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Full-Text Articles in Life Sciences

Modeling Interactions Of Browsing Predation, Infaunal Activity And Recruitment In Marine Soft-Sediment Habitats, Sara M. Lindsay, David S. Wethey, Sarah A. Woodin Oct 1996

Modeling Interactions Of Browsing Predation, Infaunal Activity And Recruitment In Marine Soft-Sediment Habitats, Sara M. Lindsay, David S. Wethey, Sarah A. Woodin

Faculty Publications

In marine soft-sediment habitats, the sediment surface is altered by activities of sediment dwellers (infauna). Such biogenic disturbance can influence recruitment success if settling larvae and juveniles avoid disturbed sites or if juveniles die as a result of disturbance after settling. Because infauna commonly lose exposed body parts to browsing predators and disturb less sediment as a result, we developed a simulation model to examine the interactions between browsing predation, infaunal adult activity, and recruitment. Sediment disturbance in the model was based on data for the polychaete Abarenicola pacifica. We simulated the activity of two general types of predators: prey …


Pelage Coloration In Oldfield Mice (Peromyscus Polionotus): Antipredator Adaptation?, Mark C. Belk, Michael H. Smith Aug 1996

Pelage Coloration In Oldfield Mice (Peromyscus Polionotus): Antipredator Adaptation?, Mark C. Belk, Michael H. Smith

Faculty Publications

Reflectance spectra (in full light and moonlight) of dorsal pelage of 469 adult oldfield mice (Peromyscus polionotus) comprising nine regional samples were compared to reflectance spectra of corresponding surface and subsurface soil samples to test for a selective effect of predation on color of pelage. Mice were slightly more reddish in hue, generally had more chroma, and were less reflective than soil at all locations. Color of pelage within locations was not significantly correlated with color of soil. Among all locations, brightness of pelage and soil were significantly positively correlated. Among mainland locations, there was a significant positive …


Morphometry Of Juvenile And Subadult Loligo Pealei And L. Plei From The Northern Gulf Of Mexico, Guillermo Sánchez, Harriet M. Perry, Christine B. Trigg, Michael Vecchione, Clyde Roper, Patricia M. Biesot Jul 1996

Morphometry Of Juvenile And Subadult Loligo Pealei And L. Plei From The Northern Gulf Of Mexico, Guillermo Sánchez, Harriet M. Perry, Christine B. Trigg, Michael Vecchione, Clyde Roper, Patricia M. Biesot

Faculty Publications

Two species of Loligo are abundant in northern Gulf waters: the long-finned squid, Loligo pealei. and the arrow squid, Loligo plei. Variability within species and similarities between the species often hamper accurate identification. The two species more closely resemble each other in areas of sympatry. and there is overlap in almost all of the diagnostic characters. Small specimens of Loligo are not easily identified. and there are few studies detailing their morphometry. Because of the taxonomic uncertainties associated with the identification of juveniles and subadults of L. pealei and L. plei, the species were differentiated by isoelectric …


Abundant Protein-Containing Particles In The Sea, Richard A. Long, Farooq Azam Jun 1996

Abundant Protein-Containing Particles In The Sea, Richard A. Long, Farooq Azam

Faculty Publications

The interaction of bacteria with particulate organic matter has implications for organic matter cycling and bacterial ecology in the ocean. Until recently, the focus has been on 'classical' particles visible by unaided eye (marine snow) or light microscopy. Recent discoveries of several new types of abundant particles, from sub-micrometer to sub-marine snow, are changing our ideas of the physical and chemical nature of the particle field with which pelagic bacteria interact. Previous workers have discovered polysaccharide-containing (Alcian Blue stainable) transparent exopolymer particles (TEP) ranging from 3 to 100s of micrometers. Looking for additional components of the sub-marine snow particle field, …


Settlement And Early Post-Settlement Survival Of Sessile Marine Invertebrates On Topographically Complex Surfaces: The Importance Of Refuge Dimensions And Adult Morphology, Linda J. Walters, David S. Wethey Jun 1996

Settlement And Early Post-Settlement Survival Of Sessile Marine Invertebrates On Topographically Complex Surfaces: The Importance Of Refuge Dimensions And Adult Morphology, Linda J. Walters, David S. Wethey

Faculty Publications

We predicted that both refuge dimension and growth form would influence settlement and short-term post-settlement success (≤7 d) of sessile marine invertebrates that live attached to hard substrata in low energy environments. Individuals with unlimited attachment to the substrata should rapidly be protected by their growth form, thus decreasing their need to settle in refuges and limiting the length of time any locations on heterogeneous substrata act as refuges. Alternatively, organisms with limited attachment to the substrata should remain susceptible to the causes of mortality for a longer time, and as a result should settle in high quality refuges (sites …


