Limits...
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.

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

Principle coordinate analysis of V.filiformis using Nei&Li[57]similarity distances.A. Discrimination based on geographic region and crossing group. B. Discrimination based on genetic cluster. Colors for native populations correspond to the geographic distribution in Figure A and to genetic clusters identified during the STRUCTURE analyses of the AFLP experiment in part B. Samples left of the double dashed line are introduced populations, whereas those to the right are native populations. Colors for introduced populations correspond to crossing groups identified during the crossing experiments in part A and to genetic clusters identified in the STRUCTURE analyses of the AFLP experiment in part B. Black circles are individuals without crossing data from the Großaitingen population in part A and unclassified sample from the STRUCTURE analyses of the AFLP experiment (Mü) in part B. The dotted line corresponds to separate clusters highly supported (see Results for details). Hw = Hohenwittlingen; Tl = Tübingen Lustnau; Mü = Münsingen; Mt = Mehrstetten.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3539859&req=5

Figure 4: Principle coordinate analysis of V.filiformis using Nei&Li[57]similarity distances.A. Discrimination based on geographic region and crossing group. B. Discrimination based on genetic cluster. Colors for native populations correspond to the geographic distribution in Figure A and to genetic clusters identified during the STRUCTURE analyses of the AFLP experiment in part B. Samples left of the double dashed line are introduced populations, whereas those to the right are native populations. Colors for introduced populations correspond to crossing groups identified during the crossing experiments in part A and to genetic clusters identified in the STRUCTURE analyses of the AFLP experiment in part B. Black circles are individuals without crossing data from the Großaitingen population in part A and unclassified sample from the STRUCTURE analyses of the AFLP experiment (Mü) in part B. The dotted line corresponds to separate clusters highly supported (see Results for details). Hw = Hohenwittlingen; Tl = Tübingen Lustnau; Mü = Münsingen; Mt = Mehrstetten.

Mentions: The PCoA based on standard similarity distances allowed the visual differentiation of clusters in our data set in three axes (x, y, z) accounting for 28.80% of the molecular variability (12.92%, 9.34%, 6.54%; Figure4). Based on the PCoA coordinates, the native populations were separated easily from the introduced ones (Mann–Whitney-U-test: U = 28.8, p-value < 0.0001; Figure4A). Within the introduced area, the groups of individuals based on the crossing experiment results (Figure4A) can be compared with the genetic clusters of the STRUCTURE analysis in Figure4B. Populations Mü and Mt belonged to different crossing groups (pink and violet groups, respectively, Figure2) but cannot be distinguished from each other in the AFLP-analysis (p-value > 0.05; Figure4A). The same is true for the samples belonging to the blue and green crossing groups (p-value > 0.05; Figure4A). On the other hand, the individuals of the Hohenwittlingen (Hw) population are significantly distant to the remaining individuals belonging to the green crossing group (U = 10.84, p-value < 0.001; Figure4A). Moreover, the samples of the Gß population belonged to three different genetic clusters (Pink, Red and Blue; Figure4B compared to Figure4A) but cannot be statistically differentiated (Red/Pink: U = 7.35, p-value = 0.0067 but with Red/Blue: U = 2.53, p-value =0.1110; Pink/Blue: U = 0.011, p-value = 0.917;Figure4B).


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

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

Principle coordinate analysis of V.filiformis using Nei&Li[57]similarity distances.A. Discrimination based on geographic region and crossing group. B. Discrimination based on genetic cluster. Colors for native populations correspond to the geographic distribution in Figure A and to genetic clusters identified during the STRUCTURE analyses of the AFLP experiment in part B. Samples left of the double dashed line are introduced populations, whereas those to the right are native populations. Colors for introduced populations correspond to crossing groups identified during the crossing experiments in part A and to genetic clusters identified in the STRUCTURE analyses of the AFLP experiment in part B. Black circles are individuals without crossing data from the Großaitingen population in part A and unclassified sample from the STRUCTURE analyses of the AFLP experiment (Mü) in part B. The dotted line corresponds to separate clusters highly supported (see Results for details). Hw = Hohenwittlingen; Tl = Tübingen Lustnau; Mü = Münsingen; Mt = Mehrstetten.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Principle coordinate analysis of V.filiformis using Nei&Li[57]similarity distances.A. Discrimination based on geographic region and crossing group. B. Discrimination based on genetic cluster. Colors for native populations correspond to the geographic distribution in Figure A and to genetic clusters identified during the STRUCTURE analyses of the AFLP experiment in part B. Samples left of the double dashed line are introduced populations, whereas those to the right are native populations. Colors for introduced populations correspond to crossing groups identified during the crossing experiments in part A and to genetic clusters identified in the STRUCTURE analyses of the AFLP experiment in part B. Black circles are individuals without crossing data from the Großaitingen population in part A and unclassified sample from the STRUCTURE analyses of the AFLP experiment (Mü) in part B. The dotted line corresponds to separate clusters highly supported (see Results for details). Hw = Hohenwittlingen; Tl = Tübingen Lustnau; Mü = Münsingen; Mt = Mehrstetten.
Mentions: The PCoA based on standard similarity distances allowed the visual differentiation of clusters in our data set in three axes (x, y, z) accounting for 28.80% of the molecular variability (12.92%, 9.34%, 6.54%; Figure4). Based on the PCoA coordinates, the native populations were separated easily from the introduced ones (Mann–Whitney-U-test: U = 28.8, p-value < 0.0001; Figure4A). Within the introduced area, the groups of individuals based on the crossing experiment results (Figure4A) can be compared with the genetic clusters of the STRUCTURE analysis in Figure4B. Populations Mü and Mt belonged to different crossing groups (pink and violet groups, respectively, Figure2) but cannot be distinguished from each other in the AFLP-analysis (p-value > 0.05; Figure4A). The same is true for the samples belonging to the blue and green crossing groups (p-value > 0.05; Figure4A). On the other hand, the individuals of the Hohenwittlingen (Hw) population are significantly distant to the remaining individuals belonging to the green crossing group (U = 10.84, p-value < 0.001; Figure4A). Moreover, the samples of the Gß population belonged to three different genetic clusters (Pink, Red and Blue; Figure4B compared to Figure4A) but cannot be statistically differentiated (Red/Pink: U = 7.35, p-value = 0.0067 but with Red/Blue: U = 2.53, p-value =0.1110; Pink/Blue: U = 0.011, p-value = 0.917;Figure4B).

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