Understanding the evolutionary response of organisms to environmental gradients is important in light of increasing anthropogenic changes to our environment. In this study, we use ecological genetic tools to determine local adaptation of the model organism, Daphnia pulicaria, across a pH gradient in three North American lakes. We predicted that there would be genetic differentiation and local adaptation among the three populations of D. pulicaria. To assess the degree of genetic differentiation, we genotyped individual D. pulicaria using 15 microsatellite loci across the three populations and performed a STRUCTURE analysis corroborated with PCA based upon Nei’s genetic distance and multiple Fst comparisons. To test for signatures of local adaptation, a survivorship experiment across a pH gradient under common-garden conditions was performed. We determined that each of the three populations was genetically differentiated from one another, with Hill and Madison Lake populations of D. pulicaria being more similar to each other than that of the Frenchman Lake population. The results of the survivorship experiment showed a signal of local adaptation, with Frenchman Lake showing higher survivorship at lower pH [~6.5] when compared to Hill and Madison populations, while both Hill and Madison had higher survivorship at higher pH [7.9 and 8.6, respectively] when compared to the Frenchman population.
|Original language||English (US)|
|Number of pages||14|
|State||Published - Jan 1 2018|
Bibliographical noteFunding Information:
Acknowledgements This study was supported by the U.S. National Science Foundation (NSF-IOS-OEI) grant to L. J. Weider (#0924289 and #1256881), the U. of Oklahoma Department of Biology Adams Scholarship to B.W Culver, and the U. of Oklahoma Biological Station Summer Research Grant to B.W. Culver. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. We thank the U. of Minnesota LacCORE staff (in particular R. O’Grady) at the University of Minnesota, for assistance with coring and providing D. pulicaria samples from Madison Lake, MN. A. Harris, J. Medders, and F. Speer facilitated genotyping of D. pulicaria and R. Hartnett for logistical support with survivorship experiment. We thank K. Milette (McGill University) and M. Edlund (St. Croix River Watershed Station, MN) for providing Daphnia samples. We also thank L.J. Weider for his advice, mentorship, and comments on this manuscript. In addition, we thank R. Broughton, K.D. Hambright, I. Schlupp, R. Cichewicz, J. Beyer, T. Hallidayschult, B. Tweedy, P. Morton, and A. Yousey for their input. This manuscript constitutes a portion of BWC’s doctoral dissertation at the U. of Oklahoma. There are no known conflict of interests associated with this article and its authors.
© 2017, Springer International Publishing AG.
Copyright 2017 Elsevier B.V., All rights reserved.
- Ecological genetics
- Environmental stressors
- Local adaptation
- Population structure
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