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In plant conservation, restoration (the augmentation or reestablishment of an extinct population or community) is a valuable tool to mitigate the loss of habitat. However, restoration efforts can result in the introduction of novel genes and genotypes into populations when plant materials used are not of local origin. This movement is potentially important(More)
While small-scale studies show that more diverse native communities are less invasible by exotics, studies at large spatial scales often find positive correlations between native and exotic diversity. This large-scale pattern is thought to arise because landscapes with favorable conditions for native species also have favorable conditions for exotic(More)
High-impact biological invasions often involve establishment and spread in disturbed, high-resource patches followed by establishment and spread in biotically or abiotically stressful areas. Evolutionary change may be required for the second phase of invasion (establishment and spread in stressful areas) to occur. When species have low genetic diversity and(More)
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Polyploidy has been ubiquitous in plant evolution and is thought to be an important engine of biodiversity that facilitates speciation, adaptation, and range expansion. Polyploid species can exhibit higher ecological tolerance than their progenitor species. For allotetraploid species, this higher tolerance is often attributed to the existence of heterosis(More)
Although exotic species cause tremendous economic and ecological loss, we know relatively little about the post-introduction evolutionary dynamics of the invasive species themselves. Barbed goatgrass, Aegilops triuncialis L., is a cleistogamous annual grass with a native range throughout the Mediterranean Basin and Asia and introduced to California during(More)
Root plasticity, a trait that can respond to selective pressure, may help plants forage for nutrients in heterogeneous soils. Agricultural breeding programs have artificially selected for increased yield under comparatively homogeneous soil conditions, potentially decreasing the capacity for plasticity in crop plants like barley (Hordeum vulgare). However,(More)
Understanding how genetic variation shapes species' distributions involves examining how variation is distributed across a species' range as well as how it responds to underlying environmental heterogeneity. We examined patterns of fitness variation across the local distribution of an annual composite (Lasthenia fremontii) spanning a small-scale inundation(More)
Multiple introductions can play a prominent role in explaining the success of biological invasions. One often cited mechanism is that multiple introductions of invasive species prevent genetic bottlenecks by parallel introductions of several distinct genotypes that, in turn, provide heritable variation necessary for local adaptation. Here, we show that the(More)
Species interactions play a critical role in biological invasions. For example, exotic plant and microbe mutualists can facilitate each other's spread as they co-invade novel ranges. Environmental context may influence the effect of mutualisms on invasions in heterogeneous environments, however these effects are poorly understood. We examined the mutualism(More)