Desert Ecology Commons^™

Precipitation Patterns And Fungal Community Succession In A Seasonally Dry Secondary Tropical Savanna, Sara R. López-Rodríguez

Biology ETDs

In the northwestern part of South America, seasonally dry forests have undergone extensive conversion to savannas to support ranching and agriculture. The combination of fire and vegetation removal employed for clearing, together with extensive agricultural practices, often lead to loss of soil fertility. This results in land that is no longer useful for agriculture and on which historical forests are unable to regenerate. This study examined the effects of common agricultural practices on soil fungal communities by simulating the effects of fire followed by plant removal. The goal was to determine whether common practices have rapid effects on soil communities, …

Plant-Microbial Interactions Are Strong Determinants Of Plant Population And Community Dynamics, Yan-Yi Anny Chung 9485698

Biology ETDs

Plant-microbial interactions are ubiquitous and yet the consequences of these interactions on plant population and community dynamics are relatively unknown. Here, we used two different classes of plant-microbial interactions to examine their effects on key plant population and community characteristics such as commonness and rarity, competition and coexistence, as well as community stability.

Vertically-transmitted endophytes had stage-dependent effects on the population growth of two grass species Poa sylvestris and Poa alsodes, and generally increased host population growth rates. However, it was the intrinsic demographic advantage of P. sylvestris that allowed its population to grow at a much faster rate …

Direct And Indirect Effects Of Climate Change On Plant Populations And Communities In Sagebrush Steppe, Andrew R. Kleinhesselink

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Rapid climate change presents humanity with a number of big problems. Foremost among these is the sad fact that the climate we will pass on to our children will likely be nothing like the climate that we inherited from our parents. Ecologists have collected solid evidence that climate change has already begun to affect the living things around us and the ecosystems humans depend on. Unfortunately, predicting the future effects of climate change on life on earth is not easy. We focused on three research goals as part of an effort to improve our ability to predict how plants and …

Body Shape Diversification Of Pecos Pupfish (Cyprinodon Pecosensis) On Varying Habitats As Evaluated By Geometric Morphometrics, Qianna Xu

Masters Theses & Specialist Projects

During the 19th and 20th centuries, alterations to the Pecos River in New Mexico and Texas, USA due to anthropogenic activities, including damning and river channelization, vast water extraction for irrigation, as well as pollution of associated habitats, have greatly impacted the fish fauna within the drainage. One of the endemic fish species, the Pecos pupfish (Cyprinodon pecosensis), might be the most affected. Historically abundant and widespread large populations have been disrupted and became a series of small isolated subpopulations that persist at a few highly fragmented habitats restricted to a small area in southern New Mexico. The connectivity among …

Bat Urea-Derived Minerals In Arid Environment. First Identification Of Allantoin, C4H6N4O3, In Kahf Kharrat Najem Cave, United Arab Emirates, Philippe Audra, Pavel Bosák, Fernando Gázquez, Didier Cailhol, Roman Skála, Lenka Lisá, Šárka Jonášová, Amos Frumkin, Martin Knez, Tadej Slabe, Nadja Zupan Hajna, Asma Al-Farraj

International Journal of Speleology

Kahf Kharrat Najem Cave is a small cave in United Arab Emirates (UAE) that hosts a bat colony which is the source of guano deposits and peculiar centimeter-long yellowish stalactites. The mineralogy and geochemistry of these deposits were analyzed using powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopic microanalysis (EDX), scanning electron microscope (SEM), and stable isotope composition (δ¹³C and δ¹⁵N). Urea CO(NH₂)₂ was found to be the main compound of these stalactites, while allantoin C₄H₆N₄O₃ was found to be an accessory urea byproduct. This paper …

Effects Of Wildfires On Rattlesnake (Crotalus Oreganus) Growth And Movement In Washington State, Joseph Chase

All Master's Theses

Fire is a dominant force in the Pacific Northwest that shapes ecosystems and influences wildlife, yet little is known of its effects on local predators. Northern Pacific rattlesnakes (Crotalus oreganus) comprise an excellent model to investigate how fire may influence wildlife because they are important predators that contribute to controlling prey populations, but are also unable to readily escape from wildfires. We developed a novel technique to assess growth rates of rattlesnakes by using digital photography to analyze differences in widths of their rattle segments laid down over time. We compared growth rates of rattlesnakes in habitats that …

Drivers And Feedbacks Of The Fire-Grazing Interaction In The Northern Great Plains, Jacob E. Powell

Graduate Student Theses, Dissertations, & Professional Papers

The fire-grazing interaction is well studied in mesic grasslands worldwide, but research is lacking in semiarid systems. In addition, the fire-grazing interaction reduces the invasion of exotic forage species in mesic grasslands by increasing the scale of grazing selection and may be a tool to control invasive plants in other grasslands. We examined the principal drivers and feedbacks of the fire-grazing interaction on the strength of cattle grazing selection, forage quantity and quality, and vegetation structure and composition in two pastures in northeast Montana at The Nature Conservancy’s Matador Ranch. We also determined the influence of time since fire, within …

