Matching Items (4)
Description
Lactase persistence is the ability of adults to digest lactose in milk (Segurel & Bon, 2017). Mammals are generally distinguished by their mammary glands which gives females the ability to produce milk and feed their newborn children. The new born therefore requires the ability to breakdown the lactose in the milk to ensure its proper digestion (Segurel & Bon, 2017). Generally, humans lose the expression of lactase after weaning, which prevents them being able to breakdown lactose from dairy (Flatz, 1987).
My research is focused on the people of Turkana, a human pastoral population inhabiting Northwest Kenya. The people of Turkana are Nilotic people that are native to the Turkana district. There are currently no conclusive studies done on evidence for genetic lactase persistence in Turkana. Therefore, my research will be on the evolution of lactase persistence in the people of Turkana. The goal of this project is to investigate the evolutionary history of two genes with known involvement in lactase persistence, LCT and MCM6, in the Turkana. Variants in these genes have previously been identified to result in the ability to digest lactose post-weaning age. Furthermore, an additional study found that a closely related population to the Turkana, the Massai, showed stronger signals of recent selection for lactase persistence than Europeans in these genes. My goal is to characterize known variants associated with lactase persistence by calculating their allele frequencies in the Turkana and conduct selection scans to determine if LCT/MCM6 show signatures of positive selection. In doing this, we conducted a pilot study consisting of 10 female Turkana individuals and 10 females from four different populations from the 1000 genomes project namely: the Yoruba in Ibadan, Nigeria (YRI); Luhya in Webuye, Kenya; Utah Residents with Northern and Western European Ancestry (CEU); and the Southern Han Chinese. The allele frequency calculation suggested that the CEU (Utah Residents with Northern and Western European Ancestry) population had a higher lactase persistence associated allele frequency than all the other populations analyzed here, including the Turkana population. Our Tajima’s D calculations and analysis suggested that both the Turkana population and the four haplotype map populations shows signatures of positive selection in the same region. The iHS selection scans we conducted to detect signatures of positive selection on all five populations showed that the Southern Han Chinese (CHS), the LWK (Luhya in Webuye, Kenya) and the YRI (Yoruba in Ibadan, Nigeria) populations had stronger signatures of positive selection than the Turkana population. The LWK (Luhya in Webuye, Kenya) and the YRI (Yoruba in Ibadan, Nigeria) populations showed the strongest signatures of positive selection in this region. This project serves as a first step in the investigation of lactase persistence in the Turkana population and its evolution over time.
My research is focused on the people of Turkana, a human pastoral population inhabiting Northwest Kenya. The people of Turkana are Nilotic people that are native to the Turkana district. There are currently no conclusive studies done on evidence for genetic lactase persistence in Turkana. Therefore, my research will be on the evolution of lactase persistence in the people of Turkana. The goal of this project is to investigate the evolutionary history of two genes with known involvement in lactase persistence, LCT and MCM6, in the Turkana. Variants in these genes have previously been identified to result in the ability to digest lactose post-weaning age. Furthermore, an additional study found that a closely related population to the Turkana, the Massai, showed stronger signals of recent selection for lactase persistence than Europeans in these genes. My goal is to characterize known variants associated with lactase persistence by calculating their allele frequencies in the Turkana and conduct selection scans to determine if LCT/MCM6 show signatures of positive selection. In doing this, we conducted a pilot study consisting of 10 female Turkana individuals and 10 females from four different populations from the 1000 genomes project namely: the Yoruba in Ibadan, Nigeria (YRI); Luhya in Webuye, Kenya; Utah Residents with Northern and Western European Ancestry (CEU); and the Southern Han Chinese. The allele frequency calculation suggested that the CEU (Utah Residents with Northern and Western European Ancestry) population had a higher lactase persistence associated allele frequency than all the other populations analyzed here, including the Turkana population. Our Tajima’s D calculations and analysis suggested that both the Turkana population and the four haplotype map populations shows signatures of positive selection in the same region. The iHS selection scans we conducted to detect signatures of positive selection on all five populations showed that the Southern Han Chinese (CHS), the LWK (Luhya in Webuye, Kenya) and the YRI (Yoruba in Ibadan, Nigeria) populations had stronger signatures of positive selection than the Turkana population. The LWK (Luhya in Webuye, Kenya) and the YRI (Yoruba in Ibadan, Nigeria) populations showed the strongest signatures of positive selection in this region. This project serves as a first step in the investigation of lactase persistence in the Turkana population and its evolution over time.