Effects Of High-Molecular-Weight Dissolved Organic Matter On Nitrogen Dynamics In The Mississippi River Plume, Wayne S. Gardner, Ronald Benner, Rainer M.W. Amon, James B. Cotner Jr., Joann F. Cavaletto, Jeffrey R. Johnson Mar 1996

Effects Of High-Molecular-Weight Dissolved Organic Matter On Nitrogen Dynamics In The Mississippi River Plume, Wayne S. Gardner, Ronald Benner, Rainer M.W. Amon, James B. Cotner Jr., Joann F. Cavaletto, Jeffrey R. Johnson

Faculty Publications

The dynamics of N and its interactions with labile dissolved organic C (DOC), bacteria, and phytoplankton were studied to determine potential effects of dissolved organic matter (DOM) and light on N dynamics in surface waters of the Mississippi River (USA) plume in the Gulf of Mexico. Bacterial uptake of added labeled N compounds ( 15NH4+ or 15N-labeled dissolved free amino acids. DFAA) was stimulated more by high-molecular-weight (HMW, >l kDa) DOM than by low-molecular-weight (LMW, < l kDa) DOM. An index that inversely indicated the presence of labile DOC was defined as the fraction of assimilated Amino acid-15N that was Recovered as 15N -Ammonium (ANRA), following the additions of high-levels (4 µM) of 15N -DFAA. …


Partnerships As A Potential Means Of Increasing The Production Of Hardwood Timber On Nipf Lands In North Mississippi, John J. Curry, Steven H. Bullard, G. Wayne Kelly Jan 1996

Partnerships As A Potential Means Of Increasing The Production Of Hardwood Timber On Nipf Lands In North Mississippi, John J. Curry, Steven H. Bullard, G. Wayne Kelly

Faculty Publications

North Mississippi has significant hardwood timber resources. Hardwood timber in the region has traditionally been an important source of raw material for furniture and other wood-based industries. In recent years, however, demand has greatly increased for hardwood timber for use in the pulp and paper industry, resulting in increased harvest levels of pole-sized and small sawtimber-sized hardwoods in the region. Increased harvests of hardwood timber have given rise to concerns about the longerterm availability of hardwoods that are large enough in size to be efficiently converted into lumber and other solid wood products. Futures options, futures contracts, leases, and limited …


Atta Texana, Texas Leaf-Cutting Ant, On Typic Quartzipsamments: Ecological Considerations, David L. Kulhavy, W. G. Ross, R. R. Cahal Iii Jan 1996

Atta Texana, Texas Leaf-Cutting Ant, On Typic Quartzipsamments: Ecological Considerations, David L. Kulhavy, W. G. Ross, R. R. Cahal Iii

Faculty Publications

Pine plantations on Typic Quartzipsamments in East Texas are difficult to establish. Forest management options following clearcutting are limited. An 8-year regeneration study of the growth and survival of loblolly, Pinus taeda, L. shortleaf, P. echinata Mill., slash, P. elliotii Engelm and longleaf pines P. palustris Mill. was conducted to determine optimum tree species and treatments for reforestation, and to recommend practical alternative land uses and management strategies for Typic Quartzipsamments. Successful regeneration provides new opportunities for insects and pathogens. Impacts of the Nantucket pine tip moth, R}iyacionia frustrana (Comstock), the Deodar weevil, Pissodes nemorensis, Germar, Annosus root rot, Heterobasidion …


Predicting Survival Of East Texas Loblolly And Slash Pine Plantations Infected With Fusiform Rust, J. David Lenhart, A. Beth Vaughn, Adams D.E. Jan 1996

Predicting Survival Of East Texas Loblolly And Slash Pine Plantations Infected With Fusiform Rust, J. David Lenhart, A. Beth Vaughn, Adams D.E.

Faculty Publications

Repeated measurement during 1982-1992 of East Texas Pine Plantation Research Project permanent plots in loblolly( Pinus taedaL .) and slash( Pinus elliottii Engelm.) pine plantations throughout East Texas were used to develop equations for predicting the future number of trees per acre. A typical condition of East Texas pine plantations is the incidence of fusiform rust( Cronatrium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme). A regression procedure for fitting nonlinear systems of equations was used to fit survival models that considered the possibility that trees with no rust galls on the stem could either (1) remain uninfected and alive, …


Total And Partial Stand-Level Yield Prediction For Loblolly And Slash Pine Plantations In East Texas, J. David Lenhart Jan 1996

Total And Partial Stand-Level Yield Prediction For Loblolly And Slash Pine Plantations In East Texas, J. David Lenhart

