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Occurrence of an herbicide-resistant plant trait in agricultural field margins.

Gage KL, Gibson DJ, Young BG, Young JM, Matthews JL, Weller SC, Wilson RG - Ecol Evol (2015)

Bottom Line: We found that geographic location was an important factor in the occurrence of GR C. canadensis in field margins.Although not consistently associated with either glyphosate resistance or glyphosate susceptibility, there were differences in phenology, survivorship, and herbivory among biotypes of C. canadensis.We found equal or greater fitness in GR biotypes, compared to GS biotypes, and GR plants were present in field margins.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant, Soil, and Agricultural Systems Southern Illinois University Carbondale Illinois 62901 ; Department of Plant Biology Center for Ecology Southern Illinois University Carbondale Illinois 06460.

ABSTRACT
Agricultural environments allow study of evolutionary change in plants. An example of evolution within agroecological systems is the selection for resistance to the herbicide glyphosate within the weed, Conyza canadensis. Changes in survivorship and reproduction associated with the development of glyphosate resistance (GR) may impact fitness and influence the frequency of occurrence of the GR trait. We hypothesized that site characteristics and history would affect the occurrence of GR C. canadensis in field margins. We surveyed GR occurrence in field margins and asked whether there were correlations between GR occurrence and location, crop rotation, GR crop trait rotation, crop type, use of tillage, and the diversity of herbicides used. In a field experiment, we hypothesized that there would be no difference in fitness between GR and glyphosate-susceptible (GS) plants. We asked whether there were differences in survivorship, phenology, reproduction, and herbivory between 2 GR and 2 GS populations of C. canadensis in agrestal and ruderal habitats. We found that geographic location was an important factor in the occurrence of GR C. canadensis in field margins. Although not consistently associated with either glyphosate resistance or glyphosate susceptibility, there were differences in phenology, survivorship, and herbivory among biotypes of C. canadensis. We found equal or greater fitness in GR biotypes, compared to GS biotypes, and GR plants were present in field margins. Field margins or ruderal habitats may provide refugia for GR C. canadensis, allowing reproduction and further selection to occur as seeds recolonize the agrestal habitat. Agricultural practices may select for ecological changes that feed back into the evolution of plants in ruderal habitats.

No MeSH data available.


Related in: MedlinePlus

Comparison of reproductive measures of glyphostate‐resistant (GR) and glyphosate‐susceptible (GS) populations in the agrestal habitat: (A) Capitulae count by number of flowering individuals; number of individuals are GR1 = 3, GR2 = 10, GS1 = 11, GS2 = 6, (B) Capitulae count normalized by total number of individuals, N = 50, (C) Average number (N = 3) of seeds per capitulum per individual; number of individuals are GR1 = 3, GR2 = 9, GS1 = 10, GS2 = 5. Mean values with the same letter are not significantly different (α = 0.05). (D) Total number of seeds produced by population as a derived measure from total number of flowering plants × average number of capitulae per plant × average number of seeds per capitulum. Abbreviations for the four populations are: GR1 – GR population 1, GR2 – GR population 2, GS1 – GS population 1, GS2 – GS population 2.
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ece31667-fig-0004: Comparison of reproductive measures of glyphostate‐resistant (GR) and glyphosate‐susceptible (GS) populations in the agrestal habitat: (A) Capitulae count by number of flowering individuals; number of individuals are GR1 = 3, GR2 = 10, GS1 = 11, GS2 = 6, (B) Capitulae count normalized by total number of individuals, N = 50, (C) Average number (N = 3) of seeds per capitulum per individual; number of individuals are GR1 = 3, GR2 = 9, GS1 = 10, GS2 = 5. Mean values with the same letter are not significantly different (α = 0.05). (D) Total number of seeds produced by population as a derived measure from total number of flowering plants × average number of capitulae per plant × average number of seeds per capitulum. Abbreviations for the four populations are: GR1 – GR population 1, GR2 – GR population 2, GS1 – GS population 1, GS2 – GS population 2.

Mentions: None of the reproductive measures were significantly different between populations in the ruderal habitat, possibly because of the low number of plants reaching reproductive maturity (number of individuals: GR1 = 3, GR2 = 5, GS1 = 2, GS2 = 2) (Table S4). Of the plants that reached the flowering stage, the GR biotype, GR1, had the highest capitulae count in the agrestal habitat, although not significantly different from GR2 (Fig. 4A). However, once capitulae production was normalized by the total number of plants in each population, including those that did not reproduce, GR2 had almost 1000 more capitulae per plant than GR1 (Fig. 4B). Population GS1 produced among the lowest capitulae counts and the lowest number of seeds per capitulum (Fig. 4C) of all the populations in the agrestal habitat. Although two GS1 plants reached the reproductive stage in the ruderal habitat, no mature capitulae were produced. There was no difference in weight per seed by population in either habitat (agrestal: N = 26, mean = 0.053 mg ± SE 0.002; ruderal: N = 10, mean = 0.021 mg ± 0.008). The result with the greatest implications was produced by calculating the total number of seeds produced by population. The GR2 population produced over 300,000 seeds more than any of the other populations in the agrestal habitat (Fig. 4D).


