SEED SET AND SEED MASS IN IPOMOPSIS AGGREGATA: VARIANCE PARTITIONING AND INFERENCES ABOUT POSTPOLLINATION SELECTION

Area of Science:

• Plant reproductive biology
• Evolutionary ecology
• Quantitative genetics

Background:

• Postpollination events like seed development are crucial for angiosperm reproduction.
• Differential success in these stages can indicate phenotypic selection or parent-offspring interactions.
• Diallel crossing designs are powerful tools for dissecting variance in reproductive success.

Purpose of the Study:

• To partition phenotypic variance in postpollination success in *Ipomopsis aggregata*.
• To investigate the roles of maternal effects, paternal effects, and parental interactions.
• To assess the influence of crossing distance on reproductive success.

Main Methods:

• Conducted three partial diallel crosses with 69 *Ipomopsis aggregata* individuals.
• Included crossing distance treatments (1 m, 10 m, 100 m) to vary genetic similarity.
• Utilized restricted maximum-likelihood (REML) analysis to partition variance in seed set and seed mass.

Main Results:

• Maternal effects (V_mat) accounted for 12%-35% of seed set variance and 62% of seed mass variance.
• No significant paternal variance (V_pat) was detected for seed set or mass.
• Parental interaction did not significantly contribute to phenotypic variance; crossing distance had minor effects.

Conclusions:

• Maternal effects are primary drivers of postpollination success in *I. aggregata*.
• Limited paternal variance suggests minimal opportunity for postpollination sexual selection via male function.
• Findings align with previous studies on natural plant populations regarding variance components.