Faculty Publications

Observations from East Texas Pine Plantation Research Project permanent plots in loblolly (Pinus taeda L.) and slash (Pinus elliottii Engelm.) pine plantations throughout East Texas were utilized to develop methods to estimate stand-level yield values. Predicted yields are volume in cubic feet and green weight in pounds. Predictor variables for total yield are plantation age, site index (base age 25 yr) and surviving trees per acre. Partial yield is derived using total yield and plantation quadratic mean diameter in conjunction with specified threshold dbh and upper stem dob values. Expected total yield per acre is converted to partial yield per …


Red-Cockaded Woodpecker Nesting Success, Forest Structure, And Southern Flying Squirrels In Texas, Richard N. Conner, D. Craig Rudolph, Daniel Saenz, Richard R. Schaefer Jan 1996

Red-Cockaded Woodpecker Nesting Success, Forest Structure, And Southern Flying Squirrels In Texas, Richard N. Conner, D. Craig Rudolph, Daniel Saenz, Richard R. Schaefer

Faculty Publications

For several decades general opinion has suggested that southern flying squirrels (Gluucomys volans) have a negative effect on Red-cockaded Woodpeckers (Picoides borealis) through competition for cavities and egg/nestling predation. Complete removal of hardwood trees from Red-cockaded Woodpecker cavity tree clusters has occurred on some forests because southern flying squirrel abundance was presumed to be associated with the presence and abundance of hardwood vegetation. In some locations, southern flying squirrels have been captured and either moved or killed in the name of Red-cockaded Woodpecker management. We determined southern flying squirrel occupancy of Red-cockaded Woodpecker cavities in loblolly (Pinus taeda)-shortleaf (P. echinata) …


Red-Cockaded Woodpeckers And Silvicultural Practice: Is Uneven-Aged? Silviculture Preferable To Even-Aged, D. Craig Rudolph, Richard N. Conner Jan 1996

Red-Cockaded Woodpeckers And Silvicultural Practice: Is Uneven-Aged? Silviculture Preferable To Even-Aged, D. Craig Rudolph, Richard N. Conner

Faculty Publications

The endangered red-cockaded woodpecker (Picoides borealis) has become a high-profile management issue in the southeastern United States. Suitable habitat consists of mature to old pine, or mixed pine-hardwood forest, with minimal hardwood midstory vegetation. Loss of habitat, detrimental silvicultural practices, and changes in the fire regime have resulted in small fragmented populations, most of which have been declining precipitously in recent decades (Costa and Escano 1989, Conner and Rudolph 1989). The current population of l0-12 thousand birds occurs across much of the original range from Virginia and Florida west to Oklahoma and Texas (James 1995). However, populations are restricted to …


Deer Use Of Riparian Zones And Adjacent Pine Plantations In Texas, Micah L. Poteet, Ronald E. Thill, R. Montague Whiting Jr., R. Lee Rayburn Jan 1996

Deer Use Of Riparian Zones And Adjacent Pine Plantations In Texas, Micah L. Poteet, Ronald E. Thill, R. Montague Whiting Jr., R. Lee Rayburn

Faculty Publications

The authors monitored white-tailed deer (Odocoileus virginianus) use of riparian zones (RZ’s) and adjacent pine plantations of 3 age classes (young, 1 to 3 years old; intermediate, 5 to 7 years old; and older, 9 to 13 years old) using radio telemetry for 2 years on a 1,300 ha study area near Alto, TX. Riparian zones comprised 22.0 percent of the area; young, intermediate, and older pine plantations comprised 19.1 percent, 45.7 percent, and 13.2 percent, respectively. Based on data from 4 to 9 deer the first year and 12 to 17 deer the second year, home ranges averaged 103, …


The Land Expectation Value Calculated In Timberland Valuation, T. J. Straka, Steven H. Bullard Jan 1996

The Land Expectation Value Calculated In Timberland Valuation, T. J. Straka, Steven H. Bullard

Faculty Publications

Appraisers often use discounted cash flow (DCF) techniques to value timber and timberland. Land expectation value (LEV) is a standard DCF technique applied to many timberland situations. LEV calculates the value of bare land in perpetual timber production and is often used to value evenaged pine plantations. However, it is also useful in the valuation of immature timber stands and uneven-aged timber stands cut periodically. These models have wide applicability in timberland appraisal situations.


Infection And Fungal Development Of Tubakia Dryina On Sweet Gum (Liquidambar Styraciflua), Josephine Taylor, Shane Clark Jan 1996

Infection And Fungal Development Of Tubakia Dryina On Sweet Gum (Liquidambar Styraciflua), Josephine Taylor, Shane Clark

Faculty Publications

Infection and fungal development of Tubakia dryina were investigated on leaves of sweet gum using a combination of microscopic techniques. Conidia of T. dryina adhered to the leaf surface and formed septate germ tubes. Germ tubes terminated in small appressoria that formed directly over epidermal cells. Intra- and intercellular hyphae ramified extensively throughout the leaf tissue. Host cells associated with the infection site became necrotic and collapsed, resulting in macroscopic disease symptoms.


