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Degradation of sexual reproduction in Veronica filiformis after introduction to Europe.

Scalone R, Albach DC - BMC Evol. Biol. (2012)

Bottom Line: These results were similar to intrapopulation crossings, but this depended on the populations used for crossings.Results from AFLP fingerprinting confirmed a lack of genetic diversity in the area of introduction, which is best explained by the dispersal of clones.This came at the cost of an accumulation of phenotypically observable mutations in reproductive characters, i.e. Muller's ratchet.

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Affiliation: Institut für Spezielle Botanik und Botanischer Garten, Johannes Gutenberg-Universität Mainz, Bentzelweg 9, Mainz 55099, Germany.

ABSTRACT

Background: Baker's law predicts that self-incompatible plant species are generally poor colonizers because their mating system requires a high diversity of genetically differentiated individuals and thus self-compatibility should develop after long-distance dispersal. However, cases like the introduction of the self-incompatible Veronica filiformis (Plantaginaceae) to Europe constitute an often overlooked alternative to this rule. This species was introduced from subalpine areas of the Pontic-Caucasian Mountains and colonized many parts of Central and Western Europe in the last century, apparently without producing seeds. To investigate the consequences of the absence of sexual reproduction in this obligate outcrosser since its introduction, AFLP fingerprints, flower morphology, pollen and ovule production and seed vitality were studied in introduced and native populations.

Results: Interpopulation crossings of 19 introduced German populations performed in the greenhouse demonstrated that introduced populations are often unable to reproduce sexually. These results were similar to intrapopulation crossings, but this depended on the populations used for crossings. Results from AFLP fingerprinting confirmed a lack of genetic diversity in the area of introduction, which is best explained by the dispersal of clones. Flower morphology revealed the frequent presence of mutations affecting the androecium of the flower and decreasing pollen production in introduced populations. The seeds produced in our experiments were smaller, had a lower germination rate and had lower viability than seeds from the native area.

Conclusions: Taken together, our results demonstrate that V. filiformis was able to spread by vegetative means in the absence of sexual reproduction. This came at the cost of an accumulation of phenotypically observable mutations in reproductive characters, i.e. Muller's ratchet.

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Distribution of V. filiformis in the native (green zone) and introduced (red zone) areas. The red points correspond to the introduced populations of V. filiformis mentioned in the references given in the introduction. The orange and green crosses correspond to the populations used during this study from the introduced and the native areas, respectively. Bk = Bakuriani (Samtskhe-Javakhéti region), Bo = Bonn (North Rhine-Westphalia), Bt = Batumi (Adjara region), Kz = Kazbegi (Kazbegi region), Lg = Lagodekhi (Kakheti region), Mz = Mainz (Rhineland-Palatinate), T-U-A = transect Tübingen-Ulm-Augsburg, (Baden-Württemberg and Bavaria), UzT = Uzungöl-Trabzon (Trabzon province).
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Figure 1: Distribution of V. filiformis in the native (green zone) and introduced (red zone) areas. The red points correspond to the introduced populations of V. filiformis mentioned in the references given in the introduction. The orange and green crosses correspond to the populations used during this study from the introduced and the native areas, respectively. Bk = Bakuriani (Samtskhe-Javakhéti region), Bo = Bonn (North Rhine-Westphalia), Bt = Batumi (Adjara region), Kz = Kazbegi (Kazbegi region), Lg = Lagodekhi (Kakheti region), Mz = Mainz (Rhineland-Palatinate), T-U-A = transect Tübingen-Ulm-Augsburg, (Baden-Württemberg and Bavaria), UzT = Uzungöl-Trabzon (Trabzon province).

Mentions: One model to address these questions is the Pontic-Anatolian-Caucasian Veronica filiformis (Figure1), an obligate self-incompatible (SI) and perennial species[39-41]. The first European records of V. filiformis came from Great Britain (1780, 1838) but it was not recorded again there until 1927[42,43]. In mainland Europe, the first record (1893, Marseille, southern France) is associated with plants being packed around the roots of vine shoots imported from Georgia[44]. From that time, the history of introduction in the rest of Europe through horticultural trade is fairly well-known starting in Switzerland (1903), other parts of France (1904), Germany (Tübingen 1909; München 1923; Ulm 1936, Augsburg 1939), Great Britain, Austria, the Netherlands and then other regions of Europe[40,43-45] Figure1. Most European populations of this species are described as sterile since no seed production was observed in the introduced area[39,42].


