Hybrid Garlic Species Discovered in South America Shows Genomic Instability Despite Morphological Similarity
Researchers have confirmed that two wild garlic species, Nothoscordum montevidense and N. bonariense, are hybridizing in the wild, producing offspring with intermediate chromosome numbers and signs of genomic instability. The study used an integrative approach combining cytogenetics, flow cytometry, genome sequencing, and species distribution modeling to characterize the hybrids and their parent species. The findings demonstrate that profound genomic complexity can exist in plants that appear morphologically indistinguishable, underscoring the limitations of relying on physical traits alone to identify species.
A new preprint study published on bioRxiv documents natural hybridization between two sympatric South American wild garlic species, Nothoscordum montevidense (2n=16) and N. bonariense (2n=26), within the family Amaryllidaceae. Researchers discovered plants with intermediate morphological traits growing alongside both parent species and employed multiple analytical methods—including chromosome banding, fluorescence in situ hybridization (FISH), flow cytometry, genotyping-by-sequencing (GBS), and chloroplast genome assembly—to confirm their hybrid origin. Hybrid individuals were found to carry 2n=21 or 2n=25 chromosomes, with genome sizes intermediate between the two parents, and exhibited meiotic irregularities consistent with interspecific hybridization. Chloroplast phylogenetics identified N. montevidense as the maternal parent, while GBS data pointed to N. bonariense as the paternal contributor and also revealed evidence of backcrossing with parental species. Notably, reduced diversity in 35S ribosomal DNA in the hybrids suggests post-hybridization genomic restructuring, a hallmark of genomic instability in this genus. Despite this complexity, no clear morphological differences were detected among hybrid individuals, highlighting how physical appearance can mask deep genomic divergence. Species distribution models and phenological data confirmed broad geographic and temporal overlap between the two parent species, explaining the conditions that facilitate ongoing hybridization.
What's missing
As a preprint, this study has not yet undergone formal peer review, so its methods and conclusions have not been independently validated. The study does not address whether the identified hybrids are fertile or capable of establishing stable hybrid lineages, nor does it quantify how frequently hybridization occurs across the broader range of these species. The long-term evolutionary fate of these hybrids—whether they represent a dead end or a pathway toward new species—remains an open question.
What different sources said
- bioRxivCenter
Genomic instability within a sympatric complex of South American garlics (Nothoscordum spp., Amaryllidaceae)
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