Constructing linkage maps with achiasmatic gametogenesis.

Maximum likelihood (ML) approach is used for estimating recombination frequency based on the achiasmatic model and the corresponding software package is developed for constructing linkage maps for achiasmatic organisms (F2 populations). The detection of sex-linked markers is done through a chi-square test. Monte Carlo simulations were conducted for comparing estimation of recombination frequency and mapping powers between these two genetic models (chiasmatic and achiasmatic models) when the achiasmata occurs. Simulation results showed that the achiasmatic model could provide unbiased estimations, while the chiasmatic model (without correction) gave under-estimates. The powers of grouping and ordering by the achiasmatic model were greater than those by the chiasmatic model (without correction) for all cases. ML approach based on the achiasmatic model can be used without correcting the data to obtain desirable linkage map powers in achiasmatic organisms.