Biology Commons^™

Variation In Stem Mortality Rates Determines Patterns Of Above-Ground Biomass In Amazonian Forests: Implications For Dynamic Global Vegetation Models, Michelle O. Johnson, David R. Galbraith, Manuel Gloor, Hannes De Deurwaerder, Matthieu Guimberteau, Anja Rammig, Kirsten Thonicke, Hans Verbeeck, Celso Von Randow, Bradley O. Christoffersen

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Understanding the processes that determine above-ground biomass (AGB) in Amazonian forests is important for predicting the sensitivity of these ecosystems to environmental change and for designing and evaluating dynamic global vegetation models (DGVMs). AGB is determined by inputs from woody productivity [woody net primary productivity (NPP)] and the rate at which carbon is lost through tree mortality. Here, we test whether two direct metrics of tree mortality (the absolute rate of woody biomass loss and the rate of stem mortality) and/or woody NPP, control variation in AGB among 167 plots in intact forest across Amazonia. We then compare these relationships …

Plasticity In Leaf-Level Water Relations Of Tropical Rainforest Trees In Response To Experimental Drought, Oliver J. Binks, Patrick Meir, Lucy Rowland, Antonio Carlos Lola Da Costa, Steel Silva Vasconcelos, Alex Antonio Ribeiro De Oliveira, Leandro Ferreira, Bradley O. Christoffersen, Andrea Nardini, Maurizio Mencuccini

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Summary

• The tropics are predicted to become warmer and drier, and understanding the sensitivity of tree species to drought is important for characterizing the risk to forests of climate change. This study makes use of a long-term drought experiment in the Amazon rainforest to evaluate the role of leaf-level water relations, leaf anatomy and their plasticity in response to drought in six tree genera.
• The variables (osmotic potential at full turgor, turgor loss point, capacitance, elastic modulus, relative water content and saturated water content) were compared between seasons and between plots (control and through-fall exclusion) enabling a comparison between short- …

Beyond The Adaptationist Legacy: Updating Our Teaching To Include A Diversity Of Evolutionary Mechanisms, Rebecca M. Price, Kathryn E. Perez

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

A paradigm shift away from viewing evolution primarily in terms of adaptation - the "adaptationist programme" of Gould and Lewontin - began in evolutionary research more than 35 years ago, but that shift has yet to occur within evolutionary education research or within teaching standards. We review three instruments that can help education researchers and educators undertake this paradigm shift. The instruments assess how biology undergraduates understand three evolutionary processes other than natural selection: genetic drift, dominance relationships among allelic pairs, and evolutionary developmental biology (evo-devo). Testing with these instruments reveals that students often explain a diversity of evolutionary mechanisms …

Modeled Inflow Validation & Nutrient Loading Estimation In Two Subwatersheds Of The Lower Laguna Madre, Hudson R. Deyoe, Warren Pulich, Nelun Fernando

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

University of Texas Rio Grande Valley will characterize nutrient loading rates into the Lower Laguna Madre for subwatersheds by monitoring stream flow and water quality (particularly total nitrogen and phosphorus). This information will be used to evaluate Texas Rainfall-Runoff model performance in estimating ungaged inflows and to establish a relationship between ungaged inflows and nutrient loading regimes to the Lower Laguna Madre. View on Map

Horticultural Technique For Rearing And Redistribution Of The Sessile Biological Control Agent, Rhizaspidiotus Donacis On Its Host Plant, Arundo Donax, Joseph M. Villarreal, John A. Goolsby, Ann T. Vacek, Adalberto A. Perez De Leon, Alexis Racelis

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Arundo donax, giant reed is an invasive weed in the riparian habitats of the Rio Grande Basin. A biological control program using specialist insects from the native range in Mediterranean Europe, including the arundo scale, Rhi-zaspidiotus donacis has been implemented. The arundo scale is a sessile insect that spends most of its life cycle affixed to its host plant, thus creating challenges for its rearing and redistribution to field sites. A horticultural technique was developed which allowed for rearing of the scale on small, potted A. donax microplants, which could later be transplanted to field sites. Female scale reach maturity …