Occurrence of an herbicide-resistant plant trait in agricultural field margins.

Gage KL, Gibson DJ, Young BG, Young JM, Matthews JL, Weller SC, Wilson RG - Ecol Evol (2015)

Comparison of reproductive measures of glyphostate‐resistant (GR) and glyphosate‐susceptible (GS) populations in the agrestal habitat: (A) Capitulae count by number of flowering individuals; number of individuals are GR1 = 3, GR2 = 10, GS1 = 11, GS2 = 6, (B) Capitulae count normalized by total number of individuals, N = 50, (C) Average number (N = 3) of seeds per capitulum per individual; number of individuals are GR1 = 3, GR2 = 9, GS1 = 10, GS2 = 5. Mean values with the same letter are not significantly different (α = 0.05). (D) Total number of seeds produced by population as a derived measure from total number of flowering plants × average number of capitulae per plant × average number of seeds per capitulum. Abbreviations for the four populations are: GR1 – GR population 1, GR2 – GR population 2, GS1 – GS population 1, GS2 – GS population 2.
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Related In: Results  -  Collection

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ece31667-fig-0004: Comparison of reproductive measures of glyphostate‐resistant (GR) and glyphosate‐susceptible (GS) populations in the agrestal habitat: (A) Capitulae count by number of flowering individuals; number of individuals are GR1 = 3, GR2 = 10, GS1 = 11, GS2 = 6, (B) Capitulae count normalized by total number of individuals, N = 50, (C) Average number (N = 3) of seeds per capitulum per individual; number of individuals are GR1 = 3, GR2 = 9, GS1 = 10, GS2 = 5. Mean values with the same letter are not significantly different (α = 0.05). (D) Total number of seeds produced by population as a derived measure from total number of flowering plants × average number of capitulae per plant × average number of seeds per capitulum. Abbreviations for the four populations are: GR1 – GR population 1, GR2 – GR population 2, GS1 – GS population 1, GS2 – GS population 2.
Mentions: None of the reproductive measures were significantly different between populations in the ruderal habitat, possibly because of the low number of plants reaching reproductive maturity (number of individuals: GR1 = 3, GR2 = 5, GS1 = 2, GS2 = 2) (Table S4). Of the plants that reached the flowering stage, the GR biotype, GR1, had the highest capitulae count in the agrestal habitat, although not significantly different from GR2 (Fig. 4A). However, once capitulae production was normalized by the total number of plants in each population, including those that did not reproduce, GR2 had almost 1000 more capitulae per plant than GR1 (Fig. 4B). Population GS1 produced among the lowest capitulae counts and the lowest number of seeds per capitulum (Fig. 4C) of all the populations in the agrestal habitat. Although two GS1 plants reached the reproductive stage in the ruderal habitat, no mature capitulae were produced. There was no difference in weight per seed by population in either habitat (agrestal: N = 26, mean = 0.053 mg ± SE 0.002; ruderal: N = 10, mean = 0.021 mg ± 0.008). The result with the greatest implications was produced by calculating the total number of seeds produced by population. The GR2 population produced over 300,000 seeds more than any of the other populations in the agrestal habitat (Fig. 4D).

Bottom Line: We found that geographic location was an important factor in the occurrence of GR C. canadensis in field margins.Although not consistently associated with either glyphosate resistance or glyphosate susceptibility, there were differences in phenology, survivorship, and herbivory among biotypes of C. canadensis.We found equal or greater fitness in GR biotypes, compared to GS biotypes, and GR plants were present in field margins.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant, Soil, and Agricultural Systems Southern Illinois University Carbondale Illinois 62901 ; Department of Plant Biology Center for Ecology Southern Illinois University Carbondale Illinois 06460.

ABSTRACT
Agricultural environments allow study of evolutionary change in plants. An example of evolution within agroecological systems is the selection for resistance to the herbicide glyphosate within the weed, Conyza canadensis. Changes in survivorship and reproduction associated with the development of glyphosate resistance (GR) may impact fitness and influence the frequency of occurrence of the GR trait. We hypothesized that site characteristics and history would affect the occurrence of GR C. canadensis in field margins. We surveyed GR occurrence in field margins and asked whether there were correlations between GR occurrence and location, crop rotation, GR crop trait rotation, crop type, use of tillage, and the diversity of herbicides used. In a field experiment, we hypothesized that there would be no difference in fitness between GR and glyphosate-susceptible (GS) plants. We asked whether there were differences in survivorship, phenology, reproduction, and herbivory between 2 GR and 2 GS populations of C. canadensis in agrestal and ruderal habitats. We found that geographic location was an important factor in the occurrence of GR C. canadensis in field margins. Although not consistently associated with either glyphosate resistance or glyphosate susceptibility, there were differences in phenology, survivorship, and herbivory among biotypes of C. canadensis. We found equal or greater fitness in GR biotypes, compared to GS biotypes, and GR plants were present in field margins. Field margins or ruderal habitats may provide refugia for GR C. canadensis, allowing reproduction and further selection to occur as seeds recolonize the agrestal habitat. Agricultural practices may select for ecological changes that feed back into the evolution of plants in ruderal habitats.

No MeSH data available.


Related in: MedlinePlus