Testing a pollen-parent fecundity distribution model on seed-parent fecundity distributions in bee-pollinated forage legume polycrosses

Authors: Riday, Heathcliffe; Peel, Michael

Submitted to: Eucarpia Fodder Crops and Amenity Grasses Section Symposium
Publication Type: Proceedings
Publication Acceptance Date: 12/1/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary: Recently a model was developed that predicts pollen-parent fertility distributions (i.e., pollen-parent pollination success) based on number of individuals in a group of mating individuals. In this study, observed seed-parent fertility distributions (i.e., seed-parent seed production) were compared to the pollen-parent fertility distribution model predictions. In almost all cases a very good fit was observed. This study shows that the recently developed pollen-parent fertility distribution prediction model can be used to predict seed-parent fertility distributions as well. The recently developed model could therefore potentially be incorporated into quantitative genetic models and simulations that currently utilize a panmixis, or random matting, assumption for their seed-parent fertility distributions. These improved models and simulations will help scientists more realistically model plant mating in plant breeding programs and in natural settings.

Technical Abstract: Random mating (i.e., panmixis) is a fundamental assumption in quantitative genetics. In outcrossing bee-pollinated perennial forage legume polycrosses, mating is assumed by default to follow theoretical random mating. This assumption informs breeders of expected inbreeding estimates based on polycross size. In examining forage legume pollen-parent fecundity distributions, it is obvious that the pollen-parent fecundity distribution is not uniform (i.e., panmixis expectation). Using an empirical approach, a Weibull distribution-based model has been developed to accurately predict a polycross’ pollen-parent fecundity distribution depending only on polycross size. In this study we wanted to determine if this pollen-parent fecundity distribution model was able to predict seed-parent fecundity distributions in bee-pollinated forage legume polycrosses of varying sizes. We found that the pollen-parent fecundity distribution model worked very well in predicting observed seed-parent fecundity distributions with R-sq. for eight polycrosses tested ranging from 0.83 to 0.99. A poor fit was observed for a ninth polycross tested (R-sq. = 0.30). Preliminarily we attributed this poor fit to the fact that parent plants in this polycross were clonally replicated. Using the Weibull-based model, both expected pollen-parent and seed-parent fecundity distributions can be predicted for forage legume polycrosses knowing only polycross size. This model should allow breeders to estimate more realistic inbreeding expectations based on polycross size.