Testing assisted gene flow in restoration of winterfat, Krascheninnikovia lanata, a Great Basin desert shrub
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Authors
Silliman, Catherine M.
Issue Date
2024
Type
Thesis
Language
en_US
Keywords
assisted migration , climate change adaptation , ecological restoration , herbivory , outplanting , seed germination
Alternative Title
Abstract
Climate strongly influences the distribution of plant species, and as the climate has shifted, plants have historically responded by evolving, migrating, or perishing. However, anthropogenic climate change may be occurring at a rate such that local, native plant populations cannot respond. In addition to climate change, changes in disturbances such as wildfires and weed invasion can pose challenges for natural regeneration of native plant communities. To combat these challenges and increase the diversity and density of native plant communities, active restoration is used to restore landscapes, and increasingly, practitioners are considering the use of non-local seeds from warmer or drier locations in restoration. Here, focusing on the Great Basin and Mojave deserts, we focused on restoration of a widespread shrub, winterfat (Krascheninnikovia lanata), asking how seedling emergence and outplant seedling survival vary among 15 populations collected across both deserts. Populations were sampled across a 116,893 km2 boundary. We monitored seedling emergence in a greenhouse, grew plants for 9 months, and outplanted seedlings into two northern gardens and one container experiment. In the greenhouse, populations from cooler, wetter, northern and western populations emerged fastest, taking an average of 100 hours for the fastest population to emerge (relative to 158 hours for the slowest). Seedlings grown in the greenhouse differed in size among populations before outplanting, with southern populations tending to be larger. Regardless of source, larger outplanted seedlings had a higher probability of surviving the first growing season, and size, rather than population of origin, best predicted survival. However, after an herbivory event in the second growing season, there was a strong signal of local adaptation in one field garden, where non-local plants disproportionately experienced strong herbivory by native Mormon crickets, which increased mortality and resulted in a strong signal of local adaptation. Though an assisted gene flow strategy could potentially increase genetic diversity in Great Basin populations, our results suggest that more southern populations are not inherently able to survive the conditions in the northern Great Basin, and highlight the importance of field studies to identify barriers to assisted gene flow.