Engaging Minority Students In Sustainable Bioenergy And Water Quality Through An Education And Research Network, Krystel Castillo, Mauricio Cabrera-Rios, Michael W. Persans, Hudson R. Deyoe

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Growing energy demand is connected to water availability and climate change and it places additional stress on the environment. Thereby, It is critical to prepare the next generation of engineers and professionals to face the challenges in bioenergy, expand sustainable alternatives to fossil fuels1 and enable climate-smart agriculture2,3. To address this challenge, a career-oriented multidisciplinary educational model is being implemented at three minority-serving institutions. This paper discusses the foundation of this educational program, which provides a robust response to the current sustainability issues by conducting multidisciplinary coordinated education, mentoring, research and extension activities among multiple universities and laboratories. This educational …

Diabetes And Physical Activity, Jameela Banu

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Diabetes has been on the rise globally. Although many factors contribute to the increasing risk and manifestation of this disease lack and decreased physical activity/ exercise stands out as one of the major factors. Treatment interventions for prediabetic and diabetic patients include diet and lifestyle changes with enhanced physical activity/ exercise. Several types of physical activity are available for these patients but, recommendations have to be made on an individual basis after giving due consideration to the comorbidities and other risks and barriers. Implementation of progressive resistance therapy may be successful in maintaining glucose homeostasis in diabetic patients.

Two Complete Mitochondrial Genomes From Praticolella Mexicana Perez, 2011 (Polygyridae) And Gene Order Evolution In Helicoidea (Mollusca, Gastropoda), Russell L. Minton, Marco A. Martinez Cruz, Mark L. Farman, Kathryn E. Perez

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Helicoidea is a diverse group of land snails with a global distribution. While much is known regarding the relationships of helicoid taxa, comparatively little is known about the evolution of the mitochondrial genome in the superfamily. We sequenced two complete mitochondrial genomes from Praticolella mexicana Perez, 2011 representing the first such data from the helicoid family Polygyridae, and used them in an evolutionary analysis of mitogenomic gene order. We found the mitochondrial genome of P. mexicana to be 14,008 bp in size, possessing the typical 37 metazoan genes. Multiple alternate stop codons are used, as are incomplete stop codons. Mitogenome …

Impact Of The Biological Control Agent Tetramesa Romana (Hymenoptera: Eurytomidae) On Arundo Donax (Poaceae: Arundinoideae) Along The Rio Grande River In Texas, John A. Goolsby, Patrick J. Moran, Alexis Racelis, Kenneth R. Summy, Maricela Martinez Jimenez, Ronald D. Lacewell

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Five years post-release of the arundo gall wasp, Tetramesa romana, into the riparian habitats of the lower Rio Grande River, changes in the health of the invasive weed, Arundo donax, or giant reed, have been documented. These changes in plant attributes are fairly consistent along the study area of 558 river miles between Del Rio and Brownsville, TX, and support the hypothesis that the arundo wasp has had a significant impact as a biological control agent. Plant attributes were measured prior to release in 10 quadrats at each of 10 field sites in 2007, and measured again …

Effects Of Shrub Encroachment And Removal On South Texas Coastal Prairie Flora, Parker Alex Watson

Theses and Dissertations

Watson, Parker Alex, Effects of shrub encroachment and removal on South Texas coastal prairie flora. Master of Science, December, 2015. 60 pages, 14 tables, 11 figures, 47 references, 5 appendices. Native-invasive honey mesquite (Prosopis glandulosa) and huisache (Acacia farnesiana) are aggressively encroaching onto South Texas coastal prairies, outcompeting Gulf cordgrass (Spartina spartinae) and associated prairie vegetation with potential legacy effects on the landscape. To measure conditions in the presence of shrubs, data loggers were installed for 16 mos in shrub understories and grass cover to monitor light, soil and air temperatures. Vegetation and canopy surveys were also conducted to evaluate …

