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Full-Text Articles in Life Sciences

Hawai‘I Forest Review: Synthesizing The Ecology, Evolution, And Conservation Of A Model System, Kasey E. Barton, Andrea Westerband, Rebecca Ostertag, Elizabeth Stacy, Kawika Winter, Donald R. Drake, Lucas Berio Fortini, Creighton M. Litton, Susan Cordell, Paul Krushelnycky, Kapua Kawelo, Kealoha Feliciano, Gordon Bennett, Tiffany Knight Aug 2021

Hawai‘I Forest Review: Synthesizing The Ecology, Evolution, And Conservation Of A Model System, Kasey E. Barton, Andrea Westerband, Rebecca Ostertag, Elizabeth Stacy, Kawika Winter, Donald R. Drake, Lucas Berio Fortini, Creighton M. Litton, Susan Cordell, Paul Krushelnycky, Kapua Kawelo, Kealoha Feliciano, Gordon Bennett, Tiffany Knight

Life Sciences Faculty Research

As the most remote archipelago in the world, the Hawaiian Islands are home to a highly endemic and disharmonic biota that has fascinated biologists for centuries. Forests are the dominant terrestrial biome in Hawai‘i, spanning complex, heterogeneous climates across substrates that vary tremendously in age, soil structure, and nutrient availability. Species richness is low in Hawaiian forests compared to other tropical forests, as a consequence of dispersal limitation from continents and adaptive radiations in only some lineages, and forests are dominated by the widespread Metrosideros species complex. Low species richness provides a relatively tractable model system for studies of community …


Dynamic Differential Evolution Schemes Of Wrky Transcription Factors In Domesticated And Wild Rice, Anne J. Villacastin, Keeley S. Adams, Rin Boonjue, Paul J. Rushton, Mira Han, Jeffery Q. Shen Jul 2021

Dynamic Differential Evolution Schemes Of Wrky Transcription Factors In Domesticated And Wild Rice, Anne J. Villacastin, Keeley S. Adams, Rin Boonjue, Paul J. Rushton, Mira Han, Jeffery Q. Shen

Life Sciences Faculty Research

WRKY transcription factors play key roles in stress responses, growth, and development. We previously reported on the evolution of WRKYs from unicellular green algae to land plants. To address recent evolution events, we studied three domesticated and eight wild species in the genus Oryza, an ideal model due to its long history of domestication, economic importance, and central role as a model system. We have identified prevalence of Group III WRKYs despite differences in breeding of cultivated and wild species. Same groups of WRKY genes tend to cluster together, suggesting recent, multiple duplication events. Duplications followed by divergence may result …


Evapotranspiration Of Urban Landscape Trees And Turfgrass In An Arid Environment: Potential Trade-Offs In The Landscape, Tamara Wynne, Dale Devitt Aug 2020

Evapotranspiration Of Urban Landscape Trees And Turfgrass In An Arid Environment: Potential Trade-Offs In The Landscape, Tamara Wynne, Dale Devitt

Life Sciences Faculty Research

Irrigation in arid urban landscapes can use significant amounts of water. Water conservation must be based on plant species and the ability to meet plant water requirements while minimizing overirrigation. However, actual evapotranspiration (ET) estimates for landscape trees and turfgrass in arid environments are poorly documented, especially direct comparisons to assess potential trade-offs. We conducted research to quantify ET of 10 common landscape tree species grown in southern Nevada and compared these values with the ET of both a warm season and cool season turfgrass species. The trees were grown in a plot with a high-density planting (256 trees/ha). A …


Effects Of Rate Of Drying, Life History Phase, And Ecotype On The Ability Of The Moss Bryum Argenteum To Survive Desiccation Events And The Influence On Conservation And Selection Of Material For Restoration, Joshua Lee Greenwood, Lloyd R. Stark, Lindsay P. Chiquoine Oct 2019

