Invasion away from roadsides was not driven by adaptation to grassland habitats in Dittrichia graveolens (stinkwort)

Invasive plants along transportation corridors can significantly threaten ecosystems and biodiversity if they spread beyond anthropogenic environments. Rapid evolution may increase the ability of invading plant populations to establish in resident plant communities over time, posing a challenge to invasion risk assessment. We tested for adaptive differentiation in Dittrichia graveolens (stinkwort), an invasive species of ruderal habitat in California that is increasingly spreading away from roadsides into more established vegetation. We collected seeds from eight pairs of vegetated sites and their nearest (presumed progenitor) roadside population. We assessed differentiation between populations in roadside and vegetated habitat for germination behavior and for response to competition in a greenhouse experiment. We also tested for increased performance in vegetated habitat with a grassland field experiment including a neighbor removal treatment. Germination rates were slightly reduce..., Plant community survey: Data was collected at 8 sites of Dittrichia graveolens in Santa Clara County, CA, USA, from July 1st through August 14th, 2020. Each site had a roadside and vegetated population pair. At each population, we laid a 50 m transect tape along the longest axis of the population (for roadsides, transects were always parallel to the road) and placed a 0.5 x 0.5 m quadrat at three equidistant points along the axis. We visually estimated percent cover within each quadrat for D. graveolens, other vegetation, and bare ground (sum equaling 100%). We identified species within the three quadrats for each population and then walked the area to search for additional rare species. Taxa were identified to species when possible using The Jepson Manual: Vascular Plants of California (Second Edition). We calculated the average percent cover of bare ground, D. graveolens, and other vegetation per population by taking the mean of the three quadrats along each transect. Species richness..., , **1) Title of Dataset:** Data from \"Invasion away from roadsides was not driven by adaptation to grassland habitats in Dittrichia graveolens (stinkwort)\"

[https://doi.org/10.5061/dryad.wdbrv15wz](https://doi.org/10.5061/dryad.wdbrv15wz)

**2) Author Information:**

Principal Investigator Contact Information

* Name: Miranda Melen
* Institution: University of California, Santa Cruz
* Address: 130 McAllister Way, Santa Cruz, CA 9506
* Email: [[e-mail]](mailto:[e-mail])

Associate or Co-investigator Contact Information

* Name: Ingrid Parker
* Institution: University of California, Santa Cruz
* Address: 130 McAllister Way, Santa Cruz, CA 9506
* Email: [[e-mail]](mailto:[e-mail])

**3) Year of data collection:**

* community_survey.csv - 2020
* quadrat_data.csv - 2020
* community_surveys_presence_absence_E.csv - 2020
* cox_germ_filter_paper8-2-21.csv - 2021
* cox_germ_constructionsoil8-2-21.csv - 2021
* cox_germ_fieldsoil8-2-21.cs...