Matching Items (7)
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- All Subjects: Evolution
- Creators: Pfeifer, Susanne
Description
Biogeography is the study of the spatial distribution of the earth's biota, both in the present and the past. Traditionally, biogeographical studies have relied on a combination of surveys of existing populations, fossil evidence, and the geological record of the earth. However, with the advent of relatively inexpensive methods of DNA sequencing, it is now possible to use information concerning the genetic relatedness of individuals in populations to address questions about how those populations came to be where they are today. For example, biogeographical studies of HIV-I provide strong support for the hypothesis that this virus arose in Africa through a host switch from chimpanzees to humans and only began to spread to human populations located on other continents some 60 to 70 years ago (Sharp & Hahn, 2010).
ContributorsZheng, Wenyu (Author) / Taylor, Jesse (Thesis director) / Escalante, Ananias (Committee member) / Thieme, Horst (Committee member) / Barrett, The Honors College (Contributor)
Created2015-05
Description
The complex life cycle and widespread range of infection of Plasmodium parasites, the causal agent of malaria in humans, makes them the perfect organism for the study of various evolutionary mechanisms. In particular, multigene families are considered one of the main sources for genome adaptability and innovation. Within Plasmodium, numerous species- and clade-specific multigene families have major functions in the development and maintenance of infection. Nonetheless, while the evolutionary mechanisms predominant on many species- and clade-specific multigene families have been previously studied, there are far less studies dedicated to analyzing genus common multigene families (GCMFs). I studied the patterns of natural selection and recombination in 90 GCMFs with diverse numbers of gene gain/loss events. I found that the majority of GCMFs are formed by duplications events that predate speciation of mammal Plasmodium species, with many paralogs being neutrally maintained thereafter. In general, multigene families involved in immune evasion and host cell invasion commonly showed signs of positive selection and species-specific gain/loss events; particularly, on Plasmodium species is the simian and rodent clades. A particular multigene family: the merozoite surface protein-7 (msp7) family, is found in all Plasmodium species and has functions related to the erythrocyte invasion. Within Plasmodium vivax, differences in the number of paralogs in this multigene family has been previously explained, at least in part, as potential adaptations to the human host. To investigate this I studied msp7 orthologs in closely related non-human primate parasites where homology was evident. I also estimated paralogs’ evolutionary history and genetic polymorphism. The emerging patterns where compared with those of Plasmodium falciparum. I found that the evolution of the msp7 multigene family is consistent with a Birth-and-Death model where duplications, pseudogenization and gene lost events are common. In order to study additional aspects in the evolution of Plasmodium, I evaluated the trends of long term and short term evolution and the putative effects of vertebrate- host’s immune pressure of gametocytes across various Plasmodium species. Gametocytes, represent the only sexual stage within the Plasmodium life cycle, and are also the transition stages from the vertebrate to the mosquito vector. I found that, while male and female gametocytes showed different levels of immunogenicity, signs of positive selection were not entirely related to the location and presence of immune epitope regions. Overall, these studies further highlight the complex evolutionary patterns observed in Plasmodium.
ContributorsCastillo Siri, Andreina I (Author) / Rosenberg, Michael (Thesis advisor) / Escalante, Ananias (Committee member) / Taylor, Jesse (Committee member) / Collins, James (Committee member) / Arizona State University (Publisher)
Created2016
Description
Previous recombination rate estimation studies in rhesus macaques have been mostly restricted to a singular approach (e.g., using microsatellite loci). Here, we employ a bilateral method in estimating recombination rates—pedigree-based and linkage-disequilibrium-based—from whole-genome data of rhesus macaques to estimate CO and NCO recombination events and to compare contemporary and historical rates of recombination.
ContributorsWeiss, Sarah (Author) / Pfeifer, Susanne (Thesis director) / Versoza, Cyril (Committee member) / Barrett, The Honors College (Contributor) / School of Art (Contributor) / School of Life Sciences (Contributor)
Created2023-05
ContributorsWeiss, Sarah (Author) / Pfeifer, Susanne (Thesis director) / Versoza, Cyril (Committee member) / Barrett, The Honors College (Contributor) / School of Art (Contributor) / School of Life Sciences (Contributor)
Created2023-05
ContributorsWeiss, Sarah (Author) / Pfeifer, Susanne (Thesis director) / Versoza, Cyril (Committee member) / Barrett, The Honors College (Contributor) / School of Art (Contributor) / School of Life Sciences (Contributor)
Created2023-05
ContributorsWeiss, Sarah (Author) / Pfeifer, Susanne (Thesis director) / Versoza, Cyril (Committee member) / Barrett, The Honors College (Contributor) / School of Art (Contributor) / School of Life Sciences (Contributor)
Created2023-05
Description
Humans have evolved in many ways. Just look at how life for mankind has changed over the past few decades. It is amazing how different life can be in just a short amount of time. While it is evident that we have impacts of the environment, it should be just as evident that we impact the animals around us. However, there are a few subtle ways in which we impact the evolution of life.
Through man-made structures, human interference, artificial lights at night, and electromagnetic fields we have caused animals and insects to evolve and fit these new environments. While we tail the world around us to convince ourselves, the animals also living in these environments need to adapt to survive. In this essay, I will discuss how the affects mentioned above have cause crows, moths, snails, bobcats, blackbirds, mosquitoes, elephants, diurnal animals, fireflies, dung beetles, birds and bats to evolve. The adaptations these organisms made were caused by the subtle ways in which we have impact the landscapes around us.
Through man-made structures, human interference, artificial lights at night, and electromagnetic fields we have caused animals and insects to evolve and fit these new environments. While we tail the world around us to convince ourselves, the animals also living in these environments need to adapt to survive. In this essay, I will discuss how the affects mentioned above have cause crows, moths, snails, bobcats, blackbirds, mosquitoes, elephants, diurnal animals, fireflies, dung beetles, birds and bats to evolve. The adaptations these organisms made were caused by the subtle ways in which we have impact the landscapes around us.
ContributorsFikse, Sydney D (Author) / Sterner, Beckett (Thesis director) / Pfeifer, Susanne (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05