Class Year




Document Type


Degree Name

Bachelor of Arts (BA)

Department or Program


First Advisor

Lynn Westley

Second Advisor

Glenn Adelson

Third Advisor

Sean Menke


Exploring the geographic and temporal shifts of hybrid zones provides practical evidence for conservation biologists investigating the dynamics of species invasions (Aldridge and campbell 2006, Buggs 2007, Ellstrand 1992, Endler 1977, Rhymer and Simberloff, 1996). I measured Ipomopsis floral and vegetative traits in 12 populations along an elevational gradient near Gothic, Colorado. Plants in this population were measured in the early 1990s and in 2015, allowing me to track trait changes over time. Corolla length increased by an average of 4.4mm, and corolla width increased by 0.11mm between 1992 and 2015. Reciprocal transplant experiments found genetic and environmental bases for variation in corolla length and anther position. Genetic-based variation in the corolla length over 23 years could represent and evolutionary change and a plastic response to environmental variation. Contrastingly, corolla width did not change systematically over time. Floral trait variation in this hybrid zone involves a complex assortment of selection pressures, mediated by multiple pollinators and varied environmental conditions, which may be the cause of differential change in floral traits throughout the cline.

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