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Articles 631 - 660 of 745

Full-Text Articles in Biology

Long-Term Observations Of A Harbor Seal Haul-Out Site In A Protected Cove In Casco Bay, Gulf Of Maine, David Harris Phd, Barbarai Lelli, Sat Gupta Jan 2003

Long-Term Observations Of A Harbor Seal Haul-Out Site In A Protected Cove In Casco Bay, Gulf Of Maine, David Harris Phd, Barbarai Lelli, Sat Gupta

Faculty Publications

We counted the numbers of seals hauled out at low tide on two near-shore ledges in a protected cove in Casco Bay, Gulf of Maine a minimum of 12 times per month, for four years starting in August 1997. The highest mean monthly counts were in August (molting season) and the lowest in either January or February. Counts during pupping season (May and June) were lower than during April or July. As no mother-pup pairs were observed, these ledges are molting but not pupping ledges. Time-series analysis revealed no overall trend in the number of seals present. but did show …

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Effects Of Weather On Autumn Hawk Movements At Fort Morgan, Alabama, Stefan Woltmann, David Cimprich Jan 2003

Effects Of Weather On Autumn Hawk Movements At Fort Morgan, Alabama, Stefan Woltmann, David Cimprich

Faculty Publications

Migrating hawks were observed at Fort Morgan, Alabama during autumn 1995-1998. The three most abundant migrants were Sharp-shinned Hawk (Accipiter striatus), Broad-winged Hawk (Buteo platypterus) and American Kestrel (Falco sparverius). The three species accounted for 84% of all observations. Most individuals (> 80%) were seen heading west. Compared with days with east and south winds, days with north winds were associated with significantly higher passage rates for all species, and passage rates of Broadwinged Hawks were significantly higher on days when both a cold front and north winds occurred than on days with north winds only. …

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Sibling Recurrence Risk Ratio Analysis Of The Metabolic Syndrome And Its Components Over Time., Wei J. Chen, Pi Hua Liu, Yen Yi Ho, Kuo Liong Chien, Min Tzu Lo, Wei Liang Shih, Yu Chun Yen, Wen Chung Lee Jan 2003

Sibling Recurrence Risk Ratio Analysis Of The Metabolic Syndrome And Its Components Over Time., Wei J. Chen, Pi Hua Liu, Yen Yi Ho, Kuo Liong Chien, Min Tzu Lo, Wei Liang Shih, Yu Chun Yen, Wen Chung Lee

Faculty Publications

The purpose of this study was to estimate both cross-sectional sibling recurrence risk ratio (lambdas) and lifetime lambdas for the metabolic syndrome and its individual components over time among sibships in the prospectively followed-up cohorts provided by the Genetic Analysis Workshop 13. Five measures included in the operational criteria of the metabolic syndrome by the Adult Treatment Panel III were examined. A method for estimating sibling recurrence risk with correction for complete ascertainment was used to estimate the numerator, and the prevalence in the whole cohort was used as the denominator of lambdas. Considerable variability in the lambdas was found …

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Rotational Lift: Something Different Or More Of The Same?, Jeffrey A. Walker Phd Dec 2002

Rotational Lift: Something Different Or More Of The Same?, Jeffrey A. Walker Phd

Faculty Publications

This paper addresses the question, do the rotational forces in the hovering fruit fly Drosophila melanogaster reflect something different (the Magnus effect) or more of the same (circulatory-and-attached-vortex force)? The results of an unsteady blade-element model using empirically derived force coefficients from translating (root-oscillating) wings are compared with recent results derived from both the measured forces on a dynamically scaled Drosophila wing and the computational fluid dynamic (CFD)-modeled forces on a virtual Drosophila wing. The behavior of the forces in all three models during wing rotation supports the hypothesis that rotational lift is not a novel aerodynamic mechanism but is …

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Bergmann's Rule In Ectotherms: A Test Using Freshwater Fishes, Mark C. Belk, Derek D. Houston Dec 2002

Bergmann's Rule In Ectotherms: A Test Using Freshwater Fishes, Mark C. Belk, Derek D. Houston

Faculty Publications

Understanding patterns of variation in body size within and among species is a central question in evolutionary ecology (Schlichting and Pigliucci 1998). The most well known pattern of variation in body size is Bergmann's rule (Bergmann 1847; Mayr 1956). The intraspecific version of Bergmann's rule holds that within endothermic species, body size increases with increasing latitude (or decreasing temperature; Blackburn et al. 1999; Ashton et al. 2000). In general, mammals conform to this rule (Ashton et al. 2000).

