Dearth of polymorphism associated with a sustained response to selection for flowering time in maize

Table 1 Response to selection and variance components between generations G0 and G6

Family	df	Response	stde	p-value	R ²	Median(H ²)	Max(H ²)
FL1	330	16.04	1.20	0.00000	0.35	0.32	0.64
FL2	310	3.66	1.10	0.00104	0.03	0.01	0.30
ML1	226	8.89	1.51	0.00000	0.13	0.00	0.28
ML2	303	12.38	1.19	0.00000	0.26	0.17	0.44
ML3	171	7.68	2.05	0.00025	0.07	0.05	0.29
FE1	316	-8.47	0.82	0.00000	0.25	0.02	0.35
FE2	313	-6.04	0.80	0.00000	0.15	0.13	0.19
ME1	332	-11.22	1.14	0.00000	0.22	0.07	0.25
ME2	326	-10.32	1.17	0.00000	0.19	0.02	0.40
F-CONTROL	142	-0.39	1.49	0.80	0.00
M-CONTROL	137	-2.68	2.21	0.23	0.00

The response to selection was analyzed separately in each family from progenitor phenotypic data after correction for block and year effects. Response (degree-days per generation) is measured as the slope of the linear regression of flowering date (thermal time) on generations of selection (see Methods section). df is the number of degrees of freedom. Note that variation between families mainly denotes variations in the number of progenitors. stde is the standard error for the response, and R ² the adjusted R-squared of the regression model. Broad-sense heritability (H ²) was estimated at each generation as the ratio of the variance between progenitors belonging to the same family on the total phenotypic variance

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