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Temporal population genetic structure in the pollen pool for flowering time: A field experiment with Brassica rapa (Brassicaceae)
Author(s) -
Ison Jennifer L.,
Weis Arthur E.
Publication year - 2017
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.1700210
Subject(s) - biology , pollen , brassica rapa , genetic structure , brassicaceae , heritability , population , evolutionary biology , genetic variation , botany , brassica , genetics , gene , demography , sociology
PREMISE OF THE STUDY: Assortative mating by flowering time can cause temporal genetic structure in species with heritable flowering times. A strong temporal structure, when coupled with a seasonal shift in selection, may lead to adaptive temporal clines. We implemented a prospective and retrospective method to estimate the temporal genetic structure in the pollen pool of Brassica rapa . METHODS: The prospective method uses flowering schedules to estimate the seasonal shift in the pollen donors’ phenotype. By examining the offspring generation, we can get a direct estimate of temporal genetic structure, i.e., a retrospective estimate. However, this estimate is problematic because of the phenotypic correlation of the trait of interest, flowering time, between dam and sire. We developed a novel retrospective method that isolates flowering time by holding the maternal contribution constant and sampled the pollen pool in eight open‐pollinated field plots throughout the flowering season. KEY RESULTS: We found temporal genetic structure for flowering time in seven of the eight field plots. Interestingly, the direct (retrospective) temporal structure estimate was 35% larger than the prospective estimate based on flowering schedules. Spatial clumping of pollen donors did not affect temporal structure, but structure intensified when heritability was experimentally enhanced. CONCLUSIONS: Temporal genetic structure, especially for flowering time, likely occurs in many plant populations and may be underestimated using a prospective method. We discuss the genome‐wide consequences of temporal genetic structure and the potential for adaptive temporal clines in plant populations.