DOI: 10.5061/dryad.7bj60
title: Data from: Dearth of polymorphism associated with a sustained response to selection for flowering time in maize

description: Background: Long term selection experiments bring unique insights on the
 genetic architecture of quantitative traits and their evolvability.
 Indeed, they are utilized to (i) monitor changes in allele frequencies and
 assess the effects of genomic regions involved traits determinism; (ii)
 evaluate the role of standing variation versus new mutations during
 adaptation; (iii) investigate the contribution of non allelic
 interactions. Here we describe genetic and phenotypic evolution of two
 independent Divergent Selection Experiments (DSEs) for flowering time
 conducted during 16 years from two early maize inbred lines. Results: Our
 experimental design uses selfing as the mating system and small population
 sizes, so that two independent families evolved within each population,
 Late and Early. Observed patterns are strikingly similar between the two
 DSEs. We observed a significant response to selection in both directions
 during the first 7 generations of selection. Within Early families, the
 response is linear through 16 generations, consistent with the maintenance
 of genetic variance. Within Late families and despite maintenance of
 significant genetic variation across 17 generations, the response to
 selection reached a plateau after 7 generations. This plateau is likely
 caused by physiological limits. Residual heterozygosity in the initial
 inbreds can partly explain the observed responses as evidenced by 42
 markers derived from both Methyl-Sensitive Amplification- and Amplified
 Fragment Length- Polymorphisms. Among the 42, a subset of 13 markers most
 of which are in high linkage disequilibrium, display a strong association
 with flowering time variation. Their fast fixation throughout DSEs’
 pedigrees results in strong genetic differentiation between populations
 and families. Conclusions: Our results reveal a paradox between the
 sustainability of the response to selection and the associated dearth of
 polymorphisms. Among other hypotheses, we discuss the maintenance of
 heritable variation by few mutations with strong epistatic interactions
 whose effects are modified by continuous changes of the genetic background
 through time.
description: Flowering time Records
 in the F252 DSECompilation of field
 notations for flowering time realized between 1997 (generation G1) and
 2014 (generation G18) in the F252 DSE. Columns description in the Read.me
 filesdpreco_STcor_F252.csvFlowering time Records in the MBS DSECompilation of field notations for flowering time realized between 1997 (generation G1) and 2014 (generation G18) in the MBS DSE. Columns description are in the Read.me filesdpreco_STcor_MBS.csvPedigrees from the F252 DSEPedigree of the progenitors since generation G0 (1993) in the F252 DSE.sdpreco_PEDIGREE_F252.csvPedigrees from the MBS DSEPedigree of the progenitors since generation G0 (1993) of the MBS DSE.sdpreco_PEDIGREE_MBS.csvDescription of the AFLP/MSAP systemsDescription of the AFLP/MSAP systems used for genotyping the F252 and MBS DSEs between Generations G0 and G6.AFLP_markers_description.csvraw AFLP/MSAP data for the F252 DSERaw AFLP/MSAP data recorded on each progenitor of the F252 DSE between generations G0 and G6.sdpreco_AFLP_F252.csvraw AFLP/MSAP data for the MBS DSERaw AFLP/MSAP data recorded on each progenitor of the MBS DSE between generations G0 and G6.sdpreco_AFLP_MBS.csv