Ecology and Evolutionary Biology Commons^™

Effects Of Riverine Barriers On Avian Evolution In The Amazon Basin, Andre Eugene Moncrieff

LSU Doctoral Dissertations

The high biodiversity found in the Amazon Basin has long captivated the attention of naturalists and evolutionary biologists seeking to explain its origins. Early observations by Alfred Wallace highlighted the role of rivers in delimiting the geographic ranges of many species; furthermore, where rivers narrow towards their headwaters, he noted that some species cross rivers freely. A major goal of this dissertation is to investigate how these and other observations about riverine barriers might inform our understanding of how speciation unfolds in Amazonia. My approach involved generating genomic data with dense geographic sampling for manakins in the genus Lepidothrix, …

Genetic Structuring And Community Assembly In Neotropical Birds, Oscar Johnson

LSU Doctoral Dissertations

The factors that influence how species form is of fundamental interest to biology. Under the framework of the speciation cycle, the process begins by population subdivision creating structured populations that then diverge until two new species form. Following speciation, however, continued divergence is necessary for these new species to be able to coexist without adverse interactions, known as the transition to secondary sympatry. At this point the speciation cycle is complete and the process can begin anew. Many of the factors influencing these processes remain poorly understood. Here, I explore the factors that influence speciation and community assembly in Neotropical …

Micro- And Macroevolution Of Drab Plumage Color In Birds, Rafael Marcondes

LSU Doctoral Dissertations

I address the evolution of drab bird colors at micro- and macroevolutionary scales. I use as a study system the Furnariida, a clade of >600 Neotropical passerine species that, despite tremendous ecological and morphological diversity, are colored almost exclusively in shades of brown and grey produced by melanin pigments.

In chapters two and three, I took a macroevolutionary approach and showed that (1) plumage colors in the Furnariida evolve at similar rates in a monochromatic clade, males of a dichromatic clade, and females of a dichromatic clade; (2) ventral plumage color evolves faster than dorsal; (3) bird species that occupy …

Quantifying Structure And Variation In Complex Phylogenetic Data, Genevieve Geraldine Mount

LSU Doctoral Dissertations

Identifying the source and structure of variation in nature is crucial to understanding fundamental aspects of evolution. Despite a recent plethora of genetic and morphological data, many interesting questions about the relationships between different groups remain unresolved. My dissertation evaluates three approaches for identifying and quantifying the variation within phylogenetic datasets. Characterizing variation within datasets and across analytical methods gives insight into biologically interesting characters, unusual evolutionary processes, and areas for model improvement.

Network-based community detection approaches offer a powerful tool to describe variation in phylogenetic signal across the genome (i.e., gene tree variation). In Chapter 2, I investigate the …

Natural Variation And Evolutionary Responses To Climate Change Stressors In Marine Invertebrates, Joanna Sarah Griffiths

LSU Doctoral Dissertations

Our rapidly changing climate is putting many species at risk of extinction and there is an urgent need to understand how species will respond to these changes. In this dissertation, I evaluate how three species of marine invertebrates (corals, oysters, and copepods) respond to stressful conditions in their current environments and how plasticity and evolutionary adaptation could alter their response to future climate change stressors. I first employed a space for time study to elucidate population differences in the response of cold-water corals, Balanophyllia elegans, to future ocean acidification. I found evidence that upwelling history (natural low pH exposure) influences …

Computational Analysis Of Papionini Evolution Using Alu Insertions, Vallmer Edward Jordan Ii

LSU Doctoral Dissertations

Alu elements are primate specific retrotransposons that have remained active throughout the course of primate evolution. As a result of this sustained mobilization. Alu elements are present in greater copy number in primate genomes than any other transposable element. An average of over one million Alu elements has been identified in every sequenced haplorrhine genome to date. These characteristics qualify Alu elements as ideal characters for studying evolutionary relationship among primates.

The increasing availability of whole genome sequencing data presents novel challenges and opportunities for comparative genomic analyses. Genomic data is now publicly available for most primate species. Such an …

Determining Bioindicators For Coastal Tidal Marsh Health Using The Food Web Of Larvae Of The Greenhead Horse Fly (Tabanus Nigrovittatus), Devika Rajeev Bhalerao

LSU Master's Theses

The greenhead horse fly Tabanus nigrovittatus Macquart is native to coastal marshlands from Texas to Nova Scotia. The larvae are apex invertebrate predators and their development is dependent on the food web in the soil. Surveillance of T. nigrovittatus after the 2010 Deepwater Horizon oil spill in the Gulf of Mexico showed population crashes of adults in the coastal marshes of East Louisiana near places where oil made landfall, but not in West Louisiana where the oil did not reach. Sediment collection in 2011 from West and East Louisiana revealed larval population crashes in the Eastern coastal region. We hypothesized …

A Path To Success? A Review Of Evolution, Development, And The Predictable Genome By David L. Stern, Hope Hollocher, Charles H. Pence, Grant Ramsey, Michelle M. Wirth

Faculty Publications

No abstract provided.