Validating Side Scan Sonar As A Fish Survey Tool, Michael A. Bollinger

Theses and Dissertations

Hydroacoustic methods can be used to answer a variety of questions regarding fish populations and behavior. In this study, side scan sonar methodology was developed to quantify abundance and biomass and compared to established visual observation methods on SCUBA over artificial reef structures in the western Gulf of Mexico. Side scan sonar methods were equivalent to SCUBA surveys for measuring fish abundance over the same reef areas, however, abundances were significantly higher when the larger area sampled by side scan was utilized. Side scan sonar methods were also more time efficient than SCUBA, ROV and long line fishing methods (66.7%, …

Examination Of The Chagas Disease Vector, Triatoma Gerstackeri, In The Lower Rio Grande Valley, Alfredo Flores

Theses and Dissertations

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi, which is carried by an insect vector of the family Reduviidae, and of the subfamily Triatomina. The species Triatoma gerstaeckeri is identified as the primary vector of T. cruzi within the Rio Grande Valley. Species of Triatoma gerstaeckeri were trapped in La Sal del Rey National Refuge in 2012 and 2013.

Data indicates a seasonal dispersal pattern of activity for T. gerstaeckeri. Optimal time of capture was between 1-2 hours after sunset. Different methods were utilized to determine the best combination of lures. Results indicate that the UV-light alone is …

Decomposition And Nitrogen Dynamics Of Turtle Grass (Thalassia Testudinum) In A Subtropical Estuarine System, Monica Delgado

Theses and Dissertations

Seagrass beds are pivotal in the functioning of coastal ecosystems in terms of productivity, organic matter turnover and nutrient cycling. Aiming to document decay and nitrogen (N) dynamics of turtle grass (Thalassia testudinum) in a subtropical estuarine system, decomposition patterns of leaves and rhizomes were characterized and compared. Nitrogen usage during decomposition of tissues, and of live tissues and epiphytes growing on live leaves, was also quantified and compared. Stable isotope ratios allowed tracing N within the seagrass bed, following N incorporation into seagrass tissues from the surrounding media (water, sediment). Leaves had a higher N content and decomposed at …

Activation Of Microglia In The Rotenone Lymnaea Stagnalis Model Of Parkinson's Disease, Xiomara Galvan

Theses and Dissertations

Parkinson’s disease (PD) is the most common irreversible neurodegenerative movement disorder affecting approximately ten million people worldwide. In the central nervous system (CNS), PD is known by the selective loss of Dopamine (DA) cells of the substantia nigra pars compacta. Although the disease has been very widely studied, the underlying mechanisms are not yet understood. Several hypotheses have arisen as result of injury of the mitochondria, some experiments include microglia activation, microtubule damage, and reactive oxidative species, which all result in the death of DA cells. The theory of microglia activation upon inflammation was explored in this study. Using the …

Balanus Eburneus (Crustacea: Cirripedia) As A Potential Indicator Of Estuarine System Recovery In South Texas: A Study Of Recruitment, Growth And Stable Isotopes, Crystal Martinez

Theses and Dissertations

Population characteristics of the barnacle Balanus eburneus were analyzed with the purpose of exploring its potential use as a discriminating indicator among sites exhibiting different disturbances or stages of recovery. The study was conducted from May 2012 to May 2013 at four estuaries in the Lower Laguna Madre, TX including a) Bahia Grande, currently under restoration and divided into Bahia Grande North and Bahia Grande South, b) San Martin Lake, which receives runoff water and c) South Bay, a relatively undisturbed reference estuary. In general, similar barnacle recruitment and growth trends in Bahia Grande South and South Bay were explained …

Comparing Reproductive Capacity Of Nearshore And Offshore Red Snapper, Lutjanus Campechanus, On Artificial Reefs In The Western Gulf Of Mexico, Ricky J. Alexander

