%0 PDF %T THE MECHANISMS AND CONSEQUENCES OF PHENOLOGICAL EVOLUTION %A Wadsworth, Crista. %8 2017-04-19 %R http://localhost/files/jh344440x %X Abstract: Phenological shifts are clearly biologically important as they contribute to both ecological speciation and persistence during global warming. However, the genetic and physiological mechanisms behind shifts remain unclear. This is due to complicated genetic and genomic bases, as well as the cryptic nature of the phenotype. The consequences of phenological shifts also remain largely unexplored. We expect that a novel temporal habitat will have a different thermal profile than the ancestral habitat due to seasonal thermal variation. Therefore, for successful phenological shifts we predict correlated evolution in thermal tolerance. My dissertation investigates both the mechanisms and evolutionary consequences of phenological shifts, and adds to a growing body of literature on these topics. I first investigate the physiological mechanism underlying evolution in life-history timing of corn borers. Using metabolic trajectories, I find that variation in the length of the diapause termination phase underlies an ~30-day shift observed in seasonal timing between E and Z-strains. While the E-strain exits diapause within 7 days, the Z-strain remains in diapause termination for ~30 more days. These metabolic trajectories are further used to target days for whole transcriptome profiling to nominate molecular mechanisms for the shift in timing. I nominate 48 candidate genes within the quantitative trait locus (QTL) for seasonal timing, and find that shorter E-strain termination is defined by a burst of genome-wide transcriptional activity involved in cell cycling, the stress response, and hormone production. I next interrogate the genomic architecture surrounding the QTL for differences in seasonal timing. I investigate if a chromosomal inversion could be present near the QTL for timing as previous studies found evidence of a large region of suppressed recombination in this region. Our results confirm that there is evidence for a large-scale rearrangement covering at least 20% of the Z (sex) chromosome that harbors the basis for seasonal timing differences. A final study looks at the consequences for evolved differences in seasonal timing between corn borer strains. As shifts in phenology displace populations across a season, they also expose populations to novel thermal environments. I find that earlier-emergence from winter diapause is correlated with enhanced cold-tolerance.; Thesis (Ph.D.)--Tufts University, 2016.; Submitted to the Dept. of Biology.; Advisor: Erik Dopman.; Committee: Sean Mullen, Frances Chew, Philip Starks, and Colin Orians.; Keyword: Biology. %[ 2022-10-11 %9 Text %~ Tufts Digital Library %W Institution