Integrative Biology Commons^™

A Phylogenomic Investigation Of The Historical Biogeography Of Livebearers (Cyprinodontiformes: Poeciliidae), Sheila Rodríguez Machado

LSU Doctoral Dissertations

The Neotropics contain several biodiversity hotspots and harbor the highest diversity of freshwater fishes globally. Yet, recognizing the patterns and processes driving this richness remains a challenge. Similarly, all groups and subregions have not received the same attention, especially in the genomics era. Addressing these knowledge gaps will help us to better understand the region’s evolutionary and biogeographic complexity. The goal of this dissertation is to examine phylogenetic and biogeographic patterns of Neotropical freshwater fishes, with emphasis on the Greater Antilles, across multiple taxonomic and geographic scales. To achieve this goal, I generated a genomic dataset of hundreds of ultraconserved …

Metabolic Transitions In Embryos Of Artemia Franciscana: Regulation And Consequences For Oxidative Stress, Daniel Anthony Arabie

LSU Doctoral Dissertations

Embryos of Artemia franciscana survive harsh conditions in diapause and anoxia-induced quiescence for years by undergoing deep metabolic transitions. I investigated the relationship between phosphorylation of pyruvate dehydrogenase (PDH) and carbon flux to the tricarboxylic acid (TCA) cycle during metabolic depression. The difference in catalytic activity of the PDH complex (PDC) in maximally phosphorylated and dephosphorylated samples was 16.5-fold. Western blot analysis confirmed the changes in phosphorylation of PDH. Analysis of PDH expression in diapause and post-diapause embryos via phospho-PDH showed no significant differences. Investigation of post-diapause embryos under anoxia showed that phosphorylation of PDH decreased and activated the enzyme. …

Consequences Of Gulf Of Mexico Estuarine Tropical Cyclone Disturbance Regimes For Fish Assemblage Dynamics Conditionally Depend On Life-History Traits And Niche Characteristics, Stephen Edward Potts

LSU Doctoral Dissertations

Tropical cyclones (TC) are intense, localized disturbances that can potentially cause extensive damage to ecosystems. This dissertation is motivated by a need for interdisciplinary study of TC-ecosystem dynamics with applications to ecology, geography, and analytical methodology. I explore concept linkages between TC dynamics and ecosystems to characterize TC-ecosystem relationships as ecological disturbance regimes. This dissertation tests hypotheses and relationships of TC effects on estuarine fish assemblages in the north-western Gulf of Mexico. I explore concepts in TC-ecosystem relationships to link biotic dynamics with physical disturbance.

In Chapter 2, I compared spatial performance of generalized linear models (GLMs) and generalized additive …

Sodium Mediates Developmentally Plastic Responses In Plants And Herbivores, Luis Santiago-Rosario

LSU Doctoral Dissertations

Sodium plays a crucial role in organismal performance, trophic-level interactions, and eco-evolutionary dynamics. For plants, sodium impacts osmoregulation, growth, and water uptake. For animals, sodium is essential influencing osmoregulatory processes, muscle and neural development, and blood regulation. My dissertation aims to disentangle why sodium mismatch affects resource-consumer interactions and its influence on morphological and behavioral plasticity. First, I identified how sodium impacts plant performance and sodium accumulation strategies. I initially focused my research on understanding how increasing substrate sodium affects plant growth and tissue sodium accumulation strategies in controlled settings using a systematic review approach. I found that saltier plants …

Late Embryogenesis Abundant Proteins And Mitochondrial Membranes From An Animal Extremophile: Insights Into Severe Water Stress, John Marcus Anderson

LSU Doctoral Dissertations

This dissertation focuses on two major topics germane to mechanisms by which animals tolerate extreme water stress. First, the impact of transgenic expression of late embryogenesis abundant proteins (LEA) on water stress tolerance of the fruit fly Drosophila melanogaster was investigated. The overall aim was to extend current understanding of the protective properties of LEA proteins documented with isolated cells to a desiccation-sensitive organism during exposure to drying and hyperosmotic stress. Four lines of D. melanogaster were created that expressed transgenes encoding selected LEA proteins originally identified in embryos of the extremophile Artemia franciscana. After 80% tissue water loss, …

Evolution Of Extreme Habitat Specialists In The Dark: Cavefishes And Anglerfishes, Pamela Hart

LSU Doctoral Dissertations

Extremophilic organisms are fascinating in that they thrive in physiologically demanding environments. Extreme habitats include subsurface caves and the deep sea, which share several qualities like low light and cold temperatures. Extremophiles have adapted bizarre characteristics that allow them to thrive in such harsh environments including eye and pigment loss (cavefishes) and development of a lure in anglerfishes. These traits are integral to the health and fitness of these organisms, yet the evolutionary history of these traits is unclear.

Cave adaptation has evolved repeatedly across the Tree of Life, famously leading to eye degeneration and loss, yet its macroevolutionary implications …

Insights Into Desiccation Tolerance: Properties Of Late Embryogenesis Abundant Proteins From Embryos Of Artemia Franciscana, Blase Matthew Leblanc

LSU Doctoral Dissertations

LEA proteins are a family of intrinsically disordered proteins that are expressed in various life stages of anhydrobiotic organisms and have been strongly associated with survival during water stress. The brine shrimp Artemia franciscana is the only known anhydrobiotic animal that expresses LEA proteins from Groups 1, 3, and 6. Here, I report that AfrLEA6, a novel Group 6 LEA protein, is most highly expressed in embryos during diapause and decreases throughout pre-emergence development. Notably, there is an acute drop in expression upon termination of the diapause state and the titer of AfrLEA6 during diapause is 10-fold lower than values …

The Impact Of Anthropogenic Noise On Fish Behavior, Communication, And Development, Julie Butler

LSU Doctoral Dissertations

Noise pollution is pervasive to nearly all aquatic and terrestrial ecosystems and was labeled a pollutant of global concern by the World Health Organization in 2011. In the past few decades, underwater ambient noise levels have risen almost 30 dB SPL re: 1 µPa in the frequency range that most fish produce and detect acoustic stimuli due to rises in shipping, oil exploration, and pile driving. Changes to the natural soundscape can impact almost all aspects of an animal’s life. My dissertation research takes an integrative, whole-animal approach to examining how increased background noise impacts fish behavior, physiology, development, and …