Detection of genetically divergent clone mates in apomictic dandelions

Abstract

This study aims to identify genetically diverged clone mates in apomictic dandelions. Clone mates are defined as individuals that may have diverged as a result of mutation accumulation and that have undergone only clonal reproduction since their most recent common ancestor. Based on distinctive morphology and an aberrant and rare chloroplast haplotype, northwest European individuals of Taraxacum section Naevosa are well suited for the detection of clonal lineages in which mutation has occurred. In the case of strictly clonal reproduction, nuclear genetic variability was expected to be hierarchically organized. Nucleotide polymorphisms in internal transcribed spacer (ITS) sequences, however, were incompatible with a clonal structure of the Norwegian individuals, probably due to persistent ancestral polymorphisms that pre-date the origin of the Naevosa clone. This interpretation is supported by the presence of ITS variants in section Naevosa that were also found in distantly related dandelions. In contrast to the ITS sequence data, amplified fragment length polymorphisms (AFLPs), isozymes and microsatellites strongly supported the contention of prolonged clonal reproduction and mutation accumulation in Norwegian Naevosa. Because these markers are generally considered to be more variable and more rapidly evolving than ITS sequences, mutations in these markers probably evolved after the origin of the clone. Within the Norwegian clone, a surprising number of markers distinguished the clone mates. As a consequence, incorporation of mutation in the detection of clone mates is anticipated to have a big impact on estimates of size, geographical range and age of clones as well as on experimental designs of studies of clonal plants.

Evolution of Hypervariable Microsatellites in Apomictic Polyploid Lineages of Ranunculus carpaticola: Directional Bias at Dinucleotide Loci

“…Due to the high levels of polymorphism, two microsatellite loci were sufficient to detect divergent ''clone mates'' (Mes et al 2002) within the apomictic R. carpaticola lineages identified by isozymes and AFLPs (Hö randl and Greilhuber 2002; Paun et al 2006a), with almost as many multilocus genotypes as individuals. This relates to the high mutation rate at microsatellite loci (10 À2 -10 À6 ; Schlö tterer 2000).…”

Retrotransposon Sequence Variation in Four Asexual Plant Species

“…In Europe, the source of the North American populations, sexual dandelions are common. By focusing on a particularly conspic-uous section of Taraxacum in Norway, Mes et al (2002) were able to detect genetically divergent clone mates, suggesting that Taraxacum populations are quite capable of persisting for thousands of generations. However, most European asexual Taraxacum lineages are probably quite young (Menken et al 1995;van Dijk 2003).…”

The Potential for Evolutionary Responses to Cell‐Lineage Selection on Growth Form and Its Plasticity in a Red Seaweed

“…Although mosaicism at specific loci may be hidden or rare (!5%), phenotypic mosaics resulting from mutational effects on quantitative traits should be relatively widespread (Antolin and Strobeck 1985;Gill et al 1995). Accordingly, intraclonal genetic variation has been reported in seaweeds, fungi, and plants (Meneses et al 1999;Mes et al 2002;Sanders et al 2003), and it affects morphological, biochemical, and life-history traits in plants at frequencies as high as 19% (Gill et al 1995). Selection among mutant cell lineages that differ by phenotype may subsequently favor the spread of beneficial mutations and hinder that of deleterious ones, thereby purging the mutation load of clonal populations and shaping adaptive change in the absence of sex (Fagerström et al 1998;Otto and Hastings 1998).…”