Estimates of the rate of adaptive evolution in four wild populations of Nemophila menziesii
- 1University of California, Santa Barbara
Abstract
Populations that have detectable additive genetic variance for fitness (VA(W)) have the capacity for increase in their mean fitness through natural selection. The extent to which the magnitude of VA(W) in wild populations is predictive of the rate of adaptation is not well known, because few empirical field-based studies have been designed to address this question. Here, we report a two-year field experiment with pedigreed seeds embedded in four natural populations of the annual wildflower Baby Blue Eyes (Nemophila menziesii H. & A.), a species native to western North America. We first estimated VA(W) in a parental generation and then evaluated whether that estimate accurately predicted the adaptive response observed in the subsequent offspring generation grown under natural field conditions. We achieved this by directly comparing the mean fitnesses of the parental generation and their progeny grown under the same environmental conditions. We detected VA(W) and evidence of adaptation in all populations despite inter-annual differences in environmental conditions that directly affected fitness. Genotype-by-year interactions in fitness indicate that the fitness ranking of families differed between years, implying that the selective environment shifted over time. Additionally, although the environment in the second year reduced population mean fitness in three sites, the offspring generation maintained mean fitness at or above replacement, suggesting that adaptive evolution may have buffered the effects of environmental change. Overall, our results suggest that the four populations harbored sufficient VA(W) for adaptation through natural selection to the environmental conditions observed during the two years of this study.
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BibTeX
@misc{payne2026estimates,
title = {{Estimates of the rate of adaptive evolution in four wild populations of Nemophila menziesii}},
author = {H. Payne and D. Gamble and L. Kim and A. R. Peschel and S. J. Mazer},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.21.753227},
url = {https://www.biorxiv.org/content/10.64898/2026.09.21.753227v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Estimates of the rate of adaptive evolution in four wild populations of Nemophila menziesii
AU - H. Payne
AU - D. Gamble
AU - L. Kim
AU - A. R. Peschel
AU - S. J. Mazer
PY - 2026
DA - 2026/09/21
PB - bioRxiv
DO - 10.64898/2026.09.21.753227
UR - https://www.biorxiv.org/content/10.64898/2026.09.21.753227v1
AB - Populations that have detectable additive genetic variance for fitness (VA(W)) have the capacity for increase in their mean fitness through natural selection. The extent to which the magnitude of VA(W) in wild populations is predictive of the rate of adaptation is not well known, because few empirical field-based studies have been designed to address this question. Here, we report a two-year field experiment with pedigreed seeds embedded in four natural populations of the annual wildflower Baby Blue Eyes (Nemophila menziesii H. & A.), a species native to western North America. We first estimated VA(W) in a parental generation and then evaluated whether that estimate accurately predicted the adaptive response observed in the subsequent offspring generation grown under natural field conditions. We achieved this by directly comparing the mean fitnesses of the parental generation and their progeny grown under the same environmental conditions. We detected VA(W) and evidence of adaptation in all populations despite inter-annual differences in environmental conditions that directly affected fitness. Genotype-by-year interactions in fitness indicate that the fitness ranking of families differed between years, implying that the selective environment shifted over time. Additionally, although the environment in the second year reduced population mean fitness in three sites, the offspring generation maintained mean fitness at or above replacement, suggesting that adaptive evolution may have buffered the effects of environmental change. Overall, our results suggest that the four populations harbored sufficient VA(W) for adaptation through natural selection to the environmental conditions observed during the two years of this study.
ER -