Haplotype richness in refugial areas: phylogeographical structure of Saxifraga callosa

Abstract

This paper illustrates the phylogeographical structure of Saxifraga callosa in order to describe its genetic richness in refugial areas and to reconstruct its glacial history. S. callosa is a species spread throughout south-east France and Italy with a high distribution in the Maritime Alps. Four chloroplast microsatellite and AFLP markers were analyzed in populations of S. callosa. The size variants of all tested loci amount to 11 different haplotypes. Intrapopulational haplotype variation was found in two of the populations analyzed: on the Mt. Toraggio in the Maritime Alps, and in the Apuan Alps. On the other hand, no intrapopulational variation was found in 25 populations, most of which were sampled from isolated areas. Analysis of the haplotype distribution showed that population subdivision across all populations was high (G (ST) = 0.899). Moreover, its genetic structure was studied using AMOVA and STRUCTURE analysis. The study legitimated inferred conclusions about the phylogeographical structure of the species and identified centers of diversity. Considerations concerning genetic structure and divergence among three major clades (Maritime Alps, Apuan Alps and Apennines), the patchy distribution of haplotypes, and the high number of private haplotypes support the proposal that S. callosa survived in some refugia within the Italian Peninsula refugium, and that mainly northern populations of refugia were involved in postglacial recolonization.

Allopatric divergence and secondary contacts in Euphorbia spinosa L: Influence of climatic changes on the split of the species

“…Ribotype abbreviations are given in Table 3 Grassi et al 2009). On the other hand, this phylogeographic pattern is not completely comparable with the genetic diversity observed for S. callosa and A. alpina within the Apuan Alps (Ansell et al 2008;Grassi et al 2009). Indeed, AFLP and haplotype markers supported the proposal that these two alpine species survived in a refugia within the Apuan Alps, whereas, for E. spinosa, there is no evidence of glacial refugia in the Apuan Alps.…”

“…They were the primary refugia for numerous animal and plant species that later re-colonized the continent. In addition, the diversification of genetic lineages occurred among smaller range fragments within these refugial areas and within other small areas (Ansell et al 2008;Grassi et al 2009;Médail and Diadema 2009). Many endemic taxa inhabiting refugial areas were characterized by allopatric fragmentation.…”

“…Unfortunately, plant material from the Apennines has not been studied to any great extent (Ansell et al 2008;Grassi et al 2009), and so the existence of multiple refugia, or "refugia within refugia" (Gómez and Lunt 2007) in the southern part of the Italian Peninsula has not been examined. A phylogeographic study might clarify the role of this area in the genetic structure of mountain plants during the latest climatic changes.…”

Genetic Biodiversity and Phylogenetic Studies in Poplar by Means of the Metallothionein Multigene Family

“…The mean h value of the Sele population was slightly higher in comparison with that calculated by Salvini et al (2001) in the case of five populations of P. tremula distributed along the Italian peninsula (0.51 Vs 0.33). These moderately high level of both genetic variability and number of haplotypes with respect to the same P. tremula Italian populations [8 Vs 6 - (Salvini et al, 2001)] can possibly be attributed to the fact that the white poplar population here analysed is located in an area (the Cilento) considered as a glacial refugium and a hot spot of biodiversity for several angiosperm species (Cottrell et al, 2005;Fineschi & Vendramin, 2004;Grassi et al, 2009;Petit et al, 2002;Petit et al, 2003). The nSSR analysis carried out on the same population revealed that the expected heterozygosity was relatively high (He 0.460), but in accordance with those reported by Castiglione et al (2010) in the case of three populations distributed along the banks of three rivers in northern and central Italy and with that calculated by Lexer et al (2005) for two populations of P. alba (0.419 and 0.341), and two of P. tremula (0.466 and 0.483 -Lexer et al 2005).…”

The plant endemism in the Maritime and Ligurian Alps

“…(Grassi et al 2009) survived glacial age in refugia within the MLA too. The phylogeographical pattern based on molecular data of Euphorbia spinosa (Zecca et al 2011) supports the hypothesis of long-term separation of the north-western (Maritime Alps, Sardinia, Corsica, North Apennines) and south-eastern (South Apennines and Balkan area) lineages; together with the estimated divergence time this result suggests the survival of the species into at least two glacial refugia during the Quaternary glaciations.…”