Hybridization and Speciation in Plant Systems

Hybridization in plants is a pervasive evolutionary process that can both blur species boundaries and generate new lineages. It occurs when individuals from distinct taxa interbreed, producing offspring with admixed genomes. Depending on genomic architecture and ecological context, hybrid populations may either collapse back into parental species or persist and diverge through speciation. Two primary routes of hybrid speciation are recognised: homoploid hybrid speciation, where chromosome number remains constant, and allopolyploid speciation, which involves genome doubling. Hybrid lineages can acquire novel trait combinations, exploit unique ecological niches and evolve reproductive barriers against parental gene flow. Advances in genomics have revealed that the fate of hybrids hinges on the interaction between recombination landscapes, selection against incompatible gene combinations and the sorting of parental barrier regions. Across diverse plant groups, hybridisation has been linked to adaptive introgression of beneficial alleles, bursts of phenotypic innovation and the origin of reproductively isolated populations that contribute to global biodiversity.

Research from Nature Portfolio

Recent studies have applied genomic approaches to chestnut trees to reveal hybrid speciation via mosaic genomes and recombination landscapes that reposition parental barrier regions, underscoring the role of selection in shaping novel lineages. Investigations of mountain spiny fescues have demonstrated independent homoploid hybrid origins in distinct mountain ranges, driven by post-glacial contact and climate-mediated niche divergence that established reproductive isolation without chromosome doubling.

Hybridization and Speciation in Plant Systems publication trend

The graph below shows the total number of articles in hybridization and speciation in plant systems across all publications each year (not limited to Nature Index journals).

Technical terms

Homoploid hybrid speciation: Formation of a new species through hybridisation without change in chromosome number.

Allopolyploid speciation: Speciation via hybridisation accompanied by whole-genome duplication resulting in multiple sets of parental chromosomes.

Reproductive isolation: Mechanisms that prevent gene flow between diverging populations or species.

Introgression: Incorporation of genetic material from one species into the gene pool of another through repeated backcrossing.

Genomic admixture: The presence of genetic contributions from multiple ancestral lineages within an individual’s genome.

Recombination rate: The frequency at which genetic exchange occurs between homologous chromosomes during meiosis.

Dobzhansky–Muller incompatibility: Genetic incompatibilities that arise when interacting loci from different lineages reduce hybrid fitness.

References

1. Genomic basis of homoploid hybrid speciation within chestnut trees. Nature Communications (2020).
2. Past climate changes facilitated homoploid speciation in three mountain spiny fescues (Festuca, Poaceae). Scientific Reports (2016).
3. Genetic factors predict hybrid formation in the British flora. Proceedings of the National Academy of Sciences of the United States of America (2023).
4. A few genetic variants go a long way in differentiating Penstemon species. PLOS Biology (2023).
5. Genomics of Evolutionary Novelty in Hybrids and Polyploids. Frontiers in Genetics (2020).