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- All Subjects: Birds
- Creators: Amdam, Gro
Description
Speciation, or the process by which one population diverges into multiple populations that can no longer interbreed with each other, has brought about the incredible diversity of life. Mechanisms underlying this process can be more visible in the early stages of the speciation process. The mechanisms that restrict gene flow in highly mobile species with no absolute barriers to dispersal, especially marine species, are understudied. Similarly, human impacts are reshaping ecosystems globally, and we are only just beginning to understand the implications of these rapid changes on evolutionary processes. In this dissertation, I investigate patterns of speciation and evolution in two avian clades: a genus of widespread tropical seabirds (boobies, genus Sula), and two congeneric passerine species in an urban environment (cardinals, genus Cardinalis). First, I explore the prevalence of gene flow across land barriers within species and between sympatric species in boobies. I found widespread evidence of gene flow over all land barriers and between 3 species pairs. Next, I compared the effects of urbanization on the spatial distributions of two cardinal species, pyrrhuloxia (Cardinalis sinuatus) and northern cardinals (Cardinalis cardinalis), in Tucson, Arizona. I found that urbanization has different effects on the spatial distributions of two closely related species that share a similar environmental niche, and I identified environmental variables that might be driving this difference. Then I tested for effects of urbanization on color and size traits of these two cardinal species. In both of these species, urbanization has altered traits involved in signaling, heat tolerance, foraging, and maneuverability. Finally, I tested for evidence of selection on the urban populations of both cardinal species and found evidence of both parallel selection and introgression between the species, as well as selection on different genes in each species. The functions of the genes that experienced positive selection suggest that light at night, energetics, and air pollution may have acted as strong selective pressures on these species in the past. Overall, my dissertation emphasizes the role of introgression in the speciation process, identifies environmental stressors faced by wildlife in urban environments, and characterizes their evolutionary responses to those stressors.
ContributorsJackson, Daniel Nelson (Author) / McGraw, Kevin J (Thesis advisor) / Amdam, Gro (Committee member) / Sweazea, Karen (Committee member) / Taylor, Scott (Committee member) / Arizona State University (Publisher)
Created2023
Description
In 1996, a floral and faunal inventory of the southeastern slopes of the Marojejy Massif, which falls in a protected area known as the Parc national de Marojejy, was conducted in an ascending series of altitudinal transect zones. The 1996 research team worked in five altitudinal zones (referred to as transect zones). Between 3 October and 15 November 2021, a floral and faunal inventory was completed, replicating the locations surveyed in 1996 and closely the dates. Detected bird species were analyzed for changes in elevational distribution between 1996 and 2021. Birds were divided into three feeding behavior groups and tolerance to forest habitat degradation was considered.
ContributorsLangrand, Tahiry (Author) / Schoon, Michael (Thesis director) / Goodman, Steve (Committee member) / Barrett, The Honors College (Contributor) / School of Complex Adaptive Systems (Contributor) / School of International Letters and Cultures (Contributor) / School of Sustainability (Contributor)
Created2022-05