Abstract
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 short selection history, within-generation phenotypic plasticity is often cited as the mechanism through which spread across multiple habitat types can occur. We show that trans-generational plasticity (TGP) can result in pre-adapted progeny that exhibit traits associated with increased fitness both in high-resource patches and in stressful conditions. In the invasive sedge, Cyperus esculentus, maternal plants growing in nutrient-poor patches can place disproportional number of propagules into nutrient-rich patches. Using the invasive annual grass, Aegilops triuncialis, we show that maternal response to soil conditions can confer greater stress tolerance in seedlings in the form of greater photosynthetic efficiency. We also show TGP for a phenological shift in a low resource environment that results in greater stress tolerance in progeny. These lines of evidence suggest that the maternal environment can have profound effects on offspring success and that TGP may play a significant role in some plant invasions.
Highlights
Post-invasion ecotypic variation in introduced environments (Rice and Mack 1991b; Sexton et al 2002; Maron et al 2004) can occur and may be the result of adaptation, genetic drift, within-generation plasticity, transgenerational plasticity (TGP; i.e. maternal environmental effects) or combinations of these evolutionary responses
We make a distinction between simple phenotypic plasticity (PP) and trans-generational plasticity (TGP), and we show that TGP can be important in both phases of invasion by increasing offspring fitness in both high-resource and stressful environments
We suggest that TGP provides a mechanism for increasing invasive plant fitness in both habitat types
Summary
Post-invasion ecotypic variation in introduced environments (Rice and Mack 1991b; Sexton et al 2002; Maron et al 2004) can occur and may be the result of adaptation, genetic drift, within-generation plasticity, transgenerational plasticity (TGP; i.e. maternal environmental effects) or combinations of these evolutionary responses. The important role of plastic responses is not surprising given that most populations experience strong demographic contractions during the dispersal process. These demographic contractions are often, but not always, correlated with reductions in genetic diversity; post-invasion adaptive potential is predicted to be highly reduced as a direct consequence (Barrett and Kohn 1991; Ghalambor et al 2007). In the primary a 2010 Blackwell Publishing Ltd 3 (2010) 179–192
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