Genetic structure and diversity in Ramonda myconi (Gesneriaceae): effects of historical climate change on a preglacial relict species

Abstract

The importance of the Mediterranean Basin as a long-term reservoir of biological diversity has been widely recognized, although much less effort has been devoted to understanding processes that allow species to persist in this area. Ramonda myconi (Gesneriaceae) is a Tertiary relict plant species restricted to the NE Iberian Peninsula. We used RAPD and chloroplast markers to assess the patterns of genetic structure in eight mountain regions covering almost the full species range, to identify the main historical processes that have shaped its current distribution and to infer the number and location of putative glacial refugia. While no cpDNA variation was detected, the species had relatively high levels of RAPD variation. Maximum levels of diversity were found within populations (71%), but there was also a significant differentiation between geographical regions (20%) and among populations within regions (9%). A spatial AMOVA identified three main groups of populations, corresponding to previously recognized centers of endemism and species richness. In addition, we found a marked geographical pattern of decreasing genetic diversity and increasing population differentiation from west to east. Our results support a complex phylogeographic scenario in the Iberian Peninsula of "refugia-within-refugia" and suggest that the higher diversity observed in western regions might be associated with prolonged and more stable climatic conditions in this area during the Quaternary.

Population size, center–periphery, and seed dispersers’ effects on the genetic diversity and population structure of the Mediterranean relict shrub Cneorum tricoccon

“…Limited gene flow among populations is also in agreement with the strong genetic drift observed in certain populations (e.g., CA and ME), where many alleles were fixed. Finally, as has been documented in other long live Tertiary relicts, gene flow may have been interrupted during some historic periods, increasing isolation and therefore F ST values (Dubreuil, Riba, & Mayol, 2008; Rodríguez‐Sánchez, Guzman, Valido, Vargas, & Arroyo, 2009; Rodríguez‐Sánchez et al., 2008). …”

Pollen and seed morphology of resurrection plants from the genus Ramonda (Gesneriaceae): relationship with ploidy level and relevance to their ecology and identification

“…The 2 species cooccur only in SE Serbia, establishing a sympatric zone with mixed syntopic populations (Stevanović et al, 1986b). On the other side of Europe, R. myconi survives in limestone gorges and humid mountain valleys of the Pyrenees (Pico and Riba, 2002;Dubreuil et al, 2008). They all prefer limestone rocks, but R. nathaliae can also be found on ophiolitic bedrock (Košanin, 1921;Stevanović and Stevanović, 1985).…”

Initial Determination of Polymorphism andIn VitroConservation of SomeRamonda SerbicaandRamonda NathaliaePopulations from Albania, Macedonia and Bulgaria

“…The importance of the Balkan and Mediterranean areas as a reservoir of genetic diversity has been supported by the numerous phylogeographic studies and has benefited from the application of molecular markers and theoretical models of population genetics. Recent studies have shown that this higher genetic diversity only holds at the regional scale and that most Mediterranean relict populations often have reduced withinpopulation genetic diversity and high genetic distinctiveness, in vitro thereby increasing their conservation interest (5).…”

“…1). Ramonda myconi (L.) Rchb., another member of Gesneriads, is found in northeastern Spain and the central Pyrenees (5,15). Because of beautiful flowers in lilac and violet colours with an orange-yellow centre and rosette leaves, these species are mentioned as decorative plants (1,2,7,9).…”