Genetic Variability in Balkan Paleoendemic Resurrection Plants Ramonda serbica and R. nathaliae Across Their Range and in the Zone of Sympatry

• Published in: Frontiers in plant science Vol. 13; p. 873471
• Main Authors: Lazarević, Maja, Siljak-Yakovlev, Sonja, Sanino, Agathe, Niketić, Marjan, Lamy, Françoise, Hinsinger, Damien D, Tomović, Gordana, Stevanović, Branka, Stevanović, Vladimir, Robert, Thierry
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers 28.04.2022; Frontiers Media S.A
• Subjects: AFLP; gene flow; genetic diversity; genome size; Gesneriaceae; interploidy hybridization; Life Sciences; Plant Science; Gesneriaceae; gene flow; genetic diversity; interploidy hybridization; sympatry; mixed-ploidy zones; AFLP; genome size; AFLP gene flow genetic diversity genome size Gesneriaceae interploidy hybridization mixed-ploidy zones sympatry
• ISSN: 1664-462X; 1664-462X
• DOI: 10.3389/fpls.2022.873471

The genus includes three Paleoendemic and Tertiary relict species that survived in refugial habitats of the Balkan Peninsula ( and ) and the Iberian Peninsula ( ). They are all "resurrection plants," a rare phenomenon among flowering plants in Europe. and are diploids (2  = 2  = 48), while is a hexaploid (2  = 6  = 144). The two Balkan species occur in sympatry in only two localities in eastern Serbia, where tetraploid potential hybrids (2  = 4  = 96) were found. This observation raised questions about the existence of gene flow between the two species and, more generally, about the evolutionary processes shaping their genetic diversity. To address this question, genetic markers (AFLP) and an estimate of genome size variation were used in a much larger sample and at a larger geographic scale than previously. The combination of AFLP markers and genome size results suggested ongoing processes of interspecific and interploidy hybridization in the two sites of sympatry. The data also showed that interspecific gene flow was strictly confined to sympatry. Elsewhere, both species were characterized by low genetic diversity within populations and high population differentiation. This is consistent with the fact that the two species are highly fragmented into small and isolated populations, likely a consequence of their postglacial history. Within sympatry, enormous variability in cytotypes was observed, exceeding most reported cases of mixed ploidy in complex plant species (from 2 to >8 ). The AFLP profiles of non-canonical ploidy levels indicated a diversity of origin pathways and that backcrosses probably occur between tetraploid interspecific hybrids and parental species. The question arises whether this diversity of cytotypes corresponds to a transient situation. If not, the question arises as to the genetic and ecological mechanisms that allow this diversity to be maintained over time.