Plant reintroductions typically start from a limited genetic base. When that genetic base is known, an opportunity to quantify genetic erosion and test the genetic consequences of small founding population size through generations in a natural experiment is enabled. The Corrigin Grevillea, G. scapigera, has been the focus of a sustained recovery program for over 25 years. Translocation trials were first established in 1996 with what were thought to be equal numbers of 10 genets, ramets of which were propagated by tissue culture. Subsequent plantings occurred in following years, largely from seed harvested at this site. Flowering and natural seed set has been very high in all years, and some natural recruitment occurred in most years. In 1998, 2007, 2012 and 2021 we genotyped plants and a sample of their seed to assess genetic fidelity and genetic erosion over multiple generations.
Following establishment, we found that eight genets, not ten, were present, that 54% of all plants were a single genotype, and the F1's were on average 22% more inbred than their parents. The genetic consequences of this initial dramatic erosion on descendents 20 years later will be presented. A positive association between survivorship and increasing genetic dissimilarity of parents of seedlings indicates inbreeding depression associated with genetic erosion. Our results highlight that rapid genetic erosion may be a feature of many small, translocated populations, which may ultimately threaten their long-term survival. Strategies to prevent genetic decline in rare species translocations are discussed.