Effects Of Rate Of Drying, Life History Phase, And Ecotype On The Ability Of The Moss Bryum Argenteum To Survive Desiccation Events And The Influence On Conservation And Selection Of Material For Restoration, Joshua Lee Greenwood, Lloyd R. Stark, Lindsay P. Chiquoine

Life Sciences Faculty Research

Desiccation stress is frequently experienced by the moss Bryum argenteum and can influence survival, propagation and niche selection. We attempted to disentangle the interacting factors of life history phase (five categories) and rate of desiccation (time allotted for induction of desiccation tolerance) for 13 ecotypes of B. argenteum. Using chlorophyll fluorescence as a stress index, we determined how these parameters influenced desiccation tolerance. Rate of drying and life phase significantly affected desiccation tolerance. The reaction norms of desiccation tolerance displayed by the 13 ecotypes showed a substantial degree of variation in phenotypic plasticity. We observed differences in survival and fluorescence …


Leaf Micromorphology Aids Taxonomic Delineation Within The Hypervariable Genus Metrosideros (Myrtaceae) On O'Ahu, Gary L. Sur, Richard Keating, Elizabeth Stacy Jul 2018

Leaf Micromorphology Aids Taxonomic Delineation Within The Hypervariable Genus Metrosideros (Myrtaceae) On O'Ahu, Gary L. Sur, Richard Keating, Elizabeth Stacy

Life Sciences Faculty Research

Variation in leaf micromorphology can aid delimitation of taxonomically difficult groups. The woody genus Metrosideros (Myrtaceae) dominates Hawai'i's native forests and comprises striking, predominantly infraspecific, macromorphological variation, including many forms unrecognized in current taxonomic treatments. On taxonomically rich O'ahu, 10 taxa (varieties or unnamed morphotypes of M. polymorpha and other species) occur in a predictable sequence with overlapping ranges from low to high elevation along the numerous leeward ridges of the Ko'olau Range. We used scanning electron and light microscopy to examine mature, nonsenescing sun leaves from each of these 10 taxa. Parametric and nonparametric tests were used to compare …


Age And Sex-Specific Rates Of Leaf Regeneration In The Mojave Desert Moss Syntrichia Caninervis, Lloyd Stark, L. Nichols, Nicholas N. Mcletchie, S. D. Smith, C. Zundel Jan 2004

Age And Sex-Specific Rates Of Leaf Regeneration In The Mojave Desert Moss Syntrichia Caninervis, Lloyd Stark, L. Nichols, Nicholas N. Mcletchie, S. D. Smith, C. Zundel

Life Sciences Faculty Research

The extremely skewed female-biased sex ratio in the desert moss Syntrichia caninervis was investigated by assessing the regeneration capacity of detached leaves. Juvenile, green, yellow-green, and brown leaves equating to approximately 0, 2, 6, and 12 yr of age, respectively, were detached from individuals of S. caninervis collected from 10 field populations and grown in a growth chamber for 58 d at a light intensity of 33–128 µmol · m–2 · s–1. Younger leaves (0–2 yr old) tended to have a greater viability, regenerate more quickly, extend their protonemal filaments farther, produce shoots (gametophores) more quickly, produce more shoots, and …


On The Relationship Between Stomatal Characters And Atmospheric Co2, C. D. Reid, H. Maherali, H. B. Johnson, S. D. Smith, S. D. Wullschleger, R. B. Jackson Jan 2003

On The Relationship Between Stomatal Characters And Atmospheric Co2, C. D. Reid, H. Maherali, H. B. Johnson, S. D. Smith, S. D. Wullschleger, R. B. Jackson

Life Sciences Faculty Research

Leaf stomatal characters influence the response of terrestrial evapotranspiration to climate change and are used as proxies for the reconstruction of past atmospheric [CO2]. We examined the phenotypic response of stomatal index (SI), density (SD) and aperture (AP) to rising atmospheric CO2 in 15 species after four years exposure to a field CO2 gradient (200 to 550 μmol mol−1 atmospheric [CO2]) or at three Free Air CO2 Enrichment (FACE) sites. Along the CO2 gradient, SI and SD showed no evidence of a decline to increasing [CO2], while AP decreased slightly. There was no significant change in SI, SD or AP …


