Maternal effects and inbreeding depression in post-translocation progeny of Campanula glomerata.

Abstract

Evaluation of plant translocation success based on fitness-related quantitative traits combined with molecular markers may contribute to a finer assessment of inbreeding, selective and rescue processes, which might have long-term consequences for population dynamics and viability. We investigated fitness traits (seed germination, seedling viability, and juvenile growth and mortality) combined with 15 microsatellite loci of the first post-translocation seed progeny from two translocated populations of Campanula glomerata, an insect-pollinated, self-incompatible perennial herb. We examined whether inbreeding, heterosis through admixture, translocation site and maternal transplant seed source origin and lineage might affect seed quality and juvenile growth in controlled cultivation conditions. Flower production and seed germination of the transplants was higher in one of the two translocation sites, which might be related to differences in soil and vegetation composition and cover. Strong maternal effects related to seed source origin and lineage were found on progeny size, with the largest transplants producing the largest progeny. The differences in rosette diameter were maintained across the whole growth period measured. There was inbreeding depression (rather than heterosis) related to biparental inbreeding at the early progeny growth stage, also expressed through juvenile mortality. Our findings highlight that maternal transplant origin, especially when seed sources consisted of small, fragmented remnants, might have a selective value on fitness in the post-translocation generations. If maternal effects and inbreeding depression persist, they might affect global genetic diversity patterns in the long term. Further admixture in the next generations might buffer maternal and inbreeding effects or lead to outbreeding depression.