ContributorsJobe, Ndey Bassin (Author) / Wilson Sayres, Melissa (Thesis director) / Paaijmans, Krijn (Committee member) / Taravella, Angela (Committee member) / School of Earth and Space Exploration (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
ContributorsOill, Christopher (Performer) / Carlisi, Daniel (Performer) / Jarosz, Jack (Performer) / Martinez, Anarbol (Performer) / Taravella, Angela (Performer) / Brown, Zane (Performer) / Clark, Kelly (Performer) / Ly, Sylvan (Performer) / Clark, Connor (Performer) / Dulaney, Kianna (Performer) / Guo, Xiaoxin (Performer) / Gong, Yuerong (Performer) / ASU Library. Music Library (Publisher)
Created2018-04-23
Description
Contrary to common thought at the end of the 20th century, the forces of globalization over the last several decades have contributed to more rigid rather than more permeable international borders as countries have enacted strict immigration and travel policies. This growing rigidity of international borders has paradoxically occurred as international tourism steadily grew up until the COVID-19 pandemic and conservationists adopted a landscape-scale approach to conserving and restoring ecosystems, often across international borders. Considering this paradox, this dissertation research examined the interactions between tourism development, ecological restoration, and bordering processes by utilizing bordering and stakeholder theories; core-periphery, cross-border tourism, and border frameworks; political ecology; and polycentric governance and cross-border collaboration literature. Together, these conceptualizations were used to assess stakeholder attitudes towards tourism development and ecological restoration, compare resource governance characteristics of private protected areas, and analyze shared appreciation for natural and cultural heritage at the U.S.-Mexico border. To collect data, the researcher utilized in-depth interviews, photo-elicitation interviews, focus groups, secondary data analysis, and observations to engage key tourism and conservation stakeholders from the region, such as tourism businesses, tourists, state and federal agencies, conservation nonprofits, ranchers, and residents The findings of this research revealed a political ecology of a border landscape that included social and environmental injustices and unequal stakeholder partnerships in tourism and ecological restoration initiatives. Unequal partnerships were also found in cross-border resource governance systems, largely due to the U.S. government’s border wall construction actions, and the necessity for government leadership in establishing vertical and horizontal linkages in polycentric governance structures was evident. The results also demonstrated how a shared appreciation for natural and cultural heritage contributes to debordering despite the rebordering actions of border security and strict travel policies. This study contributes to tourism literature by highlighting the need for tourism and ecological restoration initiatives to consider social and environmental justice issues, develop stronger cross-border linkages with governments and resource users, and foster cross-border collaboration and integration. This consideration of social and environmental justice issues involves sharing benefits of tourism and restoration, restoring and preserving resources that stakeholders value, and facilitating access to resources.
ContributorsClark, Connor (Author) / Nyaupane, Gyan P (Thesis advisor) / Timothy, Dallen (Committee member) / Budruk, Megha (Committee member) / Coronado, Irasema (Committee member) / Arizona State University (Publisher)
Created2022
Description
A new study on sex chromosome evolution in papaya helps to illuminate sex chromosome biology, including deviations from expected trajectories.
ContributorsTaravella, Angela (Author) / Wilson Sayres, Melissa (Author) / College of Liberal Arts and Sciences (Contributor)
Created2016-11-29