Phytophagous Insect Oviposition Shifts In Response To Probability Of Flower Abortion Owing To The Presence Of Basal Fruits, Shivani Jadeja, Brigitte Tenhumberg

School of Biological Sciences: Faculty Publications

Phytophagous insects use a wide range of indicators or associated cues to avoid laying eggs in sites where offspring survival is low. For insects that lay eggs in flowers, these unsuitable sites may be created by the host plant’s resource allocation to flowers. In the sequentially flowering host plant, Yucca glauca, late-opening distal flowers are more likely to be aborted in the presence of already-initiated basal fruits because they are strong resource sinks. If flowers are aborted, all eggs of the phytophagous insect, Tegeticula yuccasella, within the flower die. We used the phytophagous insect T. yuccasella that lays …

Rewiring Metabolism Under Oxygen Deprivation: Naked Mole-Rats Evolved A Means To Cope With Anoxia, Jay F. Storz, Grant B. Mcclelland

Jay F. Storz Publications

When faced with a reduced availability of oxygen in the environment (hypoxia), vertebrates can make a variety of respiratory, cardiovascular, and hematological adjustments to ensure an uninterrupted supply of oxygen to the cells of metabolizing tissues (1, 2). These are adaptive solutions for “aerobic organisms in an aerobic world” (3). Coping with the complete absence of oxygen (anoxia) requires more fundamental alterations of cellular metabolism that are typically nothing more than emergency stopgap measures to buy time until the oxygen supply is (hopefully) reestablished (4). On page 307 of this issue [Science 356 (6335)], Park et al. (5) identify a …

Can Functional Traits Predict Plant Community Response To Global Change?, Sarah Kimball, Jennifer L. Funk, Marko J. Spasojevic, Katharine N. Suding, Scot Parker, Michael K. Goulden

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

One primary goal at the intersection of community ecology and global change biology is to identify functional traits that are useful for predicting plant community response to global change. We used observations of community composition from a long-term field experiment in two adjacent plant communities (grassland and coastal sage shrub) to investigate how nine key plant functional traits were related to altered water and nitrogen availability following fire. We asked whether the functional responses of species found in more than one community type were context dependent and whether community-weighted mean and functional diversity were significantly altered by water and nitrogen …

Plant-Biocrust Interactions Mediated By The Fungal Loop, Eva Dettweiler-Robinson

Biology ETDs

Plant-microbial interactions influence biogeochemical cycles. Plants and biological soil crusts are primary producers in drylands. Biocrusts include cyanobacteria, lichens, mosses, algae, fungi, bacteria, and archaea on the soil surface, some of which fix atmospheric nitrogen. I investigated controls on biocrust carbon fluxes and their contribution to ecosystem fluxes, the incorporation of plant-derived carbon into biocrusts, and the role of soil fungi in promoting performance of plants and biocrusts. Biocrusts responded to temperature and moisture differently by biome. Biocrusts in grasslands/shrublands contributed >25% of total summertime ecosystem respiration, but biocrusts in savannas/woodlands contributed < 1%. Biocrusts contributed < 2% to GPP in any biome. To augment their native photosynthesis, biocrusts may include 16% plant-derived carbon. Fungal connections improved plant and biocrust performance and reduced differences in the CN ratio between organisms compared to when connections were impeded. Investigation of interactions among biocrusts, plants, and fungi has improved understanding of resource cycling in drylands.

Comparative Population Genomics And Speciation Of Snakes Across The North American Deserts, Edward A. Myers

Dissertations, Theses, and Capstone Projects

Understanding the process of speciation is of central interest to evolutionary biologists. Speciation can be studied using a phylogeographic approach, by identifying regions that promote lineage divergence, addressing whether speciation has occurred with gene flow, and when extended to multiple taxa, addressing if the same patterns of speciation are shared across codistributed groups with different ecologies. Here I examine the comparative phylogeographic histories and population genomics of thirteen snake taxa that are widely distributed and co-occur across the arid southwest of North America. I first quantify the degree to which these species groups have a shared history of population divergence …

The Effects Of Drought On Diets Of Apex Predators In The South African Lowveld Inferred By Fecal Hair Analysis, Shelby Wade

Mahurin Honors College Capstone Experience/Thesis Projects

To properly manage offtake quotas and conservation efforts, Balule Nature Reserve (South Africa) instituted a study in 2014 to determine prey species selection by megapredators. In 2015, Balule Nature Reserve received about 190 mm less rainfall between the months of January and June than in 2014 (116 mm less than average). This study compares the diets of lions and hyaenas between 2014 and 2015. Prey species consumed were determined by fecal analysis, and results were compared to prey availability. Sixteen, 1 km2 plots were chosen from the 400 km2 Reserve. Between June and August 2015, we walked three, 1 km …

An Investigation Of Herbivory And Seed Predation On Slickspot Peppergrass, Michelle I. Jeffries

