ORCID

Document Type

Article

Abstract

Biological invasions are natural experiments for studying the evolutionary and ecological processes underlying colonization success and range expansion. Using genome-wide data—generated via genotyping-by-sequencing (GBS) from 30 populations spanning Europe and South Africa—we investigated the colonization history and successful spread of the invasive buttonweed Cotula coronopifolia, an annual plant introduced into Europe from South Africa about 300 years ago. Our analyses identified three major lineages in Europe distributed across the continent, often co-occurring without evidence of admixture. Phylogenomic dating revealed that these lineages diverged > 2,000 years ago—well before the earliest European records—suggesting divergence within the native range and either multiple introductions or a single introduction with multiple lineages. Mating-system inference shows that reproduction occurs primarily via self-fertilization (∼70% on average), although outcrossing predominates in some populations, revealing a facultative mating system. This high selfing rate has led to extremely low heterozygosity in most populations and a strong genetic structure. Genetic clustering also revealed admixed individuals resulting from rare inter-lineage outcrossing; comparisons of empirical and simulated data indicate that increased diversity after sporadic admixture events decays rapidly under subsequent selfing. Both the introduction history and long-distance dispersal facilitated by waterbirds likely explain the scattered distribution of lineages across Europe. Altogether, these results illustrate Baker's “ideal weed” concept, highlighting the role of a flexible mating system in providing reproductive assurance during colonization and showing how predominant selfing can shape the genomic landscape of an invasive species.

Publication Date

2026-06-01

Publication Title

Genome Biology and Evolution

Volume

18

Issue

6

ISSN

1759-6653

Acceptance Date

2026-05-15

Deposit Date

2026-10-28

Funding

We thank for the sampling permits to the Junta de Andalucía (project 2021/13), English Nature, The Wildfowl & Wetlands Trust, The Royal Society for the Protection of Birds, Instituto da Conservacão da Natureza e Florestas, and the competent environmental authorities in and all the Netherlands. We are grateful to Salinas de Cetina for granting permission to access ES-CADI. Logistic support was provided by Laboratorio de Ecología Molecular (LEM-EBD) at Estación Biológica de Doñana (CSIC). We also thank Centro de Supercomputación de Galicia (CESGA) and Doñana's Singular Scientific-Technical Infrastructure (ICTS-RBD) for access to computational resources. We thank Prof. Glynis Goodman-Cron for the taxonomic clarification of the specimens collected in South Africa, and two anonymous reviewers for their constructive and valuable comments on an earlier version of the manuscript. This research was funded by the Spanish Ministerio de Ciencia e Innovacion (project number PID2020–112774GB-I00/AEI/10.13039/501100011033). RSG was supported by an FPI fellowship from the Spanish Ministerio de Ciencia, Innovacion y Universidades (PRE2021-099466). Sampling in Portugal was funded by FCT—Foundation for Science and Technology (UID/04326/2025 and LA/P/0101/2020). This research was funded by the Spanish Ministerio de Ciencia e Innovacion (project number PID2020–112774GB-I00/AEI/10.13039/501100011033). RSG was supported by an FPI fellowship from the Spanish Ministerio de Ciencia, Innovacion y Universidades (PRE2021-099466). Sampling in Portugal was funded by FCT—Foundation for Science and Technology (UID/04326/2025 and LA/P/0101/2020).

Keywords

Cotula coronopifolia, buttonweed, genomics of invasions, population genomics, seed dispersal, selfing

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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