Arbuscular Mycorrhizae Of Mojave Desert Plants, J. H. Titus, P. J. Titus, R. S. Nowak, S. D. Smith Jan 2002

Arbuscular Mycorrhizae Of Mojave Desert Plants, J. H. Titus, P. J. Titus, R. S. Nowak, S. D. Smith

Life Sciences Faculty Research

Roots of 15 Mojave Desert plant species were assessed for arbuscular mycorrhizal (AM) colonization in spring and autumn 1999. Another 19 species were assessed in autumn only. Perennial species were AM colonized, whereas annual species contained very low levels of AM hyphae or were nonmycorrhizal. The nonnative tree Tamarix ramosissima was also nonmycorrhizal. Levels of hyphae changed over the season in 2 species, arbuscle levels increased in 1 species, and vesicles decreased in 7 species. Mycorrhizal inoculum potential (MIP) was assessed in the soils associated with spring-collected plants. All soils were found to contain MIP. MIP values were not correlated …


Effect Of Atmospheric Co2 Enrichment On Root Growth And Carbohydrate Allocation Of Phaseolus Spp., Katrina J. Salsman, Dean N. Jordan, S. D. Smith, D. S. Neuman Jan 1999

Effect Of Atmospheric Co2 Enrichment On Root Growth And Carbohydrate Allocation Of Phaseolus Spp., Katrina J. Salsman, Dean N. Jordan, S. D. Smith, D. S. Neuman

Life Sciences Faculty Research

A glasshouse experiment was conducted with plants of Phaseolus grown in liquid culture. Root growth parameters (biomass, diameter, length, growth rate, zone of cell division), root rheological components (wall extensibility, water potential yield threshold, water potential), shoot growth, carbon allocation, and abscisic acid (ABA) concentration were measured in Phaseolus acutifolius A. Gray at ambient (550 μmol mol−1) and elevated (700 μmol mol−1) atmospheric CO2 concentrations. For contrast, measurements of above‐ and belowground growth were conducted on Phaseolus vulgaris L. in the same treatments. Under nonlimiting conditions of water and nutrients, elevated CO2 increased root and shoot growth of P. acutifolius …


Bowen Ratio Estimates Of Evapotranspiration For Stands On The Virgin River In Southern Nevada, Dale A. Devitt, A. Sala, S. D. Smith, J. Cleverly, L. K. Shaulis, R. Hammett Jan 1998

Bowen Ratio Estimates Of Evapotranspiration For Stands On The Virgin River In Southern Nevada, Dale A. Devitt, A. Sala, S. D. Smith, J. Cleverly, L. K. Shaulis, R. Hammett

Life Sciences Faculty Research

A Bowen ratio energy balance was conducted over a Tamarix ramosissima (saltcedar) stand growing in a riparian corridor along the Virgin River in southern Nevada. Measurements in two separate years were compared and contrasted on the basis of changes in growing conditions. In 1994, a drought year, record high temperatures, dry winds, and a falling water table caused partial wilt of outer smaller twigs in the canopy of many trees in the stand around the Bowen tower. Subsequently, evapotranspiration (ET) estimates declined dramatically over a 60‐day period (11 mm d−1 tod−1). In 1995, the Virgin River at the Bowen tower …


Evapotranspiration From A Saltcedar-Dominated Desert Floodplain: A Scaling Approach, S. D. Smith, A. M. Sala, Dale A. Devitt Jan 1996

Evapotranspiration From A Saltcedar-Dominated Desert Floodplain: A Scaling Approach, S. D. Smith, A. M. Sala, Dale A. Devitt

Life Sciences Faculty Research

The purpose of this study was to investigate evapotranspiration (ET) from a variety of scales (leaf to landscape) in saltcedar-dominated floodplain vegetation along the lower Virgin River of southern Nevada. Leaf-level gas exchange indicated that saltcedar exhibits similar stomatal conductance as the sympatric phreatophytes arrowweed, mesquite, and willow. However, sap flow in saltcedar was higher per unit sapwood area than the other species, suggesting that it maintains higher leaf area per unit sapwood area. At the stand level, saltcedar ET was found to exceed potential ET early in the summer when soils were moist and the water table was near …


