Is Plant Fitness Proportional to Seed Set? An Experiment and a Spatial Model
AffiliationUniv Arizona, Sch Nat Resources & Environm
MetadataShow full item record
PublisherUNIV CHICAGO PRESS
CitationIs Plant Fitness Proportional to Seed Set? An Experiment and a Spatial Model 2017, 190 (6):818 The American Naturalist
JournalThe American Naturalist
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AbstractIndividual differences in fecundity often serve as proxies for differences in overall fitness, especially when it is difficult to track the fate of an individual's offspring to reproductive maturity. Using fecundity may be biased, however, if density-dependent interactions between siblings affect survival and reproduction of offspring from high- and low-fecundity parents differently. To test for such density-dependent effects in plants, we sowed seeds of the wildflower Ipomopsis aggregata (scarlet gilia) to mimic partially overlapping seed shadows of pairs of plants, one of which produced twice as many seeds. We tested for differences in offspring success using a genetic marker to track offspring to flowering multiple years later. Without density dependence, the high-fecundity parent should produce twice as many surviving offspring. We also developed a model that considered the geometry of seed shadows and assumed limited survivors so that the number of juvenile recruits is proportional to the area. Rather than a ratio of 2:1 offspring success from high- versus low-fecundity parents, our model predicted a ratio of 1.42:1, which would translate into weaker selection. Empirical ratios of juvenile offspring and of flowers produced conformed well to the model's prediction. Extending the model shows how spatial relationships of parents and seed dispersal patterns modify inferences about relative fitness based solely on fecundity.
Note12 month embargo; Published online: 27 Sept 2017
VersionFinal published version
SponsorsNational Science Foundation [DEB-9805034]