Dubreuil M., Riba M., Mayol M. (2008) Genetic structure and diversity in Ramonda myconi (Gesneriaceae): Effects of historical climate change on a preglacial relict species. American Journal of Botany. 95: 577-587.LinkDoi: 10.3732/ajb.2007320
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.
Dubreuil M., Sebastiani F., Mayol M., González-Martínez S.C., Riba M., Vendramin G.G. (2008) Isolation and characterization of polymorphic nuclear microsatellite loci in Taxus baccata L.. Conservation Genetics. 9: 1665-1668.LinkDoi: 10.1007/s10592-008-9515-3
Seven polymorphic nuclear microsatellite markers for Taxus baccata L. (English yew) were developed using an enriched-library method. An additional polymorphic SSR was obtained by testing eight primer pairs from the congeneric species Taxus sumatrana. Mendelian inheritance for the seven Taxus baccata SSRs was proved by genotyping 17 individuals and 124 megagametophytes (conifer seed haploid tissue). A total of 96 individuals from 5 different populations (10-26 samples per population) were used to estimate genetic diversity parameters. High levels of genetic diversity, with values ranging from 0.533 to 0.929 (6-28 alleles per SSR) were found. No linkage disequilibrium between pairs of loci was detected. All loci but one showed significant departures from Hardy-Weinberg equilibrium. Excess of homozygosity was probably due to high inbreeding in English yew populations, an outcome of low effective population size and/or fragmented distribution. Highly polymorphic SSRs will be used to conduct population genetic studies at different geographical scales and to monitor gene flow. © 2008 Springer Science+Business Media B.V.
Dubreuil M, Riba M, Mayol M (2008) Genetic structure and diversity in Ramonda myconi (L.) Rchb. (Gesneriaceae): effects of historical climate change on a preglacial relict species. American Journal of Botany 95: 577-587.
Dubreuil M, Sebastiani F, Mayol M, González-Martínez SC, Riba M, Vendramin GG (2008) Isolation and characterization of polymorphic nuclear microsatellite loci in Taxus baccata L. Conservation Genetics 9: 1665-1668.
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