Modeling Demographics and Genetic Diversity in Ex Situ Collections during Seed Storage and Regeneration

Gene banks have a critical role in preserving genetic diversity for many conservation uses. A key challenge in this task is maintaining both the genetic integrity and the viability of a collection during regeneration and long-term storage. In this study we examine the interacting effects of sampling and viability decline from seed aging on genetic diversity. To do this, we developed a model that simulates sampling during regeneration of individual genotypes using two commonly used but contrasting regeneration protocols. Critically, the model simulates a realistic nonlinear decline in viability across time, and the combined effects of sampling and mortality were evaluated for their effect on allelic diversity. In addition, the model was used to contrast the kinetics of allelic richness among rounds of regeneration in accessions with different heterozygosity levels (e.g., cultivars vs. wild) and different breeding systems (outcrossing vs. inbred). Results underscore a significant interaction between regeneration timing and regeneration size. Regeneration procedures should consider viability kinetics and intra-accession diversity to best manage genetic erosion. These changes highlight the trade-off faced by curators between the logistics of increasing regeneration sampling size and improving the technical procedures for seed storage and monitoring.