Phenotypic Selection and Evolution in Experimentally Introduced Brassica rapa in a Novel Environment

Michael Robert Sekor, Fordham University


While examining phenotypic selection and rapid evolution in introduced species has been a recent focus of evolutionary biology, little is known about the selective pressures, and the potential for rapid evolution, experienced by introduced populations within the first few generations following introduction. This dissertation research project uses the novel approach of combining an experimental introduction with the resurrection approach of comparing ancestors and descendants in a common garden to examine selection and evolution directly following introduction. In 2011, two thousand seeds of the annual plant Brassica rapa were introduced from Southern California to New York. During the first three years following introduction, the introduced population experienced direct selection for larger size that varied in strength, but generally not direction. The introduced population also experienced direct selection for earlier flowering in 2011 and 2012, as well as direct selection for shorter duration of flowering in 2011 and longer duration of flowering in 2013. However, the resurrection experiment examining the evolution of adult traits demonstrated rapid evolution of smaller size, earlier flowering, and shorter duration of flowering since introduction. Resurrection experiments examining the evolution of seed traits, including dormancy in the autumn and a stratification requirement, were also conducted, and did not demonstrate evolution in these traits. These results suggest that rapid evolution within three years is possible and demonstrates the utility of the resurrection approach in examining rapid evolution following introduction. These findings also suggest that traditional phenotypic selection analyses may not always accurately predict rapid evolution directly following introduction.^

Subject Area

Botany|Ecology|Evolution & development

Recommended Citation

Sekor, Michael Robert, "Phenotypic Selection and Evolution in Experimentally Introduced Brassica rapa in a Novel Environment" (2017). ETD Collection for Fordham University. AAI10274250.