3.4 Evident local adaptation detected in the early-season WR
populations
Evident local adaptation (LA) in the early-season WR populations was
detected in the native early rice-cultivation environment (Table 2),
based on the method recommended by Hereford (2009). For example, the
average level of LA was 0.15 for plant height and 0.14 for reproductive
traits. Generally, the positive values of LA indicate local adaptation
for traits, but the early flowering was regarded as an adaptive trait in
this study. Therefore, the negative value of -0.04 also indicated local
adaptation for flowering time in the early-season WR populations.
However, no such evident local adaptation was detected in the
late-season WR populations in the native late rice-cultivation season
(Table S7). These results indicated that ecological environment such as
temperature and daylength played an important role in local adaptation
of weedy rice (Figure 7).
In addition, the LA for plant height was stronger in population CDE
(e.g., 0.32) and DCE (e.g., 0.21) than that in HJE (e.g., 0.14), as well
as flowering time (Table 2). This result suggested more pronounced local
adaptation of the early-season WR populations in CDE/L and DCE/L
population pairs, likely associated with population histories of WR
infesting cultivated rice field at different periods of times.
Furthermore, the evident local adaptation for the number of seeds per
plant and seed setting ratio were detected in all early-season WR
populations, and it indicated that the local adaptation in the early
rice-cultivation season may be conducive to the reproductive traits of
the early-season WR populations.