Ecological Archives A024-068-A2

Katherine M. Marchetto, Katriona Shea, Dave Kelly, Ronny Groenteman, Zeynep Sezen, Eelke Jongejans. 2014. Unrecognized impact of a biocontrol agent on the spread rate of an invasive thistle. Ecological Applications 24:1178–1187.

Appendix B. Median Carduus nutans seed dispersal distances.


Fig. B1. Median projected C. nutans seed dispersal distances (m) for (A) the United States population and (B) the New Zealand population. Medians were calculated by drawing 10,000 simulated dispersal distances from the WALD model and changing a proportion of these values to zero, representing the proportion of seeds expected to be caught in capitula under a certain average number of R. conicus cysts per capitulum. The vertical lines indicate the average number of cysts per capitulum in (A) the US population and (B) the NZ population (7.0 in the US and 2.5 in NZ). Interestingly, failure of a proportion of seeds to release from the parent plant can have a large effect on median dispersal distances, but has virtually no effect on spread rates (Fig. 2). This may be because reducing the proportion of seeds that disperse does not change the shape of the tail of the dispersal kernel. Whether or not there is the potential for some seeds to disperse long distances is more important for spread than having a proportion of seeds stay near the parent plant.

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