Introgression shapes fruit color convergence in invasive Galápagos tomato

Abstract

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 Galapagos 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 Galapagos.

Solanum galapagense-derived purple tomato fruit color is conferred by novel alleles of the Anthocyanin fruit and atroviolacium loci

“…One plausible explanation for selection and maintenance of pigmentation may be related to the role of fruit pigmentation in enticing organisms that disperse seed (Grotewold, 2006). AS an example, orange fruit are postulated to have a selective advantage on the Galápagos Islands as the result seed disperser color preferences (Gibson et al, 2021). An Investigation of known seed disperser preferences on the Galápagos islands and LA1141 fruit could elucidate a possible evolutionary mechanism, but more exploration is required.…”

Prevalent Introgression Underlies Convergent Evolution in the Diversification ofPungitiusSticklebacks

“…The four cytonuclear discordances are cases in point: the results show that they have experienced introgression, and the recipient species/populations have preserved much more of the introgressed variation than the donor populations. It is known that introgression can shape trait evolution in both animals and plants, and can generate apparently convergent patterns of evolution ( Lamichhaney et al 2015 ; Zhang et al 2016 ; Jones et al 2018 ; Giska et al 2019 ; Gibson et al 2021 ). To explore the possible role of introgression in the phenotype transfer in Pungitius sticklebacks, we investigated introgression signatures in the core gene regulatory networks of armor trait development in the recipient populations.…”

Solanum galapagense‐derived purple tomato fruit color is conferred by novel alleles of the anthocyanin fruit and atroviolacium loci

“…It is also possible that purple pigmentation serves an adaptive role related to the synthesis of protective anthocyanins under high irradiance or the enticement of organisms that disperse seed (Grotewold, 2006 ). As an example, orange fruit is postulated to have a selective advantage on the Galápagos Islands due to seed disperser color preferences (Gibson et al, 2021 ). An Investigation of known seed disperser preferences on the Galápagos Islands and LA1141 fruit could elucidate a possible evolutionary mechanism.…”

“…The sequence data presented here suggest that multiple loss of function alleles at atv occurs on the Galápagos Islands. It is possible that purple pigmentation is not costly for the plant, and there is a lack of selective pressure on the Galápagos Islands to maintain the function of atv :similar to the loss of function of phytoene synthase‐1 at the yellow flesh ( r ) locus resulting in yellow fruit with low carotenoids (Gibson et al, 2021 ). A lack of selective pressure may explain why atv alleles may be more widespread in Galápagos tomatoes.…”