Fire In A Riparian Shrub Community: Postburn Water Relations In The Tamarix-Salix Association Along The Lower Colorado River, S. D. Smith, D. E. Busch Jan 1992

Fire In A Riparian Shrub Community: Postburn Water Relations In The Tamarix-Salix Association Along The Lower Colorado River, S. D. Smith, D. E. Busch

Life Sciences Faculty Research

Higher water potentials in recovering burned salt-cedar (Tamarix ramosissima) relative to unburned plants and the opposite situation in willow (Salix gooddingii) provide evidence that postfire water stress is reduced in the former but not the latter. Similarly, diurnal patterns of stomatal conductance in these taxa are consistent with the existence of more vigor in burned salt-cedar than willow. Plots of water potential and transpiration demonstrate that hydraulic efficiencies may contribute to differences in fire recovery.


Riparian Plant Water Relations Along The North Fork Of The Kings River, California, J. L. Nachlinger, S. D. Smith, R. J. Risser Jan 1989

Riparian Plant Water Relations Along The North Fork Of The Kings River, California, J. L. Nachlinger, S. D. Smith, R. J. Risser

Life Sciences Faculty Research

Plant water relations of five obligate ripar-ian species were studied along California's North Fork Kings River. Diurnal stomatal conductance, transpi-ration, and xylem pressure potentials were measured throughout the 1986 growing season and in mid-season in 1987. Patterns were similar for all species although absolute values varied considerably. Maximum stomatal conductance occurred early in the day and season during favorable environmental conditions and decreased as air temperature and the vapor pressure difference between the leaf and air increased. Maximum transpiration rates occurred in mid-morning and mid-summer resulting in estimated daily water losses per unit sunlit leaf area of 163-328 mol H2O …


Water Relations Of Obligate Riparian Plants As A Function Of Streamflow Diversion On The Bishop Creek Watershed, S. D. Smith, J. L. Nachlinger, A. B. Wellington, C. A. Fox Jan 1989

Water Relations Of Obligate Riparian Plants As A Function Of Streamflow Diversion On The Bishop Creek Watershed, S. D. Smith, J. L. Nachlinger, A. B. Wellington, C. A. Fox

Life Sciences Faculty Research

We investigated the water relations of obli-gate riparian plants on paired diverted and undiverted reaches on Bishop Creek, Eastern Sierra Nevada. Ri-parian plants on diverted reaches had reduced stomatal conductance and water potential compared to plants on undiverted reaches in a dry year, but not in a high runoff year. Juvenile plants on diverted reaches had reduced stomatal conductance and lower midday water potentials relative to surrounding mature trees, a trend that was not observed on undiverted reaches. Plants on diverted reaches possessed significantly smaller, thicker leaves and a reduced total leaf area relative to trees on streamside reaches. Reduced …


An Isotopic Analysis Of The Hydrology And Riparian Vegetation Water Sources On Bishop Creek, M. L. Space, J. W. Hess, S. D. Smith Jan 1989

An Isotopic Analysis Of The Hydrology And Riparian Vegetation Water Sources On Bishop Creek, M. L. Space, J. W. Hess, S. D. Smith

Life Sciences Faculty Research

Five power generation plants along an eleven kilometer stretch divert Bishop Creek water for hydro-electric power. Stream diversion may be adversely affecting the riparian vegetation. Stable isotopic analysis is employed to determine surface water/ground-water interactions along the creek. surface water originates primarily from three headwater lakes. Discharge into Bishop Creek below the headwaters is primarily derived from ground water. The average δD and δ18O values are significantly different for surface water and ground water that an isotopic analysis can delineate between these two components of flow. Therefore isotopic shifts along the creek can determine gaining reaches. In addition, by knowing …