Despite the importance of adaptation in shaping biological diversity over many generations, little is known about populations’ capacities to adapt at any particular time. Theory predicts that a population's rate of ongoing adaptation is the ratio of its additive genetic variance for fitness, (Formula presented.), to its mean absolute fitness, (Formula presented.). We conducted a transplant study to quantify (Formula presented.) and standing (Formula presented.) for a population of the annual legume Chamaecrista fasciculata in one field site from which we initially sampled it and another site where it does not currently occur naturally. We also examined genotype-by-environment interactions, G × E, as well as its components, differences between sites in (Formula presented.) and in rank of breeding values for fitness. The mean fitness indicated population persistence in both sites, and there was substantial (Formula presented.) for ongoing adaptation at both sites. Statistically significant G × E indicated that the adaptive process would differ between sites. We found a positive correlation between fitness of genotypes in the “home” and “away” environments, and G × E was more pronounced as the life-cycle proceeds. This study exemplifies an approach to assessing whether there is sufficient (Formula presented.) to support evolutionary rescue in populations that are declining.
Bibliographical noteFunding Information:
We are grateful to C. Geyer and F. Shaw for valuable input on statistical analyses. Amber Eule-Nashoba provided assistance in the lab and greenhouse, V. Eckhart contributed feedback during various stages of this project, and S. Weaver assisted with field censuses. Field work was supported by the Minnesota Department of Natural Resources and Friends of the Mississippi River. Associate editor, J. Anderson, and two anonymous reviewers provided insightful feedback on this manuscript. This work was funded by the National Science Foundation (DEB 1257462) to R.G.S. An NSF DBI-1523866 and USDA National Institute of Food and Agriculture Hatch project 1016272 supported SNS during the analysis and writing stages of this work.
- Chamaecrista fasciculata
- G × E
- aster models
- breeding values
- quantitative genetics