Abstract Detail

Evolutionary insights from studies of geographic variation: Establishing a baseline and looking ahead to future change

Schneider, Heather [1], Mazer, Susan J [2].

Predicting the effects of climate change on life history and floral traits of selfing and outcrossing Clarkia taxa along an elevation gradient.

The most common explanations of the evolution of self pollination focus on advantages related to reproductive success. For example, if pollinators are lost or become phenologically mismatched with flowering time, selection may favor selfing. However, climate change predictions for much of California predict increased warming and drought, potentially leading to a shortened growing season for spring wildflowers. Under this scenario, selection could favor traits that may be correlated to selfing, such as a rapid life cycle and small flowers with short anther-stigma distance (herkogamy). If these traits are genetically linked to selfing, this could lead to the “indirect” evolution of selfing. We conducted a greenhouse experiment to detect evidence for genetically based variation among wild plant populations of two closely related species in the Clarkia genus, a widespread genus of native Californian wildflowers. Previous research has demonstrated that selfing species of Clarkia tend to have faster life cycles, faster photosynthesis, and smaller flowers with lower pollen:ovule ratios than their outcrossing sister taxa. Using field-collected seeds of two sister taxa: C. unguiculata (outcrossing) and C. exilis (selfing) from 11 populations across an elevation gradient, we looked for population level variation in traits such as first flower date, herkogamy, flower size, and gas exchange rates. We sought to determine whether populations of outcorssers that are more like their selfing sister taxa with respect to flowering time were also more similar to selfing taxa with respect to other traits and vice versa. For example, do outcrossing populations that tend to flower early also exhibit lower herkogamy? Similarly, do selfing populations that tend to flower late exhibit other characteristics that are similar to outcrossers? Furthermore, is there an elevational pattern to these relationships? Our preliminary results support the aforementioned results of previous studies, but also demonstrate elevational patterns within taxa. Both selfing and outcrossing populations had earlier first flower and sixth flower dates at low elevations and later dates at high elevations. Herkogamy in selfing populations tended to decrease with increasing elevation, while the herkogamy of outcrossing populations had no relationship to elevation. 

1 - University of California, Santa Barbara, Ecology, Evolution, & Marine Biology, Santa Barbara, CA, 93106, USA
2 - University of California, Santa Barbara, Ecology, Evolution & Marine Biology, 4119 Life Sciences Bldg, Santa Barbara, CA, 93106, USA

Keywords:
Climate change
Clarkia
Geographic variation
Evolution
floral traits.

Presentation Type: Symposium or Colloquium Presentation
Session: SY08
Location: Firs North/Boise Centre
Date: Wednesday, July 30th, 2014
Time: 9:15 AM
Number: SY08004
Abstract ID:267
Candidate for Awards:None