Hypericum hybrids trapped in their polyploid gene pool

The underlying genetic causes of the switch to apomixes are not yet fully understood, but in Hypericum there is good evidence for the existence of ‘apomictic factors’.

Asexual reproduction via seed is correlated with hybridization of sexual, often diploid, ancestors. The evolutionary success of apomictic hybrid species has been explained by niche differentiation separating them from their sexual progenitors.

An abstract image of molecular data in plants

Molecular evidence provides a window into the evolutionary history of Hypericum perforatum, demonstrating reticulation among various gene pools. Scheriau et al. found that hybrid polyploids do not show significant niche differences compared to their diploid progenitors, and are trapped in the polyploid gene pool and the ecological climatic niche space of their diploid ancestors. The authors conclude that the observed absence of niche divergence precludes further differentiation and geographic partitioning of new polyploid lineages.

Further reading

Scheriau, C. L., Nuerk, N. M., Sharbel, T. F., & Koch, M. A. (2017). Cryptic gene pools in the Hypericum perforatum–H. maculatum complex: diploid persistence versus trapped polyploid melting. Annals of Botany, 120(6), 955–966. https://doi.org/10.1093/aob/mcx110