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Nonadditive Genetic Effects In Animal Behavior, Lisa M. Meffert, Sara K. Hicks, Jennifer L. Regan Dec 2002

Nonadditive Genetic Effects In Animal Behavior, Lisa M. Meffert, Sara K. Hicks, Jennifer L. Regan

Faculty Publications

Heritabilities, commonly used to predict evolutionary potential, are notoriously low for behaviors. Apart from strong contributions of environmental variance in reducing heritabilities, the additive genetic components can be very low, especially when they are camouflaged by nonadditive genetic effects. We first report the heritabilities of courtship traits in founder‐flush and control populations of the housefly (Musca domestica L.). We estimated the heritability of each male and female display through the regression of the courtships involving daughters and sons (with randomly selected mates) onto the “midparental” courtship values of their parents. Overall, the average heritability was significantly higher for the …

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Fluid Dynamics Of Flapping Aquatic Flight In The Bird Wrasse: Three-Dimensional Unsteady Computations With Fin Deformation, Ravi Ramamurti, William C. Sandberg, Rainald Lӧhner, Jeffrey A. Walker Phd, Mark W. Westneat Oct 2002

Fluid Dynamics Of Flapping Aquatic Flight In The Bird Wrasse: Three-Dimensional Unsteady Computations With Fin Deformation, Ravi Ramamurti, William C. Sandberg, Rainald Lӧhner, Jeffrey A. Walker Phd, Mark W. Westneat

Faculty Publications

Many fishes that swim with the paired pectoral fins use fin-stroke parameters that produce thrust force from lift in a mechanism of underwater flight. These locomotor mechanisms are of interest to behavioral biologists, biomechanics researchers and engineers. In the. present study, we performed the first three-dimensional unsteady computations of fish swimming with oscillating and deforming fins. The objective of these computations was to investigate the fluid dynamics of force production associated with the flapping aquatic flight of the bird wrasse Gomphosus varius. For this computational work, we used the geometry of the wrasse and its pectoral fin, and previously measured …

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Simple, Compact Source For Low-Temperature Air Plasmas, D. P. Sheehan, J. Lawson, M. Sosa, Richard A. Long Jul 2002

Simple, Compact Source For Low-Temperature Air Plasmas, D. P. Sheehan, J. Lawson, M. Sosa, Richard A. Long

Faculty Publications

A simple, compact source of low-temperature, spatially and temporally uniform air plasma using a Telsa induction coil driver is described. The low-power ionization discharge plasma is localized (2 cm X 0.5 cm X 0.1 cm) and essentially free of arc channels. A Teflon coated rolling cylindrical electrode and dielectric coated ground plate are essential to the source’s operation and allow flat test samples to be readily exposed to the plasma. The plasma is a copious source of ozone and nitrogen oxides. Its effects on various microbes are discussed.

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Seasonal Niche Strategy Of The Bloom-Forming Dinoflagellate Heterocapsa Triquetra, R. W. Litaker, P. A. Tester, C. S. Duke, B. E. Kenney, James L. Pinckney, J. Ramus May 2002

Seasonal Niche Strategy Of The Bloom-Forming Dinoflagellate Heterocapsa Triquetra, R. W. Litaker, P. A. Tester, C. S. Duke, B. E. Kenney, James L. Pinckney, J. Ramus

Faculty Publications

Heterocapsa triquetra is one of the most common bloom-forming dinoflagellates found in estuaries and near shore regions around the world. This work examined the environmental factors associated with 3 separate wintertime H. triquetra blooms in the shallow tidally mixed Newport River estuary, North Carolina, USA. During 2 of the blooms in 1982 and 1983, the estuary was sampled from a fixed, single location every hour for 14 d. During the third study, the estuary was sampled at 9 fixed locations over its entire length each week from late December 1997 through March 1998. This time period included the formation and …

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Estimating The Spatial Extent Of Bottom-Water Hypoxia And Habitat Degradation In A Shallow Estuary, Christopher P. Buzzelli, Richard A. Luettich Jr., Sean P. Powers, Charles H. Peterson, Jesse E. Mcninch, James L. Pinckney, Hans W. Paerl Apr 2002

Estimating The Spatial Extent Of Bottom-Water Hypoxia And Habitat Degradation In A Shallow Estuary, Christopher P. Buzzelli, Richard A. Luettich Jr., Sean P. Powers, Charles H. Peterson, Jesse E. Mcninch, James L. Pinckney, Hans W. Paerl