Theses and Dissertations

Red snapper collected quarterly from four artificial reefs in south Texas were examined to compare total length, total weight, age, and the proportion of male to female red snapper, calculate gonadosomatic index values, batch fecundity, annual spawning frequency, and annual fecundity, and estimate size and age at maturity. Spawning occurred from April to September, with most active spawning observed in June (58%). Despite larger red snapper producing more eggs, and fish being larger offshore, most active spawning (68%) and egg production (74%) was observed nearshore. Female red snapper reached 50% maturity (L50) between 350-550 mm, and L75 by 600 mm. …

After More Than A Decade Of Soil Moisture Deficit, Tropical Rainforest Trees Maintain Photosynthetic Capacity, Despite Increased Leaf Respiration, Lucy Rowland, Raquel L. Lobo-Do-Vale, Bradley O. Christoffersen, Eliane A. Melém, Bart Kruijt, Steel S. Vasconcelos, Tomas Domingues, Oliver J. Binks, Alex A. R. Oliveira, Daniel Metcalfe

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Determining climate change feedbacks from tropical rainforests requires an understanding of how carbon gain through photosynthesis and loss through respiration will be altered. One of the key changes that tropical rainforests may experience under future climate change scenarios is reduced soil moisture availability. In this study we examine if and how both leaf photosynthesis and leaf dark respiration acclimate following more than 12 years of experimental soil moisture deficit, via a through-fall exclusion experiment (TFE) in an eastern Amazonian rainforest. We find that experimentally drought-stressed trees and taxa maintain the same maximum leaf photosynthetic capacity as trees in corresponding control …

Effects Of Control Release Fertilizers On Nutrient Leaching, Palm Growth And Production Cost, Pushpa Soti, Angie Fleurissaint, Stewart Reed, Krish Jayachandran

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Objective of this study was to evaluate the effect of different controlled release fertilizer technologies on nutrient leaching and plant growth parameters of two palm species, Chinese Fan (Livistona chinensis) and Queen (Syagrus romanzoffiana). We compared Nutri-Pak (12-4-12 controlled release packet) and Harrell’s (12-4-12 controlled release polymer coated urea) against Atlantic (8-4-12 controlled release polymer coated urea, coated sulfate of potash), the most commonly used palm fertilizer in South Florida. Plants were grown in 25 cm (11 L) pots under 70% shade, watered weekly, with pest and weed control done as required. Plant growth parameters: number of leaves, leaf length …

Ca2+/Calmodulin Regulates Kvβ1.1-Mediated Inactivation Of Voltage-Gated K+ Channels, Sandip M. Swain, Nirakar Sahoo, Sophie Dennhardt, Roland Schönherr, Stefan H. Heinemann

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

A-type K+ channels open on membrane depolarization and undergo subsequent rapid inactivation such that they are ideally suited for fine-tuning the electrical signaling in neurons and muscle cells. Channel inactivation mostly follows the so-called ball-and-chain mechanism, in which the N-terminal structures of either the K+ channel’s α or β subunits occlude the channel pore entry facing the cytosol. Inactivation of Kv1.1 and Kv1.4 channels induced by Kvβ1.1 subunits is profoundly decelerated in response to a rise in the intracellular Ca2+ concentration, thus making the affected channel complexes negative feedback regulators to limit neuronal overexcitation. With electrophysiological and biochemical experiments we …

A Bomb Set To Drop: Parthenogenetic Marmorkrebs For Sale In Ireland, A European Location Without Non-Indigenous Crayfish, Zen Faulkes

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

Ireland is one of the few locations in Europe where non-indigenous North American crayfish species have not been introduced, and is a refuge for endangered white-clawed crayfish, Austropotamobius pallipes (Lereboullet, 1858). The parthenogenetic crayfish species Marmorkrebs, Procambarus fallax f. virginalis (Hagen, 1870), is sold in the pet trade in Ireland within the recorded range of A. pallipes. Marmorkrebs risk being introduced into Irish waters, where they could threaten A. pallipes populations, particularly as a vector for crayfish plague.

