Could grouping animals by generation reveal genetic changes that conservation monitoring would otherwise miss?

Details

Incorporating genetic data into conservation programmes improves management outcomes, but how different ways of grouping samples affect genetic diversity analyses is poorly understood.

Researchers used the multi-source reintroduction of the eastern bettong (Bettongia gaimardi) as a long-term case study to investigate how sampling regimes may affect common genetic metrics and, in turn, management decisions.

The dataset comprised 5307 single-nucleotide polymorphisms (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. Monitoring took place at Mulligan’s Flat Woodland Sanctuary, with 121 samples across eight generations, and Tidbinbilla Nature Reserve, with 97 samples across nine generations.

Grouping samples into generational cohorts was the most management-informative sampling regime, providing detailed long-term trends in genetic diversity.

When these generation-specific trends were not investigated, recent changes in population genetics were masked, and management recommendations would have been less appropriate.

The results also highlighted the importance of treating establishment and persistence as separate phases of a multi-source reintroduction.

The establishment phase, which can inform early adaptive management, should last no fewer than two generations and continue until admixture is achieved. Here, admixture was defined as >80% of individuals possessing >60% of source genotypes, with no single source composing >70% of the genotype of >20% of individuals.

This separation ensures that analyses of population trends during the persistence phase remain minimally biased.

Based on this case study, the researchers recommend emphasizing generation-specific analyses and collecting DNA samples throughout both the establishment and persistence phases, rather than collecting genetic samples only when analysis is imminent.

They also recommend that population genetic analyses of multi-source reintroductions consider whether admixture has been achieved when calculating descriptive genetic metrics.