Faculty Publications

Bottom-water hypoxia (≤ 2 mg 1-1 dissolved oxygen [DO]) greatly modifies the benthic habitat of estuaries, depending upon spatial extent, duration, and frequency. Bottom-water hypoxia often develops under conditions of density stratification, which inhibits vertical mixing, and warm temperatures, which enhance biological oxygen demand. Long-term, mid-channel data from the Neuse River Estuary in North Carolina permitted evaluation of how stratification and temperature combined to affect DO concentrations at the bottom. Salinity stratification (DS) and water temperature (T) explained respectively 30 and 23% of the variance in bottom-water DO concentrations. The amount of salinity stratification required to induce bottom-water …

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Thin Laser Light Sheet Microscope For Microbial Oceanography, Eran Fuchs, Jules S. Jaffe, Richard A. Long, Farooq Azam Jan 2002

Thin Laser Light Sheet Microscope For Microbial Oceanography, Eran Fuchs, Jules S. Jaffe, Richard A. Long, Farooq Azam

Faculty Publications

Despite a growing need, oceanographers are limited by existing technological constrains and are unable to observe aquatic microbes in their natural setting. In order to provide a simple and easy to implement solution for such studies, a new Thin Light Sheet Microscope (TLSM) has been developed. The TLSM utilizes a well-defined sheet of laser light, which has a narrow (23 micron) axial dimension over a 1 mm x 1 mm field of view. This light sheet is positioned precisely within the depth of field of the microscope’s objective lens. The technique thus utilizes conventional microscope optics but replaces the illumination …

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Are Pileated Woodpeckers Attracted To Red-Cockaded Woodpecker Cavity Trees?, Richard N. Conner, Daniel Saenz, James R. Mccormick Jan 2002

Are Pileated Woodpeckers Attracted To Red-Cockaded Woodpecker Cavity Trees?, Richard N. Conner, Daniel Saenz, James R. Mccormick

Faculty Publications

Pileated Woodpeckers (Dryocopus pileatus) cause damage to Red-cockaded Woodpecker (Picoides borealis) cavity trees in the form of cavity enlargement or other excavations on the surface of the pine tree. However, it is not known whether Pileated Woodpeckers excavate more frequently on Red-cockaded Woodpecker cavity trees than on noncavity trees or how stand structure is related to the frequency of Pileated Woodpecker excavation. Also, it is unclear whether the cavity itself provides the stimulus to Pileated Woodpeckers to excavate or whether the presence of Red-cockaded Woodpeckers and their activities are attracting them. We surveyed all of the …

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Prey Handling And Diet Of Louisiana Pine Snakes (Pituophis Ruthveni) And Black Pine Snakes (P. Melanoleucus Lodingi), With Comparisons To Other Selected Colubrid Snakes, D. Craig Rudolph, Shirley J. Burgdorf, Richard N. Conner, Christopher S. Collins, Daniel Saenz, Richard R. Schaefer, Toni Trees, C. Michael Duran, Marc Ealy, John G. Himes Jan 2002

Prey Handling And Diet Of Louisiana Pine Snakes (Pituophis Ruthveni) And Black Pine Snakes (P. Melanoleucus Lodingi), With Comparisons To Other Selected Colubrid Snakes, D. Craig Rudolph, Shirley J. Burgdorf, Richard N. Conner, Christopher S. Collins, Daniel Saenz, Richard R. Schaefer, Toni Trees, C. Michael Duran, Marc Ealy, John G. Himes

Faculty Publications

Diet and prey handling behavior were determined for Louisiana pine snakes (Pituophis ruthveni) and black pine snakes (P. melanoleucus lodingi). Louisiana pine snakes prey heavily on Baird's pocket gophers (Geomys breviceps), with which they are sympatric, and exhibit specialized behaviors that facilitate handling this prey species within the confines of burrow systems. Black pine snakes, which are not sympatric with pocket gophers, did not exhibit these specialized behaviors. For comparative purposes, prey handling of P. sayi sayi and Elaphe obsoleta lindheimeri was also examined.

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An Automated Technique For Monitoring Nocturnal Avian Vocalizations., Brent Burt, James B. Johnson, Daniel Saenz, Richard N. Conner Jan 2002

An Automated Technique For Monitoring Nocturnal Avian Vocalizations., Brent Burt, James B. Johnson, Daniel Saenz, Richard N. Conner

Faculty Publications

Using audio recording dataloggers, we collected nocturnal bird vocalizations at different sites within the Davy Crockett National Forest and the Stephen F. Austin Experimental Forest. We detected vocalizations of a variety of nocturnal and diurnal species. This technology is useful for its application to avifauna.

