Biosystematics and phenology of Alnus maritima (Betulaceae)

Alnus maritima (Marsh.) Muhl. ex Nutt. (seaside alder) is a rare woody plant species found naturally in only three small disjunct populations in the United States. Concern for the conservation of A. maritima and questions regarding the proper classification of its disjunct populations have generated a need for information concerning its ecology and biosystematics, while growing interest in the use of A. maritima in managed landscapes has demonstrated the need for information concerning its ecophysiology and landscape fitness. My first objective was to recount the taxonomic and horticultural history of A. maritima and to report on its current landscape usage and cultivation. Although it has received little attention from horticulturists since its introduction into cultivation over 100 years ago, A. maritima is now being recognized as a stress-resistant large shrub or small tree. My second objective was to derive the infraspecific systematics of A. maritima by morphometric analysis and to classify the three disjunct populations properly. Taxonomic distances were compatible with the modern definition of subspecies, and the subspecific epithets oklahomensis, georgiensis, and maritima were given the three taxa. My third objective was to characterize the molecular systematics of A. maritima according to ISSR polymorphisms. The molecular phylogeny of eight species of Alnus confirmed that A. maritima is most closely related to the other members of subg. Clethropsis and was the first member of its subgenus to diverge. At the infraspecific level, molecular and morphometric phylogenies agreed and showed that subsp. oklahomensis was the first to diverge. My fourth objective was to characterize the cold hardiness of A. maritima in native habitats and in colder climates. Analyses showed that the subspecies are similar in cold hardiness, that plants from all three subspecies can survive mid-winter extremes as low as -80°C, and that cold acclimation differs between plants grown in colder climates and those in native habitats. Results from these studies support the theory that A. maritima originated in Asia, migrated into North America across the Bering land bridge, and was established over a large range before being forced into its present meager distribution

Propagation of Alnus maritima from its three disjunct populations

My third objective was to evaluate the use of softwood cuttings to propagate A. maritima. Indole-3-butyric acid (IBA) at 8 g÷kg⁻ù caused a greater rooting percentage (68%), root count (36), and root length (9.1 cm) than did IBA at 0 and 1 g÷kg⁻ù when applied to cuttings from Oklahoma in June. Cuttings from Oklahoma had greater survival, callus development, and root length, and had a higher rooting percentage and root count, than cuttings from Delmarva. More cuttings collected 14 June rooted (41%) than those collected 23 Aug. (8%). This information will be important for future management of naturally occurring A. maritima and for optimizing its production as a new crop for landscaping.Alnus maritima [Marsh.] Nutt. (seaside alder) is a rare woody plant species known to occur naturally in three disjunct populations in south-central Oklahoma, northwestern Georgia, and the Delmarva Peninsula. Ecological concerns and interest in producing this species for use in managed landscapes underscore the need for information on reproduction, population biology, and propagation of A. maritima. My first objective was to examine reproductive limitations of A. maritima caused by timing of seed dispersal. In Oklahoma, 65.7% of seeds were dispersed during winter months. A model simulating the fate of these seeds showed germination percentage was reduced from 63.3% to 19.5% after exposure of seeds to winter temperatures typical of native habitats. Germination percentage declined from 57.9% to 39.7% for seeds that overwintered on trees.I propose that timing of seed dispersal reduces seed germinability, thereby limiting the natural distribution of A. maritima. My second objective was to examine effects of provenance and environment on seed germination and effects of provenance on the growth and morphology of seedlings. Six weeks of stratification at 4ðC optimized germination of seeds from Oklahoma at 73.2%. When this treatment was applied to seeds from all populations, seeds from Oklahoma had a higher germination percentage (55.0%) than did seeds from Georgia (31.4%) and Delmarva(14.7%). Leaves of seedlings from Oklahoma were longer, more narrow, and less bullate than those from Georgia and Delmarva. Seedlings from Oklahoma and Georgia had higher growth rates than seedlings from Delmarva, while seedlings from Oklahoma and Delmarva were more densely foliated

At the interface of phylogenetics and population genetics, the phylogeography of Dirca occidentalis (Thymelaeaceae)

