One genotype dominates a facultatively outcrossing plant invasion

Authors: Gaskin, John; ENDRISS, STACY - Cornell University; FETTIG, CHRISTA - Colorado State University; HUFBAUER, RUTH - Colorado State University; NORTON, ANDREW - Colorado State University; SFORZA, RENE FH - European Biological Control Laboratory (EBCL)

Submitted to: Biological Invasions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2021
Publication Date: 2/18/2021
Publication URL: https://handle.nal.usda.gov/10113/7389723
Citation: Gaskin, J.F., Endriss, S.B., Fettig, C., Hufbauer, R., Norton, A., Sforza, R. 2021. One genotype dominates a facultatively outcrossing plant invasion. Biological Invasions. https://doi.org/10.1007/s10530-021-02480-0.
DOI: https://doi.org/10.1007/s10530-021-02480-0

Interpretive Summary: Common mullein (Verbascum thapsus) is an invasive plant in the USA. We used molecular genetic analyses to determine the diversity of the invasion, where the diversity exists in the USA, and the origins of the invasion. We found the invasion dominated (61% of plants) by a single genotype, which is spread across the USA and even in Hawaii. Further, we determined that the origin of the invasion is Belgium and Germany. The identification of the most common and diverse invasive genotypes of common mullein allows their use in tests of management tools and further studies of mechanisms of this invasion.

Technical Abstract: Plant invasions are rarely homogenous. Processes such as selection, drift, gene flow, and founding events can rapidly shape the genetic diversity and spatial population structure of an invasion. We investigated the diversity, origins and population structure of Verbascum thapsus (common mullein), an introduced plant in North America. Despite this species being facultatively outcrossing, we found the invasion dominated by a single genotype (61% of plants were identical amplified fragment length polymorphism [AFLP] genotypes in the western USA). 50% of the invasion populations were monotypic, and we found 32 genotypes overall in the 431 plants sampled from the invasion. In contrast, populations were much more diverse in the native Eurasian range, with 394 genotypes found in 479 plants. Further, we found an exact genetic match between the common genotype 1 in the USA and plants from Belgium and Germany. The identification of the most common and diverse invasive genotypes of common mullein allows their use in tests of management tools and further studies of mechanisms of this invasion.