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Performance Limits Of Labriform Propulsion And Correlates With Fin Shape And Motion, Jeffrey A. Walker Phd, Mark W. Westneat Jan 2002

Performance Limits Of Labriform Propulsion And Correlates With Fin Shape And Motion, Jeffrey A. Walker Phd, Mark W. Westneat

Faculty Publications

Labriform locomotion, which is powered by oscillating the paired pectoral fins, varies along a continuum from rowing the fins back and forth to flapping the fins up and down. It has generally been assumed (i) that flapping is more mechanically efficient than rowing, a hypothesis confirmed by a recent simulation experiment, and (ii) that flapping should be associated with wing-shaped fins while rowing should be associated with paddle-shaped fins, To determine whether these hypotheses and the results of the simulation experiment are consistent with natural variation, we compared the steady swimming performance (critical swimming speed) of four species of labrid …

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Microscale Patchiness Of Bacterioplankton Assemblage Richness In Seawater, Richard A. Long, Farooq Azam Dec 2001

Microscale Patchiness Of Bacterioplankton Assemblage Richness In Seawater, Richard A. Long, Farooq Azam

Faculty Publications

We sought to test the hypothesis that bacterial species richness and composition vary at the millimeter scale in the marine pelagic environment, in response to the heterogeneous distribution of organic matter. To test this hypothesis, it was necessary to design and test a protocol to sample, lyse and analyze (by polymerase chain reaction/denaturing gradient gel electrophoresis [PCR-DGGE]) bacterioplankton species richness in a single microliter of seawater. Significant variation in bacterial species richness was found amongst 1 μl samples. Greater species richness was seen when seawater was enriched with diatom detritus. Examination of species richness at 2 mm intervals over a …

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Host-Switching Does Not Circumvent The Ni-Based Defence Of The Ni Hyperaccumulator Streptanthus Polygaloides (Brassicaceae), Micheal A. Davis, Robert S. Boyd, James H. Cane Nov 2001

Host-Switching Does Not Circumvent The Ni-Based Defence Of The Ni Hyperaccumulator Streptanthus Polygaloides (Brassicaceae), Micheal A. Davis, Robert S. Boyd, James H. Cane

Faculty Publications

Elevated tissue concentrations of metals have been shown to defend metal-hyperaccumulating plants against both herbivores and pathogens. Tolerance of metal-based defences presents a challenge to herbivores, because heavy metals cannot be degraded or metabolized. One strategy that herbivores can employ to counter high-metal defences is dietary dilution, or host switching. Highly mobile herbivores are most likely to use this strategy, but less mobile lepidopteran larvae can also Improve their performance on toxic hosts if early instar development occurs on more favourable hosts. We examined the effects of host switching on growth and survival of a generalist folivore. Specifically, we tested …

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Molecular Diversity, Structure And Domestication Of Grasses, Edward S. Buckler Iv, Jeffry M. Thornsberry, Stephen Kresovich Jun 2001

Molecular Diversity, Structure And Domestication Of Grasses, Edward S. Buckler Iv, Jeffry M. Thornsberry, Stephen Kresovich

Faculty Publications

Over the last 10,000 years, crop domestication has been the single most important human cultural development. Grasses are prominent among these crops, and provide the vast majority of the world's food. Similar traits have been selected during the domestication and breeding of these critically important grasses, and since they share a similar complement of genes, the same set of genes may have been selected. Even though the process of domestication occurred over the same 5000 to 10,000 year period, the domesticated grasses have major differences in genome structure, diversity, and life history. Molecular investigations of grass domestication have succeeded in …

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Comparative Phylogeography Of Mesoamerican Highland Rodents: Concerted Versus Independent Response To Past Climatic Fluctuations, Duke S. Rogers, Jack Sullivan, Elizabeth Arellano Jun 2001

Comparative Phylogeography Of Mesoamerican Highland Rodents: Concerted Versus Independent Response To Past Climatic Fluctuations, Duke S. Rogers, Jack Sullivan, Elizabeth Arellano

Faculty Publications

The phylogeography of Sumichrast's harvest mouse (Reithrodontomys sumichrasti) was examined through maximumlikelihood and parsimony analyses of 1,130 bp of mitochondrial Cytochrome b sequence data from 43 individuals. The phylogeography of this Middle American highland forest-dwelling species was compared to that previously published for the codistributed Aztec deer mouse complex (Peromyscus aztecus/Peromyscus hylocetes complex) in order to test competing hypotheses of concerted versus independent responses of codistributed forms to past climatic fluctuations. Qualitatively, there were strong similarities in the phylogeographic patterns of the two groups, yet there were also areas of incongruence. Likelihood-ratio tests (Kishino-Hasegawa-Templeton and parametric bootstrap tests) indicated that …

