| 1. |
- Prentice, Honor C, et al.
(author)
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Allozyme and chloroplast DNA variation in island and mainland populations of the rare Spanish endemic, Silene hifacensis (Caryophyllaceae)
- 2003
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In: Conservation Genetics. - 1566-0621. ; 4:5, s. 543-555
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Journal article (peer-reviewed)abstract
- Silene hifacensis is a narrowly endemic plant, restricted to a few small populations on limestone cliffs in the Spanish province of Alicante and on the Balearic island of Ibiza. The species was collected to extinction in its original mainland location by the early 20th century. Attempts have been made to reintroduce S. hifacensis to this area but conservation efforts are limited by a lack of information on the geographic structure of genetic variation in the species. We used nuclear (allozyme) and chloroplast DNA (cpDNA) PCR/RFLP markers to investigate the structure of genetic variation in 2 mainland and 6 Ibizan populations. Levels of allozyme variation were low, with a mean of 2 alleles per polymorphic locus. Mean (over polymorphic loci) total allozyme diversity (H-tot) was 0.203 and mean within-population diversity (H-pop) was 0.085. Most diversity was explained by the between-population diversity component (G(pop).reg = 57%). Both mainland populations showed allozyme fixation. Three composite cpDNA haplotypes were identified. The first is unique to a mainland population that is also allozymically distinct from all the other populations. The second haplotype is found in the other mainland population and one Ibizan population: these two populations are allozymically identical. The remaining Ibizan populations contain the third haplotype. The geographic distribution of allozymes and cpDNA haplotypes is discussed in terms of population history, dispersal and, speculatively, in terms of the possibility that there has been undocumented translocation of material between populations.
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| 2. |
- Gil-Lopez, Manuel J., et al.
(author)
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Different historical backgrounds determine contrasting phylogeographical patterns in two co-distributed Erica species (Ericaceae) across the Strait of Gibraltar
- 2017
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In: Botanical journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4074 .- 1095-8339. ; 185:3, s. 359-375
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Journal article (peer-reviewed)abstract
- Erica australis and Erica arborea are morphologically and ecologically similar heather species. Erica australis is restricted to the western Mediterranean Basin where it overlaps with the westernmost distribution of E. arborea. Here we investigate the role of the Strait of Gibraltar (SG) as a potential biogeographical barrier to dispersal and/or as glacial refugium in these two Erica spp. in the western Mediterranean (WMed) region with contrasting geographical origins and distributions. Samples were collected from 55 and 54 populations of E. australis and E. arborea, respectively. One individual each of 52 and 45 populations of E. australis and E. arborea, respectively, were sequenced for plastid DNA regions, and 1304 and 1214 individuals from 44 and 42 populations of E. australis and E. arborea, respectively, were genotyped using nuclear microsatellites (SSRs). Plastid DNA sequences were used to estimate divergence time of lineages and to construct haplotype networks. SSR data helped to infer population genetic diversity and fixation indices and genetic structure patterns through Bayesian analysis, analysis of molecular variance and isolation by distance. Plastid haplotype diversity of E. australis was higher in the SG than in the WMed area, whereas the opposite was found in E. arborea. SSRs revealed high genetic diversity within populations of both species and population genetic structure patterns were consistent with those retrieved from plastid DNA. The SG was identified as the likely area of origin and diversification for E. australis in the late Pliocene-Pleistocene, where it survived the Last Glacial Maximum (LGM) and expanded northwards into the western Iberian Peninsula. In contrast, two separate evolutionary lineages were found for E. arborea in the Iberian Peninsula. The SG and southern WMed areas represent the western Mediterranean expansion limit of an E. arborea lineage from East Africa/Arabia in the late Pliocene-Pleistocene, whereas the northern WMed populations were relicts from an older refugium that survived LGM in north-western Iberia. This study illustrates how geographical range and origin explain differences in the phylogeographical structure of co-distributed Mediterranean plants and highlights the role of the SG as a Pleistocene refugium and biogeographical crossroads in the Mediterranean.
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