Analysis Of Variables Related To Corridor Use By Ocelots And Bobcats In South Texas, Sarah E. Nordlof

Theses and Dissertations - UTB/UTPA

Biologists estimate that less than 50 endangered ocelots (Leopardus pardalis) remain in the United States, restricted to two small populations in Cameron and Willacy Counties located in deep south Texas. Conversely, bobcats (Lynx rufus) are abundant in south Texas; however, two of the biggest threats to both species are vehicle collisions and habitat fragmentation. To mitigate these threats, the installation of wildlife crossings has been proposed to decrease the number of road mortalities, and wildlife corridors have been suggested as a useful tool for providing increased habitat connectivity. However, research on ocelot use of corridors and wildlife crossings in Texas …

Infection Rates And Distribution Of Trypanosoma Cruzi In Triatomine Insects From Several Public Parks Of Starr, Hidalgo And Cameron Counties, Carlos Guzman Jr.

Theses and Dissertations - UTB/UTPA

Chagas disease is caused by the protozoan Trypanosoma cruzi and is a major public health concern in many areas of the world, including the United States. The disease is transmitted by insect vectors known as kissing bugs from the subfamily Triatominae. While the majority of studies focus on domestic and peri-domestic collections, this study collected insect vectors from state parks in the Lower Rio Grande Valley. PCR analysis was done to obtain infection rates for collected insects, and a morphological examination was done to check insects for gender. In total 18 insects were captured with 12 of the captured insects …

Ecosystem Services Of Urban Trees And The Impacts Of Urbanization, Jorge E. Cantu

Theses and Dissertations - UTB/UTPA

The University of Texas- Pan American has conducted a complete survey of campus trees in partial fulfillment of the requirements for membership in the International Society of Arboriculture Designation of Tree Campus USA. This tree inventory was accomplished with the help of students whom were trained by faculty and foresters. Other than the completion of the tree inventory, this thesis had two main goals; 1) valuate the ecosystem services provided by campus trees 2) create a unique service learning project that other institutions can model. According to our calculations, the trees on campus have sequestered 568,652 kg of CO2, avoided …

Loss Of Mitochondrial Dna Causes Decreased Cell Viability, Alan M. Herrera

Theses and Dissertations - UTB/UTPA

Mitochondria are an organellar network involved in cellular bioenergetics and apoptosis, and dynamically balance their organization between fusion and fission events. Mitochondrial DNA (mtDNA) and nuclear DNA combine to encode polypeptides for the complexes of oxidative phosphorylation (OXPHOS) in the mitochondrial inner membrane, which generate a transmembrane potential (ΔΨm) to synthesize ATP. Loss of ΔΨm causes mitochondrial fission, which appears to be associated with the progression of apoptosis, a critical cell death mechanism that allows tissue homeostasis, developmental sculpturing, and the removal of unwanted cells. Using cultured human cell models of decreased ΔΨm (both genetic mtDNA-depleted ρ 0 and pharmacological …

Exploration Of Nickel Tolerance And Hyperaccumulation In Arabidopsis Thaliana Transformed With Streptanthus Polygaloides Metal Tolerance Protein 1 (Spmtp1) Cdna, Madeleine K. Sano

Theses and Dissertations - UTB/UTPA

This study evaluated the role of hyperaccumulator S. polygaloides Metal Tolerance Protein 1 (SpMTP1) in conferring Ni tolerance and accumulation in the non-accumulator Arabidopsis thaliana. Analysis for Ni content in transgenic Arabidopsis transformed with SpMTP1, following a 12-day treatment of 100 µM Ni, showed a significant increase in Ni concentration in comparison to the wild-type Arabidopsis and empty vector transformed plants. Exposure of transgenic Arabidopsis to nickel also resulted in a coordinated increase of antioxidant enzyme (superoxide dismutase, glutathione reductase, and catalase) activities in the transgenic Arabidopsis, suggesting that increased activities of these oxidative stress response (OSR) proteins may be …