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Restoration Of Fish Habitat In The Provo River: A Multispecies Approach, Mark C. Belk Jun 2001

Restoration Of Fish Habitat In The Provo River: A Multispecies Approach, Mark C. Belk

Faculty Publications

Historically, the Provo river, located in Utah and Wasatch Cos., Utah, was a clear-flowing stream with headwaters in the western edge of the Uinta mountains that emptied into Utah Lake near Provo, Utah. The river had a wide flood plain and a braided channel, especially in the Heber valley and Utah valley areas. Diversion of water and construction of water storage facilities began in the late 1800's and intensified in the 1900's. Deer Creek reservoir was built in the 1950's and diking and channelization continued until the construction of Jordanelle reservoir in the late 1980's. The Provo River Restoration Project, …

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Variations In Bacterial Community Structure During A Dinoflagellate Bloom Analyzed By Dgge And 16s Rdna Sequencing, Laura B. Fandino, Lasse Riemann, Grieg F. Steward, Richard A. Long, Farooq Azam Jan 2001

Variations In Bacterial Community Structure During A Dinoflagellate Bloom Analyzed By Dgge And 16s Rdna Sequencing, Laura B. Fandino, Lasse Riemann, Grieg F. Steward, Richard A. Long, Farooq Azam

Faculty Publications

The relationship between bacterial 16S rRNA gene composition and carbon metabolism was analyzed during an intense dinoflagellate bloom off the Southern California coast during the spring of 1997. Bacterial numbers and rate processes, chlorophyll a, and the dissolved and particulate organic matter pools were measured during the bloom to provide a framework within which to assess bacterial community composition. Free bacteria were numerically dominant, generally comprising >90% of the total, and were responsible for >70% of bacterial production. Attached bacteria had higher cell-specific growth rates than free bacteria (range = 0.5 to 15.1 and 0.7 to 2.5 d-1 …

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Pycnothyrium Ultrastructure In Tubakia Dryina [Abstract], Josephine Taylor Jan 2001

Pycnothyrium Ultrastructure In Tubakia Dryina [Abstract], Josephine Taylor

Faculty Publications

No abstract provided.

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A Red-Cockaded Woodpecker Group With Two Simultaneous Nest Trees, Richard N. Conner, James R. Mccormick, Richard R. Schaefer, Daniel Saenz, D. Craig Rudolph Jan 2001

A Red-Cockaded Woodpecker Group With Two Simultaneous Nest Trees, Richard N. Conner, James R. Mccormick, Richard R. Schaefer, Daniel Saenz, D. Craig Rudolph

Faculty Publications

During a study of Red-cockaded Woodpecker (Picoides borealis) nesting in eastern Texas, we discovered a single breeding pair of woodpeckers with two simultaneous nests in nest trees that were 24 m apart. Incubation of eggs in each nest tree was at least 13 d and may have been as long as 16 d. The breeding male incubated and fed a nestling in one nest tree, and the breeding female incubated and fed a nestling in the other nest tree until the nestlings were >24 d old. Prior to fledging, both the breeding male and female were observed feeding …

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An Unusually Large Number Of Eggs Laid By A Breeding Red-Cockaded Woodpecker Female, Richard N. Conner, Daniel Saenz, James R. Mccormick Jan 2001

An Unusually Large Number Of Eggs Laid By A Breeding Red-Cockaded Woodpecker Female, Richard N. Conner, Daniel Saenz, James R. Mccormick

Faculty Publications

The Red-cockaded Woodpecker (Picoides borealis) is a cooperatively breeding species that typically uses a single cavity for nesting (Ligon 1970, Walters et al. 1988). A single tree, or aggregation of cavity trees, termed the cluster, is inhabited by a group of woodpeckers that includes a single breeding pair and up to several helpers, which are typically male offspring of previous breeding seasons (Ligon 1970, Lennartz et al. 1987). Each group of Red-cockaded Woodpeckers usually produces one nest per breeding season, but will often nest again during the same breeding season if the first nest fails. Double clutching and …

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Delayed Reproduction Of Translocated Red-Cockaded Woodpeckers., Brent Burt, James R. Mccormick, Richard N. Conner, Daniel Saenz Jan 2001

Delayed Reproduction Of Translocated Red-Cockaded Woodpeckers., Brent Burt, James R. Mccormick, Richard N. Conner, Daniel Saenz

Faculty Publications

Twelve pairs of Red-cockaded Woodpeckers were translocated to the Angelina National Forest. Five breeding pairs produced eggs/nestlings within the first breeding season after translocation. Clutch initiation dates for all five pairs were later than those of resident breeders. The observed delay in reporductive timing by translocated woodpeckers may have resulted from a variety of factors.