Dirca occidentalis is a rare shrub indigenous to only six counties near the San Francisco Bay in California, United States. We used intersimple sequence repeat (ISSR) markers and automated genotyping to probe 29 colonies of D. occidentalis from four geographically disjunct populations (East Bay, North Bay, Salmon Creek, and Peninsula) and used methods of phylogenetics and population genetics to model variation across the species. Results show that the four disjunct populations are genetically isolated and have undergone divergence. Phylogenetic analyses indicate that the East Bay population was the first to diverge, followed by the North Bay, then the Salmon Creek and Peninsula populations. This order of divergence suggests an intriguing natural history for D. occidentalis that is explained by the dynamic geological and climatic history of the Bay Area. Spatial genetic structure detected for the species suggests an interaction of four factors: limited seed dispersal, clonal regeneration, distances traveled by pollinators, and genetic isolation of the four populations. Genetic diversity within the North Bay and Salmon Creek populations is low, indicating poor ecological fitness and risk of decline. ISSRs resolved phylogeographic structure within D. occidentalis, results unattainable with ITS methods, and the integration of tools of phylogenetics and population biology led to an enhanced understanding of this endemic species

Constructing Galois 2-extensions of the 2-adic Numbers

Let Q_2 denote the field of 2-adic numbers, and let G be a group of order 2^n for some positive integer n. We provide an implementation in the software program GAP of an algorithm due to Yamagishi that counts the number of nonisomorphic Galois extensions K/Q_2 whose Galois group is G. Furthermore, we describe an algorithm for constructing defining polynomials for each such extension by considering quadratic extensions of Galois 2-adic fields of degree 2^{n−1}. While this method does require that some extensions be discarded, we show that this approach considers far fewer extensions than the best general construction algorithm currently known, which is due to Pauli- Sinclair based on the work of Monge. We end with an application of our approach to completely classify all Galois 2-adic fields of degree 16, including defining polynomials, ramification index, residue degree, valuation of the discriminant, and Galois group

XPS and AFM study of interaction of organosilane and sizing with e-glass fibre surface

Organosilanes are often used in commercial sizings for glass fibres to provide wettability with the resin and promote strong interfacial adhesion to the matrix in a fibre reinforced polymer composite. The silane treatment is introduced as part of a complex deposition from an aqueous emulsion immediately at the spinaret and determines the optimum properties of the cured composite. To understand the interaction of organosilanes contained in sizings for glass surfaces, XPS was used to investigate the adsorption of γ-aminopropyltriethoxysilane (APS) from a simple sizing system containing a polyurethane (PU) film former. It has been found that both APS and the sizing (containing APS and PU) deposits on E-glass fibre surfaces contained components of differing hydrolytic stability. The differences observed in the AFM images of APS coated E-glass fibres before and after water extraction also confirmed that the APS deposit contained components with different water solubility

Differences in Shade Tolerance Help Explain Varying Success of Two Sympatric Alnus Species

Alnus maritima and Alnus serrulata are riparian shrubs that occur in similar habitats in the southern and eastern United States.Alnus serrulata is abundant throughout this range, but A. maritima is rare, occurring only in small populations in Oklahoma and Georgia and on the Delmarva Peninsula. Alnus maritima is more resistant than A. serrulata to water and temperature stresses, but the degree to which insolation influences the restricted distribution of A. maritima is unknown. Our goals were to characterize the shade tolerance of A. maritima and A. serrulata and determine whether differences in shade tolerance could help explain the differing ecological success of the two species. Measurements in nature showed that leaves of A. serrulatahave greater concentrations of chlorophyll than do leaves of A. maritima, and a greater percentage of A. serrulata inhabit shaded sites. Two experiments evaluating the resistance of seedlings to light‐deficit stress revealed that A. maritima had a greater photosynthetic capacity and grew more quickly than A. serrulata in full sunlight. In shade, survival of seedlings was lower and reductions in photosynthesis and growth were greater for A. maritima than for A. serrulata. We conclude that A. serrulata is tolerant and A. maritima is intolerant of shade. Moreover, we conclude that shade intolerance strongly restricts the potential niches of A. maritima within the region where the shade‐tolerant A. serrulata is comparatively abundant

Usefulness of the Lang Stereotest with an infant population

Sixty-four healthy full term infants between 6 and 24 months of age were tested using the Lang Stereotest. A full vision examination including visual acuity assessment using the Teller acuity card preferential looking procedure, near point of convergence, Worth test for eccentric fixation, Hirschberg test, and monocular estimate method to measure accommodative posture was performed. Ocular health was also assessed to rule out pathology. Results showed that 90% of the 6.0 to 12.0 month age group, 100% of both the 12.0 to 18.0 and 18.0 to 24.0 month age groups were able to respond positively to at least one stereo image on the Lang Stereotest. Performance showed improvement with age