Dynamics of genotypic structure in clonal Rhododendron ferrugineum (Ericaceae) populations

Abstract

Two populations of Rhododendron ferrugineum growing at subalpine level in the Pyrenees (France) were studied in two sites (Bethmale and Mourtis). Identification and delimitation of genets were inferred from amplified fragment length polymorphism (AFLP) markers, along a closure gradient (from meadow to more closed heath) in each site. Surface and age of genets, genotypic diversity (Simpson's index D), 'proportion distinguishable' genotypes and genetic relationships between genets were then estimated. Amplification of the 312 DNA samples with three selective primer pairs gave a mean of 98 detectable peaks (i.e. bands) per sample, with size ranging from 60 to 300 bp. In total 60% (Bethmale) and 70% (Mourtis) of the peaks were polymorphic, and a total of 31 and 23 multilocus genotypes were identified, in Bethmale and Mourtis, respectively. We inferred that pioneer genotypes began arriving 110 years ago mainly over a 40-year period in the Mourtis meadow, and began about 130 years ago over a 100-year period in the Bethmale meadow. After this pioneer stage, populations extended vegetatively. Two different patterns of genotypic dynamics can be identified. At Bethmale, population closure could have led to a dramatic loss of genets and to the selection of highly genetically related genotypes. In contrast, at Mourtis, genotypic diversity and genet density did not change fundamentally along the closure gradient. However the range of genetic diversity diminished from the open to the closed situation, suggesting that thinning could have occurred in the past.

Sexual reproduction, clonal diversity and genetic differentiation in patchily distributed populations of the temperate forest herb Paris quadrifolia (Trilliaceae)

“…Investigation of belowground rooting systems in four populations occurring at both extremes of the observed environmental gradient showed that individuals in favorable sites are in general smaller [in favorable sites genets usually consist of 1-3 interconnected shoots, most of which flower, whereas genets in unfavorable sites may consist of up to 15 interconnected shoots, the majority of which is vegetative (H. Jacquemyn and R. Brys, unpublished results)]. Dominance of a limited number of genets adapted to dry conditions is therefore a likely explanation for the lower clonal diversity in dry sites (Pornon et al 2000). This increased investment in vegetative reproduction may be an effective means to maintain viable genets under high density or unfavorable site conditions.…”

Genetic patterns in range-edge populations of <i>Vaccinium</i> species from the central Balkans: implications on conservation prospects and sustainable usage

“…V. myrtillus, V. uliginosum and V. vitis-idaea are clonal plant species which reproduce generatively (predominantly by outcrossing) and vegetativelly (through rhizomes). In such species, an increase in levels of genetic diversity depends on the efficiency of the production of out-crossed seeds and mobilization of generatively reproduced plants (Eriksson 1989;Eriksson and Fröborg 1996;Persson and Gustavsson 2001;Albert et al 2004), while clonal propagation reduces levels of out-crossing, the formation of new genetic combinations (Charpentier 2002;Honnay and Bossuyt 2005) and ultimately levels of genetic diversity through the prevalence and domination of more competitive genotypes (genets) which are more efficient in producing ramets (Eriksson 1989(Eriksson , 1993Jacquemart et al 1994;Pornon et al 2000;Honnay and Bossuyt 2005;Clark-Tapia et al 2006). Although lower levels of genetic diversity are generally expected in clonal plant species (Hamrick and Godt 1989;Bartish et al 1999;Nybom and Bartish 2000), several studies revealed as much genetic diversity in clonal as in non-clonal plants (Ellstrand and Roose 1987), and this holds also for Vaccinium species (e.g.…”

Intra-clonal variation and a similarity threshold for identification of clones: application to Salix exigua using AFLP molecular markers

“…They found a mean value of 0.17 for all 21 species. In other studies Pornon et al (2000) found a PD of 0.16 to 0.18 in Rhododendron, while Suyama et al (2000) found 0.43 for dwarf bamboo and Parks and Werth (1993) calculated a value of 0.51 for bracken fern. In this study we calculated a PD value of 0.22.…”

“…Molecular genetic methods, on the other hand, allow for the identification of clones independent of environmental variation, can be easily tested for accuracy and reproducibility, and can give results after a single collection of vegetative material from the field. Increasingly, studies are using Amplified Fragment Length Polymorphisms (AFLPs) for the identification of plant clones (Arens et al 1998;Escaravage et al 1998;Winfield et al 1998;Pornon et al 2000;Suyama et al 2000;van der Hulst et al 2000;Cabrita et al 2001). AFLPs can reveal large numbers of markers with a high degree of reproducibility, overcoming problems inherent with isoenzyme and RAPD methods, and so are particularly suitable for surveys of fingerprint data.…”