Download or read book Human Effects on Intraspecific Genetic Diversity written by Katie Millette and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Intraspecific genetic diversity allows species to adapt and evolve in response to environmental disruptions and novel stressors. As the frequency and severity of environmental disturbances increases, species may be eroded of their evolutionary potential and unable to keep pace with their changing world. The complexity of the processes affecting intraspecific genetic diversity across spatial scales compromises our ability to predict how the patterns observed in nature translate to future evolutionary outcomes. Measuring and observing patterns of intraspecific genetic diversity contributes to our understanding of the extent to which we are affecting the resilience and future adaptability of populations.In this thesis, I extend research on what is known about patterns in intraspecific genetic diversity in the laboratory and nature, using a combination of experimental, field, and data surveys. First, I conducted a laboratory experiment to determine the mechanistic process(es) maintaining diversity in populations with divergent amounts of initial genetic diversity. I found that an initial high input of genetic diversity does not result in a proportional maintenance of genetic diversity. The composition of genotypic diversity shifted significantly to few genotypes, suggesting competition within populations may eliminate supplemental genetic diversity in populations and that the window for establishing local population genetic structure can be exceptionally short. I then conducted a population genetic survey of Daphnia from lakes across a landscape of variable environmental disturbance. My prediction of eroded intraspecific genetic diversity was upheld in some populations, except for the most polluted, which maintained high genetic diversity as a result of hybridization and introgression of closely related ecological species. This indicates that stressed habitats can have selective effects on genotypic structure but can also break pre-existing ecological barriers and facilitate habitat transitions. I then extend my assessment to the global scale, to evaluate how human land use and population density affect trends in intraspecific diversity in species of birds, fish, mammals, and insects worldwide. I show that human impacts on mitochondrial intraspecific genetic diversity changes with species and spatial scale, indicating that in the taxa assessed there is no global monotonic net effect of humans. The results indicate that some species experienced an increase, while other species experienced a decrease in genetic diversity over the period 1980-2016. Divergent effects of humans on the ecological processes governing population genetic structure, brief timespans in monitoring, as well as species-specific life history traits likely underlie the globally inconsistent effect of humans on animal intraspecific genetic diversity. My thesis demonstrates the dynamic nature of intraspecific genetic diversity in response to biological and anthropogenic conditions. These findings support the conservation strategy of preserving genetic variation within species and the management of populations from diverse environments as a solution to the elevated extinction risk of species"--