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Assessing the benefits and risks of translocations in depauperate species: a theoretical framework with an empirical validation

Citation

Furlan, Elise et al. (2020), Assessing the benefits and risks of translocations in depauperate species: a theoretical framework with an empirical validation, Dryad, Dataset, https://doi.org/10.5061/dryad.rv15dv44x

Abstract

1. Conservation translocations are becoming more common to assist in the management of threatened native species. While many translocation programs focus on maximizing survival in newly established populations, consideration is also required for the persistence of source populations. 2. Here, we present and test a theoretical framework that assesses the translocation trade-off between increasing a species probability of survival and decreasing a species’ overall genetic diversity. We anticipate that i) the genetic diversity of translocated populations will be reduced compared to the source due to a failure to capture and retain genetic diversity, and ii) the genetic diversity of the source population will decline due to the removal of founder individuals. 3. We test this framework with an empirical study of redfin blue eye, Scaturiginichthys vermeilipinnis; a critically endangered fish species which has undergone several replicate translocations, established with founders sourced from a single remnant population. Several generations after reintroduction, we show that the predicted survival of the species has improved as a result of these translocations. 4. While the species’ genetic diversity has been retained across all populations combined (translocated and source), we show that genetic diversity in each individual population (including the source) is reduced compared to the source population prior to translocation. 5. Synthesis and applications. Conservation translocations can provide great benefits to species survival, enabling extinction risk to be spread across multiple populations. Translocated populations, however, often harbour reduced genetic diversity compared to source populations and initiating translocated populations can decrease the genetic diversity of source populations, placing them at an increased risk of extinction. The framework presented here enables the trade-off between extinction risk and retention of genetic diversity to be established. This will enable the optimal conservation strategy to be employed to increase the long-term persistence and evolutionary potential of a species.

Methods

Samples were collected from six populations of redfin blue eye in 1990, 2010 and 2014 (including the source population, four translocated populations and one now extinct population). Fish were randomly sampled from across the available habitat in each individual spring. DNA from samples collected in 1990 and 2010 were extracted using a salting out method (Sunnucks & Hales, 1996) while 2014 samples were extracted by Diversity Arrays Technologies (DArT Pty Ltd, Canberra, Australia) as per Georges et al. (2018). Genome-wide data in the form of SNPs (single nucleotide polymorphisms) were generated for all samples by DArT Pty Ltd using the DArTseqTM method (see Supplementary Material). This resulted in 5,181 high quality SNPs, which formed the basis of the analyses.

Usage Notes

The data is in the format 0 = reference homozygous, 2 = alternate homozygous, 1 = heterozyous, and NA = missing SNP assignment.

This script writes to file the SNP genotypes with specimens as entities (columns) and loci as attributes (rows). Each row has associated locus metadata. Each column, with header of specimen id, has population in the first row. 

Funding

Bush Heritage Australia

the Royal Zoological Society of NSW

Desert Fishes Council