Adaptations Facilitating Facultative Oophagy In The Gray Rat Snake, Elaphe Obsoleta Spiloides [Abstract], Stephen J. Mullin Jan 1996

Adaptations Facilitating Facultative Oophagy In The Gray Rat Snake, Elaphe Obsoleta Spiloides [Abstract], Stephen J. Mullin

Faculty Publications

No abstract provided.


Dietary Overview Of Hemidactylus Turcicus With Possible Implications Of Food Partitioning, Daniel Saenz Jan 1996

Dietary Overview Of Hemidactylus Turcicus With Possible Implications Of Food Partitioning, Daniel Saenz

Faculty Publications

A stomach content analysis was conducted on Hemidactylus turcicus, the Mediterranean gecko, from 19 April 1990 to 15 October 1990, on the campus of Stephen F. Austin State University, Nacogdoches, Texas. Geckos (N = 167) were placed into four size groups based on snout-vent-length (5 29 mm, 30-39 mm, 40-49 mm, and z 50 mm) and three microhabitat groups based on perch height (those occupying perch sites < 1.52 m, 2 1.52 m to 5 3.05 m, and > 3.05 m). Stomach contents were analyzed and sex, size, and microhabitat groups were compared using Schoener's percent overlap index. Volumetrically, the most important prey items taken were Orthoptera, Lepidoptera, and Isopoda. Geckos of …


Rosalind Elsie Franklin (1920-1958) Biologist, Margaret Sylvia Jan 1996

Rosalind Elsie Franklin (1920-1958) Biologist, Margaret Sylvia

Faculty Publications

A biography of the biologist Rosalind Elsie Franklin whose work on x-ray crystallography contributed to Watson and Crick's elucidation of the structure of DNA.


The Arabidopsis Homeotic Genes Apetala3 And Pistillata Are Sufficient To Provide The B Class Organ Identity Function, Beth A. Krizek, Elliot M. Meyerowitz Jan 1996

The Arabidopsis Homeotic Genes Apetala3 And Pistillata Are Sufficient To Provide The B Class Organ Identity Function, Beth A. Krizek, Elliot M. Meyerowitz

Faculty Publications

The class B organ identity genes, APETALA3 and PISTILLATA, are required to specify petal and stamen identity in the Arabidopsis flower. We show here that the activities of these two genes are sufficient to specify petals and stamens in flowers, in combination with the class A and C genes, respectively. Flowers of plants constitutively expressing both PISTILLATA and APETALA3 under the control of the 35S promoter from cauliflower mosaic virus consist of two outer whorls of petals and inner whorls of stamens. These plants also exhibit vegetative phenotypes that are not present in either of the singly (APETALA3 …


Rosalyn Sussman Yalow (1921-) Endocrinologist, Medical Physicist, Margaret Sylvia Jan 1996

Rosalyn Sussman Yalow (1921-) Endocrinologist, Medical Physicist, Margaret Sylvia

Faculty Publications

A biography of Rosalyn Yalow, Nobel Prize winner in Physiology/Medicine for the development of radioimmunoassay of peptides hormones. She was the second woman to win a Nobel Prize in Medicine and first American woman to do so.


Intraspecific Life History Variation In Sceloporus Undulatus: A Factor Analysis, Geoffrey R. Smith, John W. Rowe, R. E. Ballinger Jan 1996

Intraspecific Life History Variation In Sceloporus Undulatus: A Factor Analysis, Geoffrey R. Smith, John W. Rowe, R. E. Ballinger

Faculty Publications

No abstract provided.


A New High Pressure Sapphire Nuclear Magnetic Resonance Cell, Shi Bai, Craig M. Taylor, Charles L. Mayne, Ronald J. Pugmire, David M. Grant Jan 1996

A New High Pressure Sapphire Nuclear Magnetic Resonance Cell, Shi Bai, Craig M. Taylor, Charles L. Mayne, Ronald J. Pugmire, David M. Grant

Faculty Publications

A new version of a single-crystal sapphire high pressure nuclear magnetic resonance (NMR) cell is described that is capable of controlling the sample pressure independent of the temperature. A movable piston inside the cell adjusts and controls the sample pressure from ambient conditions to 200 atm within plus or minus 0.3 atm. The linewidth at half-height for a 13C spectrum of carbon dioxide at 15degrees C and 57.8 atm is found to be 0.5 Hz. The carbon dioxide gas/liquid phase transition is clearly observed by measuring 13C chemical shifts as the sample pressure approaches equilibrium. The time required for this …