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Abstract
In this study we investigated the hypothesis that the pattern of allometric gender allocation in Ambrosia artemisiifolia (common ragweed) will vary depending on the type of environmental variation causing variation in size and on the measure of size. We predicted that variation in size measured as height resulting from variation in neighbour effects (light availability), will generate allometric gender allocation consistent with the pollen dispersal hypothesis, whereas variation in size measured as biomass resulting from variation in soil resources or defoliation intensity, will generate allometric gender allocation consistent with the size advantage hypothesis. Field and greenhouse experiments were conducted to produce a range of plant sizes in response to a gradient of neighbour effects, light availability, soil resource availability or defoliation intensity. Only the pollen dispersal hypothesis is supported. (Abstract shortened by UMI.)
