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

Seed variation between seeds collected in the native area and those produced from German plants of V.filiformis. A. Seed size (width). B. Seed viability test. C. Seed germination test. Significance level: * = P ≤ 0.05, ** = P ≤ 0.01 and *** = P ≤ 0.001; 1 graduation = 0.12 mm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Seed variation between seeds collected in the native area and those produced from German plants of V.filiformis. A. Seed size (width). B. Seed viability test. C. Seed germination test. Significance level: * = P ≤ 0.05, ** = P ≤ 0.01 and *** = P ≤ 0.001; 1 graduation = 0.12 mm.

Mentions: Capsules produced in the greenhouse after hand-pollination contained more seeds than capsules collected in the field after open-pollination (Kruskal-Wallis-test: H = 5.064; p-value = 0.024; Additional file6). Variation in seed number per capsule was also found between the native and introduced area and within the introduced area between populations, crossing groups and genetic clusters (Additional file6). Seeds from the introduced area were also smaller than seeds of the native area (Figure5A; Kruskal-Wallis-test: H = 88.053; p-value < 0.001). Significant differences were found between Georgian populations for seed size (H = 169.202; p-value < 0.001; Additional file6). In the REML analysis for seed number, area and population were the most important factors as indicated by AIC and BIC (699.66, 719.61 respectively), which means that the number of seeds per capsule is different between areas and between populations. For seed size using the mean width of seeds per capsule, the model with area and number of seeds per fruit as fixed factors and population as random factor proved to be the best (AIC −172.69; BIC −156.51). The next best model had an AIC difference of 2 and included more parameters, and was thus discarded[58]. For the introduced area alone, again, population had the strongest effect (AIC −60.99; BIC −50.61), whereas crossing group and genetic group were less important. The model was again better for the above mentioned criteria. For seed number the model with area and population was also the best (AIC 699.66; BIC 719.61).


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

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

Seed variation between seeds collected in the native area and those produced from German plants of V.filiformis. A. Seed size (width). B. Seed viability test. C. Seed germination test. Significance level: * = P ≤ 0.05, ** = P ≤ 0.01 and *** = P ≤ 0.001; 1 graduation = 0.12 mm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Seed variation between seeds collected in the native area and those produced from German plants of V.filiformis. A. Seed size (width). B. Seed viability test. C. Seed germination test. Significance level: * = P ≤ 0.05, ** = P ≤ 0.01 and *** = P ≤ 0.001; 1 graduation = 0.12 mm.
Mentions: Capsules produced in the greenhouse after hand-pollination contained more seeds than capsules collected in the field after open-pollination (Kruskal-Wallis-test: H = 5.064; p-value = 0.024; Additional file6). Variation in seed number per capsule was also found between the native and introduced area and within the introduced area between populations, crossing groups and genetic clusters (Additional file6). Seeds from the introduced area were also smaller than seeds of the native area (Figure5A; Kruskal-Wallis-test: H = 88.053; p-value < 0.001). Significant differences were found between Georgian populations for seed size (H = 169.202; p-value < 0.001; Additional file6). In the REML analysis for seed number, area and population were the most important factors as indicated by AIC and BIC (699.66, 719.61 respectively), which means that the number of seeds per capsule is different between areas and between populations. For seed size using the mean width of seeds per capsule, the model with area and number of seeds per fruit as fixed factors and population as random factor proved to be the best (AIC −172.69; BIC −156.51). The next best model had an AIC difference of 2 and included more parameters, and was thus discarded[58]. For the introduced area alone, again, population had the strongest effect (AIC −60.99; BIC −50.61), whereas crossing group and genetic group were less important. The model was again better for the above mentioned criteria. For seed number the model with area and population was also the best (AIC 699.66; BIC 719.61).

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