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Whitney, Kenneth D. Miller, Thomas E. Rudolf, Volker H. W. Sneck, Michelle 2013-07-24T19:47:57Z 2013-07-24T19:48:01Z 2013-07-24T19:47:57Z 2013-07-24T19:48:01Z 2012-12 2013-07-24 December 2012 2013-07-24T19:48:01Z Sneck, Michelle. "Evolutionary responses to global change: an experimental test of the effect of altered precipitation on hybridization rates in sunflower (Helianthus)." (2013) Master’s Thesis, Rice University. <a href="https://hdl.handle.net/1911/71692">https://hdl.handle.net/1911/71692</a>. https://hdl.handle.net/1911/71692 123456789/ETD-2012-12-329 Climate change is rapidly altering natural ecosystems. Plastic and adaptive responses to climate change (i.e., range shifts and phenology) have been widely noted across taxa. However, the effects of climate change on evolutionary processes such as interspecific gene flow (hybridization) are less well known. In this study, we quantified hybridization rates in response to experimental manipulations of rainfall, an important dimension of global change. We used rain-out shelters in the field and quantified rates of hybridization between two congeners, Helianthus annuus (common sunflower) and H. petiolaris (prairie sunflower). We found that H. annuus maternal plants produced hybrid progeny more than H. petiolaris maternal plants, with a trend for decreased rates of hybridization with increased soil moisture (when rain-out shelters were absent). The relative number of open inflorescences of each species predicted hybridization rates. Thus, this study demonstrates how changing environmental conditions, specifically precipitation, could influence hybridization rates. application/pdf eng Copyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder. Climate change Evolution Phenology Gene flow Hybridization Evolutionary responses to global change: an experimental test of the effect of altered precipitation on hybridization rates in sunflower (Helianthus) Thesis Text Ecology and Evolutionary Biology Natural Sciences Rice University Masters Master of Arts open.access