Boise State University Theses and Dissertations

This study was completed during the summers of 2014 and 2015 to continue research on the relationship between harvester ants (Pogonomyrmex salinus) and slickspot peppergrass (Lepidium papilliferum). Slickspot peppergrass is a rare mustard endemic to south western Idaho. Over the past century, the species has declined in abundance, largely as a result of habitat degradation and fragmentation. In addition to these reasons for decline, seed foraging by harvester ants and plant destruction by harvester ants and small mammal herbivores have been recently indicated as potential factors. This study confirmed that harvester ants remove large numbers of …

Rapidly Restoring Biological Soil Crusts And Ecosystem Functions In A Severely Disturbed Desert Ecosystem, Lindsay P. Chiquoine, Scott R. Abella, Matthew A. Bowker

Life Sciences Faculty Research

Restoring biological soil crusts (biocrusts) in degraded drylands can contribute to recovery of ecosystem functions that have global implications, including erosion resistance and nutrient cycling. To examine techniques for restoring biocrusts, we conducted a replicated, factorial experiment on recently abandoned road surfaces by applying biocrust inoculation (salvaged and stored dry for two years), salvaged topsoil, an abiotic soil amendment (wood shavings), and planting of a dominant perennial shrub (Ambrosia dumosa). Eighteen months after treatments, we measured biocrust abundance and species composition, soil chlorophyll a content and fertility, and soil resistance to erosion. Biocrust addition significantly accelerated biocrust recovery on disturbed …

Diversity-Dependent Cladogenesis Throughout Western Mexico: Evolutionary Biogeography Of Rattlesnakes (Viperidae: Crotalinae: Crotalus And Sistrurus), Christopher Blair, Santiago Sánchez-Ramírez

Publications and Research

Rattlesnakes (Crotalus and Sistrurus) represent a radiation of approximately 42 species distributed throughout the New World from southern Canada to Argentina. Interest in this enigmatic group of snakes continues to accrue due, in part, to their ecomorphological diversity, contributions to global envenomations, and potential medicinal importance. Although the group has garnered substantial attention from systematists and evolutionary biologists for decades, little is still known regarding patterns of lineage diversification. In addition, few studies have statistically quantified broad-scale biogeographic patterns in rattlesnakes to ascertain how dispersal occurred throughout the New World, particularly among the different major biomes of the …

Wildlife And Local Community Investigation In Trans-Boundary Area Between China-Mongolia Borders, Weikang Yang, Wenxuan Xu, Canjun Xia, Wei Liu, Xingyi Gao

Erforschung biologischer Ressourcen der Mongolei / Exploration into the Biological Resources of Mongolia, ISSN 0440-1298

During June 2008, and August and December 2010, we investigated both the status of wildlife and local human communities in the great Gobi trans-boundary area between China and Mongolia. We surveyed Baytik Mountain (called Baitag Bogdt on the Mongolian side of the border)( 44°59′ - 45°21′N，90°30′ - 90°53′E), which is located in the West of Great Gobi B strict protected area (GGB) and connected with Dzungarian Gobi. The Kazakh shepherds still maintain their nomadic life here in Baytik Mountains. The region was divided into summer, winter and transitional pasture, and most of the livestock were goats and sheep. We also …

Genetic Structure And Connectivity Of The Endangered Giant Kangaroo Rat (Dipodomys Ingens) In A Heterogeneous Environment, Nathan Alexander

Cal Poly Humboldt theses and projects

Movement ecology and dispersal are important aspects of species’ life histories that can inform conservation and management. Dispersal is often cryptic and difficult to detect, but recent advances genetic technology and applications have provided new approaches to identifying and describing dispersal patterns. Giant kangaroo rats (Dipodomys ingens) are an endangered heteromyid that appear to persist in small subpopulations in a heterogeneous environment of their northern range, the Ciervo-Panoche Natural Area, California. Previous work suggested high levels of genetic diversity between populations with genetic distances not being correlated to geographic distances. Here, I identified landscape population structure through clustering …

Positive Interactions In Temperate And Tropical Alpine Plant Communities: The Role Of Facilitation In Species-Specific Interactions, Invasion, And Landscape-Scale Distribution, Nicole Hupp

Graduate Student Theses, Dissertations, & Professional Papers

No abstract provided.

Genome Wide Epigenetic Analyses Of Araptus Attenuatus, A Bark Beetle, Chitra Seshadri

Theses and Dissertations

Phylogeographic studies have relied on surveying neutral genetic variation in natural populations as a way of gaining better insights into the evolutionary processes shaping present day population demography. Recent emphasis on understanding putative adaptive variation have brought to light the role of epigenetic variation in influencing phenotypes and the mechanisms underlying local adaptation. While much is known about how methylation acts at specific loci to influence known phenotypes, there is little information on the spatial genetic structure of genome-wide patterns of methylation and the extent to which it can extend our understanding of both neutral and putatively adaptive processes. This …