Invasive species represent one of the foremost risks to global biodiversity. Here, we use population genomics to evaluate the history and consequences of an invasion of wild tomato- Solanum pimpinellifolium-onto the Galápagos Islands from continental South America. Using >300 archipelago and mainland collections, we infer this invasion was recent and largely the result of a single event from central Ecuador. Patterns of ancestry within the genomes of invasive plants also reveal post-colonization hybridization and introgression between S. pimpinellifolium and the closely related Galápagos endemic Solanum cheesmaniae. Of admixed invasive individuals, those that carry endemic alleles at one of two different carotenoid biosynthesis loci also have orange fruits-characteristic of the endemic species-instead of typical red S. pimpinellifolium fruits. We infer that introgression of two independent fruit color loci explains this observed trait convergence, suggesting that selection has favored repeated transitions of red to orange fruits on the Galápagos.
Bibliographical noteFunding Information:
We thank the Galápagos Science Center staff on San Cristóbal for logistic and permitting support, and the Galápagos National Park for assistance locating and sampling endemic populations. On-site field support was provided by Marcelo Loyola and Genaro Garcia. We also thank two anonymous reviewers for valuable comments that greatly improved the manuscript. This work was supported by a United States National Science Foundation award (IOS 1127059) to LCM and the Indiana University Brackenridge award to MJSG. All field collections were made with appropriate permits and prior authorization by the Galápagos National Park and Ecuadorian Ministry of Environment (Permits PC-40-18 and PC-72-19).
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