You are not currently logged in.
Access JSTOR through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Population Structure and Local Selection in Impatiens pallida (Balsaminaceae), A Selfing Annual
Douglas W. Schemske
Vol. 38, No. 4 (Jul., 1984), pp. 817-832
Published by: Society for the Study of Evolution
Stable URL: http://www.jstor.org/stable/2408393
Page Count: 16
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
Population structure in a predominantly self-pollinating annual, Impatiens pallida (Balsaminaceae), was investigated at two localities, Allerton and Brownfield, in central Illinois, USA. A hierarchical ANOVA based on 19 quantitative characters measured for 60 families at each locality indicated significant genetic differentiation between transects (3 transects/locality, 32-50 m apart) and among-families within transects (20 families/transect). Discriminant function analysis conducted on family means indicated complete multivariate discrimination between transects. Among-family variance, calculated by transect, was significant for virtually all characters at both localities and was heterogenous across transects for a number of characters. These results demonstrate that inbreeding populations can maintain significant genetic variation, with local differences in the magnitude of variation. Reciprocal seed-transplant experiments demonstrated local adaptation at Brownfield, but not Allerton. Differential fitness of Brownfield transplants was due to variation in post-germination survivorship to reproduction. Striking local differences in survivorship at Brownfield have resulted in spatial variation in selection pressures, and life-history evolution. Catastrophic mortality caused by a specialist herbivore in the Brownfield forest interior has promoted the evolution of early reproduction in forest plants, as compared to neighboring, herbivore-free sites. A significant negative regression of seed production on flowering time for seedling transplants at a Brownfield forest transect indicated the potential for local selection. These results illustrate that the population structure of inbreeding plant species is a complex function of ecological and genetic factors.
Evolution © 1984 Society for the Study of Evolution