Parentage analysis of conservation translocations in the endangered, self-incompatible shrub Pseudoziziphus celata reveals reproductive constraints, variable survival and a case for genetics-driven conservation

BACKGROUND: Conservation translocations of imperiled plants with high genetic diversity are more viable, but the genetic composition of such populations is often unknown. Pseudoziziphus celata, a rare shrub native to central Florida, experiences mate limitation due to clonality, self-incompatibility, and few mating types. An ex situ collection containing cross-compatible genotypes produced seedlings used for 12 translocations. This study examined factors affecting the genetic composition of these translocations, including: 1) reproductive dynamics of the ex situ collection, including variation in the contribution of parent pairs and differences in parental roles among genotypes, 2) whether full-sib groups varied in survival, and 3) how using genetic data to design translocations affected genetic diversity and genotypic composition. METHODS: We genotyped 1,120 translocated individuals at 12 microsatellites and identified their parents and which genotypes served as maternal vs. paternal parents. We analyzed the relative contribution of parent pairs, the survival time of full-sib groups, the contribution of genotypes as maternal vs. paternal parents, and compared genetic diversity and full-sib group representation in translocations that differed in whether genetic data was used in its design. KEY RESULTS: Only six reproductive genotypes in the ex situ collection served as parents. Parental pairs exhibited variable reproductive output and survival times. All six genotypes served as maternal parents, but only two were paternal parents for 90% of seedlings. Translocations designed using genetic data contained more full-sib groups in more equal proportions, but genetic diversity did not vary. CONCLUSIONS: Limited parental contributors, uneven reproductive output, and variable survival negatively affected the genetic composition of translocations, but designing translocations with genetic data resulted in more even representation of more full-sib groups. To increase genotypic diversity and reduce potential inbreeding, future management should include hand pollinations and augmentations with underrepresented genotypes. The study highlights how incorporating genetic data improves conservation translocations.