IBB researchers discover a new hybrid species in Montjuïc
The diversity of flowering and fruiting plants, also called angiosperms, is absolutely bewildering, so much so that Charles Darwin himself called it “the abominable mystery”. This phenomenon is even more striking if we consider that our knowledge of the plants that exist or have existed is partial, with a world of species yet to be discovered in remote and inaccessible places, or as we are going to see here, on our doorstep.
This is the case of the new species described in Montjuïc, the product of hybridization between two closely related taxa. The hybrid is “born” when Urospermum picroides acts as the father (pollen donor) and U. dalechampii acts as the mother (ovule donor), resulting in apparently sterile individuals with a morphology intermediate between the parents (Figure 1). In fact, it was this intermediate morphology that led to think about the hybrid origin of these individuals, however, as plants usually have a high morphological variability, this hypothesis had to be confirmed using more tools.
To this end, chromosome number counts were carried out, revealing 12 chromosomes in the hybrid, just halfway between those observed in the parents (10 in U. picroides and 14 in U. dalechampii). The genome size and the composition of a special type of DNA, the repetitive elements, were studied, also showing intermediate values between the hybrid and its parents. Finally, chloroplast DNA, which is only passed from mother to offspring, was analyzed, confirming that it was U. dalechampii that acted as the egg donor.
Once the hybrid origin of these individuals was verified, the new hybrid species was described: Urospermum ×siljakii Hidalgo, Balant & Pellicer. When a taxon originates via hybridization, it is called a noto-species, with an “×” in the name to indicate that it has arisen from a cross between species. The name, in Latin, can refer to a characteristic of the plant or a geographical origin, but also to a person. In the present case, it was dedicated to a collaborator of our research group, Sonja Siljak-Yakovlev (University of Paris-Saclay, France). The reference sheet of the new species, called the type, has been deposited in the BC herbarium and is available for researchers to consult.
The discovery of this new hybrid species in Barcelona illustrates the urgent need to pay more attention to the flora around us. In the current context of global environmental crisis, it is essential to consider the impact of changes in the flowering periods of species, which could lead to new hybridizations such as the one observed in Urospermum.
Pellicer, J., Balant, M., Fernández, P., Rodríguez González, R., & Hidalgo, O. (2022). Morphological and genome-wide evidence of homoploid hybridisation in Urospermum (Asteraceae). Plants, 11(2), 182.
Hidalgo, O., Balant, M., & Pellicer, J. (2022). Urospermum ×siljakii (Asteraceae), a new natural homoploid hybrid between U. dalechampii and U. picroides. Phytotaxa, 544(2), 220-222.