Degradation of sexual reproduction in Veronica filiformis after introduction to Europe.

Scalone R, Albach DC - BMC Evol. Biol. (2012)

Distribution of V. filiformis in the native (green zone) and introduced (red zone) areas. The red points correspond to the introduced populations of V. filiformis mentioned in the references given in the introduction. The orange and green crosses correspond to the populations used during this study from the introduced and the native areas, respectively. Bk = Bakuriani (Samtskhe-Javakhéti region), Bo = Bonn (North Rhine-Westphalia), Bt = Batumi (Adjara region), Kz = Kazbegi (Kazbegi region), Lg = Lagodekhi (Kakheti region), Mz = Mainz (Rhineland-Palatinate), T-U-A = transect Tübingen-Ulm-Augsburg, (Baden-Württemberg and Bavaria), UzT = Uzungöl-Trabzon (Trabzon province).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3539859&req=5

Figure 1: Distribution of V. filiformis in the native (green zone) and introduced (red zone) areas. The red points correspond to the introduced populations of V. filiformis mentioned in the references given in the introduction. The orange and green crosses correspond to the populations used during this study from the introduced and the native areas, respectively. Bk = Bakuriani (Samtskhe-Javakhéti region), Bo = Bonn (North Rhine-Westphalia), Bt = Batumi (Adjara region), Kz = Kazbegi (Kazbegi region), Lg = Lagodekhi (Kakheti region), Mz = Mainz (Rhineland-Palatinate), T-U-A = transect Tübingen-Ulm-Augsburg, (Baden-Württemberg and Bavaria), UzT = Uzungöl-Trabzon (Trabzon province).
Mentions: One model to address these questions is the Pontic-Anatolian-Caucasian Veronica filiformis (Figure1), an obligate self-incompatible (SI) and perennial species[39-41]. The first European records of V. filiformis came from Great Britain (1780, 1838) but it was not recorded again there until 1927[42,43]. In mainland Europe, the first record (1893, Marseille, southern France) is associated with plants being packed around the roots of vine shoots imported from Georgia[44]. From that time, the history of introduction in the rest of Europe through horticultural trade is fairly well-known starting in Switzerland (1903), other parts of France (1904), Germany (Tübingen 1909; München 1923; Ulm 1936, Augsburg 1939), Great Britain, Austria, the Netherlands and then other regions of Europe[40,43-45] Figure1. Most European populations of this species are described as sterile since no seed production was observed in the introduced area[39,42].

Bottom Line: These results were similar to intrapopulation crossings, but this depended on the populations used for crossings.Results from AFLP fingerprinting confirmed a lack of genetic diversity in the area of introduction, which is best explained by the dispersal of clones.This came at the cost of an accumulation of phenotypically observable mutations in reproductive characters, i.e. Muller's ratchet.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut für Spezielle Botanik und Botanischer Garten, Johannes Gutenberg-Universität Mainz, Bentzelweg 9, Mainz 55099, Germany.

ABSTRACT

Background: Baker's law predicts that self-incompatible plant species are generally poor colonizers because their mating system requires a high diversity of genetically differentiated individuals and thus self-compatibility should develop after long-distance dispersal. However, cases like the introduction of the self-incompatible Veronica filiformis (Plantaginaceae) to Europe constitute an often overlooked alternative to this rule. This species was introduced from subalpine areas of the Pontic-Caucasian Mountains and colonized many parts of Central and Western Europe in the last century, apparently without producing seeds. To investigate the consequences of the absence of sexual reproduction in this obligate outcrosser since its introduction, AFLP fingerprints, flower morphology, pollen and ovule production and seed vitality were studied in introduced and native populations.

Results: Interpopulation crossings of 19 introduced German populations performed in the greenhouse demonstrated that introduced populations are often unable to reproduce sexually. These results were similar to intrapopulation crossings, but this depended on the populations used for crossings. Results from AFLP fingerprinting confirmed a lack of genetic diversity in the area of introduction, which is best explained by the dispersal of clones. Flower morphology revealed the frequent presence of mutations affecting the androecium of the flower and decreasing pollen production in introduced populations. The seeds produced in our experiments were smaller, had a lower germination rate and had lower viability than seeds from the native area.

Conclusions: Taken together, our results demonstrate that V. filiformis was able to spread by vegetative means in the absence of sexual reproduction. This came at the cost of an accumulation of phenotypically observable mutations in reproductive characters, i.e. Muller's ratchet.

Show MeSH
Related in: MedlinePlus