Eastern bettong (Bettongia gaimardi) reintroduced to Mulligan's Flat Woodland Sanctuary and Tidbinbilla Nature Reserve: DArT SNPs + individual information

Incorporating genetic data into conservation programmes improves
management outcomes, but the impact of different sample-grouping
methods on genetic diversity analyses is poorly
understood. To this end, the multi-source reintroduction of the eastern
bettong (Bettongia gaimardi) was used as a long-term case study
to investigate how sampling regimes may affect common
genetic metrics, and hence management decisions. The dataset
comprised 5307 SNPs sequenced across 263 individuals. Samples included 45
founders from five genetically
distinct Tasmanian source regions, and 218 of their
descendants captured during annual monitoring
at Mulligan’s Flat Woodland Sanctuary (MFWS; 121 samples
across eight generations), and Tidbinbilla Nature Reserve (TNR;
97 samples across nine generations). The most management-informative
sampling regime was found to be generational cohorts, providing
detailed long-term trends in genetic diversity. When
these generation-specific trends were not investigated, recent changes in
population genetics were masked, and it became apparent that
management recommendations would be less appropriate. The results
also illuminated the importance of considering establishment and
persistence as separate phases of a multi-source reintroduction. The
establishment phase (useful for informing early
adaptive management) should consist of no less
than two generations, and continue
until admixture is achieved (admixture defined here
as >80% of individuals
possessing >60% of source genotypes, with no one
source composing >70% of >20% individuals’
genotype) is achieved.
This ensures that the persistence phase analyses of population trends remain minimally biased. Based on this case study, we recommend that emphasis be given to the value of generationally specific analyses, and that conservation programmes collect DNA samples throughout the establishment and persistence phases, and avoid collecting genetic samples only when analysis is imminent. We also recommend that population genetic analyses for multi-source reintroductions consider whether admixture has been achieved when calculating descriptive genetic metrics.