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The geographic mosaic of herbicide resistance evolution in the common morning glory, Ipomoea purpurea: Evidence for resistance hotspots and low genetic differentiation across the landscape.

Kuester A, Chang SM, Baucom RS - Evol Appl (2015)

Bottom Line: We uncovered a mosaic pattern of resistance across the landscape, with some populations exhibiting high-survival postherbicide and other populations showing high death.SSR genotyping revealed little evidence of isolation by distance and very little neutral genetic structure associated with geography.An approximate Bayesian computation (ABC) analysis uncovered evidence for migration and admixture among populations before the widespread use of glyphosate rather than the very recent contemporary gene flow.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology and Evolutionary Biology, 830 North University, University of Michigan Ann Arbor, MI, USA.

ABSTRACT
Strong human-mediated selection via herbicide application in agroecosystems has repeatedly led to the evolution of resistance in weedy plants. Although resistance can occur among separate populations of a species across the landscape, the spatial scale of resistance in many weeds is often left unexamined. We assessed the potential that resistance to the herbicide glyphosate in the agricultural weed Ipomoea purpurea has evolved independently multiple times across its North American range. We examined both adaptive and neutral genetic variations in 44 populations of I. purpurea by pairing a replicated dose-response greenhouse experiment with SSR genotyping of experimental individuals. We uncovered a mosaic pattern of resistance across the landscape, with some populations exhibiting high-survival postherbicide and other populations showing high death. SSR genotyping revealed little evidence of isolation by distance and very little neutral genetic structure associated with geography. An approximate Bayesian computation (ABC) analysis uncovered evidence for migration and admixture among populations before the widespread use of glyphosate rather than the very recent contemporary gene flow. The pattern of adaptive and neutral genetic variations indicates that resistance in this mixed-mating weed species appears to have evolved in independent hotspots rather than through transmission of resistance alleles across the landscape.

No MeSH data available.


Related in: MedlinePlus

PCoA of pairwise differences in resistance values between populations at 1.7 kg a.i./ha. Populations are assigned to state (shape) and resistance level by color (red-blue gradient). Coordinate 1 explained 16.4%, and coordinate 2 explained 13.5% of the variation in survival. The dashed open circle represents the coordinate space representing all of the Midwestern US populations.
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fig04: PCoA of pairwise differences in resistance values between populations at 1.7 kg a.i./ha. Populations are assigned to state (shape) and resistance level by color (red-blue gradient). Coordinate 1 explained 16.4%, and coordinate 2 explained 13.5% of the variation in survival. The dashed open circle represents the coordinate space representing all of the Midwestern US populations.

Mentions: Although the species' ED50 value was very close to the recommended field dose, we found a significant effect of population of origin (χ2 = 145.34, P < 0.001) and state on survival (F5,8182 = 2.540; P = 0.030, Table 1), indicating the presence of geographic variation in the level of resistance. We found no effect of region, although we observed that northern sites tended to exhibit lower survival than southern populations at 1.7 and 3.4 kg a.i./ha (Figs 1A,B and 3A,B, respectively). The interaction between population and herbicide dose (Population × Treatment χ2 = 0.040; P = 0.980, Table 1) was not significant, suggesting that even though some populations exhibited higher survival then others, the populations responded in a relatively consistent manner to the different herbicide doses, namely increasing death at a higher herbicide application rate. There was significant spatial autocorrelation of resistance at distances at a local scale (within 40 miles, Moran's I = 0.829, P = 0.013), but we observed no isolation by geographic distance across all sampled populations in survival (R = 0.020, P = 0.269). The Southeastern USA exhibits greater diversity in the proportion survival per population than the Midwestern USA; although the most resistant populations do not, in general, cluster together in a PCoA (Fig. 4). An exception to this was the highly resistant TN populations, which tended to cluster together.


The geographic mosaic of herbicide resistance evolution in the common morning glory, Ipomoea purpurea: Evidence for resistance hotspots and low genetic differentiation across the landscape.

Kuester A, Chang SM, Baucom RS - Evol Appl (2015)

PCoA of pairwise differences in resistance values between populations at 1.7 kg a.i./ha. Populations are assigned to state (shape) and resistance level by color (red-blue gradient). Coordinate 1 explained 16.4%, and coordinate 2 explained 13.5% of the variation in survival. The dashed open circle represents the coordinate space representing all of the Midwestern US populations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4561571&req=5

fig04: PCoA of pairwise differences in resistance values between populations at 1.7 kg a.i./ha. Populations are assigned to state (shape) and resistance level by color (red-blue gradient). Coordinate 1 explained 16.4%, and coordinate 2 explained 13.5% of the variation in survival. The dashed open circle represents the coordinate space representing all of the Midwestern US populations.
Mentions: Although the species' ED50 value was very close to the recommended field dose, we found a significant effect of population of origin (χ2 = 145.34, P < 0.001) and state on survival (F5,8182 = 2.540; P = 0.030, Table 1), indicating the presence of geographic variation in the level of resistance. We found no effect of region, although we observed that northern sites tended to exhibit lower survival than southern populations at 1.7 and 3.4 kg a.i./ha (Figs 1A,B and 3A,B, respectively). The interaction between population and herbicide dose (Population × Treatment χ2 = 0.040; P = 0.980, Table 1) was not significant, suggesting that even though some populations exhibited higher survival then others, the populations responded in a relatively consistent manner to the different herbicide doses, namely increasing death at a higher herbicide application rate. There was significant spatial autocorrelation of resistance at distances at a local scale (within 40 miles, Moran's I = 0.829, P = 0.013), but we observed no isolation by geographic distance across all sampled populations in survival (R = 0.020, P = 0.269). The Southeastern USA exhibits greater diversity in the proportion survival per population than the Midwestern USA; although the most resistant populations do not, in general, cluster together in a PCoA (Fig. 4). An exception to this was the highly resistant TN populations, which tended to cluster together.

Bottom Line: We uncovered a mosaic pattern of resistance across the landscape, with some populations exhibiting high-survival postherbicide and other populations showing high death.SSR genotyping revealed little evidence of isolation by distance and very little neutral genetic structure associated with geography.An approximate Bayesian computation (ABC) analysis uncovered evidence for migration and admixture among populations before the widespread use of glyphosate rather than the very recent contemporary gene flow.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology and Evolutionary Biology, 830 North University, University of Michigan Ann Arbor, MI, USA.

ABSTRACT
Strong human-mediated selection via herbicide application in agroecosystems has repeatedly led to the evolution of resistance in weedy plants. Although resistance can occur among separate populations of a species across the landscape, the spatial scale of resistance in many weeds is often left unexamined. We assessed the potential that resistance to the herbicide glyphosate in the agricultural weed Ipomoea purpurea has evolved independently multiple times across its North American range. We examined both adaptive and neutral genetic variations in 44 populations of I. purpurea by pairing a replicated dose-response greenhouse experiment with SSR genotyping of experimental individuals. We uncovered a mosaic pattern of resistance across the landscape, with some populations exhibiting high-survival postherbicide and other populations showing high death. SSR genotyping revealed little evidence of isolation by distance and very little neutral genetic structure associated with geography. An approximate Bayesian computation (ABC) analysis uncovered evidence for migration and admixture among populations before the widespread use of glyphosate rather than the very recent contemporary gene flow. The pattern of adaptive and neutral genetic variations indicates that resistance in this mixed-mating weed species appears to have evolved in independent hotspots rather than through transmission of resistance alleles across the landscape.

No MeSH data available.


Related in: MedlinePlus