Selfing and biparental inbreeding: a mating system analysis in Lymnaea peregra (Gastropoda: Lymnaeidae)

Abstract

The mating system was analysed in three populations of Lymnaea peregra, under the mixed-mating model (MMM) and the effective selfing model (ESM), using progeny array data and allozyme markers. The results revealed variation among populations for the outcrossing rate (tm ranged from 0.646 to 0.983). This finding modifies the earlier classification of L. peregra as a predominantly outcrossing species. The occurrence of biparental inbreeding and population substructure in one of three populations was suggested from positive (tm—ts) under the MMM, covariation of the effective selfing rate with parental fixation index, as well as the great difference between the effective selfing rate of inbred and outbred parents under the ESM. The within-population distribution of the outcrossing rates varied extensively and may involve different patterns of selection and levels of inbreeding depression among the populations studied. Consistently, the estimation of correlated matings showed different levels of the correlation of selfing within progenies in the three populations. Levels of multiple paternity for the outcrossed progeny were positively associated with higher population outcrossing rates, which may reflect the propensity of preferential outcrossers to copulate actively.