Abstract Detail

Darwins' reversals: What we now know about Feralization and Crop Wild Relatives

Drummond, Emily [1], Rieseberg, Loren [2].

Phenotypic and genotypic differences between wild and weedy annual sunflowers (Helianthus annuus L.).

Agricultural weeds represent excellent case studies of adaptation to human-mediated selection occurring on a contemporary time-scale. Weeds growing in crop fields are exposed to fertilizers and herbicides, as well as irrigation and regular disturbance from crop cultivation. Such disturbances are often highly predictable and may impose strong selection on weed populations. As a result, successful annual weeds often show changes to their life cycles, exhibiting more rapid development and earlier flowering in comparison with wild counterparts; evolved herbicide resistance is also commonly seen. Wild Helianthus annuus L. (common annual sunflower) is native to North America, where it grows naturally and occurs alongside the cultivated form (also H. annuus) with which it remains interfertile, despite morphological differences. Helianthus annuus also commonly acts as a problematic agricultural weed in North America, as well as other parts of the world where sunflower crops are grown. While weedy populations in North America most likely arose from local wild populations, elsewhere in the world, weedy sunflowers represent crop-wild hybrids (and/or de-domesticated ferals). In this study, North American populations of "weedy" sunflowers found in agricultural fields were compared to paired "wild" populations occurring in more natural habitats. Using a common garden experiment, individuals from nine matched weedy-wild population pairs were evaluated for differences in life history traits, including growth rate and flowering time. After controlling for maternal effects (using seed weight as a covariate), weedy populations showed higher growth rates (as biomass over time) and an earlier initiation of flowering. Resistance to the herbicide glyphosate was also common, but in both weedy and wild populations. Complementary to the common garden work, the genetic basis of adaptation in weedy sunflowers was also examined using whole-genome resequencing data for a subset of individuals. This analysis, which utilized genome scans based on F_ST, allowed the detection of parallel genetic changes among the weedy populations. In the preliminary results, a number of small regions of genetic differentiation between weedy and wild populations were identified.

1 - 109 - 489 West 26th Ave, Vancouver, BC, V5Y 0M8, Canada
2 - University Of British Columbia, Department Of Botany, 6270 University Blvd, Vancouver, BC, V6T 1Z4, Canada

Keywords:
agricultural weeds
invasion biology
life history evolution
Helianthus annuus
genetic differentiation
whole genome resequencing.

Presentation Type: Colloquium Presentations
Session: C03, Darwins' reversals: What we now know about Feralization and Crop Wild Relatives
Location: /
Date: Tuesday, July 20th, 2021
Time: 11:15 AM(EDT)
Number: C03006
Abstract ID:808
Candidate for Awards:None