Characterization Of Oxidative Stress Response Proteins In Metal-Tolerant And Metal-Sensitive Brassicaceae Plant Species, Luis M. De Santiago

Theses and Dissertations - UTB/UTPA

In this study the expression of oxidative stress response (OSR) proteins in nonaccumulator and hyperaccumulator plant species of the Brassicaceae family were characterized. Oxidative stress was induced via nickel treatment and proteins were characterized through western blotting and image analysis. Statistical analysis indicated that the nonaccumulator species Arabidopsis thaliana significantly decreased catalase (CAT), glutathione reductase (GR), copper/zinc-dependent superoxide dismutase (Cu/ZnSOD), iron-dependent SOD (FeSOD), manganese-dependent SOD (MnSOD) and metal tolerance protein 1 (MPT1) expression in response to Ni-treatment. The hyperaccumulator species Thlaspi montanum variety montanum displayed either no significant change or a significant increase in OSR regulation following Ni-treatment with the …

Functional Analysis Of The Mms19 Gene In Carica Papaya, Jorge A. Trujillo

Theses and Dissertations - UTB/UTPA

All organisms face DNA-damaging radiation in the form of UV light and must have mechanisms to repair or undo damage. Plants being stationary organisms must cope with damaging UV rays in a molecular fashion and so have developed many forms of resistance. MMS19 is implicated in DNA repair indirectly as a nuclear encoded gene that binds onto protein assembly complexes in the cytosol. A mutant within the SunUp variety of Carica papaya has a large deletion for MMS19 and presents a diminutive phenotype. Deficient DNA repair mechanisms will shunt cells out of the natural cell cycle and reduce cell proliferation …

Species Identification And Habitat Assessment Of The South Texas Siren, Taylor C. Lafortune

Theses and Dissertations - UTB/UTPA

At least one species of siren is endemic to the Rio Grande Valley of Texas, yet very little is known about the populations of the region. Texas Parks and Wildlife refers to the populations of Siren spp. in South Texas as the “South Texas siren (large form Siren sp. 1),” and recognizes these populations as a threatened species, yet their current population status remains unclear. The species identification of the South Texas siren has been hampered by similarity in morphology across species, and by the lack of complete siren genetic sequences in the NCBI GenBank database. In addition to species …

Development Of A Dna Barcoding Reference Library For Identification Of Medicinal Plant Materials Used In The Rio Grande Valley Of Texas: A Representative Case Study Using Arnica (Asteraceae), Hector G. Aguilar De Alba

Theses and Dissertations - UTB/UTPA

DNA barcoding is a technique that uses a short DNA fragment to identify a specimen to the species level. This technique is essential in situations where a lack of distinguishing morphological characteristics makes identification impossible. In the Río Grande Valley a variety of herbal supplements are cheap, readily available and sold as “Arnica” with no information to identify the contents. The appearance of dried and shredded material suggests that a variety of plant species are involved, belonging to the family Asteraceae. Arnica montana, also part of Asteraceae, is found in Europe and has anti-inflammatory properties used to externally treat bruises …

Restoring Semi-Arid Thornscrub Forests: Seeding Growth And Survival In Response To Shelter Tubes, Grass-Specific Herbicide, And Herbivore Exclosures, Krysten Noelle Dick

Theses and Dissertations - UTB/UTPA

This thesis is a compilation of two studies, which I have called ‘chapters.’ The first chapter, “Restoring Semi-Arid Thornscrub Forests: Seedling Growth and Survival in Response to Shelter Tubes, Grass-Specific Herbicide, and Herbivore Exclosures,” was a large study involving multiple techniques used to improve revegetation success, and the second chapter, “Shelter Tube Effects on Microclimate and Seedling Growth in Semi-arid Thornscrub Forests,” focused on the use of shelter tubes in semi-arid forest revegetation. These studies were concurrent evaluations of restoration efforts in thornscrub forests of South Texas. Revegetation is a common effort used to restore forest ecosystems that have been …