Adaptation to coastal environments in Swedish Arabidopsis thaliana /
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Author / Creator: | Merwin, Laura Alida, author. |
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Imprint: | 2015. Ann Arbor : ProQuest Dissertations & Theses, 2015 |
Description: | 1 electronic resource (214 pages) |
Language: | English |
Format: | E-Resource Dissertations |
Local Note: | School code: 0330 |
URL for this record: | http://pi.lib.uchicago.edu/1001/cat/bib/10773411 |
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100 | 1 | |a Merwin, Laura Alida, |e author. | |
245 | 1 | 0 | |a Adaptation to coastal environments in Swedish Arabidopsis thaliana / |c Merwin, Laura Alida. |
260 | |c 2015. | ||
264 | 1 | |a Ann Arbor : |b ProQuest Dissertations & Theses, |c 2015 | |
300 | |a 1 electronic resource (214 pages) | ||
336 | |a text |b txt |2 rdacontent | ||
337 | |a computer |b c |2 rdamedia | ||
338 | |a online resource |b cr |2 rdacarrier | ||
500 | |a Advisors: Joy Bergelson Committee members: Marcus R. Kronforst; Jocelyn E. Malamy; Catherine A. Pfister; David E. Salt. | ||
502 | |b Ph.D. |c The University of Chicago, Division of the Biological Sciences and Pritzker School of Medicine, Department of Ecology and Evolution |d 2015. | ||
510 | 4 | |a Dissertation Abstracts International, |c Volume: 77-05(E), Section: B. | |
520 | |a Plants display a variety of specialist adaptations to particular environments. Beach ecotypes are especially common due to a suite of abiotic stressors that act as environmental drivers of adaptation. These stressors include low water availability, salt deposition, low nutrient soil, burial by sand, and strong wind; associated phenotypes include dwarfism, succulence, cuticles and salt excluding glands, rapid growth, light coloration, reflective leaves, transpirational cooling, long hypocotyls, a high density of trichomes, and large seed size. The model organism Arabidopsis thaliana is found in a variety of environments across the globe, including coastal environments. As a predominantly selfing species, A. thaliana is a good candidate for the production of local ecotypes. Additionally, high-resolution genomic data and ease of phenotyping make A. thaliana an attractive choice for the experimental exploration of adaptation to beach environments. I use several complementary approaches to investigate coarse sand beach populations of A. thaliana on the Baltic Sea coast of southern Sweden. | ||
520 | |a In the first chapter, I investigate the genetic architecture of adaptation to beaches in A. thaliana using two types of genomic scans. First, I perform an unbiased genome wide scan using Population Branch Statistic (PBS) to identify regions of the genome under selection in the beach population of interest. I apply additional population genetic metrics to the top-scoring regions in order to identify putative genes involved in adaptation. Second, I focus on three phenotypes that differentiate beach and inland populations and are characteristic of beach plants: hypocotyl length, trichome density, and seed weight. I perform genome wide association mapping using 298 Swedish lines for each phenotype and identify significant associations with each phenotype, including a region of chromosome 4 near the candidate gene SPA2 significantly associated with hypocotyl length and a region on chromosome 2 strongly associated with trichome density and the candidate genes TCL1/TCL2/ETC2. Combining the two approaches described above, I ask whether the most closely associated SNPs for each phenotype have a higher average PBS value than expected. This test asks whether SNPs associated with phenotypes of interest show evidence of adaptation in the beach population, something I find to be true for hypocotyl length and seed weight, but not trichome density. Thus, hypocotyl length and seed weight appear to be under selection in the beach population. | ||
520 | |a In the second chapter, I investigate hypocotyl length more deeply. I demonstrate that plants from coarse sand beaches have significantly longer hypocotyls than inland and fine sand beach conspecifics and identify a genetic variant accounting for 18% of the variance in hypocotyl length in the mapping population. I confirm the correlation between this genetic variant and hypocotyl length in two additional populations, a global set of lines from the RegMap panel and in a set of Bay x Sha RIL lines, and demonstrate that this genetic variant increases seedling emergence frequency when seeds are buried. I conclude that this genetic variant is in linkage with a gene involved in hypocotyl elongation, possibly SPA2 (a suppressor of phytochrome A important for growth in darkness) and that this gene confers a fitness advantage when seeds are buried. | ||
520 | |a In the third chapter, I test the hypothesis that beach lines are more tolerant of drought and salt stress than inland conspecifics. I use total seed production as a proxy for lifetime fitness and quantify reductions in fitness under several levels of drought and salt spray stress. I detect no significant response to salt spray. While drought has a negative effect on fecundity, beach lines do not consistently show different responses to drought than inland lines. | ||
520 | |a This set of complementary studies approaches adaptation to beaches from genotypic, phenotypic, and environmental perspectives. I identify phenotypes and genetic regions important for adaptation in this population of A. thaliana, as well as an environmental driver of selection. Additionally, I introduce a new method of combining types of genomic data to yield information about phenotypes under selection in populations of interest. | ||
546 | |a English | ||
590 | |a School code: 0330 | ||
690 | |a Ecology. | ||
690 | |a Evolution & development. | ||
690 | |a Genetics. | ||
710 | 2 | |a University of Chicago. |e degree granting institution. | |
720 | 1 | |a Joy Bergelson |e degree supervisor. | |
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856 | 4 | 0 | |u http://dx.doi.org/10.6082/M19021PR |y Knowledge@UChicago |
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