Based on the day of parturition, we pre-calculated litter emergence date for each female (assuming pups stayed in the burrow for 20 d until natal emergence).
A likely mechanism for growth depensation is size-based competitive interactions between larger, early emergers and smaller late emergers (Curry et al. 1995; Letcher et al. 2004), although an unpredictable environment for early emergers combined with small body size of late emergers should provide stabilizing selection on emergence date (e.g. Brannon 1987).
For example, we assume juvenile survivorship depends only on emergence date (i.e., no density-dependence), spawning behavior does not influence other traits, and genetic variance remains constant during adaptation.
Major QTL for flowering time overlapped with Prq1a, Praq1b, and Prq7 [ 5, 17], which could indicate a pleiotropic effect on flag emergence date and crown rust symptom development.
Based on the natal emergence date (i.e. when juveniles left the natal burrow for the first time), we defined three post-emergence intervals for each individual.
We observed a consistent cross type specific trend of a decrease in direct selection on early season leaf length corresponding with reduced total (direct and indirect) phenotypic selection (s) occurring on height and emergence date (Table 3).
Note that the emergence date we provide here is based on a small number of strains, all collected within the last 50 years, and so the confidence intervals are quite wide.
To follow up on anova results for emergence date, we performed failure-time analysis using Proc Lifetest and compared seedling emergence curves for each cross type using a log rank test.
One example of how management actions could have unanticipated and delayed effects on body size acting through emergence date is stream flow regulation.
Average emergence date was not influenced by the maternal cross type on which seeds were produced, which can be seen by the lack of mean separation between the F1 and F2 cross types for this trait (Fig. 2).
