Discussion
Research on the degree of local adaptation in plant communities is urgently needed to inform ecosystem restoration efforts (Bischoff et al. 2006, Vander Mijnsbrugge et al. 2010, Bischoff et al. 2010, Breed et al. 2018). Here, we devised a common garden experiment using both cleistogamous and chasmogamous seeds of D. californica and expected to see a local advantage for seeds of both types. However, we did not find any evidence for local seeds outperforming seeds sourced from other populations (nonlocal seeds) at either of our common garden sites. These results align with the findings of Hereford (2010) who, in a review of reciprocal transplant experiments, found that mating system does not generally influence local adaptation. Instead, we found that seeds of both types sourced from the north of our HD common garden performed significantly better than seeds sourced both locally and from more southern locations.
An absence of local adaptation could stem from intermediate levels of either inbreeding or gene flow, or a lack of strong divergent selective pressure on either of our common garden populations (Lenormand 2002, Hereford 2010). Another possibility for why we may not have seen local adaptation could be because our study looked exclusively at germination. Adaptation patterns may come from the accumulation of small fitness advantages over a plant’s life history, which are not always consistent with those of the establishment stage (Rice & Knapp 2008, Jin et al. 2020).