruction. Phylogenetic analysis of combined data yielded a fully resolved tree depicting four well-supported, major clades within Hydrocharitaceae. We use these results to propose a phylogenetic classification of Hydrocharitaceae recognizing four subfamilies that correspond to these clades: Anacharidoideae, Hydrilloideae, Hydrocharitoideae, and Stratioideae. Phylogenetic analysis also indicated the pattern of derivation with respect to submersed lifeforms, hydrophilous pollination, and marine habitation in the family. Character reconstructions indicated that several features, (e.g., ovule type; occurrence of detaching male flowers), once thought to provide strong phylogenetic markers in Hydrocharitaceae, actually are highly homoplasious and have acutely mislead past attempts at classification of the family

Speciation in Duckweeds (Lemnaceae): Phylogenetic and Ecological Inferences

Species of duckweeds (Letnnaceae) that were resolved as sister taxa in a phylogeny based on combined molecular and non-molecular data were compared for morphological, physiological, and ecological attributes to infer factors important in the initial divergence leading to speciation. The ability to survive extreme conditions such as desiccation and cold temperatures is the most common difference identified between species. Two morphological characters facilitating survival in extreme environments are production of special resting buds called turions and increased seed production. The prevalent geographic pattern for species pairs consists of one restricted species occurring on the periphery of a more widespread taxon; this pattern indicates that divergence of peripheral isolates is a common geographical mode of speciation in duckweeds. Other species differ in optimal environmental conditions for growth, and these species are largely sympatric. In only one instance does it appear that divergence and speciation occurred following long-distance dispersal. Sympatric species pairs have the lowest molecular divergence; widespread primarily allopatric, and distantly allopatric species have the highest molecular divergence. Despite infrequent sexual reproduction, some degree of detectable variation (molecular, physiological, etc.) occurs within populations and among populations of the same species. Molecular evidence indicates that variation within duckweeds extends from the population and intraspecific levels to very different levels of divergence among recognized species. Contrary to the appearance of morphological and ecological uniformity implied by their reduced morphology and restricted occurrence in fresh water habitats, duckweeds are not a group in evolutionary stasis. Rather, these smallest of all flowering plants are dynamic evolutionarily, and comprise a model system for studying plant evolution and speciation

New Record of Bacopa egensis (Plantaginaceae) for the Flora of Mexico

Bacopa egensis is newly reported for the flora of Mexico and an updated key is provided for the Mexican Bacopa specie

Lemnaceae and Orontiaceae Are Phylogenetically and Morphologically Distinct from Araceae

Duckweeds comprise a distinctive clade of pleustophytic monocots that traditionally has been classified as the family Lemnaceae. However, molecular evidence has called into question their phylogenetic independence, with some authors asserting instead that duckweeds should be reclassified as subfamily Lemnoideae of an expanded family Araceae. Although a close phylogenetic relationship of duckweeds with traditional Araceae has been supported by multiple studies, the taxonomic disposition of duckweeds must be evaluated more critically to promote nomenclatural stability and utility. Subsuming duckweeds as a morphologically incongruent lineage of Araceae effectively eliminates the family category of Lemnaceae that has been widely used for many years. Instead, we suggest that Araceae subfamily Orontioideae should be restored to family status as Orontiaceae, which thereby would enable the recognition of three morphologically and phylogenetically distinct lineages: Araceae, Lemnaceae, and Orontiaceae

Allozyme variation and the taxonomy of Wolffiella

Abstract Allozyme electrophoresis was carried out to estimate genetic diversity within and assess divergence between the 10 recognized species in three sections of the aquatic angiosperm genus Wolffiella. Eleven presumptive loci were used in the calculations. Crawford et al. /Aquatic Botany 58 (1997) [43][44][45][46][47][48][49][50][51][52][53][54] Allozyme data support the recognition of sect. Stipitatae as now constituted and provide evidence for the circumscription of sect. Wolffiella as presently recognized. However, W. denticulata is rather isolated within this section. © 1997 Elsevier Science B.V

Can patient-led surveillance detect subsequent new primary or recurrent melanomas and reduce the need for routinely scheduled follow-up? A protocol for the MEL-SELF randomised controlled trial

This research project is funded by a National Health and Medical Research Council (NHMRC) Project grant (#1163054). The funder had no role in the design of the study and will have no role in the collection, analysis, and interpretation of the data; the writing of the report; or the decision to submit the report for publication. Funding Information: AEC is funded by a Career Development Fellowship from the National Health and Medical Research Council (NHMRC; 1147843). JFT is a recipient of an NHMRC Program Grant (1093017). RPMS is supported by Melanoma Institute Australia. RAS is supported by a NHMRC Program Grant and Practitioner Fellowship. For RAS, support from the from colleagues at Melanoma Institute Australia, Royal Prince Alfred Hospital and NSW Health Pathology is also gratefully acknowledged. RLM is supported with an NHMRC Investigator grant (1194703) and a University of Sydney Robinson Fellowship. HPS holds an NHMRC MRFF Next Generation Clinical Researchers Program Practitioner Fellowship (APP1137127). JH is supported by an NHMRC Early Career Fellowship (1112509). KB is supported by an NHMRC Investigator Grant (1174523) and a University of Sydney Research Accelerator (SOAR) Prize.Peer reviewedPublisher PD

Phylogenetics of Seed Plants: An Analysis of Nucleotide Sequences from the Plastid Gene rbcL

We present the results of two exploratory parsimony analyses of DNA sequences from 475 and 499 species of seed plants, respectively, representing all major taxonomic groups. The data are exclusively from the chloroplast gene rbcL, which codes for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO or RuBPCase). We used two different state-transformation assumptions resulting in two sets of cladograms: (i) equal-weighting for the 499-taxon analysis; and (ii) a procedure that differentially weights transversions over transitions within characters and codon positions among characters for the 475-taxon analysis. The degree of congruence between these results and other molecular, as well as morphological, cladistic studies indicates that rbcL sequence variation contains historical evidence appropriate for phylogenetic analysis at this taxonomic level of sampling. Because the topologies presented are necessarily approximate and cannot be evaluated adequately for internal support, these results should be assessed from the perspective of their predictive value and used to direct future studies, both molecular and morphological. In both analyses, the three genera of Gnetales are placed together as the sister group of the flowering plants, and the anomalous aquatic Ceratophyllum (Ceratophyllaceae) is sister to all other flowering plants. Several major lineages identified correspond well with at least some recent taxonomic schemes for angiosperms, particularly those of Dahlgren and Thorne. The basalmost clades within the angiosperms are orders of the apparently polyphyletic subclass Magnoliidae sensu Cronquist. The most conspicuous feature of the topology is that the major division is not monocot versus dicot, but rather one correlated with general pollen type: uniaperturate versus triaperturate. The Dilleniidae and Hamamelidae are the only subclasses that are grossly polyphyletic; an examination of the latter is presented as an example of the use of these broad analyses to focus more restricted studies. A broadly circumscribed Rosidae is paraphyletic to Asteridae and Dilleniidae. Subclass Caryophyllidae is monophyletic and derived from within Rosidae in the 475-taxon analysis but is sister to a group composed of broadly delineated Asteridae and Rosidae in the 499-taxon study