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Amaranthus Rudis And A. Tuberculatus, One Species Or Two? [Abstract], Donald B. Pratt, Lynn G. Clark Jan 2001

Amaranthus Rudis And A. Tuberculatus, One Species Or Two? [Abstract], Donald B. Pratt, Lynn G. Clark

Faculty Publications

No abstract provided.

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Human Immunodeficiency Virus Type 1 Quasi Species That Rebound After Discontinuation Of Highly Active Antiretroviral Therapy Are Similar To The Viral Quasi Species Present Before Initiation Of Therapy, Keith A. Crandall, Hiromi Imamichi, Ven Natarajan, Min Kang Jiang, Robin L. Dewar, Steve Berg, Arunasri Gaddam, Marjorie Bosche, Julie A. Metcalf, Richard T. Davey Jr., H. Clifford Lane Jan 2001

Human Immunodeficiency Virus Type 1 Quasi Species That Rebound After Discontinuation Of Highly Active Antiretroviral Therapy Are Similar To The Viral Quasi Species Present Before Initiation Of Therapy, Keith A. Crandall, Hiromi Imamichi, Ven Natarajan, Min Kang Jiang, Robin L. Dewar, Steve Berg, Arunasri Gaddam, Marjorie Bosche, Julie A. Metcalf, Richard T. Davey Jr., H. Clifford Lane

Faculty Publications

In an effort to identify the sources of the viruses that emerge after discontinuation of therapy, analyses of human immunodeficiency virus (HIV) quasi species were done for 3 patients with sustained levels of HIV RNA of <50 copies/mL for 1-3 years. The sequences found in the rebounding plasma virus were closely related to those of the actively replicating form of viruses present before the initiation of combination therapy. All quasi species found in the rebounding plasma virus were also present in proviral DNA, cell-associated RNA in peripheral blood mononuclear cells (PBMC), and virion RNA derived from PBMC coculture during periods when plasma HIV RNA levels were <50 copies/mL. These findings suggest that the rapid resurgence of plasma viremia observed after discontinuation of therapy and the viruses cocultured from PBMC are derived from a relatively stable pool of the replicating form of virus rather than from activation of a previously latent pool.

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Sexual Dimorphism And Body Temperatures Of Sceloporus Siniferus From Guerrero, Mexico, J. A. Lemos-Espinal, Geoffrey R. Smith, R. E. Ballinger Jan 2001

Sexual Dimorphism And Body Temperatures Of Sceloporus Siniferus From Guerrero, Mexico, J. A. Lemos-Espinal, Geoffrey R. Smith, R. E. Ballinger

Faculty Publications

No abstract provided.

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Using Upper Boundary Constraints To Quantify Competitive Response Of Desert Annuals, Laura M. Lessin, Andrew R. Dyer, Deborah E. Goldberg Jan 2001

Using Upper Boundary Constraints To Quantify Competitive Response Of Desert Annuals, Laura M. Lessin, Andrew R. Dyer, Deborah E. Goldberg

Faculty Publications

Using a target-neighborhood approach with six annual dicot species in the Negev Desert of Israel, we tested whether neighborhood biomass constrained the upper limit of plant performance and if the slope of the upper boundary was correlated to species trait means, such as relative growth rate (RGR) and seed mass. Target individuals were measured in early spring and then collected at the onset of the dry season along with all naturally occurring neighbors within a 5-cm radius of the target. Using a minimum of 50 samples for each of the six target species, we found no significant relationships between target …

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Influence Of Habitat Use-Patterns On Cooperative Breeding In The Brown-Headed Nuthatch., Brent Burt, Albert Herb Dec 2000

Influence Of Habitat Use-Patterns On Cooperative Breeding In The Brown-Headed Nuthatch., Brent Burt, Albert Herb

Faculty Publications

Documenting the habitat use patterns of the Brown-headed Nuthatch, we describe how its habitat use patterns contribute to ecological constraints that may maintain cooperative breeding in this species.

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