Rapid Evolutionary Responses to Selection in Heterogeneous Environments among Agricultural and Nonagricultural Weeds

Agricultural settings are hypothesized to impose strong selection on invading weed species, and the direction of selection can be consistent across many generations, depending on crop‐rotation schedules. Because the history of selection is often known, agricultural environments provide a useful expe...

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Bibliographic Details
Published in:International journal of plant sciences 2005-07, Vol.166 (4), p.641-647
Main Author: Weinig, Cynthia
Format: Article
Language:English
Subjects:
Agricultural population
Botany
Corn
Crops
Evolution
Genotype & phenotype
Germination
Internodes
Phenotypic traits
Plant ecology
Plant populations
Planting
Plants
Weeds
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Summary:Agricultural settings are hypothesized to impose strong selection on invading weed species, and the direction of selection can be consistent across many generations, depending on crop‐rotation schedules. Because the history of selection is often known, agricultural environments provide a useful experimental setting for studies testing mechanisms of adaptation and rates of evolutionary response. Here, two populations ofAbutilon theophrastiwith known evolutionary histories of competing either in agricultural or nonagricultural settings were reciprocally transplanted across experimental treatments simulating the site of origin (rotating corn and soybean cultivation, local weeds, or no‐competition control). Consistent with hypotheses of local adaptation, the agricultural population had higher fitness than the nonagricultural population in the cornfield treatment. The nonagricultural population had higher fitness in the no‐competition control. Because weedy, nonagricultural sites are typically patchy and consist of both high‐ and low‐density (i.e., noncompetitive) microsites, the observed population differences in fitness in the no‐competition control also indicate local adaptation. In addition to fitness, the two populations differed in the expression of life‐history traits such that the life‐history of the agricultural population was accelerated relative to the nonagricultural population. The observed life‐history differences probably reflect adaptive synchronization of life‐history events to the shorter growth season duration of agricultural relative to nonagricultural sites. Because the two experimental populations have histories of only 10–50 yr in the site of origin, the results provide evidence of rapid differentiation.
ISSN:1058-5893
1537-5315
DOI:10.1086/429853